1.
Jmol
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Jmol is computer software for molecular modelling chemical structures in 3-dimensions. Jmol returns a 3D representation of a molecule that may be used as a teaching tool and it is written in the programming language Java, so it can run on the operating systems Windows, macOS, Linux, and Unix, if Java is installed. It is free and open-source software released under a GNU Lesser General Public License version 2.0, a standalone application and a software development kit exist that can be integrated into other Java applications, such as Bioclipse and Taverna. A popular feature is an applet that can be integrated into web pages to display molecules in a variety of ways, for example, molecules can be displayed as ball-and-stick models, space-filling models, ribbon diagrams, etc. Jmol supports a range of chemical file formats, including Protein Data Bank, Crystallographic Information File, MDL Molfile. There is also a JavaScript-only version, JSmol, that can be used on computers with no Java, the Jmol applet, among other abilities, offers an alternative to the Chime plug-in, which is no longer under active development. While Jmol has many features that Chime lacks, it does not claim to reproduce all Chime functions, most notably, Chime requires plug-in installation and Internet Explorer 6.0 or Firefox 2.0 on Microsoft Windows, or Netscape Communicator 4.8 on Mac OS9. Jmol requires Java installation and operates on a variety of platforms. For example, Jmol is fully functional in Mozilla Firefox, Internet Explorer, Opera, Google Chrome, fast and Scriptable Molecular Graphics in Web Browsers without Java3D
2.
ChemSpider
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ChemSpider is a database of chemicals. ChemSpider is owned by the Royal Society of Chemistry, the database contains information on more than 50 million molecules from over 500 data sources including, Each chemical is given a unique identifier, which forms part of a corresponding URL. This is an approach to develop an online chemistry database. The search can be used to widen or restrict already found results, structure searching on mobile devices can be done using free apps for iOS and for the Android. The ChemSpider database has been used in combination with text mining as the basis of document markup. The result is a system between chemistry documents and information look-up via ChemSpider into over 150 data sources. ChemSpider was acquired by the Royal Society of Chemistry in May,2009, prior to the acquisition by RSC, ChemSpider was controlled by a private corporation, ChemZoo Inc. The system was first launched in March 2007 in a release form. ChemSpider has expanded the generic support of a database to include support of the Wikipedia chemical structure collection via their WiChempedia implementation. A number of services are available online. SyntheticPages is an interactive database of synthetic chemistry procedures operated by the Royal Society of Chemistry. Users submit synthetic procedures which they have conducted themselves for publication on the site and these procedures may be original works, but they are more often based on literature reactions. Citations to the published procedure are made where appropriate. They are checked by an editor before posting. The pages do not undergo formal peer-review like a journal article. The comments are moderated by scientific editors. The intention is to collect practical experience of how to conduct useful chemical synthesis in the lab, while experimental methods published in an ordinary academic journal are listed formally and concisely, the procedures in ChemSpider SyntheticPages are given with more practical detail. Comments by submitters are included as well, other publications with comparable amounts of detail include Organic Syntheses and Inorganic Syntheses
3.
European Chemicals Agency
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ECHA is the driving force among regulatory authorities in implementing the EUs chemicals legislation. ECHA helps companies to comply with the legislation, advances the safe use of chemicals, provides information on chemicals and it is located in Helsinki, Finland. The Agency, headed by Executive Director Geert Dancet, started working on 1 June 2007, the REACH Regulation requires companies to provide information on the hazards, risks and safe use of chemical substances that they manufacture or import. Companies register this information with ECHA and it is freely available on their website. So far, thousands of the most hazardous and the most commonly used substances have been registered, the information is technical but gives detail on the impact of each chemical on people and the environment. This also gives European consumers the right to ask whether the goods they buy contain dangerous substances. The Classification, Labelling and Packaging Regulation introduces a globally harmonised system for classifying and labelling chemicals into the EU. This worldwide system makes it easier for workers and consumers to know the effects of chemicals, companies need to notify ECHA of the classification and labelling of their chemicals. So far, ECHA has received over 5 million notifications for more than 100000 substances, the information is freely available on their website. Consumers can check chemicals in the products they use, Biocidal products include, for example, insect repellents and disinfectants used in hospitals. The Biocidal Products Regulation ensures that there is information about these products so that consumers can use them safely. ECHA is responsible for implementing the regulation, the law on Prior Informed Consent sets guidelines for the export and import of hazardous chemicals. Through this mechanism, countries due to hazardous chemicals are informed in advance and have the possibility of rejecting their import. Substances that may have effects on human health and the environment are identified as Substances of Very High Concern 1. These are mainly substances which cause cancer, mutation or are toxic to reproduction as well as substances which persist in the body or the environment, other substances considered as SVHCs include, for example, endocrine disrupting chemicals. Companies manufacturing or importing articles containing these substances in a concentration above 0 and they are required to inform users about the presence of the substance and therefore how to use it safely. Consumers have the right to ask the retailer whether these substances are present in the products they buy, once a substance has been officially identified in the EU as being of very high concern, it will be added to a list. This list is available on ECHA’s website and shows consumers and industry which chemicals are identified as SVHCs, Substances placed on the Candidate List can then move to another list
4.
PubChem
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PubChem is a database of chemical molecules and their activities against biological assays. The system is maintained by the National Center for Biotechnology Information, a component of the National Library of Medicine, PubChem can be accessed for free through a web user interface. Millions of compound structures and descriptive datasets can be downloaded via FTP. PubChem contains substance descriptions and small molecules with fewer than 1000 atoms and 1000 bonds, more than 80 database vendors contribute to the growing PubChem database. PubChem consists of three dynamically growing primary databases, as of 28 January 2016, Compounds,82.6 million entries, contains pure and characterized chemical compounds. Substances,198 million entries, contains also mixtures, extracts, complexes, bioAssay, bioactivity results from 1.1 million high-throughput screening programs with several million values. PubChem contains its own online molecule editor with SMILES/SMARTS and InChI support that allows the import and export of all common chemical file formats to search for structures and fragments. In the text search form the database fields can be searched by adding the name in square brackets to the search term. A numeric range is represented by two separated by a colon. The search terms and field names are case-insensitive, parentheses and the logical operators AND, OR, and NOT can be used. AND is assumed if no operator is used, example,0,5000,50,10 -5,5 PubChem was released in 2004. The American Chemical Society has raised concerns about the publicly supported PubChem database and they have a strong interest in the issue since the Chemical Abstracts Service generates a large percentage of the societys revenue. To advocate their position against the PubChem database, ACS has actively lobbied the US Congress, soon after PubChems creation, the American Chemical Society lobbied U. S. Congress to restrict the operation of PubChem, which they asserted competes with their Chemical Abstracts Service
5.
