1.
Isocyanide
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An isocyanide is an organic compound with the functional group -N≡C. It is the isomer of the cyanide, hence the prefix iso. The organic fragment is connected to the group via the nitrogen atom. They are used as building blocks for the synthesis of other compounds, the C-N distance in isocyanides is very short,1.158 Å in methyl isocyanide. The C-N-C angles are near 180°, akin to carbon monoxide, isocyanides are described by two resonance structures, one with a triple bond between the nitrogen and the carbon and one with a double bond between. Surprisingly, the one, with a carbenic character is the more important. Nevertheless, the π lone pair of the nitrogen, responsible of the zwitterionic structure, isocyanides are best shown as a mixture of both resonance structures. 5 Hz for the isocyanide 13C nucleus and 5–14 Hz for the 13C nucleus which the group is attached to. To quote from Lieke, Es besitzt einen penetranten, höchst unangenehmen Geruch, das Oeffnen eines Gefässes mit Cyanallyl reicht hin, note that in Liekes day, the difference between isocyanide and nitrile was not fully appreciated. Ivar Karl Ugi states that The development of the chemistry of isocyanides has probably suffered, through the characteristic odor of volatile isonitriles, which has been described by Hofmann and Gautier as highly specific, almost overpowering, horrible, and extremely distressing. It is true that many workers in this field have been turned away by the odour. Isocyanides have been investigated as potential non-lethal weapons, some isocyanides convey less offensive odours such as malt, natural rubber, creosote, mild cherry or old wood. Non-volatile derivatives such as tosylmethyl isocyanide do not have objectionable odors, while some isocyanides are toxic, others exhibit no appreciable toxicity for mammals. Referring to ethyl isocyanide, toxicological studies in the 1960s at Bayer showed that oral, the first isocyanide, allyl isocyanide, was reported in 1859 by the chemist Lieke from the reaction of allyl iodide and silver cyanide. Normally the alkylation of a metal cyanide gives a nitrile. Commonly, isocyanides are synthesized by dehydration of a formamide, the formamide can be dehydrated with phosphorus oxychloride, phosgene, diphosgene, or the Burgess Reagent. RNHCH + POCl3 → RNC + PO2Cl +2 HCl In the carbylamine reaction potassium hydroxide reacts with chloroform to produce dichlorocarbene and this then converts primary amines to isocyanides. As it is effective for primary amines it is used as a chemical test for their presence
2.
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
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.
Polyol
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A polyol is an alcohol containing multiple hydroxyl groups. In two different technological disciplines the term polyol has a meaning, food science and polymer chemistry. They are also added to chewing gum because they are not broken down by bacteria in the mouth or metabolized to acids, maltitol, sorbitol, xylitol, erythritol, and isomalt are some of the more common types. Sugar alcohols may be formed under reducing conditions from their analogue sugars. In polymer chemistry, polyols are compounds with multiple functional groups available for organic reactions. A molecule with two groups is a diol, one with three is a triol, one with four is a tetrol and so on. Monomeric polyols such as glycerin, pentaerythritol, ethylene glycol and sucrose often serve as the point for polymeric polyols. These materials are referred to as the initiators and reacted with propylene oxide or ethylene oxide to produce polymeric polyols. However, they should not be confused with radical initiators used to promote other polymerization reactions. The functional group used as the point for a polymeric polyol need not be a hydroxyl group. A primary amino group often functions as the point for two polymeric chains, especially in the case of polyether polyols. Polymeric polyols are used to produce other polymers. They are reacted with isocyanates to make polyurethanes used to make mattresses, foam insulation for appliances, home and automotive seats, elastomeric shoe soles, fibers, polymeric polyols are usually polyethers or polyesters. Common polyether diols are polyethylene glycol, polypropylene glycol, and poly glycol, the examples shown below are fairly low molecular weight triols based on glycerin being reacted with propylene oxide, ethylene oxide or a combination of the two. In reality, the chains would not be of length in any one molecule. Polyether polyols account for about 90% of the polymeric polyols used industrially, another class of polymeric polyols is the polyesters. Polyesters are formed by condensation or step-growth polymerization of diols and dicarboxylic acids, alternatively, the hydroxyl group and the carboxylic acid may be within the same molecule, as in the case of caprolactone. The example below is a structure that could be obtained by reacting pentaerythritol with gamma-butyrolactone
5.
