1.
Ketone bodies
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These ketone bodies are readily picked up by the extra-hepatic tissues, and converted into acetyl-CoA which then enters the citric acid cycle and is oxidized in the mitochondria for energy. In the brain, ketone bodies are used to make acetyl-CoA into long-chain fatty acids. Ketone bodies are produced by the liver under the circumstances listed above as a result of intense gluconeogenesis and they are therefore always released into the blood by the liver together with newly produced glucose, after the liver glycogen stores have been depleted. When two acetyl-CoA molecules lose their -CoAs, they can form a dimer called acetoacetate, beta-hydroxybutyrate is a reduced form of acetoacetate, in which the ketone group is converted into an alcohol group. Both are 4-carbon molecules, that can readily be converted back into acetyl-CoA by most tissues of the body, ketone bodies have a characteristic smell, which can easily be detected in the breath of persons in ketosis and ketoacidosis. It is often described as fruity or like nail polish remover, fats stored in adipose tissue are released from the fat cells into the blood as free fatty acids and glycerol when insulin levels are low and glucagon and epinephrine levels in the blood are high. This occurs between meals, during fasting, starvation and strenuous exercise, when glucose levels are likely to fall. Fatty acids are very high energy fuels, and are taken up by all metabolizing cells which have mitochondria and this is because fatty acids can only be metabolized in the mitochondria. Red blood cells do not contain mitochondria and are entirely dependent on glycolysis for their energy requirements. In all other tissues the fatty acids enter the metabolizing cells are combined with co-enzyme A to form acyl-CoA chains. These are transferred into the mitochondria of the cells, where they are broken down into units by a sequence of reactions known as β-oxidation. The acetyl-CoA produced by β-oxidation enters the citric acid cycle in the mitochondrion by combining with oxaloacetate to form citrate and this results in the complete combustion of the acetyl group of acetyl-CoA to CO2 and water. The energy released in this process is captured in the form of 1 GTP and 11 ATP molecules per acetyl group oxidized and this is the fate of acetyl-CoA wherever β-oxidation of fatty acids occurs, except under certain circumstances in the liver. Under these circumstances acetyl-CoA is diverted to the formation of acetoacetate and beta-hydroxybutyrate, acetoacetate, beta-hydroxybutyrate, and their spontaneous breakdown product, acetone, are frequently, but confusingly, known as ketone bodies. The ketone bodies are released by the liver into the blood, acetoacetate has a highly characteristic smell, for the people who can detect this smell, which occurs in the breath and urine during ketosis. On the other hand, most people can smell acetone, whose sweet & fruity odor also characterizes the breath of persons in ketosis or, especially, ketone bodies can be used as fuels, yielding 2 GTP and 22 ATP molecules per acetoacetate molecule when oxidized in the mitochondria. Ketone bodies are transported from the liver to other tissues, where acetoacetate and beta-hydroxybutyrate can be reconverted to acetyl-CoA to produce reducing equivalents, ketone bodies cannot be used as fuel by the liver, because the liver lacks the enzyme β-ketoacyl-CoA transferase, also called thiophorase. Acetone in low concentrations is taken up by the liver and undergoes detoxification through the pathway which ends with lactate
2.
Chemistry
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Chemistry is a branch of physical science that studies the composition, structure, properties and change of matter. Chemistry is sometimes called the science because it bridges other natural sciences, including physics. For the differences between chemistry and physics see comparison of chemistry and physics, the history of chemistry can be traced to alchemy, which had been practiced for several millennia in various parts of the world. The word chemistry comes from alchemy, which referred to a set of practices that encompassed elements of chemistry, metallurgy, philosophy, astrology, astronomy, mysticism. An alchemist was called a chemist in popular speech, and later the suffix -ry was added to this to describe the art of the chemist as chemistry, the modern word alchemy in turn is derived from the Arabic word al-kīmīā. In origin, the term is borrowed from the Greek χημία or χημεία and this may have Egyptian origins since al-kīmīā is derived from the Greek χημία, which is in turn derived from the word Chemi or Kimi, which is the ancient name of Egypt in Egyptian. Alternately, al-kīmīā may derive from χημεία, meaning cast together, in retrospect, the definition of chemistry has changed over time, as new discoveries and theories add to the functionality of the science. The term chymistry, in the view of noted scientist Robert Boyle in 1661, in 1837, Jean-Baptiste Dumas considered the word chemistry to refer to the science concerned with the laws and effects of molecular forces. More recently, in 1998, Professor Raymond Chang broadened the definition of chemistry to mean the study of matter, early civilizations, such as the Egyptians Babylonians, Indians amassed practical knowledge concerning the arts of metallurgy, pottery and dyes, but didnt develop a systematic theory. Greek atomism dates back to 440 BC, arising in works by such as Democritus and Epicurus. In 50 BC, the Roman philosopher Lucretius expanded upon the theory in his book De rerum natura, unlike modern concepts of science, Greek atomism was purely philosophical in nature, with little concern for empirical observations and no concern for chemical experiments. Work, particularly the development of distillation, continued in the early Byzantine period with the most famous practitioner being the 4th century Greek-Egyptian Zosimos of Panopolis. He formulated Boyles law, rejected the four elements and proposed a mechanistic alternative of atoms. Before his work, though, many important discoveries had been made, the Scottish chemist Joseph Black and the Dutchman J. B. English scientist John Dalton proposed the theory of atoms, that all substances are composed of indivisible atoms of matter. Davy discovered nine new elements including the alkali metals by extracting them from their oxides with electric current, british William Prout first proposed ordering all the elements by their atomic weight as all atoms had a weight that was an exact multiple of the atomic weight of hydrogen. The inert gases, later called the noble gases were discovered by William Ramsay in collaboration with Lord Rayleigh at the end of the century, thereby filling in the basic structure of the table. Organic chemistry was developed by Justus von Liebig and others, following Friedrich Wöhlers synthesis of urea which proved that organisms were, in theory
3.
Organic compound
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An organic compound is virtually any chemical compound that contains carbon, although a consensus definition remains elusive and likely arbitrary. Organic compounds are rare terrestrially, but of importance because all known life is based on organic compounds. The most basic petrochemicals are considered the building blocks of organic chemistry, for historical reasons discussed below, a few types of carbon-containing compounds, such as carbides, carbonates, simple oxides of carbon, and cyanides are considered inorganic. The distinction between organic and inorganic compounds, while useful in organizing the vast subject of chemistry. Organic chemistry is the science concerned with all aspects of organic compounds, Organic synthesis is the methodology of their preparation. The word organic is historical, dating to the 1st century, for many centuries, Western alchemists believed in vitalism. This is the theory that certain compounds could be synthesized only from their classical elements—earth, water, air, vitalism taught that these organic compounds were fundamentally different from the inorganic compounds that could be obtained from the elements by chemical manipulation. Vitalism survived for a while even after the rise of modern atomic theory and it first came under question in 1824, when Friedrich Wöhler synthesized oxalic acid, a compound known to occur only in living organisms, from cyanogen. A more decisive experiment was Wöhlers 1828 synthesis of urea from the inorganic salts potassium cyanate, urea had long been considered an organic compound, as it was known to occur only in the urine of living organisms. Wöhlers experiments were followed by others, in which increasingly complex organic substances were produced from inorganic ones without the involvement of any living organism. Even though vitalism has been discredited, scientific nomenclature retains the distinction between organic and inorganic compounds, still, even the broadest definition requires excluding alloys that contain carbon, including steel. The C-H definition excludes compounds that are considered organic, neither urea nor oxalic acid is organic by this definition, yet they were two key compounds in the vitalism debate. The IUPAC Blue Book on organic nomenclature specifically mentions urea and oxalic acid, other compounds lacking C-H bonds but traditionally considered organic include benzenehexol, mesoxalic acid, and carbon tetrachloride. Mellitic acid, which contains no C-H bonds, is considered an organic substance in Martian soil. The C-H bond-only rule also leads to somewhat arbitrary divisions in sets of carbon-fluorine compounds, for example, CF4 would be considered by this rule to be inorganic, whereas CF3H would be organic. Organic compounds may be classified in a variety of ways, one major distinction is between natural and synthetic compounds. Another distinction, based on the size of organic compounds, distinguishes between small molecules and polymers, natural compounds refer to those that are produced by plants or animals. Many of these are extracted from natural sources because they would be more expensive to produce artificially
4.
Aldehyde
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The group—without R—is the aldehyde group, also known as the formyl group. Aldehydes are common in organic chemistry, Aldehydes feature an sp2-hybridized, planar carbon center that is connected by a double bond to oxygen and a single bond to hydrogen. The C–H bond is not ordinarily acidic, because of resonance stabilization of the conjugate base, an α-hydrogen in an aldehyde is far more acidic, with a pKa near 15, compared to the acidity of a typical alkane. This acidification is attributed to the quality of the formyl center and the fact that the conjugate base. Related to, the group is somewhat polar. Aldehydes can exist in either the keto or the enol tautomer, keto-enol tautomerism is catalyzed by either acid or base. Usually the enol is the minority tautomer, but it is more reactive, the common names for aldehydes do not strictly follow official guidelines, such as those recommended by IUPAC, but these rules are useful. IUPAC prescribes the following nomenclature for aldehydes, Acyclic aliphatic aldehydes are named as derivatives of the longest carbon chain containing the aldehyde group, thus, HCHO is named as a derivative of methane, and CH3CH2CH2CHO is named as a derivative of butane. The name is formed by changing the suffix -e of the parent alkane to -al, so that HCHO is named methanal, in other cases, such as when a -CHO group is attached to a ring, the suffix -carbaldehyde may be used. Thus, C6H11CHO is known as cyclohexanecarbaldehyde, if the presence of another functional group demands the use of a suffix, the aldehyde group is named with the prefix formyl-. This prefix is preferred to methanoyl-, the word aldehyde was coined by Justus von Liebig as a contraction of the Latin alcohol dehydrogenatus. In the past, aldehydes were sometimes named after the corresponding alcohols, for example, the term formyl group is derived from the Latin word formica ant. This word can be recognized in the simplest aldehyde, formaldehyde, Aldehydes have properties that are diverse and that depend on the remainder of the molecule. Smaller aldehydes are more soluble in water, formaldehyde and acetaldehyde completely so, the volatile aldehydes have pungent odors. Aldehydes degrade in air via the process of autoxidation, the two aldehydes of greatest importance in industry, formaldehyde and acetaldehyde, have complicated behavior because of their tendency to oligomerize or polymerize. They also tend to hydrate, forming the geminal diol, the oligomers/polymers and the hydrates exist in equilibrium with the parent aldehyde. Aldehydes are readily identified by spectroscopic methods, using IR spectroscopy, they display a strong νCO band near 1700 cm−1. In their 1H NMR spectra, the formyl hydrogen center absorbs near δH =9 and this signal shows the characteristic coupling to any protons on the alpha carbon
5.