International Chemical Identifier
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Initially developed by IUPAC and NIST from 2000 to 2005, the format and algorithms are non-proprietary. The continuing development of the standard has supported since 2010 by the not-for-profit InChI Trust. The current version is 1.04 and was released in September 2011, prior to 1.04, the software was freely available under the open source LGPL license, but it now uses a custom license called IUPAC-InChI Trust License. Not all layers have to be provided, for instance, the layer can be omitted if that type of information is not relevant to the particular application. InChIs can thus be seen as akin to a general and extremely formalized version of IUPAC names and they can express more information than the simpler SMILES notation and differ in that every structure has a unique InChI string, which is important in database applications. Information about the 3-dimensional coordinates of atoms is not represented in InChI, the InChI algorithm converts input structural information into a unique InChI identifier in a three-step process, normalization, canonicalization, and serialization. The InChIKey, sometimes referred to as a hashed InChI, is a fixed length condensed digital representation of the InChI that is not human-understandable. The InChIKey specification was released in September 2007 in order to facilitate web searches for chemical compounds and it should be noted that, unlike the InChI, the InChIKey is not unique, though collisions can be calculated to be very rare, they happen. In January 2009 the final 1.02 version of the InChI software was released and this provided a means to generate so called standard InChI, which does not allow for user selectable options in dealing with the stereochemistry and tautomeric layers of the InChI string. The standard InChIKey is then the hashed version of the standard InChI string, the standard InChI will simplify comparison of InChI strings and keys generated by different groups, and subsequently accessed via diverse sources such as databases and web resources. Every InChI starts with the string InChI= followed by the version number and this is followed by the letter S for standard InChIs. The remaining information is structured as a sequence of layers and sub-layers, the layers and sub-layers are separated by the delimiter / and start with a characteristic prefix letter. The six layers with important sublayers are, Main layer Chemical formula and this is the only sublayer that must occur in every InChI. The atoms in the formula are numbered in sequence, this sublayer describes which atoms are connected by bonds to which other ones. Describes how many hydrogen atoms are connected to each of the other atoms, the condensed,27 character standard InChIKey is a hashed version of the full standard InChI, designed to allow for easy web searches of chemical compounds. Most chemical structures on the Web up to 2007 have been represented as GIF files, the full InChI turned out to be too lengthy for easy searching, and therefore the InChIKey was developed. With all databases currently having below 50 million structures, such duplication appears unlikely at present, a recent study more extensively studies the collision rate finding that the experimental collision rate is in agreement with the theoretical expectations. Example, Morphine has the structure shown on the right, as the InChI cannot be reconstructed from the InChIKey, an InChIKey always needs to be linked to the original InChI to get back to the original structure
6.
Simplified molecular-input line-entry system
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The simplified molecular-input line-entry system is a specification in form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules, the original SMILES specification was initiated in the 1980s. It has since modified and extended. In 2007, a standard called OpenSMILES was developed in the open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, the original SMILES specification was initiated by David Weininger at the USEPA Mid-Continent Ecology Division Laboratory in Duluth in the 1980s. The Environmental Protection Agency funded the project to develop SMILES. It has since modified and extended by others, most notably by Daylight Chemical Information Systems. In 2007, a standard called OpenSMILES was developed by the Blue Obelisk open-source chemistry community. Other linear notations include the Wiswesser Line Notation, ROSDAL and SLN, in July 2006, the IUPAC introduced the InChI as a standard for formula representation. SMILES is generally considered to have the advantage of being slightly more human-readable than InChI, the term SMILES refers to a line notation for encoding molecular structures and specific instances should strictly be called SMILES strings. However, the term SMILES is also used to refer to both a single SMILES string and a number of SMILES strings, the exact meaning is usually apparent from the context. The terms canonical and isomeric can lead to confusion when applied to SMILES. The terms describe different attributes of SMILES strings and are not mutually exclusive, typically, a number of equally valid SMILES strings can be written for a molecule. For example, CCO, OCC and CC all specify the structure of ethanol, algorithms have been developed to generate the same SMILES string for a given molecule, of the many possible strings, these algorithms choose only one of them. This SMILES is unique for each structure, although dependent on the algorithm used to generate it. These algorithms first convert the SMILES to a representation of the molecular structure. A common application of canonical SMILES is indexing and ensuring uniqueness of molecules in a database, there is currently no systematic comparison across commercial software to test if such flaws exist in those packages. SMILES notation allows the specification of configuration at tetrahedral centers, and these are structural features that cannot be specified by connectivity alone and SMILES which encode this information are termed isomeric SMILES
7.
Chemical formula
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These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulas can fully specify the structure of only the simplest of molecules and chemical substances, the simplest types of chemical formulas are called empirical formulas, which use letters and numbers indicating the numerical proportions of atoms of each type. Molecular formulas indicate the numbers of each type of atom in a molecule. For example, the formula for glucose is CH2O, while its molecular formula is C6H12O6. This is possible if the relevant bonding is easy to show in one dimension, an example is the condensed molecular/chemical formula for ethanol, which is CH3-CH2-OH or CH3CH2OH. For reasons of structural complexity, there is no condensed chemical formula that specifies glucose, chemical formulas may be used in chemical equations to describe chemical reactions and other chemical transformations, such as the dissolving of ionic compounds into solution. A chemical formula identifies each constituent element by its chemical symbol, in empirical formulas, these proportions begin with a key element and then assign numbers of atoms of the other elements in the compound, as ratios to the key element. For molecular compounds, these numbers can all be expressed as whole numbers. For example, the formula of ethanol may be written C2H6O because the molecules of ethanol all contain two carbon atoms, six hydrogen atoms, and one oxygen atom. Some types of compounds, however, cannot be written with entirely whole-number empirical formulas. An example is boron carbide, whose formula of CBn is a variable non-whole number ratio with n ranging from over 4 to more than 6.5. When the chemical compound of the consists of simple molecules. These types of formulas are known as molecular formulas and condensed formulas. A molecular formula enumerates the number of atoms to reflect those in the molecule, so that the formula for glucose is C6H12O6 rather than the glucose empirical formula. However, except for very simple substances, molecular chemical formulas lack needed structural information, for simple molecules, a condensed formula is a type of chemical formula that may fully imply a correct structural formula. For example, ethanol may be represented by the chemical formula CH3CH2OH
8.
Density
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The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ, although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume, ρ = m V, where ρ is the density, m is the mass, and V is the volume. In some cases, density is defined as its weight per unit volume. For a pure substance the density has the numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity, osmium and iridium are the densest known elements at standard conditions for temperature and pressure but certain chemical compounds may be denser. Thus a relative density less than one means that the floats in water. The density of a material varies with temperature and pressure and this variation is typically small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object, increasing the temperature of a substance decreases its density by increasing its volume. In most materials, heating the bottom of a results in convection of the heat from the bottom to the top. This causes it to rise relative to more dense unheated material, the reciprocal of the density of a substance is occasionally called its specific volume, a term sometimes used in thermodynamics. Density is a property in that increasing the amount of a substance does not increase its density. Archimedes knew that the irregularly shaped wreath could be crushed into a cube whose volume could be calculated easily and compared with the mass, upon this discovery, he leapt from his bath and ran naked through the streets shouting, Eureka. As a result, the term eureka entered common parlance and is used today to indicate a moment of enlightenment, the story first appeared in written form in Vitruvius books of architecture, two centuries after it supposedly took place. Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time, from the equation for density, mass density has units of mass divided by volume. As there are units of mass and volume covering many different magnitudes there are a large number of units for mass density in use. The SI unit of kilogram per metre and the cgs unit of gram per cubic centimetre are probably the most commonly used units for density.1,000 kg/m3 equals 1 g/cm3. In industry, other larger or smaller units of mass and or volume are often more practical, see below for a list of some of the most common units of density
9.