Polyurethane
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Polyurethane is a polymer composed of organic units joined by carbamate links. While most polyurethanes are thermosetting polymers that do not melt when heated, polyurethane polymers are traditionally and most commonly formed by reacting a di- or polyisocyanate with a polyol. Both the isocyanates and polyols used to make polyurethanes contain, on average, some noteworthy recent efforts have been dedicated to minimizing the use of isocyanates to synthesize polyurethanes, because the isocyanates raise severe toxicity issues. Non-isocyanate based polyurethanes have recently developed as a new class of polyurethane polymers to mitigate health. Polyurethane products often are simply called “urethanes”, but should not be confused with ethyl carbamate, polyurethanes neither contain nor are produced from ethyl carbamate. Otto Bayer and his coworkers at IG Farben in Leverkusen, Germany, the new polymers had some advantages over existing plastics that were made by polymerizing olefins or by polycondensation, and were not covered by patents obtained by Wallace Carothers on polyesters. Early work focused on the production of fibres and flexible foams, polyisocyanates became commercially available in 1952, and production of flexible polyurethane foam began in 1954 using toluene diisocyanate and polyester polyols. These materials were used to produce rigid foams, gum rubber. Linear fibers were produced from hexamethylene diisocyanate and 1, 4-butanediol, in 1956 DuPont introduced polyether polyols, specifically poly glycol, and BASF and Dow Chemical started selling polyalkylene glycols in 1957. Polyether polyols were cheaper, easier to handle and more water-resistant than polyester polyols, union Carbide and Mobay, a U. S. Monsanto/Bayer joint venture, also began making polyurethane chemicals. In 1960 more than 45,000 metric tons of flexible polyurethane foams were produced, in 1967, urethane-modified polyisocyanurate rigid foams were introduced, offering even better thermal stability and flammability resistance. During the 1960s, automotive interior safety components, such as instrument, in 1969, Bayer exhibited an all-plastic car in Düsseldorf, Germany. Further increases in stiffness were obtained by incorporating pre-placed glass mats into the RIM mold cavity, also known broadly as resin injection molding, polyurethane foams are now used in high-temperature oil filter applications. Polyurethane foam is made using small amounts of blowing agents to give less dense foam. In the early 1990s, because of their impact on ozone depletion, polyurethanes are in the class of compounds called reaction polymers, which include epoxies, unsaturated polyesters, and phenolics. The properties of a polyurethane are greatly influenced by the types of isocyanates, long, flexible segments, contributed by the polyol, give soft, elastic polymer. High amounts of crosslinking give tough or rigid polymers, the crosslinking present in polyurethanes means that the polymer consists of a three-dimensional network and molecular weight is very high. In some respects a piece of polyurethane can be regarded as one giant molecule, one consequence of this is that typical polyurethanes do not soften or melt when they are heated, they are thermosetting polymers
6.
Polymer
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A polymer is a large molecule, or macromolecule, composed of many repeated subunits. Because of their range of properties, both synthetic and natural polymers play an essential and ubiquitous role in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure, Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. The units composing polymers derive, actually or conceptually, from molecules of low molecular mass. The term was coined in 1833 by Jöns Jacob Berzelius, though with a distinct from the modern IUPAC definition. The modern concept of polymers as covalently bonded macromolecular structures was proposed in 1920 by Hermann Staudinger, Polymers are studied in the fields of biophysics and macromolecular science, and polymer science. Polyisoprene of latex rubber is an example of a polymer. In biological contexts, essentially all biological macromolecules—i. e, proteins, nucleic acids, and polysaccharides—are purely polymeric, or are composed in large part of polymeric components—e. g. Isoprenylated/lipid-modified glycoproteins, where small molecules and oligosaccharide modifications occur on the polyamide backbone of the protein. The simplest theoretical models for polymers are ideal chains, Polymers are of two types, Natural polymeric materials such as shellac, amber, wool, silk and natural rubber have been used for centuries. A variety of natural polymers exist, such as cellulose. Most commonly, the continuously linked backbone of a used for the preparation of plastics consists mainly of carbon atoms. A simple example is polyethylene, whose repeating unit is based on ethylene monomer, however, other structures do exist, for example, elements such as silicon form familiar materials such as silicones, examples being Silly Putty and waterproof plumbing sealant. Oxygen is also present in polymer backbones, such as those of polyethylene glycol, polysaccharides. Polymerization is the process of combining many small molecules known as monomers into a covalently bonded chain or network, during the polymerization process, some chemical groups may be lost from each monomer. This is the case, for example, in the polymerization of PET polyester, the distinct piece of each monomer that is incorporated into the polymer is known as a repeat unit or monomer residue. Laboratory synthetic methods are divided into two categories, step-growth polymerization and chain-growth polymerization. However, some methods such as plasma polymerization do not fit neatly into either category
7.