Carbonyl group
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In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom, C=O. It is common to several classes of compounds, as part of many larger functional groups. A compound containing a group is often referred to as a carbonyl compound. The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex, the remainder of this article concerns itself with the organic chemistry definition of carbonyl, where carbon and oxygen share a double bond. A carbonyl group characterizes the types of compounds, Note that the most specific labels are usually employed. For example, ROR structures are known as acid anhydride rather than the more generic ester, other organic carbonyls are urea and the carbamates, the derivatives of acyl chlorides chloroformates and phosgene, carbonate esters, thioesters, lactones, lactams, hydroxamates, and isocyanates. Examples of inorganic compounds are carbon dioxide and carbonyl sulfide. A special group of compounds are 1, 3-dicarbonyl compounds that have acidic protons in the central methylene unit. Examples are Meldrums acid, diethyl malonate and acetylacetone, because oxygen is more electronegative than carbon, carbonyl compounds often have resonance structures which affect their reactivity. This relative electronegativity draws electron density away from carbon, increasing the bonds polarity, carbon can then be attacked by nucleophiles or a negatively charged part of another molecule. During the reaction, the double bond is broken. This reaction is known as addition-elimination or condensation, the electronegative oxygen also can react with an electrophile, for example a proton in an acidic solution or with Lewis acids to form an oxocarbenium ion. The polarity of oxygen also makes the alpha hydrogens of carbonyl compounds much more acidic than typical sp3 C-H bonds, for example, the pKa values of acetaldehyde and acetone are 16.7 and 19 respectively, while the pKa value of methane is extrapolated to be approximately 50. This is because a carbonyl is in resonance with an enol. The deprotonation of the enol with a base produces an enolate. Amides are the most stable of the carbonyl couplings due to their high resonance stabilization between the nitrogen-carbon and carbon-oxygen bonds, carbonyl groups can be reduced by reaction with hydride reagents such as NaBH4 and LiAlH4, with bakers yeast, or by catalytic hydrogenation. Ketones give secondary alcohols while aldehydes, esters and carboxylic acids give primary alcohols, carbonyls can be alkylated in nucleophilic addition reactions using organometallic compounds such as organolithium reagents, Grignard reagents, or acetylides. Carbonyls also may be alkylated by enolates as in aldol reactions, carbonyls are also the prototypical groups with vinylogous reactivity
6.
Hydroxy group
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A hydroxy or hydroxyl group is the entity with the formula OH. It contains oxygen bonded to hydrogen, in organic chemistry, alcohol and carboxylic acids contain hydroxy groups. The anion, called hydroxide, consists of a hydroxy group, according to IUPAC rules, the term hydroxyl refers to the radical OH only, while the functional group −OH is called hydroxy group. Water, alcohols, carboxylic acids, and many other hydroxy-containing compounds can be deprotonated readily and this behavior is rationalized by the disparate electronegativities of oxygen and hydrogen. Hydroxy-containing compounds engage in hydrogen bonding, which causes them to stick together, organic compounds, which are often poorly soluble in water, become water soluble when they contain two or more hydroxy groups, as illustrated by sugars and amino acid. The hydroxy group is pervasive in chemistry and biochemistry, many inorganic compounds contain hydroxy groups, including sulfuric acid, the chemical compound produced on the largest scale industrially. Hydroxy groups participate in the reactions that link simple biological molecules into long chains. The joining of a fatty acid to glycerol to form a triacylglycerol removes the −OH from the end of the fatty acid. The joining of two aldehyde sugars to form a disaccharide removes the −OH from the group at the aldehyde end of one sugar. The creation of a bond to link two amino acids to make a protein removes the −OH from the carboxy group of one amino acid. Hydroxyl radicals are highly reactive and undergo chemical reactions that make them short-lived, when biological systems are exposed to hydroxyl radicals, they can cause damage to cells, including those in humans, where they react with DNA, lipids, and proteins. In 2009, Indias Chandrayaan-1 satellite, NASAs Cassini spacecraft and the Deep Impact probe have each detected the presence of water by evidence of hydroxyl fragments on the Moon. As reported by Richard Kerr, A spectrometer detected an infrared absorption at a wavelength of 3.0 micrometers that only water or hydroxyl—a hydrogen, NASA also reported in 2009 that the LCROSS probe revealed an ultraviolet emission spectrum consistent with hydroxyl presence. The Venus Express orbiter sent back Venus science data from April 2006 until December 2014, results from Venus Express include the detection of hydroxyl in the atmosphere. Hydronium Ion Oxide Reece, Jane, Urry, Lisa, Cain, Michael, Wasserman, Steven, Minorsky, Peter, Jackson, berge, Susan, Golden, Brandy, Triglia, Logan
7.
Chlorine
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Chlorine is a chemical element with symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the table and its properties are mostly intermediate between them. Chlorine is a gas at room temperature. It is an extremely reactive element and a strong oxidising agent, among the elements, it has the highest electron affinity, the most common compound of chlorine, sodium chloride, has been known since ancient times. Around 1630, chlorine gas was first synthesised in a chemical reaction, Carl Wilhelm Scheele wrote a description of chlorine gas in 1774, supposing it to be an oxide of a new element. In 1809, chemists suggested that the gas might be an element, and this was confirmed by Sir Humphry Davy in 1810. Because of its reactivity, all chlorine in the Earths crust is in the form of ionic chloride compounds. It is the second-most abundant halogen and twenty-first most abundant chemical element in Earths crust and these crustal deposits are nevertheless dwarfed by the huge reserves of chloride in seawater. Elemental chlorine is produced from brine by electrolysis. The high oxidising potential of chlorine led to the development of commercial bleaches and disinfectants. As a common disinfectant, elemental chlorine and chlorine-generating compounds are used directly in swimming pools to keep them clean. Elemental chlorine at high concentrations is extremely dangerous and poisonous for all living organisms, in the form of chloride ions, chlorine is necessary to all known species of life. Other types of compounds are rare in living organisms. In the upper atmosphere, chlorine-containing organic molecules such as chlorofluorocarbons have been implicated in ozone depletion, small quantities of elemental chlorine are generated by oxidation of chloride to hypochlorite in neutrophils as part of the immune response against bacteria. Its importance in food was very well known in antiquity and was sometimes used as payment for services for Roman generals. Around 1630, chlorine was recognized as a gas by the Flemish chemist, the element was first studied in detail in 1774 by Swedish chemist Carl Wilhelm Scheele, and he is credited with the discovery. He called it dephlogisticated muriatic acid air since it is a gas and he failed to establish chlorine as an element, mistakenly thinking that it was the oxide obtained from the hydrochloric acid. He named the new element within this oxide as muriaticum, in 1809, Joseph Louis Gay-Lussac and Louis-Jacques Thénard tried to decompose dephlogisticated muriatic acid air by reacting it with charcoal to release the free element muriaticum
8.
Carboxylic acid
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A carboxylic acid /ˌkɑːrbɒkˈsɪlɪk/ is an organic compound that contains a carboxyl group. The general formula of an acid is R–COOH, with R referring to the rest of the molecule. Carboxylic acids occur widely and include the amino acids and acetic acid, salts and esters of carboxylic acids are called carboxylates. When a carboxyl group is deprotonated, its conjugate base forms a carboxylate anion, carboxylate ions are resonance-stabilized, and this increased stability makes carboxylic acids more acidic than alcohols. Carboxylic acids can be seen as reduced or alkylated forms of the Lewis acid carbon dioxide, carboxylic acids are commonly identified using their trivial names, and usually have the suffix -ic acid. IUPAC-recommended names also exist, in system, carboxylic acids have an -oic acid suffix. For example, butyric acid is butanoic acid by IUPAC guidelines, the -oic acid nomenclature detail is based on the name of the previously-known chemical benzoic acid. Alternately, it can be named as a carboxy or carboxylic acid substituent on another parent structure, for example, 2-carboxyfuran. The carboxylate anion of an acid is usually named with the suffix -ate, in keeping with the general pattern of -ic acid and -ate for a conjugate acid and its conjugate base. For example, the base of acetic acid is acetate. The radical •COOH has only a fleeting existence. The acid dissociation constant of •COOH has been measured using electron paramagnetic resonance spectroscopy, the carboxyl group tends to dimerise to form oxalic acid. Because they are both hydrogen-bond acceptors and hydrogen-bond donors, they participate in hydrogen bonding. Together the hydroxyl and carbonyl group forms the functional group carboxyl, carboxylic acids usually exist as dimeric pairs in nonpolar media due to their tendency to self-associate. Smaller carboxylic acids are soluble in water, whereas higher carboxylic acids are less due to the increasing hydrophobic nature of the alkyl chain. These longer chain acids tend to be soluble in less-polar solvents such as ethers. Carboxylic acids tend to have higher boiling points than water, not only because of their surface area. Carboxylic acids tend to evaporate or boil as these dimers, for boiling to occur, either the dimer bonds must be broken or the entire dimer arrangement must be vaporised, both of which increase the enthalpy of vaporization requirements significantly
9.
Sugar
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Sugar is the generic name for sweet, soluble carbohydrates, many of which are used in food. There are various types of derived from different sources. Simple sugars are called monosaccharides and include glucose, fructose, the table sugar or granulated sugar most customarily used as food is sucrose, a disaccharide of glucose and fructose. Sugar is used in prepared foods and it is added to some foods, in the body, sucrose is hydrolysed into the simple sugars fructose and glucose. Other disaccharides include maltose from malted grain, and lactose from milk, longer chains of sugars are called oligosaccharides or polysaccharides. Some other chemical substances, such as glycerol may also have a sweet taste, low-calorie food substitutes for sugar, described as artificial sweeteners, include aspartame and sucralose, a chlorinated derivative of sucrose. Sugars are found in the tissues of most plants and are present in sufficient concentrations for efficient commercial extraction in sugarcane, the world production of sugar in 2011 was about 168 million tonnes. The average person consumes about 24 kilograms of sugar each year, equivalent to over 260 food calories per person, since the latter part of the twentieth century, it has been questioned whether a diet high in sugars, especially refined sugars, is good for human health. Sugar has been linked to obesity, and suspected of, or fully implicated as a cause in the occurrence of diabetes, cardiovascular disease, dementia, macular degeneration, the etymology reflects the spread of the commodity. The English word sugar ultimately originates from the Sanskrit शर्करा, via Arabic سكر as granular or candied sugar, the contemporary Italian word is zucchero, whereas the Spanish and Portuguese words, azúcar and açúcar, respectively, have kept a trace of the Arabic definite article. The Old French word is zuchre and the contemporary French, sucre, the earliest Greek word attested is σάκχαρις. The English word jaggery, a brown sugar made from date palm sap or sugarcane juice, has a similar etymological origin – Portuguese jagara from the Sanskrit शर्करा. Sugar has been produced in the Indian subcontinent since ancient times and it was not plentiful or cheap in early times and honey was more often used for sweetening in most parts of the world. Originally, people chewed raw sugarcane to extract its sweetness, sugarcane was a native of tropical South Asia and Southeast Asia. Different species seem to have originated from different locations with Saccharum barberi originating in India and S. edule, one of the earliest historical references to sugarcane is in Chinese manuscripts dating back to 8th century BC that state that the use of sugarcane originated in India. Sugar was found in Europe by the 1st century AD, but only as an imported medicine and it is a kind of honey found in cane, white as gum, and it crunches between the teeth. It comes in lumps the size of a hazelnut, sugar is used only for medical purposes. Sugar remained relatively unimportant until the Indians discovered methods of turning sugarcane juice into granulated crystals that were easier to store, crystallized sugar was discovered by the time of the Imperial Guptas, around the 5th century AD
10.