Melting point
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The melting point of a solid is the temperature at which it changes state from solid to liquid at atmospheric pressure. At the melting point the solid and liquid phase exist in equilibrium, the melting point of a substance depends on pressure and is usually specified at standard pressure. When considered as the temperature of the change from liquid to solid. Because of the ability of some substances to supercool, the point is not considered as a characteristic property of a substance. For most substances, melting and freezing points are approximately equal, for example, the melting point and freezing point of mercury is 234.32 kelvins. However, certain substances possess differing solid-liquid transition temperatures, for example, agar melts at 85 °C and solidifies from 31 °C to 40 °C, such direction dependence is known as hysteresis. The melting point of ice at 1 atmosphere of pressure is close to 0 °C. In the presence of nucleating substances the freezing point of water is the same as the melting point, the chemical element with the highest melting point is tungsten, at 3687 K, this property makes tungsten excellent for use as filaments in light bulbs. Many laboratory techniques exist for the determination of melting points, a Kofler bench is a metal strip with a temperature gradient. Any substance can be placed on a section of the strip revealing its thermal behaviour at the temperature at that point, differential scanning calorimetry gives information on melting point together with its enthalpy of fusion. A basic melting point apparatus for the analysis of crystalline solids consists of an oil bath with a transparent window, the several grains of a solid are placed in a thin glass tube and partially immersed in the oil bath. The oil bath is heated and with the aid of the melting of the individual crystals at a certain temperature can be observed. In large/small devices, the sample is placed in a heating block, the measurement can also be made continuously with an operating process. For instance, oil refineries measure the point of diesel fuel online, meaning that the sample is taken from the process. This allows for more frequent measurements as the sample does not have to be manually collected, for refractory materials the extremely high melting point may be determined by heating the material in a black body furnace and measuring the black-body temperature with an optical pyrometer. For the highest melting materials, this may require extrapolation by several hundred degrees, the spectral radiance from an incandescent body is known to be a function of its temperature. An optical pyrometer matches the radiance of a body under study to the radiance of a source that has been previously calibrated as a function of temperature, in this way, the measurement of the absolute magnitude of the intensity of radiation is unnecessary. However, known temperatures must be used to determine the calibration of the pyrometer, for temperatures above the calibration range of the source, an extrapolation technique must be employed
10.
Aqueous solution
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An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending to the relevant chemical formula, for example, a solution of table salt, or sodium chloride, in water would be represented as Na+ + Cl−. The word aqueous means pertaining to, related to, similar to, as water is an excellent solvent and is also naturally abundant, it is a ubiquitous solvent in chemistry. Substances that are hydrophobic often do not dissolve well in water, an example of a hydrophilic substance is sodium chloride. Acids and bases are aqueous solutions, as part of their Arrhenius definitions, the ability of a substance to dissolve in water is determined by whether the substance can match or exceed the strong attractive forces that water molecules generate between themselves. If the substance lacks the ability to dissolve in water the molecules form a precipitate, reactions in aqueous solutions are usually metathesis reactions. Metathesis reactions are another term for double-displacement, that is, when a cation displaces to form a bond with the other anion. The cation bonded with the latter anion will dissociate and bond with the other anion, aqueous solutions that conduct electric current efficiently contain strong electrolytes, while ones that conduct poorly are considered to have weak electrolytes. Those strong electrolytes are substances that are ionized in water. Nonelectrolytes are substances that dissolve in water yet maintain their molecular integrity, examples include sugar, urea, glycerol, and methylsulfonylmethane. When writing the equations of reactions, it is essential to determine the precipitate. To determine the precipitate, one must consult a chart of solubility, soluble compounds are aqueous, while insoluble compounds are the precipitate. Remember that there may not always be a precipitate, when performing calculations regarding the reacting of one or more aqueous solutions, in general one must know the concentration, or molarity, of the aqueous solutions. Solution concentration is given in terms of the form of the prior to it dissolving. Metal ions in aqueous solution Solubility Dissociation Acid-base reaction theories Properties of water Zumdahl S.1997, 4th ed. Boston, Houghton Mifflin Company
11.
Acid dissociation constant
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An acid dissociation constant, Ka, is a quantitative measure of the strength of an acid in solution. It is the constant for a chemical reaction known as dissociation in the context of acid–base reactions. In the example shown in the figure, HA represents acetic acid, and A− represents the acetate ion, the chemical species HA, A− and H3O+ are said to be in equilibrium when their concentrations do not change with the passing of time. The definition can then be more simply H A ⇌ A − + H +, K a = This is the definition in common usage. A weak acid has a pKa value in the approximate range −2 to 12 in water, pKa values for strong acids can, however, be estimated by theoretical means. The definition can be extended to non-aqueous solvents, such as acetonitrile and dimethylsulfoxide. Denoting a solvent molecule by S H A + S ⇌ A − + S H +, K a = When the concentration of solvent molecules can be taken to be constant, K a =, as before. The value of pKa also depends on structure of the acid in many ways. For example, Pauling proposed two rules, one for successive pKa of polyprotic acids, and one to estimate the pKa of oxyacids based on the number of =O and −OH groups. Other structural factors that influence the magnitude of the dissociation constant include inductive effects, mesomeric effects. Hammett type equations have frequently applied to the estimation of pKa. The quantitative behaviour of acids and bases in solution can be only if their pKa values are known. These calculations find application in different areas of chemistry, biology, medicine. Acid dissociation constants are essential in aquatic chemistry and chemical oceanography. In living organisms, acid–base homeostasis and enzyme kinetics are dependent on the pKa values of the acids and bases present in the cell. According to Arrheniuss original definition, an acid is a substance that dissociates in solution, releasing the hydrogen ion H+. The equilibrium constant for this reaction is known as a dissociation constant. Brønsted and Lowry generalised this further to an exchange reaction
12.
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
13.
Isophthalic acid
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Isophthalic acid is an organic compound with the formula C6H42. This colourless solid is an isomer of phthalic acid and terephthalic acid, isophthalic acid is produced on the billion kilogram per year scale by oxidizing meta-xylene using oxygen. The process employs a cobalt-manganese catalyst, in the laboratory, chromic acid can be used as the oxidant. It also arises by fusing potassium meta-sulphobenzoate, or meta-brombenzoate with potassium formate, the barium salt is very soluble. Uvitic acid, 5-methylisophthalic acid, is obtained by oxidizing mesitylene or by condensing pyroracemic acid with baryta water, aromatic dicarboxylic acids are used as precursors to commercially important polymers, e. g. the fire-resistant material Nomex. Mixed with terephthalic acid, isophthalic acid is used in the production of resins for plastic bottles. The high-performance polymer polybenzimidazole is produced from isophthalic acid, also, the acid is used as an important input to produce insulation materials
14.