Cyanate
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The cyanate ion is an anion with the chemical formula written as − or −. In aqueous solution it acts as a base, forming isocyanic acid, the cyanate ion is an ambidentate ligand, forming complexes with a metal ion in which either the nitrogen or oxygen atom may be the electron-pair donor. It can also act as a bridging ligand, organic cyanates are called isocyanates when there is a C−NCO bond and cyanates when there is a C−OCN bond. The three atoms in a cyanate ion lie on a line, giving the ion a linear structure. The electronic structure is described most simply as, Ö̤−C≡N, with a single C−O bond, the infrared spectrum of a cyanate salt has a band at ca.2096 cm−1, such a high frequency is characteristic of a triple bond. The cyanate ion is a Lewis base, both the oxygen and nitrogen atoms carry a lone pair of electrons and either one or the other, or both can be donated to Lewis acid acceptors. It can be described as an ambidentate ligand, isocyanic acid, HNCO, is produced when a cyanate salt is acidified. In valence bond theory the canonical form HN+≡C-O− is the contributor to the resonance hybrid. The pure compound has a point of −86.8 °C. In aqueous solution it is a weak acid, HNCO ⇌ H+ + NCO−, pKa ≈3.7. On heating isocyanic acid is converted to the cyanuric acid. In the reverse of the synthesis of urea by Friedrich Wöhler, OC2 → HNCO + NH3 isocyanic acid is produced. The vibrational spectrum is indicative of the presence of a bond between the nitrogen and carbon atoms. Sodium cyanate is isostructural with sodium fulminate, confirming the structure of the cyanate ion. It is made industrially by heating a mixture of sodium carbonate, na2CO3 +2 OC2 →2 NaNCO + CO2 +2 NH3 + H2O A similar reaction is used to make potassium cyanate. Cyanates are produced when cyanides are oxidized, use of this fact is made in cyanide decontamination processes where oxidants such as permanganate and hydrogen peroxide are used to convert toxic cyanide to safer cyanate. Cyanate is a ligand which can donate the pair of electrons on the nitrogen atom or the oxygen atom. Structurally the isomers can be distinguished by the geometry of the complex, in N-bonded cyanate complexes the M−NCO unit has a linear structure, but with O-bonded cyanate the M−O−C unit is bent
8.
Amine
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In organic chemistry, amines are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group, important amines include amino acids, biogenic amines, trimethylamine, and aniline, see Category, Amines for a list of amines. Inorganic derivatives of ammonia are also called amines, such as chloramine, see Category, compounds with a nitrogen atom attached to a carbonyl group, thus having the structure R–CO–NR′R″, are called amides and have different chemical properties from amines. An aliphatic amine has no aromatic ring attached directly to the nitrogen atom, aromatic amines have the nitrogen atom connected to an aromatic ring as in the various anilines. The aromatic ring decreases the alkalinity of the amine, depending on its substituents, the presence of an amine group strongly increases the reactivity of the aromatic ring, due to an electron-donating effect. Amines are organized into four subcategories, Primary amines — Primary amines arise when one of three atoms in ammonia is replaced by an alkyl or aromatic. Important primary alkyl amines include, methylamine, most amino acids, Secondary amines — Secondary amines have two organic substituents bound to the nitrogen together with one hydrogen. Important representatives include dimethylamine, while an example of an aromatic amine would be diphenylamine, tertiary amines — In tertiary amines, nitrogen has three organic substituents. Examples include trimethylamine, which has a fishy smell. Cyclic amines — Cyclic amines are either secondary or tertiary amines, examples of cyclic amines include the 3-membered ring aziridine and the six-membered ring piperidine. N-methylpiperidine and N-phenylpiperidine are examples of tertiary amines. It is also possible to have four organic substituents on the nitrogen and these species are not amines but are quaternary ammonium cations and have a charged nitrogen center. Quaternary ammonium salts exist with many kinds of anions, Amines are named in several ways. Typically, the compound is given the prefix amino- or the suffix, the prefix N- shows substitution on the nitrogen atom. An organic compound with multiple amino groups is called a diamine, triamine, tetraamine, systematic names for some common amines, Hydrogen bonding significantly influences the properties of primary and secondary amines. Thus the melting point and boiling point of amines is higher than those of the corresponding phosphines, for example, methyl and ethyl amines are gases under standard conditions, whereas the corresponding methyl and ethyl alcohols are liquids. Amines possess a characteristic smell, liquid amines have a distinctive fishy smell. The nitrogen atom features a lone pair that can bind H+ to form an ammonium ion R3NH+
9.