Ketose
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A ketose is a monosaccharide containing one ketone group per molecule. With three carbon atoms, dihydroxyacetone is the simplest of all ketoses and is the one having no optical activity. Ketoses can isomerize into an aldose when the group is located at the end of the molecule
11.
Alkane
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In organic chemistry, an alkane, or paraffin, is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a structure in which all the carbon-carbon bonds are single. Alkanes have the chemical formula CnH2n+2. The alkanes range in complexity from the simplest case of methane, CH4 where n =1, in an alkane, each carbon atom has 4 bonds, and each hydrogen atom is joined to one of the carbon atoms. The longest series of linked carbon atoms in a molecule is known as its skeleton or carbon backbone. The number of atoms may be thought of as the size of the alkane. One group of the alkanes are waxes, solids at standard ambient temperature and pressure. They can be viewed as molecular trees upon which can be hung the more functional groups of biological molecules. The alkanes have two main sources, petroleum and natural gas. Saturated hydrocarbons are hydrocarbons having only single covalent bonds between their carbons, according to the definition by IUPAC, the former two are alkanes, whereas the third group is called cycloalkanes. Saturated hydrocarbons can also combine any of the linear, cyclic and branching structures, the formula is CnH 2n−2k+2. Alkanes are the ones, corresponding to k =0. Alkanes with more than three carbon atoms can be arranged in different ways, forming structural isomers. The simplest isomer of an alkane is the one in which the atoms are arranged in a single chain with no branches. This isomer is called the n-isomer. However the chain of atoms may also be branched at one or more points. The number of possible isomers increases rapidly with the number of carbon atoms, for example, 3-methylhexane and its higher homologues are chiral due to their stereogenic center at carbon atom number 3. In addition to the alkane isomers, the chain of atoms may form one or more loops
12.
Benzophenone
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Benzophenone is the organic compound with the formula 2CO, generally abbreviated Ph2CO. Benzophenone is a used building block in organic chemistry, being the parent diarylketone. Benzophenone can be used as an initiator in UV-curing applications such as inks, imaging. Benzophenone prevents ultraviolet light from damaging scents and colors in such as perfumes. Benzophenone can also be added to plastic packaging as a UV blocker to prevent photo-degradation of the packaging polymers or its contents and its use allows manufacturers to package the product in clear glass or plastic. Without it, opaque or dark packaging would be required, in biological applications, benzophenones have been used extensively as photophysical probes to identify and map peptide–protein interactions. Benzophenone is produced by the oxidation of diphenylmethane with air. A laboratory route involves the reaction of benzene with carbon tetrachloride followed by hydrolysis of the resulting diphenyldichloromethane and it can also be prepared by Friedel-Crafts acylation of benzene with benzoyl chloride in the presence of a Lewis acid catalyst. Another route of synthesis is through a palladium/oxometalate catalyst and this converts an alcohol to a ketone with two groups on each side. Another, less well-known reaction to produce benzophenone is the pyrolysis of anhydrous calcium benzoate, benzophenone is a common photosensitizer in photochemistry. It crosses from the S1 state into the state with nearly 100% yield. The resulting diradical will abstract a hydrogen atom from a hydrogen donor to form a ketyl radical. Alkali metals reduce benzophenone to the blue colored radical anion, diphenylketyl. The ketyl is soluble in the solvent being dried, so it accelerates the reaction of the sodium with water. In comparison, sodium is insoluble, and its heterogeneous reaction is much slower, the use of benzophenone-derivatives which structurally resemble a strong photosensitizer has been strongly criticized. Its use in sunscreen has been known to cause coral bleaching via algae blooms, michlers ketone has dimethylamino substituents at each para position. The high-strength polymer PEEK is prepared from derivatives of benzophenone, benzophenone derivatives are known to be pharmacologically active. From a molecular point of view interaction of benzophenone with B-DNA has been demonstrated experimentally
13.
Carbon
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Carbon is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds, three isotopes occur naturally, 12C and 13C being stable, while 14C is a radioactive isotope, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity, Carbon is the 15th most abundant element in the Earths crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. It is the second most abundant element in the body by mass after oxygen. The atoms of carbon can bond together in different ways, termed allotropes of carbon, the best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form, for example, graphite is opaque and black while diamond is highly transparent. Graphite is soft enough to form a streak on paper, while diamond is the hardest naturally occurring material known, graphite is a good electrical conductor while diamond has a low electrical conductivity. Under normal conditions, diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials, all carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form. They are chemically resistant and require high temperature to react even with oxygen, the most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and transition metal carbonyl complexes. The largest sources of carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil. For this reason, carbon has often referred to as the king of the elements. The allotropes of carbon graphite, one of the softest known substances, and diamond. It bonds readily with other small atoms including other carbon atoms, Carbon is known to form almost ten million different compounds, a large majority of all chemical compounds. Carbon also has the highest sublimation point of all elements, although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper that are weaker reducing agents at room temperature. Carbon is the element, with a ground-state electron configuration of 1s22s22p2. Its first four ionisation energies,1086.5,2352.6,4620.5 and 6222.7 kJ/mol, are higher than those of the heavier group 14 elements. Carbons covalent radii are normally taken as 77.2 pm,66.7 pm and 60.3 pm, although these may vary depending on coordination number, in general, covalent radius decreases with lower coordination number and higher bond order. Carbon compounds form the basis of all life on Earth
14.
Hydrogen
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Hydrogen is a chemical element with chemical symbol H and atomic number 1. With a standard weight of circa 1.008, hydrogen is the lightest element on the periodic table. Its monatomic form is the most abundant chemical substance in the Universe, non-remnant stars are mainly composed of hydrogen in the plasma state. The most common isotope of hydrogen, termed protium, has one proton, the universal emergence of atomic hydrogen first occurred during the recombination epoch. At standard temperature and pressure, hydrogen is a colorless, odorless, tasteless, non-toxic, nonmetallic, since hydrogen readily forms covalent compounds with most nonmetallic elements, most of the hydrogen on Earth exists in molecular forms such as water or organic compounds. Hydrogen plays an important role in acid–base reactions because most acid-base reactions involve the exchange of protons between soluble molecules. In ionic compounds, hydrogen can take the form of a charge when it is known as a hydride. The hydrogen cation is written as though composed of a bare proton, Hydrogen gas was first artificially produced in the early 16th century by the reaction of acids on metals. Industrial production is mainly from steam reforming natural gas, and less often from more energy-intensive methods such as the electrolysis of water. Most hydrogen is used near the site of its production, the two largest uses being fossil fuel processing and ammonia production, mostly for the fertilizer market, Hydrogen is a concern in metallurgy as it can embrittle many metals, complicating the design of pipelines and storage tanks. Hydrogen gas is flammable and will burn in air at a very wide range of concentrations between 4% and 75% by volume. The enthalpy of combustion is −286 kJ/mol,2 H2 + O2 →2 H2O +572 kJ Hydrogen gas forms explosive mixtures with air in concentrations from 4–74%, the explosive reactions may be triggered by spark, heat, or sunlight. The hydrogen autoignition temperature, the temperature of spontaneous ignition in air, is 500 °C, the detection of a burning hydrogen leak may require a flame detector, such leaks can be very dangerous. Hydrogen flames in other conditions are blue, resembling blue natural gas flames, the destruction of the Hindenburg airship was a notorious example of hydrogen combustion and the cause is still debated. The visible orange flames in that incident were the result of a mixture of hydrogen to oxygen combined with carbon compounds from the airship skin. H2 reacts with every oxidizing element, the ground state energy level of the electron in a hydrogen atom is −13.6 eV, which is equivalent to an ultraviolet photon of roughly 91 nm wavelength. The energy levels of hydrogen can be calculated fairly accurately using the Bohr model of the atom, however, the atomic electron and proton are held together by electromagnetic force, while planets and celestial objects are held by gravity. The most complicated treatments allow for the effects of special relativity
15.
Oxygen
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Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the group on the periodic table and is a highly reactive nonmetal. By mass, oxygen is the third-most abundant element in the universe, after hydrogen, at standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. This is an important part of the atmosphere and diatomic oxygen gas constitutes 20. 8% of the Earths atmosphere, additionally, as oxides the element makes up almost half of the Earths crust. Most of the mass of living organisms is oxygen as a component of water, conversely, oxygen is continuously replenished by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form of oxygen, ozone, strongly absorbs ultraviolet UVB radiation, but ozone is a pollutant near the surface where it is a by-product of smog. At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft, the name oxygen was coined in 1777 by Antoine Lavoisier, whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion. One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle, Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries later Leonardo da Vinci built on Philos work by observing that a portion of air is consumed during combustion and respiration, Oxygen was discovered by the Polish alchemist Sendivogius, who considered it the philosophers stone. In the late 17th century, Robert Boyle proved that air is necessary for combustion, English chemist John Mayow refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus. From this he surmised that nitroaereus is consumed in both respiration and combustion, Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it. Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract De respiratione. Robert Hooke, Ole Borch, Mikhail Lomonosov, and Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element. This may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, which was then the favored explanation of those processes. Established in 1667 by the German alchemist J. J. Becher, one part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx. The fact that a substance like wood gains overall weight in burning was hidden by the buoyancy of the combustion products
16.