Terephthalic acid
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Terephthalic acid is the organic compound with formula C6H42. This white solid is a commodity chemical, used principally as a precursor to the polyester PET, used to make clothing, several million tonnes are produced annually. Terephthalic acid was first isolated by the French chemist Amédée Cailliot in 1846, the importance of the terephthalic acid was realized after World War II. The first companies to commercialize the use of the fibers made from polyethylene terephthalate were Imperial Chemical Industries in the UK in 1949, the fibers were made from dimethyl terephthalate by transesterification with ethylene glycol. Terephthalic acid was produced by oxidation of p-xylene with dilute nitric acid and this type of oxidation involved the use of air in the initial oxidation step to minimize the consumption of nitric acid and difficulty in purification. Growth in the industry led to increase in demand of TPA. In the 1960s, all the acid produced was converted to its dimethyl ester, since TPA was infusible. Presently TPA is manufactured by oxidation of p-xylene, Terephthalic acid is poorly soluble in water and alcohols, consequently, until about 1970 terephthalic acid was purified as its dimethyl ester. In the Amoco process, terephthalic acid is produced by oxidation of p-xylene by oxygen in air, the bromide source can be sodium bromide, hydrogen bromide or tetrabromoethane where bromine functions as a regenerative source of free radicals. In this process, acetic acid is the solvent and oxygen from compressed air is the oxidant, the combination of bromine and acetic acid is found to be highly corrosive and hence the equipment is lined with titanium. A feed mixture containing p-xylene, acetic acid, the catalyst system, the oxidation of the methyl group takes place in two steps where p-xylene is converted to p-toluic acid and the byproduct undesirable 4-carboxybenzaldehyde along with crude p-toluic acid. It is further purified to obtain the p-toluic acid with the removal of the 4-carboxybenzaldehyde using crystallization, centrifugation and filtration, 98% of the p-xylene is reacted to give more than 95 mol% TPA. The solvent losses are low, and hence the Amoco process is followed by the industries. This reaction proceeds through a p-toluic acid intermediate which is oxidized to terephthalic acid. The commercial process utilizes acetic acid as solvent and a catalyst composed of cobalt and manganese salts, the most problematic impurity is 4-formylbenzoic acid, which is removed by hydrogenation of a hot aqueous solution. This solution is cooled in a stepwise manner to crystallize highly pure terephthalic acid. Despite optimized yields greater than 95% with excellent purity, the synthesis has shortcomings, due to high reaction temperature, approximately 5% of the acetic acid solvent is lost by decomposition or burning. Solvent burning is a significant economic factor in the oxidation process, in addition, product loss by decarboxylation to benzoic acid is common
15.
Phthalic anhydride
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Phthalic anhydride is the organic compound with the formula C6H42O. It is the anhydride of phthalic acid, Phthalic anhydride is a principal commercial form of phthalic acid. It was the first anhydride of an acid to be used commercially. This colourless solid is an important industrial chemical, especially for the production of plasticizers for plastics. In 2000, the production volume was estimated to be about 3 million tonnes per year. Phthalic anhydride was first reported in 1836 by Auguste Laurent, more contemporary routes include catalytic oxidation of ortho-xylene and naphthalene, although use of naphthalene has declined. Starting from o-xylene, the oxidation follows the following stoichiometry, C6H42 +3 O2 → C6H42O +3 H2O The reaction proceeds with about 70% selectivity. About 10% of maleic anhydride is produced, C6H42 +7.5 O2 → C4H2O3 +4 H2O +4 CO2 The reaction is catalyzed by a vanadium pentoxide between 320 -400 °C. The phthalic anhydride is separated from byproducts by a series of switch condensers, Phthalic anhydride and maleic anhydride are recovered by distillation. Phthalic anhydride can also be prepared from phthalic acid, The primary use of phthalic anhydride is as an intermediate in the production of plastics from vinyl chloride. Phthalate esters, which function as plasticizers, are derived from Phthalic Anhydride, phthalate plasticizers are used for the production of flexible PVC products such as cables, pipes and hoses, leather cloth, shoes, film for packaging etc. It is also utilized as a rubber scorch inhibitor and retarder, Phthalic anhydride is a versatile intermediate in organic chemistry, in part because it is bifunctional and cheaply available. Hydrolysis by hot water forms ortho-phthalic acid, hydrolysis of anhydrides is not typically a reversible process. Phthalic acid is easily dehydrated to form phthalic anhydride. Above 180 °C, phthalic anhydride re-forms, as with other anhydrides, the alcoholysis reaction is the basis of the manufacture of phthalate esters, which are widely used plasticizers. In the 1980s, approximately 6. 5×109 kg of these esters were produced annually, Phthalic anhydride is a precursor to a variety of reagents useful in organic synthesis. Important derivatives include phthalimide and its many derivatives, chiral alcohols form half-esters, and these derivatives are often resolvable because they form diastereomeric salts with chiral amines such as brucine. Phthalic anhydride is used in industry for the production of certain dyes
16.
Phthalimide
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Phthalimide is the organic compound with the formula C6H42NH. It is the derivative of phthalic anhydride. It is a white solid that is slightly soluble in water. It is used as a precursor to other compounds as a masked source of ammonia. Phthalimide can be prepared by heating phthalic anhydride with aqueous ammonia giving 95-97% yield, alternatively, it may be prepared by treating the anhydride with ammonium carbonate or urea. It can also be produced by ammoxidation of ortho-xylene, Phthalimide is used as a precursor to anthranilic acid, a precursor to azo dyes and saccharin. Alkyl phthalimides are useful precursors to amines in chemical synthesis, especially in peptide synthesis where they are used to block both hydrogens and avoid racemization of the substrates, some examples of Phthalimide drugs include Thalidomide, Amphotalide, Taltrimide & Talmetoprim. It forms salts upon treatment with such as sodium hydroxide. The high acidity of the imido N-H is the result of the pair of flanking electrophilic carbonyl groups, kladnoite is a natural mineral analog of phthalimide. It is very rarely found among a few burning coal fire sites, Phthalimide has low acute toxicity with LD50 of greater than 5000 mg/kg
17.
Terephthaloyl chloride
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Terephthaloyl chloride is the acid chloride of terephthalic acid and is one of two monomers used to make Kevlar, the other being p-phenylenediamine. Its CAS reference number is 100-20-9 and its formula is C8H4Cl2O2. TCL is used as a key component in performance polymers and aramid fibers, where it imparts flame resistance, chemical resistance, temperature stability, light weight, TCL is also an effective water scavenger, used to stabilize isocyanates and urethane prepolymers. TCL is a crystalline solid at room temperature, soluble in common organic solvents. Its melting point is 81. 5-83 °C, its point is 265 °C. TCL is used for making various copolymers and aramid polymers such as Heracron, Twaron and Kevlar, Aramid
18.