Phosgene
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Phosgene is the chemical compound with the formula COCl2. This colorless gas gained infamy as a weapon during World War I where it was responsible for about 85% of the 100,000 deaths caused by chemical weapons. It is also a valued industrial reagent and building block in synthesis of pharmaceuticals, in low concentrations, its odor resembles freshly cut hay or grass. In addition to its production, small amounts occur from the breakdown. The chemical was named by combining the Greek words phos and genesis, Phosgene is a planar molecule as predicted by VSEPR theory. The C=O distance is 1.18 Å, the C−Cl distance is 1.74 Å and it is one of the simplest acid chlorides, being formally derived from carbonic acid. Typically, the reaction is conducted between 50 and 150 °C, above 200 °C, phosgene reverts to carbon monoxide and chlorine, Keq =0.05. World production of this compound was estimated to be 2.74 million tonnes in 1989, because of safety issues, phosgene is often produced and consumed within the same plant, and extraordinary measures are made to contain this toxic gas. It is listed on schedule 3 of the Chemical Weapons Convention, upon ultraviolet radiation in the presence of oxygen, chloroform slowly converts into phosgene by a radical reaction. To suppress this photodegradation, chloroform is often stored in brown-tinted glass containers, chlorinated compounds used to remove oil from metals, such as automotive brake cleaners, are converted to phosgene by the UV rays of arc welding processes. Phosgene may also be produced during testing for leaks of older-style refrigerant gases, chloromethanes were formerly leak-tested in situ by employing a small gas torch with a sniffer tube and a copper reaction plate in the flame nozzle of the torch. If any refrigerant gas was leaking from a pipe or joint, in the process, phosgene gas would be created due to the thermal reaction. Electronic sensing of refrigerant gases phased out the use of testing for leaks in the 1980s. Phosgene can be released during building fires, in one instance, a deputy fire chief was killed ten days after inhaling fumes that wafted down outside a burning restaurant. After a two-day hospitalization he had appeared to recover, but ultimately suffered cardiac arrest at home following from tracheobronchial inflammation, alveolar hemorrhage, the phosgene was produced by decomposing freon-22 after flames ducted up from a grease fire heated an air-conditioning unit on the roof and ruptured a hose. The great majority of phosgene is used in the production of isocyanates and these two isocyanates are precursors to polyurethanes. In the research laboratory phosgene still finds limited use in organic synthesis, a variety of substitutes have been developed, notably trichloromethyl chloroformate, a liquid at room temperature, and bis carbonate, a crystalline substance. Thionyl chloride is commonly and more safely employed for this application
10.
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
11.
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
12.
Alcohol
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In chemistry, an alcohol is any organic compound in which the hydroxyl functional group is bound to a saturated carbon atom. The term alcohol originally referred to the alcohol ethanol, the predominant alcohol in alcoholic beverages. The suffix -ol in non-systematic names also typically indicates that the substance includes a functional group and, so. But many substances, particularly sugars contain hydroxyl functional groups without using the suffix, an important class of alcohols, of which methanol and ethanol are the simplest members is the saturated straight chain alcohols, the general formula for which is CnH2n+1OH. The word alcohol is from the Arabic kohl, a used as an eyeliner. Al- is the Arabic definite article, equivalent to the in English, alcohol was originally used for the very fine powder produced by the sublimation of the natural mineral stibnite to form antimony trisulfide Sb 2S3, hence the essence or spirit of this substance. It was used as an antiseptic, eyeliner, and cosmetic, the meaning of alcohol was extended to distilled substances in general, and then narrowed to ethanol, when spirits as a synonym for hard liquor. Bartholomew Traheron, in his 1543 translation of John of Vigo, Vigo wrote, the barbarous auctours use alcohol, or alcofoll, for moost fine poudre. The 1657 Lexicon Chymicum, by William Johnson glosses the word as antimonium sive stibium, by extension, the word came to refer to any fluid obtained by distillation, including alcohol of wine, the distilled essence of wine. Libavius in Alchymia refers to vini alcohol vel vinum alcalisatum, Johnson glosses alcohol vini as quando omnis superfluitas vini a vino separatur, ita ut accensum ardeat donec totum consumatur, nihilque fæcum aut phlegmatis in fundo remaneat. The words meaning became restricted to spirit of wine in the 18th century and was extended to the class of substances so-called as alcohols in modern chemistry after 1850, the term ethanol was invented 1892, based on combining the word ethane with ol the last part of alcohol. In the IUPAC system, in naming simple alcohols, the name of the alkane chain loses the terminal e and adds ol, e. g. as in methanol and ethanol. When necessary, the position of the group is indicated by a number between the alkane name and the ol, propan-1-ol for CH 3CH 2CH 2OH, propan-2-ol for CH 3CHCH3. If a higher priority group is present, then the prefix hydroxy is used, in other less formal contexts, an alcohol is often called with the name of the corresponding alkyl group followed by the word alcohol, e. g. methyl alcohol, ethyl alcohol. Propyl alcohol may be n-propyl alcohol or isopropyl alcohol, depending on whether the group is bonded to the end or middle carbon on the straight propane chain. As described under systematic naming, if another group on the molecule takes priority, Alcohols are then classified into primary, secondary, and tertiary, based upon the number of carbon atoms connected to the carbon atom that bears the hydroxyl functional group. The primary alcohols have general formulas RCH2OH, the simplest primary alcohol is methanol, for which R=H, and the next is ethanol, for which R=CH3, the methyl group. Secondary alcohols are those of the form RRCHOH, the simplest of which is 2-propanol, for the tertiary alcohols the general form is RRRCOH
13.