IUPAC
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The International Union of Pure and Applied Chemistry /ˈaɪjuːpæk/ or /ˈjuːpæk/ is an international federation of National Adhering Organizations that represents chemists in individual countries. It is a member of the International Council for Science, IUPAC is registered in Zürich, Switzerland, and the administrative office, known as the IUPAC Secretariat, is in Research Triangle Park, North Carolina, United States. This administrative office is headed by IUPACs executive director, currently Lynn Soby, IUPAC was established in 1919 as the successor of the International Congress of Applied Chemistry for the advancement of chemistry. Its members, the National Adhering Organizations, can be national chemistry societies, national academies of sciences, there are fifty-four National Adhering Organizations and three Associate National Adhering Organizations. IUPACs Inter-divisional Committee on Nomenclature and Symbols is the world authority in developing standards for the naming of the chemical elements. Since its creation, IUPAC has been run by different committees with different responsibilities. These committees run different projects which include standardizing nomenclature, finding ways to bring chemistry to the world, IUPAC is best known for its works standardizing nomenclature in chemistry and other fields of science, but IUPAC has publications in many fields including chemistry, biology and physics. IUPAC is also known for standardizing the atomic weights of the elements through one of its oldest standing committees, the need for an international standard for chemistry was first addressed in 1860 by a committee headed by German scientist Friedrich August Kekulé von Stradonitz. This committee was the first international conference to create an international naming system for organic compounds, the ideas that were formulated in that conference evolved into the official IUPAC nomenclature of organic chemistry. IUPAC stands as a legacy of this meeting, making it one of the most important historical international collaborations of chemistry societies, since this time, IUPAC has been the official organization held with the responsibility of updating and maintaining official organic nomenclature. IUPAC as such was established in 1919, one notable country excluded from this early IUPAC is Germany. Germanys exclusion was a result of prejudice towards Germans by the Allied powers after World War I, Germany was finally admitted into IUPAC during 1929. However, Nazi Germany was removed from IUPAC during World War II, during World War II, IUPAC was affiliated with the Allied powers, but had little involvement during the war effort itself. After the war, East and West Germany were eventually readmitted to IUPAC, since World War II, IUPAC has been focused on standardizing nomenclature and methods in science without interruption. In 2016, IUPAC denounced the use of chlorine as a chemical weapon, the letter stated, Our organizations deplore the use of chlorine in this manner. According to the CWC, the use, stockpiling, distribution, IUPAC is governed by several committees that all have different responsibilities. Each committee is made up of members of different National Adhering Organizations from different countries, the steering committee hierarchy for IUPAC is as follows, All committees have an allotted budget to which they must adhere. Any committee may start a project, if a projects spending becomes too much for a committee to continue funding, it must take the issue to the Project Committee
17.
Functional group
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In organic chemistry, functional groups are specific groups of atoms or bonds within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of, however, its relative reactivity can be modified by other functional groups nearby. The atoms of functional groups are linked to other and to the rest of the molecule by covalent bonds. Any subgroup of atoms of a compound also may be called a radical, and if a covalent bond is broken homolytically, Functional groups can also be charged, e. g. in carboxylate salts, which turns the molecule into a polyatomic ion or a complex ion. Complexation and solvation is also caused by interactions of functional groups. In the common rule of thumb like dissolves like, it is the shared or mutually well-interacting functional groups give rise to solubility. For example, sugar dissolves in water because both share the functional group and hydroxyls interact strongly with each other. Combining the names of groups with the names of the parent alkanes generates what is termed a systematic nomenclature for naming organic compounds. In traditional nomenclature, the first carbon atom after the carbon that attaches to the group is called the alpha carbon, the second, beta carbon. IUPAC conventions call for numeric labeling of the position, e. g. 4-aminobutanoic acid, in traditional names various qualifiers are used to label isomers, for example isopropanol is an isomer is n-propanol. The following is a list of functional groups. In the formulas, the symbols R and R usually denote an attached hydrogen, or a side chain of any length. Functional groups, called hydrocarbyl, that only carbon and hydrogen. Each one differs in type of reactivity, there are also a large number of branched or ring alkanes that have specific names, e. g. tert-butyl, bornyl, cyclohexyl, etc. Hydrocarbons may form charged structures, positively charged carbocations or negative carbanions, examples are tropylium and triphenylmethyl cations and the cyclopentadienyl anion. Haloalkanes are a class of molecule that is defined by a carbon–halogen bond and this bond can be relatively weak or quite stable. In general, with the exception of fluorinated compounds, haloalkanes readily undergo nucleophilic substitution reactions or elimination reactions, the substitution on the carbon, the acidity of an adjacent proton, the solvent conditions, etc. all can influence the outcome of the reactivity. Compounds that contain nitrogen in this category may contain C-O bonds, compounds that contain sulfur exhibit unique chemistry due to their ability to form more bonds than oxygen, their lighter analogue on the periodic table
18.
Biochemistry
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Biochemistry, sometimes called biological chemistry, is the study of chemical processes within and relating to living organisms. By controlling information flow through biochemical signaling and the flow of energy through metabolism. Biochemistry is closely related to biology, the study of the molecular mechanisms by which genetic information encoded in DNA is able to result in the processes of life. Depending on the definition of the terms used, molecular biology can be thought of as a branch of biochemistry, or biochemistry as a tool with which to investigate. The chemistry of the cell depends on the reactions of smaller molecules. These can be inorganic, for water and metal ions, or organic, for example the amino acids. The mechanisms by which cells harness energy from their environment via chemical reactions are known as metabolism, the findings of biochemistry are applied primarily in medicine, nutrition, and agriculture. In medicine, biochemists investigate the causes and cures of diseases, in nutrition, they study how to maintain health and study the effects of nutritional deficiencies. In agriculture, biochemists investigate soil and fertilizers, and try to discover ways to improve crop cultivation, crop storage and pest control. However, biochemistry as a scientific discipline has its beginning sometime in the 19th century, or a little earlier. Gowland Hopkins on enzymes and the nature of biochemistry. The term biochemistry itself is derived from a combination of biology, the German chemist Carl Neuberg however is often cited to have coined the word in 1903, while some credited it to Franz Hofmeister. Then, in 1828, Friedrich Wöhler published a paper on the synthesis of urea and these techniques allowed for the discovery and detailed analysis of many molecules and metabolic pathways of the cell, such as glycolysis and the Krebs cycle. Another significant historic event in biochemistry is the discovery of the gene and this part of biochemistry is often called molecular biology. In the 1950s, James D. Watson, Francis Crick, Rosalind Franklin, in 1958, George Beadle and Edward Tatum received the Nobel Prize for work in fungi showing that one gene produces one enzyme. In 1988, Colin Pitchfork was the first person convicted of murder with DNA evidence, mello received the 2006 Nobel Prize for discovering the role of RNA interference, in the silencing of gene expression. Around two dozen of the 92 naturally occurring elements are essential to various kinds of biological life. Most rare elements on Earth are not needed by life, while a few common ones are not used, most organisms share element needs, but there are a few differences between plants and animals
19.
Transition metal
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Many scientists describe a transition metal as any element in the d-block of the periodic table, which includes groups 3 to 12 on the periodic table. In actual practice, the lanthanide and actinide series are also considered transition metals and are called inner transition metals. Cotton and Wilkinson expand the brief IUPAC definition by specifying which elements are included, as well as the elements of groups 4 to 11, they add scandium and yttrium in group 3 which have a partially filled d subshell in the metallic state. These last two elements are included even though they do not seem to possess the properties which are so characteristic of the transition metals in general. Lanthanum and actinium in Group 3 are however classified as lanthanides and actinides respectively and these elements are now known as the d-block. In the d-block the atoms of the elements have between 1 and 10 d electrons, Sc and Y in Group 3 are also generally recognized as transition metals. However the elements La–Lu and Ac–Lr and Group 12 attract different definitions from different authors, many chemistry textbooks and printed periodic tables classify La and Ac as Group 3 elements and transition metals, since their atomic ground-state configurations are s2d1 like Sc and Y. The elements Ce-Lu are considered as the series and Th-Lr as the actinide series. The two series together are classified as elements, or as inner transition elements. Some inorganic chemistry textbooks include La with the lanthanides and Ac with the actinides, a third classification defines the f-block elements as La-Yb and Ac-No, while placing Lu and Lr in Group 3. This is based on the Aufbau principle for filling electron subshells, in which 4f is filled before 5d, zinc, cadmium, and mercury are generally excluded from the transition metals as they have the electronic configuration d10s2, with no incomplete d shell. In the oxidation state +2 the ions have the electronic configuration d10, however, these elements can exist in other oxidation states, including the +1 oxidation state, as in the diatomic ion Hg2+2. The group 12 elements Zn, Cd and Hg may therefore, under certain rules, however, it is often convenient to include these elements in a discussion of the transition elements. Another example occurs in the Irving-Williams series of stability constants of complexes, although meitnerium, darmstadtium, and roentgenium are within the d-block and are expected to behave as transition metals, this has not yet been experimentally confirmed. The general electronic configuration of the elements is d1, 10n s1,2. The period 6 and 7 transition metals also add f1,14 electrons and this rule is however only approximate – it only holds for some of the transition elements, and only then in their neutral ground state. The d-sub-shell is the next-to-last sub-shell and is denoted as d -sub-shell, the number of s electrons in the outermost s sub-shell is generally one or two except palladium, with no electron in that s-sub shell in its ground state. The s-sub-shell in the shell is represented as the ns sub-shell
20.
Oxaloacetic acid
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Oxaloacetic acid is a crystalline organic compound with the chemical formula HO2CCCH2CO2H. Oxaloacetic acid, in the form of its conjugate base oxaloacetate, is an intermediate in many processes that occur in animals. It takes part in the gluconeogenesis, urea cycle, glyoxylate cycle, amino acid synthesis, fatty acid synthesis, oxaloacetate forms in several ways in nature. A principal route is upon oxidation of L-malate, catalysed by malate dehydrogenase, malate is also oxidized by succinate dehydrogenase in a slow reaction with the initial product being enol-oxaloacetate. Oxaloacetate can also arise from trans- or de- amination of aspartic acid, oxaloacetate is an intermediate of the citric acid cycle, where it reacts with Acetyl-CoA to form citrate, catalysed by citrate synthase. It is also involved in gluconeogenesis, urea cycle, glyoxylate cycle, amino acid synthesis, oxaloacetate is also a potent inhibitor of Complex II. Gluconeogenesis is a pathway consisting of a series of eleven enzyme-catalyzed reactions. The beginning of this takes place in the mitochondrial matrix. A pyruvate molecule is carboxylated by a pyruvate carboxylase enzyme, activated by a molecule each of ATP and this reaction results in the formation of oxaloacetate. This transformation is needed to transport the molecule out of the mitochondria, once in the cytosol, malate is oxidized to oxaloacetate again using NAD+. Then oxaloacetate remains in the cytosol, where the rest of reactions take place. Oxaloacetate is later decarboxylated and phosphorylated by phosphoenolpyruvate carboxykinase and becomes 2-phosphoenolpyruvate using guanosine triphosphate as phosphate source, glucose is obtained after further downstream processing. The urea cycle is a pathway that results in the formation of urea using two ammonium molecules and one bicarbonate molecule. This route commonly occurs in hepatocytes, the reactions related to the urea cycle produce NADH), and NADH can be produced in two different ways. In the cytosol there are fumarate molecules, fumarate can be transformed into malate by the actions of the enzyme fumarase. Malate is acted on by malate dehydrogenase to become oxaloacetate, producing a molecule of NADH, after that, oxaloacetate will be recycled to aspartate, as transaminases prefer these keto acids over the others. This recycling maintains the flow of nitrogen into the cell, the glyoxylate cycle is a variant of the citric acid cycle. It is a pathway occurring in plants and bacteria utilizing the enzymes isocitrate lyase
21.