Phthalaldehyde
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O-Phthalaldehyde or ortho-phthalaldehyde is the chemical compound with the formula C6H42. Often abbreviated OPA, the molecule is a dialdehyde, consisting of two formyl groups attached to adjacent carbon centres on a benzene ring and this pale yellow solid is a building block in the synthesis of heterocyclic compounds and a reagent in the analysis of amino acids. OPA dissolves in water solution at pH <11.5 and its solutions degrade upon UV illumination and exposure to air. The compound was first described in 1887 when it was prepared from α, α, α’, a more modern synthesis is similar, the hydrolysis of the related tetrabromoxylene using potassium oxalate, followed by purification by steam distillation. The reactivity of OPA is complicated by the fact that in water it forms both a mono- and dihydrate, C6H4 and C6H42O, respectively and its reactions with nucleophiles often involves the reaction of both carbonyl groups. OPA reacts specifically with primary amines above their isoelectric point Pi in presence of thiols, OPA reacts also with thiols in presence of an amine such as n-propylamine or 2-aminoethanol. OPA is commonly used as a disinfectant for medical instruments. Disinfection with OPA is indicated for semi-critical instruments that come into contact with mucous membranes or broken skin, such as specula, laryngeal mirrors, and internal ultrasound probes. In the polymer, one of the oxygen atoms forms a bridge to the other non-ring carbon of the same phthalaldehyde unit, poly is used in making a photoresist. The Nitrogen by O-Phthaldialdehyde Assay is one of the used in winemaking to measure yeast assimilable nitrogen needed by wine yeast in order to successfully complete fermentation. Related to ortho-phthalaldehyde are the meta- and para-isomers, which are respectively named isophthalaldehyde and terephthalaldehyde
19.
Aromatic
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Aromatic molecules are very stable, and do not break apart easily to react with other substances. Organic compounds that are not aromatic are classified as aliphatic compounds—they might be cyclic, since the most common aromatic compounds are derivatives of benzene, the word “aromatic” occasionally refers informally to benzene derivatives, and so it was first defined. Nevertheless, many aromatic compounds exist. In living organisms, for example, the most common aromatic rings are the bases in RNA and DNA. An aromatic functional group or other substituent is called an aryl group, the earliest use of the term aromatic was in an article by August Wilhelm Hofmann in 1855. Hofmann used the term for a class of compounds, many of which have odors. In terms of the nature of the molecule, aromaticity describes a conjugated system often made of alternating single and double bonds in a ring. This configuration allows for the electrons in the pi system to be delocalized around the ring, increasing the molecules stability. The molecule cannot be represented by one structure, but rather a hybrid of different structures. These molecules cannot be found in one of these representations, with the longer single bonds in one location. Rather, the molecule exhibits bond lengths in between those of single and double bonds and this commonly seen model of aromatic rings, namely the idea that benzene was formed from a six-membered carbon ring with alternating single and double bonds, was developed by August Kekulé. The model for benzene consists of two forms, which corresponds to the double and single bonds superimposing to produce six one-and-a-half bonds. Benzene is a stable molecule than would be expected without accounting for charge delocalization. As is standard for resonance diagrams, the use of an arrow indicates that two structures are not distinct entities but merely hypothetical possibilities. Neither is a representation of the actual compound, which is best represented by a hybrid of these structures. A C=C bond is shorter than a C−C bond, but benzene is perfectly hexagonal—all six carbon–carbon bonds have the same length, intermediate between that of a single and that of a double bond. In a cyclic molecule with three alternating double bonds, cyclohexatriene, the length of the single bond would be 1.54 Å. However, in a molecule of benzene, the length of each of the bonds is 1.40 Å, a better representation is that of the circular π-bond, in which the electron density is evenly distributed through a π-bond above and below the ring
20.
Dicarboxylic acid
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A dicarboxylic acid is an organic compound containing two carboxyl functional groups. The general molecular formula for dicarboxylic acids can be written as HO2C−R−CO2H, in general, dicarboxylic acids show similar chemical behavior and reactivity to monocarboxylic acids. Dicarboxylic acids are used in the preparation of copolymers such as polyamides. The most widely used dicarboxylic acid in the industry is adipic acid, other examples of dicarboxylic acids include aspartic acid and glutamic acid, two amino acids in the human body. The PubChem links gives access to a wealth of information on the compounds, adipic acid, despite its name, is not a normal constituent of natural lipids but is a product of oxidative rancidity. It was first obtained by oxidation of castor oil with nitric acid and it is now produced industrially by oxidation of cyclohexanol or cyclohexane, mainly for the production of Nylon 6-6. Pimelic acid was also first isolated from oxidized oil, derivatives of pimelic acid are involved in the biosynthesis of lysine. Suberic acid was first produced by nitric acid oxidation of cork and this acid is also produced when castor oil is oxidised. Suberic acid is used in the manufacture of alkyd resins and in the synthesis of polyamides, azelaic acids name stems from the action of nitric acid oxidation of oleic acid or elaidic acid. It was detected among products of rancid fats and its origin explains for its presence in poorly preserved samples of linseed oil and in specimens of ointment removed from Egyptian tombs 5000 years old. Azelaic acid was prepared by oxidation of oleic acid with potassium permanganate, azelaic acid is used, as simple esters or branched-chain esters) in the manufacture of plasticizers, lubricants and greases. Azelaic acid is now used in cosmetics and it displays bacteriostatic and bactericidal properties against a variety of aerobic and anaerobic micro-organisms present on acne-bearing skin. Azelaic acid was identified as a molecule that accumulated at elevated levels in parts of plants and was shown to be able to enhance the resistance of plants to infections. Thenard isolated this compound from distillation products of beef tallow in 1802 and it is produced industrially by alkali fission of castor oil. Sebacic acid and its derivatives have a variety of uses as plasticizers, lubricants, diffusion pump oils, cosmetics, candles. It is also used in the synthesis of polyamide, as nylon, brassylic acid can be produced from erucic acid by ozonolysis but also by microorganisms from tridecane. This diacid is produced on a commercial scale in Japan for the manufacture of fragrances. Dodecanedioic acid is used in the production of nylon, polyamides, coatings, adhesives, greases, polyesters, dyestuffs, detergents, flame retardants and it is now produced by fermentation of long-chain alkanes with a specific strain of Candida tropicalis
21.