Carbamate
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A carbamate is an organic compound derived from carbamic acid. A carbamate group, carbamate ester, and carbamic acids are functional groups that are inter-related structurally, carbamate esters are also called urethanes. Carbamic acids are derived from amines, R2NH + CO2 → R2NCO2H Carbamic acid is about as acidic as acetic acid, n-terminal amino groups of valine residues in the α- and β-chains of deoxyhemoglobin exist as carbamates. They help to stabilise the protein, when it becomes deoxyhemoglobin and this stabilizing effect should not be confused with the Bohr effect. The ε-amino groups of the residues in urease and phosphotriesterase also feature carbamate. The carbamate derived from aminoimidazole is an intermediate in the biosynthesis of inosine, carbamoyl phosphate is generated from carboxyphosphate rather than CO2. Perhaps the most important carbamate is the one involved in the capture of CO2 by plants since this process is necessary for their growth, the enzyme ribulose 1, 5-bisphosphate carboxylase/oxygenase fixes a molecule of carbon dioxide as phosphoglycerate in the Calvin cycle. At the active site of the enzyme, a Mg2+ ion is bound to glutamate and aspartate residues as well as a lysine carbamate. The carbamate is formed when an uncharged lysine side chain near the ion reacts with a carbon dioxide molecule from the air, which renders it charged. The so-called carbamate insecticides feature the carbamate ester functional group, included in this group are aldicarb, carbofuran, carbaryl, ethienocarb, fenobucarb, oxamyl, and methomyl. These insecticides kill insects by reversibly inactivating the enzyme acetylcholinesterase, the organophosphate pesticides also inhibit this enzyme, although irreversibly, and cause a more severe form of cholinergic poisoning. Fenoxycarb has a group but acts as a juvenile hormone mimic. The insect repellent icaridin is a substituted carbamate, polyurethanes contain multiple carbamate groups as part of their structure. The urethane in the name refers to these carbamate groups. In contrast, the commonly called urethane, ethyl carbamate, is neither a component of polyurethanes. Urethanes are usually formed by reaction of an alcohol with an isocyanate, commonly, urethanes made by a non-isocyanate route are called carbamates. Polyurethane polymers have a range of properties and are commercially available as foams, elastomers. Typically, polyurethane polymers are made by combining diisocyanates, e. g. Urethane was once produced commercially in the United States as an antineoplastic agent and it was found to be toxic and largely ineffective
14.