Citric acid cycle
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Its central importance to many biochemical pathways suggests that it was one of the earliest established components of cellular metabolism and may have originated abiogenically. The name of this pathway is derived from citric acid that is consumed. In addition, the cycle consumes acetate and water, reduces NAD+ to NADH, the NADH generated by the TCA cycle is fed into the oxidative phosphorylation pathway. The net result of two closely linked pathways is the oxidation of nutrients to produce usable chemical energy in the form of ATP. In eukaryotic cells, the citric acid cycle occurs in the matrix of the mitochondrion, components of the TCA cycle were derived from anaerobic bacteria, and the TCA cycle itself may have evolved more than once. Theoretically there are alternatives to the TCA cycle, however. If several TCA alternatives had evolved independently, they all appear to have converged to the TCA cycle, the citric acid cycle is a key metabolic pathway that connects carbohydrate, fat, and protein metabolism. The reactions of the cycle are carried out by 8 enzymes that completely oxidize acetate, in the form of acetyl-CoA, through catabolism of sugars, fats, and proteins, the two-carbon organic product acetyl-CoA is produced which enters the citric acid cycle. The NADH and FADH2 generated by the citric acid cycle are in used by the oxidative phosphorylation pathway to generate energy-rich adenosine triphosphate. Acetyl-CoA may also be obtained from the oxidation of fatty acids, the citrate then goes through a series of chemical transformations, losing two carboxyl groups as CO2. The carbons lost as CO2 originate from what was oxaloacetate, not directly from acetyl-CoA, the carbons donated by acetyl-CoA become part of the oxaloacetate carbon backbone after the first turn of the citric acid cycle. Loss of the acetyl-CoA-donated carbons as CO2 requires several turns of the citric acid cycle. However, because of the role of the citric acid cycle in anabolism, they not be lost. Most of the energy available by the oxidative steps of the cycle is transferred as energy-rich electrons to NAD+. For each acetyl group that enters the citric cycle, three molecules of NADH are produced. Electrons are also transferred to the electron acceptor Q, forming QH2, at the end of each cycle, the four-carbon oxaloacetate has been regenerated, and the cycle continues. Two carbon atoms are oxidized to CO2, the energy from these reactions is transferred to other processes through GTP. The NADH generated in the TCA cycle may later be oxidized to drive ATP synthesis in a type of process called oxidative phosphorylation, FADH2 is covalently attached to succinate dehydrogenase, an enzyme which functions both in the CAC and the mitochondrial electron transport chain in oxidative phosphorylation
22.
Acetylacetone
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Acetylacetone is an organic compound that exists in two tautomeric forms that interconvert rapidly and are treated as a single compound in most applications. Although the compound is named as the diketone form, pentane-2, 4-dione. It is a liquid that is a precursor to acetylacetonate. It is also a block for the synthesis of heterocyclic compounds. The keto and enol forms of acetylacetone coexist in solution, these forms are tautomers, the enol form has C2v symmetry, meaning the hydrogen atom is shared equally between the two oxygen atoms. In the gas phase, the constant, Kketo→enol, is 11.7. The two tautomeric forms can easily be distinguished by NMR spectroscopy, IR spectroscopy, and other methods, the equilibrium constant tends to remain high in nonpolar solvents, the keto form becomes more favorable in polar, hydrogen-bonding solvents, such as water. The enol form is a analogue of a carboxylic acid. Acetylacetone is an acid, C5H8O2 ⇌ C 5H 7O−2 + H+ IUPAC recommended pKa values for this equilibrium in aqueous solution at 25 °C are 8.99 ±0.04,8.83 ±0.02 and 9.00 ±0.03. Values for mixed solvents are available, very strong bases, such as organolithium compounds, will deprotonate acetylacetone twice. The resulting dilithio species can then be alkylated at C-1, acetylacetone is prepared industrially by the thermal rearrangement of isopropenyl acetate. CH2COCMe → MeCCH2CMe Laboratory routes to acetylacetone begin also with acetone, some examples include C6H5CCH2CC6H5 and 3CCCH2CCC3. Hexafluoroacetylacetonate is also used to generate volatile metal complexes. Acetylacetone is a versatile precursor to heterocycles because both keto groups undergo condensation. Condensation with two aryl- and alkylamines to gives NacNacs, wherein the oxygen atoms in acetylacetone are replaced by NR, the acetylacetonate anion, acac−, forms complexes with many transition metal ions. Both oxygen atoms bind to the metal to form a six-membered chelate ring, in some cases the chelate effect is so strong that no added base is needed to form the complex. Since the metal complex carries no charge, it is often insoluble in water. Enzymatic breakdown, The enzyme acetylacetone dioxygenase cleaves the bond of acetylacetone, producing acetate
23.
Cyclohexanone
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Cyclohexanone is the organic compound with the formula 5CO. The molecule consists of six-carbon cyclic molecule with a functional group. This colorless oil has a reminiscent of peardrop sweets as well as acetone. Over time, samples assume a yellow color due to oxidation, cyclohexanone is slightly soluble in water and miscible with common organic solvents. Billions of kilograms are produced annually, mainly as a precursor to nylon, the oxidation involves radicals and the intermediacy of the hydroperoxide C6H11O2H. In some cases, purified cyclohexanol, obtained by hydration of cyclohexene, is the precursor, alternatively, cyclohexanone can be produced by the partial hydrogenation of phenol, C6H5OH +2 H2 → 5CO This process can also be adjusted to favor the formation of cyclohexanol. Cyclohexanone can be prepared from cyclohexanol by oxidation with chromium trioxide, an alternative method utilizes the safer and more readily available oxidant sodium hypochlorite. The great majority of cyclohexanone is consumed in the production of precursors to Nylon 6,6, about half of the worlds supply is converted to adipic acid, one of two precursors for nylon 6,6. For this application, the KA oil is oxidized with nitric acid, the other half of the cyclohexanone supply is converted to cyclohexanone oxime
24.
Nylon
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Nylon is a generic designation for a family of synthetic polymers, more specifically aliphatic or semi-aromatic polyamides. They can be melt-processed into fibers, films or shapes, the first example of nylon was produced on February 28,1935, by Wallace Carothers at DuPonts research facility at the DuPont Experimental Station. Nylon polymers have significant commercial applications in fibers, in shapes. Nylon is made of repeating units linked by bonds and is a type of polyamide and is frequently referred to as such. Nylon was the first commercially successful synthetic thermoplastic polymer, commercially, nylon polymer is made by reacting monomers which are either lactams, acid/amines or stoichiometric mixtures of diamines and diacids. Mixtures of these can be polymerized together to make copolymers, Nylon polymers can be mixed with a wide variety of additives to achieve many different property variations. Nylon was invented accidentally by Julian W. Hill, a chemist for DuPont under Wallace Carotherss supervision and it was only given this name at the 1939 New York Worlds Fair. The patents were owned by DuPont, Nylon was intended to be a synthetic replacement for silk and substituted for it in many different products after silk became scarce during World War II. It replaced silk in military applications such as parachutes and flak vests, after initial commercialization of nylon as a fiber, applications in the form of shapes and films were also developed. The main market for nylon shapes now is in auto components, in 1940, John W. Eckelberry of DuPont stated that the letters nyl were arbitrary and the on was copied from the suffixes of other fibers such as cotton and rayon. A later publication by DuPont explained that the name was intended to be No-Run. Since the products were not really run-proof, the vowels were swapped to produce nuron, for clarity in pronunciation, the i was changed to y. Most nylons are made from the reaction of an acid with a diamine or a lactam or amino acid with itself. In the first case, the structure is so-called ABAB similar to polyesters and polyurethanes, in the second case, the repeating unit corresponds to the single monomer. It is difficult to get the proportions exactly correct, and deviations can lead to termination at molecular weights less than a desirable 10,000 daltons. To overcome this problem, a crystalline, solid nylon salt can be formed at room temperature, using an exact 1,1 ratio of the acid, the salt is crystallized to purify it and obtain the desired precise stoichiometry. Heated to 285 °C, the salt reacts to form nylon polymer with the production of water, Wallace Carothers at DuPont patented nylon 66, but overlooked the possibility to use lactams. That synthetic route was developed by Paul Schlack at IG Farben, leading to nylon 6, the peptide bond within the caprolactam is broken with the exposed active groups on each side being incorporated into two new bonds as the monomer becomes part of the polymer backbone
25.
Muscone
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Muscone is an organic compound that is the primary contributor to the odor of musk. The chemical structure of muscone was first elucidated by Lavoslav Ružička and it consists of a 15-membered ring ketone with one methyl substituent in the 3-position. It is a liquid that is found naturally as the -enantiomer. Muscone has been synthesized as the pure -enantiomer as well as the racemate and it is very slightly soluble in water and miscible with alcohol. Natural muscone is obtained from musk, a secretion of the musk deer. Since obtaining natural musk requires killing the animal, nearly all muscone used in perfumery today is synthetic. It has the smell of being Musky. Muscone is now produced synthetically for use in perfumes and for scenting consumer products, isotopomers of muscone have been used in a study of the mechanism of olfaction. Global replacement of all hydrogens in muscone was achieved by heating muscone with Rh/C in D2O at 150 °C
26.
Orbital hybridisation
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In chemistry, hybridisation is the concept of mixing atomic orbitals into new hybrid orbitals suitable for the pairing of electrons to form chemical bonds in valence bond theory. Hybrid orbitals are very useful in the explanation of molecular geometry, although sometimes taught together with the valence shell electron-pair repulsion theory, valence bond and hybridisation are in fact not related to the VSEPR model. Chemist Linus Pauling first developed the theory in 1931 in order to explain the structure of simple molecules such as methane using atomic orbitals. In reality however, methane has four bonds of equivalent strength separated by the bond angle of 109. 5°. It gives a simple orbital picture equivalent to Lewis structures, hybridisation theory finds its use mainly in organic chemistry. Orbitals are a representation of the behaviour of electrons within molecules. In heavier atoms, such as carbon, nitrogen, and oxygen, hybrid orbitals are assumed to be mixtures of atomic orbitals, superimposed on each other in various proportions. For example, in methane, the C hybrid orbital which forms each carbon–hydrogen bond consists of 25% s character and 75% p character and is thus described as sp3 hybridised. Quantum mechanics describes this hybrid as an sp3 wavefunction of the form N, the ratio of coefficients is √3 in this example. Since the electron density associated with an orbital is proportional to the square of the wavefunction, the p character or the weight of the p component is N2λ2 = 3/4. The amount of p character or s character, which is decided mainly by orbital hybridisation, molecules with multiple bonds or multiple lone pairs can have orbitals represented in terms of sigma and pi symmetry or equivalent orbitals. The sigma and pi representation of Erich Hückel is the common one compared to the equivalent orbital representation of Linus Pauling. The two have mathematically equivalent total many-electron wave functions, and are related by a transformation of the set of occupied molecular orbitals. Hybridisation describes the bonding atoms from a point of view. For a tetrahedrally coordinated carbon, the carbon should have 4 orbitals with the symmetry to bond to the 4 hydrogen atoms. The carbon atom can also bond to four hydrogen atoms by an excitation of an electron from the doubly occupied 2s orbital to the empty 2p orbital, producing four singly occupied orbitals. The energy released by formation of two additional bonds more than compensates for the energy required, energetically favouring the formation of four C-H bonds. Quantum mechanically, the lowest energy is obtained if the four bonds are equivalent, a set of four equivalent orbitals can be obtained that are linear combinations of the valence-shell s and p wave functions, which are the four sp3 hybrids
27.