Naphthalene
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Naphthalene is an organic compound with formula C 10H8. It is the simplest polycyclic aromatic hydrocarbon, and is a crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalenes structure consists of a pair of benzene rings. It is best known as the ingredient of traditional mothballs. In the early 1820s, two separate reports described a white solid with a pungent odor derived from the distillation of coal tar, in 1821, John Kidd cited these two disclosures and then described many of this substances properties and the means of its production. He proposed the name naphthaline, as it had been derived from a kind of naphtha, naphthalenes chemical formula was determined by Michael Faraday in 1826. The structure of two fused benzene rings was proposed by Emil Erlenmeyer in 1866, and confirmed by Carl Gräbe three years later, a naphthalene molecule can be viewed as the fusion of a pair of benzene rings. As such, naphthalene is classified as a polycyclic aromatic hydrocarbon. There are two sets of equivalent hydrogen atoms, the positions are numbered 1,4,5, and 8, and the beta positions,2,3,6. Unlike benzene, the bonds in naphthalene are not of the same length. The bonds C1−C2, C3−C4, C5−C6 and C7−C8 are about 1.37 Å in length and this difference, established by X-ray diffraction, is consistent with the valence bond model in naphthalene and in particular, with the theorem of cross-conjugation. This theorem would describe naphthalene as an aromatic benzene unit bonded to a diene, as such, naphthalene possesses several resonance structures. Two isomers are possible for mono-substituted naphthalenes, corresponding to substitution at an alpha or beta position, bicyclodecapentaene is a structural isomer with a fused 4–8 ring system. In electrophilic aromatic substitution reactions, naphthalene reacts more readily than benzene, for example, chlorination and bromination of naphthalene proceeds without a catalyst to give 1-chloronaphthalene and 1-bromonaphthalene, respectively. In terms of regiochemistry, electrophiles attack occurs at the alpha position, for beta substitution, the intermediate has only six resonance structures, and only two of these are aromatic. Sulfonation, however, gives a mixture of the alpha product 1-naphthalenesulfonic acid, the 1-isomer forms predominantly at 25 °C, and the 2-isomer at 160 °C. Sulfonation to give the 1- and 2-sulfonic acid occurs readily, H 2SO4 + C 10H8 → C 10H 7−SO 3H + H 2O Further sulfonation occurs to give di-, tri- and these 1, 8-dilithio derivatives are precursors to a host of peri-naphthalene derivatives. With alkali metals, naphthalene forms the dark blue-green radical anion salts such as sodium naphthalenide, the naphthalenide salts are strong reducing agents
22.
Xylene
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Xylene, xylol or dimethylbenzene is any one of three isomers of dimethylbenzene, or a combination thereof. With the formula 2C6H4, each of the three compounds has a benzene ring with two methyl groups attached at substituents. They are all colorless, flammable liquids, some of which are of great industrial value, the mixture is referred to as both xylene and, more precisely, xylenes. Xylenes are an important petrochemical produced by reforming and also by coal carbonisation in the manufacture of coke fuel. They also occur in oil in concentrations of about 0. 5–1%. Small quantities occur in gasoline and aircraft fuels, xylenes are produced mainly as part of the BTX aromatics extracted from the product of catalytic reforming known as reformate. The xylene mixture is a greasy, colorless liquid commonly encountered as a solvent. Several million tons are produced annually, in 2011, a global consortium began construction of one of the world’s largest xylene plants in Singapore. Xylene was first isolated and named in 1850 by the French chemist Auguste Cahours, Xylene exists in three isomeric forms. The isomers can be distinguished by the designations ortho-, meta-, and para-, of the three isomers, the p-isomer is the most industrially sought after since it can be oxidized to terephthalic acid. Xylenes are produced by the methylation of toluene and benzene, commercial or laboratory grade xylene produced usually contains about 40-65% of m-xylene and up to 20% each of o-xylene, p-xylene and ethylbenzene. The ratio of isomers can be shifted to favor the highly valued p-xylene via the patented UOP-Isomar process or by transalkylation of xylene with itself or trimethylbenzene and these conversions are catalyzed by zeolites. The chemical and physical properties of xylene differ according to the respective isomers, the melting point ranges from −47.87 °C to 13.26 °C. The boiling point for each isomer is around 140 °C, the density of each isomer is around 0.87 g/mL and thus is less dense than water. Xylene in air can be smelled at concentrations as low as 0.08 to 3.7 ppm, xylenes form azeotropes with water and a variety of alcohols. With water the azeotrope consists of 60% xylenes and boils at 94.5 °C, as with many alkylbenzene compounds, xylenes form complexes with various halocarbons. The complexes of different isomers often have different properties from each other. P-Xylene is the precursor to terephthalic acid and dimethyl terephthalate
23.
France
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France, officially the French Republic, is a country with territory in western Europe and several overseas regions and territories. The European, or metropolitan, area of France extends from the Mediterranean Sea to the English Channel and the North Sea, Overseas France include French Guiana on the South American continent and several island territories in the Atlantic, Pacific and Indian oceans. France spans 643,801 square kilometres and had a population of almost 67 million people as of January 2017. It is a unitary republic with the capital in Paris. Other major urban centres include Marseille, Lyon, Lille, Nice, Toulouse, during the Iron Age, what is now metropolitan France was inhabited by the Gauls, a Celtic people. The area was annexed in 51 BC by Rome, which held Gaul until 486, France emerged as a major European power in the Late Middle Ages, with its victory in the Hundred Years War strengthening state-building and political centralisation. During the Renaissance, French culture flourished and a colonial empire was established. The 16th century was dominated by civil wars between Catholics and Protestants. France became Europes dominant cultural, political, and military power under Louis XIV, in the 19th century Napoleon took power and established the First French Empire, whose subsequent Napoleonic Wars shaped the course of continental Europe. Following the collapse of the Empire, France endured a succession of governments culminating with the establishment of the French Third Republic in 1870. Following liberation in 1944, a Fourth Republic was established and later dissolved in the course of the Algerian War, the Fifth Republic, led by Charles de Gaulle, was formed in 1958 and remains to this day. Algeria and nearly all the colonies became independent in the 1960s with minimal controversy and typically retained close economic. France has long been a centre of art, science. It hosts Europes fourth-largest number of cultural UNESCO World Heritage Sites and receives around 83 million foreign tourists annually, France is a developed country with the worlds sixth-largest economy by nominal GDP and ninth-largest by purchasing power parity. In terms of household wealth, it ranks fourth in the world. France performs well in international rankings of education, health care, life expectancy, France remains a great power in the world, being one of the five permanent members of the United Nations Security Council with the power to veto and an official nuclear-weapon state. It is a member state of the European Union and the Eurozone. It is also a member of the Group of 7, North Atlantic Treaty Organization, Organisation for Economic Co-operation and Development, the World Trade Organization, originally applied to the whole Frankish Empire, the name France comes from the Latin Francia, or country of the Franks
24.
Chemist
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A chemist is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties, chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms. Chemists carefully measure substance proportions, reaction rates, and other chemical properties, the word chemist is also used to address Pharmacists in Commonwealth English. Chemists may specialize in any number of subdisciplines of chemistry, materials scientists and metallurgists share much of the same education and skills with chemists. The roots of chemistry can be traced to the phenomenon of burning, fire was a mystical force that transformed one substance into another and thus was of primary interest to mankind. It was fire that led to the discovery of iron and glasses, after gold was discovered and became a precious metal, many people were interested to find a method that could convert other substances into gold. This led to the protoscience called alchemy, the word chemist is derived from the New Latin noun chimista, an abbreviation of alchimista. Alchemists discovered many chemical processes that led to the development of modern chemistry, Chemistry as we know it today, was invented by Antoine Lavoisier with his law of conservation of mass in 1783. The discoveries of the elements has a long history culminating in the creation of the periodic table by Dmitri Mendeleev. The Nobel Prize in Chemistry created in 1901 gives an excellent overview of chemical discovery since the start of the 20th century. Jobs for chemists usually require at least a degree, but many positions, especially those in research. At the Masters level and higher, students tend to specialize in a particular field, postdoctoral experience may be required for certain positions. Workers whose work involves chemistry, but not at a complexity requiring an education with a degree, are commonly referred to as chemical technicians. Such technicians commonly do such work as simpler, routine analyses for quality control or in clinical laboratories, there are also degrees specific to become a Chemical Technologist, which are somewhat distinct from those required when a student is interested in becoming a professional Chemist. A Chemical technologist is more involved in the management and operation of the equipment and they are part of the team of a chemical laboratory in which the quality of the raw material, intermediate products and finished products is analyzed. They also perform functions in the areas of quality control. The higher the level achieved in the field of Chemistry, the higher the responsibility given to that chemist. Chemistry, as a field, have so many applications that different tasks/objectives can be given to workers/scientists with these different levels of education and/or experience
25.