Alkyl
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In organic chemistry, an alkyl substituent is an alkane missing one hydrogen. The term alkyl is intentionally unspecific to include many possible substitutions, an acyclic alkyl has the general formula CnH2n+1. A cycloalkyl is derived from a cycloalkane by removal of an atom from a ring and has the general formula CnH2n-1. Typically an alkyl is a part of a larger molecule, in structural formula, the symbol R is used to designate a generic alkyl group. The smallest alkyl group is methyl, with the formula CH3−, the word root alkyl is encountered in several contexts. Alkylation is an important operation in refineries, for example in the production of high-octane gasoline, alkylating antineoplastic agents refer to a class of compounds that are used to treat cancer. In such case, the alkyl is used loosely. For example, nitrogen mustards are well-known alkylating agents, but they are more complex than a mere hydrocarbon, in chemistry, alkyl refers to a group, a substituent, that is attached to other molecular fragments. For example, alkyl lithium reagents have the empirical formula Li, a dialkyl ether is an ether with two alkyl groups, e. g. diethyl ether. In medicinal chemistry, the incorporation of alkyl chains into some chemical compounds increases their lipophilicity and this strategy has been used to increase the antimicrobial activity of flavanones and chalcones. Usually alkyl groups are attached to atoms or groups of atoms. Free alkyls occur as neutral compounds, as anions, or as cations, the neutral alkyl free radicals have no special name. Such species are encountered only as transient intermediates, but some are quite stable. Typically alkyl cations are generated using super acids, alkyl anions are observed in the presence of strong bases, alkyls are commonly observed in mass spectrometry of organic compounds. The simplest series have the general formula CnH2n+1, alkyls include methyl, CH3·, ethyl, propyl, butyl, pentyl, and so on. Alkyl groups that one ring have the formula CnH2n−1, e. g. cyclopropyl and cyclohexyl. First, five atoms comprise the longest straight chain of carbon centers, the parent five-carbon compound is named pentane. The methyl substituent or group is highlighted red, according to the usual rules of nomenclature, alkyl groups are included in the name of the molecule before the root, as in methylpentane
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Aryl
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In the context of organic molecules, aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, be it phenyl, naphthyl, thienyl, indolyl, etc. Aryl is used for the sake of abbreviation or generalization, a simple aryl group is phenyl, C6H5, it is derived from benzene. The tolyl group, CH3C6H4, is derived from toluene, the xylyl group, 2C6H3, is derived from xylene, while the naphthyl group, C10H7, is derived from naphthalene. Arylation is a process in which an aryl group is attached to a substituent. Alkyl Aryl hydrocarbon receptor, a target for dioxins Arene compound
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Diol
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A diol is a chemical compound containing two hydroxyl groups. This pairing of groups is pervasive, and many subcategories have been identified. The most common industrial diol is ethylene glycol, a geminal diol has two hydroxyl groups bonded to the same atom. These species arise by hydration of the carbonyl compounds, the hydration is usually unfavorable, but a notable exception is formaldehyde which, in water, exists in equilibrium with methanediol H2C2. Another example is 2C2, the form of hexafluoroacetone, in this case the hydration is made favorable by the electron-withdrawing trifluoromethyl groups. In a vicinal diol, the two hydroxyl groups occupy vicinal positions, that is, they are attached to adjacent atoms, examples include 1, 2-ethanediol or ethylene glycol HO−2−OH, a common ingredient of antifreeze products. Another example is propane-1, 2-diol, or alpha propylene glycol, HO−CH2−CH−CH3, used in the food and medicine industry, on commercial scales, the main route to vicinal diols is the hydrolysis of epoxides. The epoxides are prepared by oxidation with hydrogen peroxide of the alkene, using alkaline potassium manganate produces a colour change from clear deep purple to clear green, acidic potassium manganate turns clear colourless. Osmium tetroxide can similarly be used to oxidize alkenes to vicinal diols, the chemical reaction called Sharpless asymmetric dihydroxylation can be used to produce chiral diols from alkenes using an osmate reagent and a chiral catalyst. Another method is the Woodward cis-hydroxylation and the related Prévost reaction, depicted below,1, 3-Diols are often prepared industrially by aldol condensation of ketones with formaldehyde. Examples include 2-methyl-2-propyl-1, 3-propanediol and neopentyl glycol,1, 3-Diols can be prepared by hydration of α, β-unsaturated ketones and aldehydes. Another route involves the hydroformylation of epoxides followed by hydrogenation of the aldehyde and this method has been used for 1, 3-propanediol from ethylene oxide. More specialized routes to 1, 3-diols involves the reaction between an alkene and formaldehyde, the Prins reaction,1, 3-diols can be produced diastereoselectively from the corresponding β-hydroxy ketones using the Evans–Saksena, Narasaka–Prasad or Evans–Tishchenko reduction protocols. Diols where the groups are separated by several carbon centers are generally prepared by hydrogenation of diesters of the corresponding dicarboxylic acids. 1, 4-butanediol and 1, 5-pentanediol are important precursors to polyurethanes, n2 +4 H2 → n2 +2 H2O Bisphenol A is an important compound that contains two phenol groups. It is a block in the production of polycarbonate plastics. It is produced by condensation of phenol and acetone, from the industrial perspective, the dominant reactions of the diols is in the production of polyurethanes and alkyd resins. Diols react as alcohols, by esterification and ether formation, diols such as ethylene glycol are used as co-monomers in polymerization reactions forming polymers including some polyesters and polyurethanes