Trigonal planar molecular geometry
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In chemistry, trigonal planar is a molecular geometry model with one atom at the center and three atoms at the corners of an equilateral triangle, called peripheral atoms, all in one plane. In an ideal trigonal planar species, all three ligands are identical and all angles are 120°. Such species belong to the point group D3h, molecules where the three ligands are not identical, such as H2CO, deviate from this idealized geometry. Examples of molecules with trigonal planar geometry include boron trifluoride, formaldehyde, phosgene, some ions with trigonal planar geometry include nitrate, carbonate, and guanidinium. In organic chemistry, planar, three-connected carbon centers that are trigonal planar are often described as having sp2 hybridization, nitrogen inversion is the distortion of pyramidal amines through a transition state that is trigonal planar. Pyramidalization is a distortion of this molecular shape towards a tetrahedral molecular geometry, one way to observe this distortion is in pyramidal alkenes
28.
Skeletal formula
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A skeletal formula shows the skeletal structure or skeleton of a molecule, which is composed of the skeletal atoms that make up the molecule. It is represented in two dimensions, as on a page of paper and it employs certain conventions to represent carbon and hydrogen atoms, which are the most common in organic chemistry. The technique was developed by the organic chemist Friedrich August Kekulé von Stradonitz, Skeletal formulae have become ubiquitous in organic chemistry, partly because they are relatively quick and simple to draw. As in a Lewis structure, a doubled or tripled line segment indicates double or triple bonding, the skeletal structure of an organic compound is the series of atoms bonded together that form the essential structure of the compound. The skeleton can consist of chains, branches and/or rings of bonded atoms, Skeletal atoms other than carbon or hydrogen are called heteroatoms. The skeleton has hydrogen and/or various substituents bonded to its atoms, hydrogen is the most common non-carbon atom that is bonded to carbon and, for simplicity, is not explicitly drawn. For example, in the image below, the formula of hexane is shown. The carbon atom labeled C1 appears to have one bond. The carbon atom labelled C3 has two bonds to other carbons and is bonded to two hydrogen atoms as well. NOTE, It doesnt matter which end of the chain you start numbering from, the condensed formula or the IUPAC name will confirm the orientation. Some molecules will become familiar regardless of the orientation, any hydrogen atoms bonded to non-carbon atoms are drawn explicitly. In ethanol, C2H5OH, for instance, the hydrogen bonded to oxygen is denoted by the symbol H. Lines representing heteroatom-hydrogen bonds are usually omitted for clarity and compactness and these bonds are sometimes drawn out in full in order to accentuate their presence when they participate in reaction mechanisms. Shown below for comparison are a model of the actual three-dimensional structure of the ethanol molecule in the gas phase, the Lewis structure. All atoms that are not carbon or hydrogen are signified by their symbol, for instance Cl for chlorine, O for oxygen, Na for sodium. These atoms are known as heteroatoms in the context of organic chemistry. There are also symbols that appear to be chemical element symbols and these are known as pseudoelement symbols or organic elements. The most widely used symbol is Ph, which represents the phenyl group, boc for the t-butoxycarbonyl group Cbz or Z for the carboxybenzyl group Fmoc for the fluorenylmethoxycarbonyl group Two atoms can be bonded by sharing more than one pair of electrons
29.
Ester
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In chemistry, esters are chemical compounds derived from an acid in which at least one –OH group is replaced by an –O–alkyl group. Usually, esters are derived from an acid and an alcohol. Glycerides, which are fatty acid esters of glycerol, are important esters in biology, being one of the classes of lipids. Esters with low weight are commonly used as fragrances and found in essential oils. Phosphoesters form the backbone of DNA molecules, nitrate esters, such as nitroglycerin, are known for their explosive properties, while polyesters are important plastics, with monomers linked by ester moieties. The word ester was coined in 1848 by German chemist Leopold Gmelin, probably as a contraction of the German Essigäther, ester names are derived from the parent alcohol and the parent acid, where the latter may be organic or inorganic. Esters derived from more complex carboxylic acids are, on the hand, more frequently named using the systematic IUPAC name. For example, the ester hexyl octanoate, also known under the trivial name hexyl caprylate, has the formula CH36CO25CH3, the chemical formulas of organic esters usually take the form RCO2R′, where R and R′ are the hydrocarbon parts of the carboxylic acid and the alcohol, respectively. For example, butyl acetate, derived from butanol and acetic acid would be written CH3CO2C4H9, alternative presentations are common including BuOAc and CH3COOC4H9. Cyclic esters are called lactones, regardless of whether they are derived from an organic or an inorganic acid, one example of a lactone is γ-valerolactone. An uncommon class of organic esters are the orthoesters, which have the formula RC3, triethylorthoformate is derived, in terms of its name from orthoformic acid and ethanol. Esters can also be derived from an acid and an alcohol. For example, triphenyl phosphate is the derived from phosphoric acid. Organic carbonates are derived from acid, for example, ethylene carbonate is derived from carbonic acid. So far an alcohol and inorganic acid are linked via oxygen atoms, in corollary, boron features borinic esters, boronic esters, and borates. As oxygen is a group 16 chemical element, sulfur atoms can replace some oxygen atoms in carbon–oxygen–central inorganic atom covalent bonds of an ester, esters contain a carbonyl center, which gives rise to 120 ° C–C–O and O–C–O angles. Unlike amides, esters are structurally flexible functional groups because rotation about the C–O–C bonds has a low barrier and their flexibility and low polarity is manifested in their physical properties, they tend to be less rigid and more volatile than the corresponding amides. The pKa of the alpha-hydrogens on esters is around 25, the preference for the Z conformation is influenced by the nature of the substituents and solvent, if present
30.
Amide
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An amide, also known as an acid amide, is a compound with the functional group RnExNR′2. Most common are carboxamides, but many other important types of amides are known, the term amide refers both to classes of compounds and to the functional group within those compounds. Amide can also refer to the base of ammonia or of an organic amine. For discussion of these anionic amides, see Alkali metal amides, the remainder of this article is about the carbonyl–nitrogen sense of amide. The simplest amides are derivatives of ammonia wherein one hydrogen atom has replaced by an acyl group. The ensemble is represented as RCNH2 and is described as a primary amide. Closely related and even more numerous are secondary amides which can be derived from amines and have the formula RCNHR′. Tertiary amides are commonly derived from amines and have the general structure RCNR′R″. Amides are usually regarded as derivatives of carboxylic acids in which the group has been replaced by an amine or ammonia. The lone pair of electrons on the nitrogen is delocalized into the carbonyl, consequently, the nitrogen in amides is not pyramidal. It is estimated that acetamide is described by resonance structure A for 62%, in the usual nomenclature, one adds the term amide to the stem of the parent acids name. For instance, the derived from acetic acid is named acetamide. IUPAC recommends ethanamide, but this and related names are rarely encountered. When the amide is derived from a primary or secondary amine, thus, the amide formed from dimethylamine and acetic acid is N, N-dimethylacetamide. Usually even this name is simplified to dimethylacetamide, cyclic amides are called lactams, they are necessarily secondary or tertiary amides. Functional groups consisting of –PNR2 and –SO2NR2 are phosphonamides and sulfonamides, some chemists make a pronunciation distinction between the two, saying /əˈmiːd/ for the carbonyl–nitrogen compound and /ˈeɪmaɪd/ for the anion. Others replace one of these with /ˈæmᵻd/, while others pronounce both /ˈæmᵻd/, making them homonyms. Compared to amines, amides are very weak bases, while the conjugate acid of an amine has a pKa of about 9.5, the conjugate acid of an amide has a pKa around −0.5
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Chemical polarity
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In chemistry, polarity is a separation of electric charge leading to a molecule or its chemical groups having an electric dipole or multipole moment. Polar molecules must contain polar bonds due to a difference in electronegativity between the bonded atoms, a polar molecule with two or more polar bonds must have an asymmetric geometry so that the bond dipoles do not cancel each other. Polar molecules interact through dipole–dipole intermolecular forces and hydrogen bonds, Polarity underlies a number of physical properties including surface tension, solubility, and melting and boiling points. Not all atoms attract electrons with the same force, the amount of pull an atom exerts on its electrons is called its electronegativity. Atoms with high electronegativities – such as fluorine, oxygen and nitrogen – exert a pull on electrons than atoms with lower electronegativities. In a bond, this leads to sharing of electrons between the atoms, as electrons will be drawn closer to the atom with the higher electronegativity. Because electrons have a charge, the unequal sharing of electrons within a bond leads to the formation of an electric dipole. Because the amount of charge separated in such dipoles is usually smaller than a charge, they are called partial charges, denoted as δ+. These symbols were introduced by Christopher Kelk Ingold and Edith Hilda Ingold in 1926, the bond dipole moment is calculated by multiplying the amount of charge separated and the distance between the charges. These dipoles within molecules can interact with dipoles in other molecules, Bonds can fall between one of two extremes – being completely nonpolar or completely polar. A completely nonpolar bond occurs when the electronegativities are identical and therefore possess a difference of zero, a completely polar bond is more correctly called an ionic bond, and occurs when the difference between electronegativities is large enough that one atom actually takes an electron from the other. The terms polar and nonpolar are usually applied to covalent bonds, to determine the polarity of a covalent bond using numerical means, the difference between the electronegativity of the atoms is used. Bond polarity is typically divided into three groups that are based on the difference in electronegativity between the two bonded atoms. He estimated that a difference of 1.7 corresponds to 50% ionic character, see also dipole § Molecular dipoles. While the molecules can be described as covalent, nonpolar covalent, or ionic. However, the properties are typical of such molecules. A molecule is composed of one or more chemical bonds between molecular orbitals of different atoms, a polar molecule has a net dipole as a result of the opposing charges from polar bonds arranged asymmetrically. Water is an example of a polar molecule since it has a positive charge on one side
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Nucleophile