Auguste Laurent
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Auguste Laurent was a French chemist who helped in the founding of organic chemistry with his discoveries of anthracene, phthalic acid, and carbolic acid. He devised a systematic nomenclature for organic chemistry based on grouping of atoms within molecules to determine how the molecules combine in organic reactions. He studied under Jean-Baptiste Dumas as an assistant and worked with Charles Frédéric Gerhardt. Correspondance de Charles Gerhardt, tome 1, Laurent et Gerhardt, Paris, blondel-Megrelis, M. Auguste Laurent and alcaloids. Web. http, //scienceworld. wolfram. com/biography/Laurent. html Kekulé Riddle, cornelis Friedrich August Kekulé von Stradonitz
26.
Redox
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Redox is a chemical reaction in which the oxidation states of atoms are changed. Any such reaction involves both a process and a complementary oxidation process, two key concepts involved with electron transfer processes. Redox reactions include all chemical reactions in which atoms have their oxidation state changed, in general, the chemical species from which the electron is stripped is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced. It can be explained in terms, Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom. Reduction is the gain of electrons or a decrease in state by a molecule, atom. As an example, during the combustion of wood, oxygen from the air is reduced, the reaction can occur relatively slowly, as in the case of rust, or more quickly, as in the case of fire. Redox is a portmanteau of reduction and oxidation, the word oxidation originally implied reaction with oxygen to form an oxide, since dioxygen was historically the first recognized oxidizing agent. Later, the term was expanded to encompass oxygen-like substances that accomplished parallel chemical reactions, ultimately, the meaning was generalized to include all processes involving loss of electrons. The word reduction originally referred to the loss in weight upon heating a metallic ore such as an oxide to extract the metal. In other words, ore was reduced to metal, antoine Lavoisier showed that this loss of weight was due to the loss of oxygen as a gas. Later, scientists realized that the atom gains electrons in this process. The meaning of reduction then became generalized to all processes involving gain of electrons. Even though reduction seems counter-intuitive when speaking of the gain of electrons, it help to think of reduction as the loss of oxygen. Since electrons are charged, it is also helpful to think of this as reduction in electrical charge. The electrochemist John Bockris has used the words electronation and deelectronation to describe reduction and oxidation processes respectively when they occur at electrodes and these words are analogous to protonation and deprotonation, but they have not been widely adopted by chemists. The term hydrogenation could be used instead of reduction, since hydrogen is the agent in a large number of reactions. But, unlike oxidation, which has been generalized beyond its root element, the word redox was first used in 1928. The processes of oxidation and reduction occur simultaneously and cannot happen independently of one another, the oxidation alone and the reduction alone are each called a half-reaction, because two half-reactions always occur together to form a whole reaction
27.
Switzerland
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Switzerland, officially the Swiss Confederation, is a federal republic in Europe. It consists of 26 cantons, and the city of Bern is the seat of the federal authorities. The country is situated in western-Central Europe, and is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland is a country geographically divided between the Alps, the Swiss Plateau and the Jura, spanning an area of 41,285 km2. The establishment of the Old Swiss Confederacy dates to the medieval period, resulting from a series of military successes against Austria. Swiss independence from the Holy Roman Empire was formally recognized in the Peace of Westphalia in 1648. The country has a history of armed neutrality going back to the Reformation, it has not been in a state of war internationally since 1815, nevertheless, it pursues an active foreign policy and is frequently involved in peace-building processes around the world. In addition to being the birthplace of the Red Cross, Switzerland is home to international organisations. On the European level, it is a member of the European Free Trade Association. However, it participates in the Schengen Area and the European Single Market through bilateral treaties, spanning the intersection of Germanic and Romance Europe, Switzerland comprises four main linguistic and cultural regions, German, French, Italian and Romansh. Due to its diversity, Switzerland is known by a variety of native names, Schweiz, Suisse, Svizzera. On coins and stamps, Latin is used instead of the four living languages, Switzerland is one of the most developed countries in the world, with the highest nominal wealth per adult and the eighth-highest per capita gross domestic product according to the IMF. Zürich and Geneva have each been ranked among the top cities in the world in terms of quality of life, with the former ranked second globally, according to Mercer. The English name Switzerland is a compound containing Switzer, a term for the Swiss. The English adjective Swiss is a loan from French Suisse, also in use since the 16th century. The name Switzer is from the Alemannic Schwiizer, in origin an inhabitant of Schwyz and its associated territory, the Swiss began to adopt the name for themselves after the Swabian War of 1499, used alongside the term for Confederates, Eidgenossen, used since the 14th century. The data code for Switzerland, CH, is derived from Latin Confoederatio Helvetica. The toponym Schwyz itself was first attested in 972, as Old High German Suittes, ultimately related to swedan ‘to burn’
28.
Jean Charles Galissard de Marignac
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Born in Geneva, he was twenty-one years old when he began to attend the Ecole Polytechnique in Paris, and from 1837 to 1839 studied at the Ecole des Mines. Then, after a time in Liebigs laboratory at Gießen. In 1845 he was appointed professor of mineralogy also, and held both chairs until 1878, when ill-health obliged him to resign, marignacs name is well known for the careful and exact determinations of atomic weights which he carried out for fifty-seven of the elements. He prepared silicotungstic acid, one of the first examples of the complex inorganic acids, the discovery of the elements, XVI. Ador, E. Nekrolog, Jean-Charles Galissard De Marignac, the discovery of the elements, XVI. This article incorporates text from a now in the public domain, Chisholm, Hugh
29.
Potassium permanganate
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Potassium permanganate is an inorganic chemical compound and medication. As a medication it is used for cleaning wounds and dermatitis and it has the chemical formula KMnO4 and is a salt consisting of K+ and MnO−4 ions. It is an oxidizing agent. It dissolves in water to give intensely pink or purple solutions, in 2000, worldwide production was estimated at 30,000 tonnes. In this compound, manganese is in the +7 oxidation state and it is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system. The wholesale cost in the world is about 0.01 USD per gram of powder. In the United Kingdom a 400 milligram tablet costs the NHS roughly £0.51, almost all applications of potassium permanganate exploit its oxidizing properties. As a strong oxidant that does not generate toxic byproducts, KMnO4 has many niche uses, as an oxidant, potassium permanganate can act as an antiseptic. For example, dilute solutions are used to treat sores, disinfectant for the hands and treatment for mild pompholyx, dermatitis. Potassium permanganate is used extensively in the treatment industry. It is used as a chemical to remove iron and hydrogen sulfide from well water via a Manganese Greensand Filter. Pot-Perm is also obtainable at pool supply stores and is used additionally to treat waste water, historically it was used to disinfect drinking water and can turn the water pink. It currently finds application in the control of nuisance organisms such as zebra mussels in fresh water collection, aside from its use in water treatment, the other major application of KMnO4 is as a reagent for the synthesis of organic compounds. Significant amounts are required for the synthesis of ascorbic acid, chloramphenicol, saccharin, isonicotinic acid, potassium permanganate can be used to quantitatively determine the total oxidisable organic material in an aqueous sample. The value determined is known as the permanganate value, in analytical chemistry, a standardized aqueous solution of KMnO4 is sometimes used as an oxidizing titrant for redox titrations. In a related way, it is used as a reagent to determine the Kappa number of wood pulp, for the standardization of KMnO4 solutions, reduction by oxalic acid is often used. Aqueous, acidic solutions of KMnO4 are used to collect gaseous mercury in flue gas during stationary source emissions testing, in histology, potassium permanganate was used as a bleaching agent. Ethylene absorbents extend storage time of bananas even at high temperatures and this effect can be exploited by packing bananas in polyethylene together with potassium permanganate
30.