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Urea
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Urea, also known as carbamide, is an organic compound with the chemical formula CO2. This amide has two groups joined by a carbonyl functional group. Urea serves an important role in the metabolism of nitrogen-containing compounds by animals and is the main nitrogen-containing substance in the urine of mammals and it is a colorless, odorless solid, highly soluble in water, and practically non-toxic. Dissolved in water, it is neither acidic nor alkaline, the body uses it in many processes, most notably nitrogen excretion. The liver forms it by combining two molecules with a carbon dioxide molecule in the urea cycle. Urea is widely used in fertilizers as a source of nitrogen and is an important raw material for the chemical industry, Friedrich Wöhlers discovery in 1828 that urea can be produced from inorganic starting materials was an important conceptual milestone in chemistry. More than 90% of world production of urea is destined for use as a nitrogen-release fertilizer. Urea has the highest nitrogen content of all solid nitrogenous fertilizers in common use, therefore, it has the lowest transportation costs per unit of nitrogen nutrient. The standard crop-nutrient rating of urea is 46-0-0, many soil bacteria possess the enzyme urease, which catalyzes conversion of urea to ammonia or ammonium ion and bicarbonate ion. Thus urea fertilizers rapidly transform to the form in soils. Ammonium and nitrate are readily absorbed by plants, and are the dominant sources of nitrogen for plant growth, Urea is also used in many multi-component solid fertilizer formulations. Urea is highly soluble in water and is also very suitable for use in fertilizer solutions. For fertilizer use, granules are preferred over prills because of their particle size distribution. The most common impurity of synthetic urea is biuret, which impairs plant growth, Urea is usually spread at rates of between 40 and 300 kg/ha but rates vary. Smaller applications incur lower losses due to leaching, during summer, urea is often spread just before or during rain to minimize losses from volatilization. Because of the nitrogen concentration in urea, it is very important to achieve an even spread. The application equipment must be calibrated and properly used. Drilling must not occur on contact with or close to seed, Urea dissolves in water for application as a spray or through irrigation systems
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Polyurea
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Polyurea is a type of elastomer that is derived from the reaction product of an isocyanate component and a synthetic resin blend component through step-growth polymerization. The isocyanate can be aromatic or aliphatic in nature and it can be monomer, polymer, or any variant reaction of isocyanates, quasi-prepolymer or a prepolymer. The prepolymer, or quasi-prepolymer, can be made of a polymer resin. The resin blend may be made up of amine-terminated polymer resins, the amine-terminated polymer resins will not have any intentional hydroxyl moieties. Any hydroxyls are the result of conversion to the amine-terminated polymer resins. The resin blend may contain additives, or non-primary components. These additives may contain hydroxyls, such as pre-dispersed pigments in a polyol carrier, normally, the resin blend will not contain a catalyst. The word polyurea is derived from the Greek words πολυ- - poly- meaning many, the latter term refers to the substance urea, found in urine, rather than urine itself. Urea or carbamide is a compound with the chemical formula 2CO. The molecule has two groups joined by a carbonyl functional group. In a polyurea, alternating monomer units of isocyanates and amines react with other to form urea linkages. Ureas can also be formed from the reaction of isocyanates and water which forms a carbamic acid intermediate and this acid quickly decomposes by splitting off carbon dioxide and leaving behind an amine. This amine then reacts with another group to form the polyurea linkage. This two step reaction is used in what is commonly but improperly called polyurethane foams, the carbon dioxide that is liberated in this reaction is the primary blowing agent especially in many polyurethane foams which more precisely should be called polyurethane/urea foams. Polyurea and polyurethane are copolymers used in the manufacture of spandex, excellent adhesion to concrete and steel is obtained with the proper primer and surface treatment. They can also be used for molding and armor. Some polyureas reach strengths of 6000psi tensile and over 500% elongation making it a tough coating, the quick cure time allows many coats to be built up quickly. In 2014 a polyurea elastomer-based material was shown to be self-healing, melding together after being cut in half, the material also includes inexpensive commercially available compounds