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A nucleophile is a chemical species that donates an electron pair to an electrophile to form a chemical bond in relation to a reaction. All molecules or ions with a pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are by definition Lewis bases, Nucleophilic describes the affinity of a nucleophile to the nuclei. Nucleophilicity, sometimes referred to as strength, refers to a substances nucleophilic character and is often used to compare the affinity of atoms. Neutral nucleophilic reactions with solvents such as alcohols and water are named solvolysis, nucleophiles may take part in nucleophilic substitution, whereby a nucleophile becomes attracted to a full or partial positive charge. The terms nucleophile and electrophile were introduced by Christopher Kelk Ingold in 1933, the word nucleophile is derived from nucleus and the Greek word φιλος, philos for love. In general, in a row across the table, the more basic the ion the more reactive it is as a nucleophile. g. The iodide ion is more nucleophilic than the fluoride ion, many schemes attempting to quantify relative nucleophilic strength have been devised. The following empirical data have been obtained by measuring reaction rates for a number of reactions involving a large number of nucleophiles and electrophiles. Nucleophiles displaying the so-called alpha effect are usually omitted in this type of treatment. This treatment results in the values for typical nucleophilic anions, acetate 2.7, chloride 3.0, azide 4.0, hydroxide 4.2, aniline 4.5, iodide 5.0. Typical substrate constants are 0.66 for ethyl tosylate,0.77 for β-propiolactone,1.00 for 2, 3-epoxypropanol,0.87 for benzyl chloride, and 1.43 for benzoyl chloride. The equation predicts that, in a nucleophilic displacement on benzyl chloride, the Ritchie equation, derived in 1972, is another free-energy relationship, log 10 = N + where N+ is the nucleophile dependent parameter and k0 the reaction rate constant for water. In this equation, a substrate-dependent parameter like s in the Swain–Scott equation is absent, the equation states that two nucleophiles react with the same relative reactivity regardless of the nature of the electrophile, which is in violation of the Reactivity–selectivity principle. For this reason this equation is called the constant selectivity relationship. Many other reaction types have since been described. Typical Ritchie N+ values are,0.5 for methanol,5.9 for the anion,7.5 for the methoxide anion,8.5 for the azide anion. The values for the relative cation reactivities are -0.4 for the malachite green cation, +2.6 for the benzenediazonium cation, the constant s is defined as 1 with 2-methyl-1-pentene as the nucleophile
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Electrophile
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In chemistry, an electrophile is a reagent attracted to electrons. Electrophiles are positively charged or neutral species having vacant orbitals that are attracted to a rich centre. It participates in a reaction by accepting an electron pair in order to bond to a nucleophile. Because electrophiles accept electrons, they are Lewis acids, most electrophiles are positively charged, have an atom that carries a partial positive charge, or have an atom that does not have an octet of electrons. The electrophiles are attacked by the most electron-populated part of one nucleophile and these occur between alkenes and electrophiles, often halogens as in halogen addition reactions. Common reactions include use of water to titrate against a sample to deduce the number of double bonds present. Forming of a bromonium ion The alkene is working as an electron donor. The three-membered bromonium ion 2 consisted with two atoms and a bromine atom forms with a release of Br−. Attacking of bromide ion The bromonium ion is opened by the attack of Br− from the back side and this yields the vicinal dibromide with an antiperiplanar configuration. When other nucleophiles such as water or alcohol are existing, these may attack 2 to give an alcohol or an ether and this process is called AdE2 mechanism. Iodine, chlorine, sulfenyl ion, mercury cation, and dichlorocarbene also react through similar pathways, the direct conversion of 1 to 3 will appear when the Br− is large excess in the reaction medium. A β-bromo carbenium ion intermediate may be predominant instead of 3 if the alkene has a cation-stabilizing substituent like phenyl group, there is an example of the isolation of the bromonium ion 2. Hydrogen halides such as hydrogen chloride adds to alkenes to give alkyl halides in hydrohalogenation, for example, the reaction of Hcl with ethylene furnishes chloroethane. The reaction proceeds with an intermediate, being different from the above halogen addition. An example is shown below, Proton adds to one of the atoms on the alkene to form cation 1. Chloride ion combines with the cation 1 to form the adducts 2 and 3, in this manner, the stereoselectivity of the product, that is, from which side Cl− will attack relies on the types of alkenes applied and conditions of the reaction. At least, which of the two carbon atoms will be attacked by H+ is usually decided by Markovnikovs rule, thus, H+ attacks the carbon atom that carries fewer substituents so as the more stabilized carbocation will form. This process is called A-SE2 mechanism, hydrogen fluoride and hydrogen iodide react with alkenes in a similar manner, and Markovnikov-type products will be given
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Hydrogen bond
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Hydrogen bonds can occur between molecules or within different parts of a single molecule. Depending on geometry and environment, the hydrogen bond free energy content is between 1 and 5 kcal/mol and this makes it stronger than a van der Waals interaction, but weaker than covalent or ionic bonds. This type of bond can occur in molecules such as water and in organic molecules like DNA. Intermolecular hydrogen bonding is responsible for the boiling point of water compared to the other group 16 hydrides that have much weaker hydrogen bonds. Intramolecular hydrogen bonding is responsible for the secondary and tertiary structures of proteins. It also plays an important role in the structure of polymers, in 2011, an IUPAC Task Group recommended a modern evidence-based definition of hydrogen bonding, which was published in the IUPAC journal Pure and Applied Chemistry. An accompanying detailed technical report provides the rationale behind the new definition, a hydrogen atom attached to a relatively electronegative atom will play the role of the hydrogen bond donor. This electronegative atom is usually fluorine, oxygen, or nitrogen, a hydrogen attached to carbon can also participate in hydrogen bonding when the carbon atom is bound to electronegative atoms, as is the case in chloroform, CHCl3. An example of a hydrogen donor is the hydrogen from the hydroxyl group of ethanol. In a hydrogen bond, the electronegative atom not covalently attached to the hydrogen is named proton acceptor, because of the small size of hydrogen relative to other atoms and molecules, the resulting charge, though only partial, represents a large charge density. A hydrogen bond results when this positive charge density attracts a lone pair of electrons on another heteroatom. The hydrogen bond is described as an electrostatic dipole-dipole interaction. These covalent features are more substantial when acceptors bind hydrogens from more electronegative donors, the partially covalent nature of a hydrogen bond raises the following questions, To which molecule or atom does the hydrogen nucleus belong. And Which should be labeled donor and which acceptor, liquids that display hydrogen bonding are called associated liquids. Hydrogen bonds can vary in strength from weak to extremely strong. For example, the central interresidue N−H···N hydrogen bond between guanine and cytosine is much stronger in comparison to the N−H···N bond between the adenine-thymine pair, the length of hydrogen bonds depends on bond strength, temperature, and pressure. The bond strength itself is dependent on temperature, pressure, bond angle, the typical length of a hydrogen bond in water is 197 pm. The ideal bond angle depends on the nature of the hydrogen bond donor, moore and Winmill used the hydrogen bond to account for the fact that trimethylammonium hydroxide is a weaker base than tetramethylammonium hydroxide
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Acetophenone
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Acetophenone is the organic compound with the formula C6H5CCH3. It is the simplest aromatic ketone and this colourless, viscous liquid is a precursor to useful resins and fragrances. Acetophenone can be obtained by a variety of methods, in industry, acetophenone is recovered as a by-product of the oxidation of ethylbenzene, which mainly gives ethylbenzene hydroperoxide for use in the production of propylene oxide. Commercially significant resins are produced from treatment of acetophenone with formaldehyde, the resulting copolymers are conventionally described with the formula n, resulting from aldol condensation. These substances are components of coatings and inks, modified acetophenone-formaldehyde resins are produced by the hydrogenation of the aforementioned ketone-containing resins. The resulting polyol can be further crosslinked with diisocyanates and these modified resins are again found in coatings, inks, as well as adhesives. Acetophenone is an ingredient in fragrances that resemble almond, cherry, honeysuckle, jasmine and it is used in chewing gum. It is also listed as an approved excipient by the U. S. FDA, in a 1994 report released by five top cigarette companies in the U. S. acetophenone was listed as one of the 599 additives to cigarettes. C6H5CHCH3 → C6H5CH=CH2 + H2O Being prochiral, acetophenone is also a popular test substrate for asymmetric hydrogenation experiments, mannich reaction with dimethylamine and formaldehyde was described. This is used to prepare 1-chloro-1-phenyl-3-dimethylaminopropane, which is used to prepare such antidepressants as Ansoxetine, fluoxetine, atomoxetine, using diethylamine instead gives the diethyl analog. Acetophenone occurs naturally in foods including apple, cheese, apricot, banana, beef. It is also a component of castoreum, the exudate from the castor sacs of the mature beaver, in the late 19th and early 20th centuries, acetophenone was used in medicine. It was marketed as a hypnotic and anticonvulsant under brand name Hypnone, the typical dosage was 0.12 to 0.3 milliliters. It was considered to have superior sedative effects to both paraldehyde and chloral hydrate, in humans, acetophenone is metabolized to benzoic acid, carbonic acid, and acetone. Hippuric acid occurs as a metabolite and its quantity in urine may be used to confirm acetophenone exposure, although other substances, like toluene. Studies have shown that acetophenone causes chromosomal damage in hamsters
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Stereochemistry
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Stereochemistry, a subdiscipline of chemistry, involves the study of the relative spatial arrangement of atoms that form the structure of molecules and their manipulation. An important branch of stereochemistry is the study of chiral molecules, stereochemistry is also known as 3D chemistry because the prefix stereo- means three-dimensionality. The study of stereochemistry focuses on stereoisomers and spans the spectrum of organic, inorganic, biological, physical. This property, the physical property in which the two types of tartrate salts differed, is due to optical isomerism. In 1874, Jacobus Henricus van t Hoff and Joseph Le Bel explained optical activity in terms of the arrangement of the atoms bound to carbon. Cahn–Ingold–Prelog priority rules are part of a system for describing a molecules stereochemistry and they rank the atoms around a stereocenter in a standard way, allowing the relative position of these atoms in the molecule to be described unambiguously. A Fischer projection is a way to depict the stereochemistry around a stereocenter. An often cited example of the importance of stereochemistry relates to the thalidomide disaster, thalidomide is a pharmaceutical drug, first prepared in 1957 in Germany, prescribed for treating morning sickness in pregnant women. The drug was discovered to be teratogenic, causing genetic damage to early embryonic growth and development. Some of the proposed mechanisms of teratogenecity involve a different biological function for the -. In the human body however, thalidomide undergoes racemization, even if one of the two enantiomers is administered as a drug, the other enantiomer is produced as a result of metabolism. Accordingly, it is incorrect to state one of the stereoisomer is safe while the other is teratogenic. Thalidomide is currently used for the treatment of diseases, notably cancer. Strict regulations and controls have been enabled to avoid its use by pregnant women and this disaster was a driving force behind requiring strict testing of drugs before making them available to the public. Torsional strain results from resistance to twisting about a bond
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Diketone
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A diketone or dione is a molecule containing two ketone groups. The simplest diketone is diacetyl, also known as 2, 3-butanedione, diacetyl, acetylacetone, and hexane-2, 5-dione are examples of 1, 2-,1, 3-, and 1, 4-diketones, respectively. Dimedone is an example of a cyclic diketone, an important member is biacetyl, CH3CCCH3. These compounds are generated by dehydrogenation of the diols, RCHCHR → RCCR +2 H2 A distinctive feature of 1. This bond distance is about 1.54 Å, compared to 1.45 Å for the bond in 1. The effect is attributed to repulsion between the positive charges of the carbonyl carbon atoms. 1, 2-Diketones condense with many bifunctional nucleophiles, such as urea and thiourea to give heterocycles, upon condensation with aromatic amines, they convert to the diketimine ligands. An important member is acetylacetone, CH3CCH2CCH3, acetylacetone is prepared industrially by the thermal rearrangement of isopropenylacetate. CH2COCMe → MeCCH2CMe Classically,1, 3-diketones are prepared by condensation of ketones with esters,1, 3-Diketones are prone to exist as enols because of conjugation of the enol or enolate with the other carbonyl group, and the stability gained in forming a six-membered ring. Like other diketones,1, 3-diketones are versatile precursors to heterocycles, hydrazine, for example, condenses to give pyrazoles. The conjugate base derived from 1, 3-ketones form coordination complexes, in the DeMayo reaction 1, 3-diketones react with alkenes in a photochemical pericyclic reaction to form 1, 5-diketones. Diketones with two methylene groups separating the groups typically coexist with their enol tautomers. 1, 4-Diketones are useful precursors to heterocycles via the Paal-Knorr Synthesis, which gives furans, pyrroles, the condensation of 1, 4-diketones with hydrazines afford dihydropyridazines, which can be converted to pyridazines. The reactions of diketones where the centers are separated by three or more methylene groups are similar to those of simple ketones. These longer diketones are generally prone to intramolecular aldol condensations, in 2004, the EU conducted an examination of certain flavoring additives grouped together as Flavouring Group Evaluation FGE.11. As part of study, the EU found that acetylacetone was genotoxic in vivo and in vitro. The register of permitted flavoring substances was adopted in 1999
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Diacetyl
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Diacetyl is an organic compound with the chemical formula 2. It is a liquid with an intensely buttery flavor. It is a vicinal diketone with the molecular formula C4H6O2, Diacetyl occurs naturally in alcoholic beverages and is added to some foods to impart its buttery flavor. A distinctive feature of diacetyl is the long C–C bond linking the carbonyl centers and this bond distance is about 1.54 Å, compared to 1.45 Å for the corresponding C–C bond in 1, 3-butadiene. The elongation is attributed to repulsion between the carbonyl carbon centers. Diacetyl arises naturally as a byproduct of fermentation, in some fermentative bacteria, it is formed via the thiamine pyrophosphate-mediated condensation of pyruvate and acetyl CoA. Cultured cream, cultured butter, and cultured buttermilk owe their tart flavour to lactic acid bacteria and their buttery aroma, Diacetyl is produced industrially by dehydrogenation of 2, 3-butanediol. Diacetyl and acetoin are two compounds that give butter its characteristic taste, at low levels, diacetyl contributes a slipperiness to the feel of the alcoholic beverage in the mouth. As levels increase, it imparts a buttery or butterscotch flavor, in some styles of beer, the presence of diacetyl can be acceptable or desirable at low or, in some cases, moderate levels. In other styles, its presence is considered a flaw or undesirable, Diacetyl is produced during fermentation as a byproduct of valine synthesis, when yeast produces α-acetolactate, which escapes the cell and is spontaneously decarboxylated into diacetyl. The yeast then absorbs the diacetyl, and reduces the groups to form acetoin and 2. The makers of some wines, such as chardonnay, deliberately promote the production of diacetyl because of the feel, Diacetyl is present in some chardonnays known as butter bombs, although there is a trend back toward the more traditional French styles. Concentrations from 0.005 mg/L to 1.7 mg/L were measured in chardonnay wines, 1-Hexanol and diacetyl are strong inhibitors of the CO2-sensitive neurons in the Drosophila melanogaster fruit fly and the Culex mosquito, a vector of several deadly diseases. Fruit flies tend to avoid CO2, but exhaled CO2 is the main attractant for the Culex, the United States National Institute for Occupational Safety and Health has suggested diacetyl, when used in artificial butter flavoring, may be hazardous when heated and inhaled over a long period. Workers in several factories that manufacture artificial butter flavoring have been diagnosed with bronchiolitis obliterans, the cases found have been mainly in young, healthy, nonsmoking males. As with other lung diseases, transplantation is currently the most viable treatment option. However, lung transplant rejection is very common and happens to be setting in which bronchiolitis obliterans is known to occur. It has also been called flavorings-related bronchiolitis obliterans or diacetyl-induced bronchiolitis obliterans, in 2006, the International Brotherhood of Teamsters and the United Food and Commercial Workers petitioned the U. S
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Popcorn
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Popcorn is a type of corn that expands from the kernel and puffs up when heated. Popcorn is able to pop like amaranth grain, sorghum, quinoa, when heated, pressure builds within the kernel, and a small explosion is the end result. Some strains of corn are now cultivated specifically as popping corns, there are various techniques for popping corn. Along with prepackaged popcorn, which is intended to be prepared in a microwave oven. These methods require the use of minimally processed popping corn, a larger-scale, commercial popcorn machine, which resembled a modern movie theater popcorn machine on a cart with large bicycle style wheels, was invented by Charles Cretors in the late 19th century. Unpopped popcorn is considered nonperishable and will last indefinitely if stored in ideal conditions, depending on how it is prepared and cooked, some consider popcorn to be a health food, while others caution against it for a variety of reasons. Popcorn can also have applications, ranging from holiday decorations to packaging materials. Corn was first domesticated in Mexico 9,000 years ago, archaeologists have discovered that people have known about popcorn for thousands of years. In Mexico, for example, they’ve found remnants of popcorn that dates to around 3600 BC, popping of the kernels was achieved manually through the 19th century, being sold on the east coast of the USA under names such as Pearls or Nonpareil. The term popped corn first appeared in John Russell Bartlett’s 1848 Dictionary of Americanisms, Popcorn is an ingredient in Cracker Jack, and in the early years of the product, it was popped by hand. Popcorns accessibility increased rapidly in the 1890s with Charles Cretors invention of the popcorn maker, Cretors, a Chicago candy store owner, created a number of steam powered machines for roasting nuts, and applied the technology to the corn kernels. By the turn of the century, Cretors had created and deployed street carts equipped with steam powered popcorn makers, during the Great Depression, popcorn was fairly inexpensive at 5–10 cents a bag and became popular. Thus, while businesses failed, the popcorn business thrived and became a source of income for many struggling farmers, including the Redenbacher family. During World War II, sugar rations diminished candy production, the snack was popular at theaters, much to the initial displeasure of many of the theater owners, who thought it distracted from the films. Their minds eventually changed, however, and in 1938 a Midwestern theater owner named Glen W. Dickson installed popcorn machines in the lobbies of his theaters, the venture was a financial success, and the trend soon spread. In 1970, Orville Redenbachers namesake brand of popcorn was launched, in 1981, General Mills received the first patent for a microwave popcorn bag, with popcorn consumption seeing a sharp increase by tens of thousands of pounds in the years following. At least six localities claim to be the Popcorn Capital of the World, Ridgway, Illinois, Valparaiso, Indiana, Van Buren, Indiana, Schaller, Iowa, Marion, Ohio, and North Loup, Nebraska. According to the USDA, corn used for production is specifically planted for this purpose, most is grown in Nebraska and Indiana
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Alkene
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In organic chemistry, an alkene is an unsaturated hydrocarbon that contains at least one carbon–carbon double bond. The words alkene, olefin, and olefine are used often interchangeably, acyclic alkenes, with only one double bond and no other functional groups, known as mono-enes, form a homologous series of hydrocarbons with the general formula CnH2n. Alkenes have two hydrogen atoms less than the corresponding alkane, the simplest alkene, ethylene, with the International Union of Pure and Applied Chemistry name ethene, is the organic compound produced on the largest scale industrially. Aromatic compounds are drawn as cyclic alkenes, but their structure and properties are different. This double bond is stronger than a single covalent bond and also shorter, each carbon of the double bond uses its three sp2 hybrid orbitals to form sigma bonds to three atoms. The unhybridized 2p atomic orbitals, which lie perpendicular to the created by the axes of the three sp² hybrid orbitals, combine to form the pi bond. This bond lies outside the main C–C axis, with half of the bond on one side of the molecule, rotation about the carbon–carbon double bond is restricted because it incurs an energetic cost to break the alignment of the p orbitals on the two carbon atoms. As a consequence, substituted alkenes may exist as one of two isomers, called cis or trans isomers, more complex alkenes may be named with the E–Z notation for molecules with three or four different substituents. For example, of the isomers of butene, the two groups of -but-2-ene appear on the same side of the double bond, and in -but-2-ene the methyl groups appear on opposite sides. These two isomers of butene are slightly different in their chemical and physical properties, a 90° twist of the C=C bond requires less energy than the strength of a pi bond, and the bond still holds. This contradicts a common assertion that the p orbitals would be unable sustain such a bond. In truth, the misalignment of the p orbitals is less than expected because pyramidalization takes place, trans-Cyclooctene is a stable strained alkene and the orbital misalignment is only 19° with a dihedral angle of 137° and a degree of pyramidalization of 18°. The trans isomer of cycloheptene is stable only at low temperatures, as predicted by the VSEPR model of electron pair repulsion, the molecular geometry of alkenes includes bond angles about each carbon in a double bond of about 120°. The angle may vary because of steric strain introduced by nonbonded interactions between groups attached to the carbons of the double bond. For example, the C–C–C bond angle in propylene is 123. 9°, for bridged alkenes, Bredts rule states that a double bond cannot occur at the bridgehead of a bridged ring system unless the rings are large enough. The physical properties of alkenes and alkanes are similar and they are colourless, nonpolar, combustable, and almost odorless. The physical state depends on mass, like the corresponding saturated hydrocarbons, the simplest alkenes, ethene, propene. Linear alkenes of approximately five to sixteen carbons are liquids, Alkenes are relatively stable compounds, but are more reactive than alkanes, either because of the reactivity of the carbon–carbon pi-bond or the presence of allylic CH centers