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Aliphatic compound
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In organic chemistry, hydrocarbons are divided into two classes, aromatic compounds and aliphatic compounds also known as non-aromatic compounds. Aliphatics can be cyclic, but only aromatic compounds contain an especially stable ring of atoms, aliphatic compounds can be saturated, like Hexane, or unsaturated, like Hexene and Hexyne. Open-chain compounds contain no rings of any type, and are thus aliphatic, aliphatic compounds can be saturated, joined by single bonds, or unsaturated, with double bonds or triple bonds. Besides hydrogen, other elements can be bound to the chain, the most common being oxygen, nitrogen, sulfur. The least complex aliphatic compound is methane, most aliphatic compounds are flammable, allowing the use of hydrocarbons as fuel, such as methane in Bunsen burners and as liquefied natural gas, and acetylene in welding. The most important aliphatic compounds are, n-, iso- and cyclo-alkanes n-, iso- and cyclo-alkenes and -alkynes
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Trimer (chemistry)
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In chemistry, a trimer is an oligomer derived from three identical precursors. An example is the procedure of production of polymers, at first, a monomer is made. By combining two monomers, a dimer is produced, with further additions, a trimer and eventually a polymer is made. Chemical compounds that often trimerise are aliphatic isocyanates and cyanic acids, in 1866, Marcellin Berthelot reported the first example of cyclotrimerization leading to aromatic products, the cyclization of acetylene to benzene. In the Reppe synthesis, the trimerization of acetylene gives benzene, Symmetrical 1,3, the conversion commences at approximately 175 °C,3 H2N-CO-NH2 →3 +3 NH3 The endothermic synthesis of melamine can be understood in two steps. 3 HOCN →33 +3 NH3 → C3H6N6 +3 H2O This water then reacts with cyanic acid present, which helps drive the trimerization reaction, generating carbon dioxide and ammonia. 3 HOCN +3 H2O →3 CO2 + 3NH3 In total, cyclotrimerization of formaldehyde affords 1,3, 5-Trioxane,1,3, 5-Trithiane is the cyclic trimer of the otherwise unstable species thioformaldehyde. This heterocycle consists of a ring with alternating methylene bridges. It is prepared by treatment of formaldehyde with hydrogen sulfide, three molecules of acetaldehyde condense to form “paraldehyde, ” a cyclic trimer containing C-O single bonds
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Cyanuric acid
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Cyanuric acid or 1,3, 5-triazine-2,4, 6-triol is a chemical compound with the formula 3. Like many industrially useful chemicals, this triazine has many synonyms and this white, odorless solid finds use as a precursor or a component of bleaches, disinfectants, and herbicides. In 1997, worldwide production was 160 million kilograms, cyanuric acid is the cyclic trimer of the elusive species cyanic acid, HOCN. The two structures shown in the infobox readily interconvert, that is, they are tautomers, however, mixture with melamine forms melamine cyanurate, which locks cyanuric acid in the tri-keto tautomer and makes melamine cyanurate insoluble in water. The triol tautomer, which may have aromatic character, predominates in solution, the hydroxyl groups assume phenolic character. The current industrial route to CYA entails the thermal decomposition of urea, the conversion commences at approximately 175 °C,3 H2N-CO-NH2 →3 +3 NH3 CYA crystallizes from water as the dihydrate. Cyanuric acid can be produced by hydrolysis of crude or waste melamine followed by crystallization, acid waste streams from plants producing these materials contain cyanuric acid and on occasion, dissolved amino-substituted triazines, namely, ammeline, ammelide, and melamine. Melamine,3, formation occurs between 325 and 350 °C and only in small quantities. Cyanuric acid is used as a stabilizer in swimming pools. It binds to free chlorine and releases it slowly, extending the time needed to deplete each dose of sanitizer, the antineoplastic alkylating agent, teroxirone, is formed by reacting cyanuric acid with 3 equivalents of epichlorohydrin. Cyanuric acid is used as a precursor to N-chlorinated cyanurates. The dichloro derivative is prepared by chlorination,3 +2 Cl2 +2 NaOH →2 This species is typically converted to its sodium salt. Further chlorination gives trichloroisocyanuric acid,3 and these N-chloro compounds serve as disinfectants and algicides for swimming pool water. It stabilizes the chlorine in the pool and prevents the chlorine from being consumed by sunlight. Because of its trifunctionality, CYA is a precursor to crosslinking agents, testing for cyanuric acid concentration is commonly done with a turbidometric test, which uses a reagent, melamine, to precipitate the cyanuric acid. The relative turbidity of the reacted sample quantifies the CYA concentration, more recently, a sensitive method has been developed for analysis of cyanuric acid in urine. FDA permits a certain amount of acid to be present in some non-protein nitrogen additives used in animal feed. Cyanuric acid has been used as NPN, for example, Archer Daniels Midland manufactures an NPN supplement for cattle, which contains biuret, triuret, cyanuric acid and urea