Potassium dichromate
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Potassium dichromate, K2Cr2O7, is a common inorganic chemical reagent, most commonly used as an oxidizing agent in various laboratory and industrial applications. As with all hexavalent chromium compounds, it is acutely and chronically harmful to health and it is a crystalline ionic solid with a very bright, red-orange color. The salt is popular in the laboratory because it is not deliquescent, potassium dichromate is usually prepared by the reaction of potassium chloride on sodium dichromate. Alternatively, it can be obtained from potassium chromate by roasting chrome ore with potassium hydroxide and it is used to oxidize alcohols. It converts primary alcohols into aldehydes and, under more forcing conditions, in contrast, potassium permanganate tends to give carboxylic acids as the sole products. Secondary alcohols are converted into ketones, for example, menthone may be prepared by oxidation of menthol with acidified dichromate. In an aqueous solution the color change exhibited can be used to test for distinguishing aldehydes from ketones, aldehydes reduce dichromate from the +6 to the +3 oxidation state, changing color from orange to green. This color change arises because the aldehyde can be oxidized to the carboxylic acid. A ketone will show no such change because it cannot be oxidized further, when heated strongly, it decomposes with the evolution of oxygen. 4K2Cr2O7 → 4K2CrO4 + 2Cr2O3 + 3O2 When an alkali is added to a red solution containing dichromate ions. For example, potassium chromate is produced industrially using potash, K2Cr2O7 + K2CO3 →2 K2CrO4 + CO2 The reaction is reversible, the main use is as a precursor to potassium chrome alum, used in leather tanning. Like other chromium compounds, potassium dichromate has been used to prepare chromic acid for cleaning glassware, because of safety concerns associated with hexavalent chromium, this practice has been largely discontinued. It is used as an ingredient in cement in which it retards the setting of the mixture and improves its density and this usage commonly causes contact dermatitis in construction workers. Potassium dichromate has uses in photography and in screen printing. In 1852, Henry Fox Talbot discovered that exposure to light in the presence of potassium dichromate hardened organic colloids such as gelatin and gum arabic. These discoveries soon led to the print, gum bichromate. Some processes depended on the only, in combination with the differential absorption of certain dyes by the hardened or unhardened areas. Dichromated colloids were also used as photoresists in various industrial applications and this solution reconverts the elemental silver particles in the film to silver chloride
31.
Potassium hydrogen phthalate
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Potassium hydrogen phthalate, often called simply KHP, is an acidic salt compound. It forms white powder, colorless crystals, a solution. KHP is slightly acidic, and it is used as a primary standard for acid-base titrations because it is solid and air-stable. It is also used as a standard for calibrating pH meters because, besides the properties just mentioned. It also serves as a standard in thermogravimetric analysis. KHP dissociates completely in water, giving the potassium cation and hydrogen phthalate anion, as a weak acid hydrogen phthalate reacts reversibly with water to give hydronium and phthalate ions. HP− + H2O ⇌ P2− + H3O+ KHP can be used as an agent but should not be used as a buffer for decarboxylation reactions, as these will degrade the KHP. KHP is also a standard for total organic carbon testing. Most TOC analyzers are based on the oxidation of organics to carbon dioxide and water, many TOC analyzers suggest testing their instruments with two standards, one typically easy for the instrument to oxidize, and one more difficult to oxidize. For the latter, benzoquinone is suggested
32.
Analytical chemistry
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Analytical chemistry studies and uses instruments and methods used to separate, identify, and quantify matter. In practice separation, identification or quantification may constitute the entire analysis or be combined with another method, qualitative analysis identifies analytes, while quantitative analysis determines the numerical amount or concentration. Analytical chemistry consists of classical, wet chemical methods and modern, classical qualitative methods use separations such as precipitation, extraction, and distillation. Identification may be based on differences in color, odor, melting point, boiling point, classical quantitative analysis uses mass or volume changes to quantify amount. Instrumental methods may be used to separate samples using chromatography, electrophoresis or field flow fractionation, then qualitative and quantitative analysis can be performed, often with the same instrument and may use light interaction, heat interaction, electric fields or magnetic fields. Often the same instrument can separate, identify and quantify an analyte, Analytical chemistry is also focused on improvements in experimental design, chemometrics, and the creation of new measurement tools. Analytical chemistry has applications to forensics, medicine, science. Analytical chemistry has been important since the days of chemistry, providing methods for determining which elements. The first instrumental analysis was flame emissive spectrometry developed by Robert Bunsen, most of the major developments in analytical chemistry take place after 1900. During this period instrumental analysis becomes progressively dominant in the field, in particular many of the basic spectroscopic and spectrometric techniques were discovered in the early 20th century and refined in the late 20th century. The separation sciences follow a similar line of development and also become increasingly transformed into high performance instruments. In the 1970s many of these began to be used together as hybrid techniques to achieve a complete characterization of samples. Lasers have been used in chemistry as probes and even to initiate. Modern analytical chemistry is dominated by instrumental analysis, many analytical chemists focus on a single type of instrument. Academics tend to focus on new applications and discoveries or on new methods of analysis. The discovery of a present in blood that increases the risk of cancer would be a discovery that an analytical chemist might be involved in. An effort to develop a new method might involve the use of a laser to increase the specificity and sensitivity of a spectrometric method. Many methods, once developed, are kept purposely static so that data can be compared over long periods of time and this is particularly true in industrial quality assurance, forensic and environmental applications
33.
1,3-Cyclohexadiene
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1, 3-Cyclohexadiene is an organic compound with the formula 24. It is a colorless, flammable liquid, a naturally occurring derivative of 1, 3-cyclohexadiene is terpinene, a component of pine oil. Useful reactions of this diene are cycloadditions, such as the Diels-Alder reaction,1, 3-Cyclohexadiene could in principle be used as a hydrogen donor in transfer hydrogenation, since its conversion to benzene + hydrogen is exothermic by about 25 kJ/mol
34.
Structural isomer
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Structural isomerism, or constitutional isomerism, is a form of isomerism in which molecules with the same molecular formula have bonded together in different orders, as opposed to stereoisomerism. There are multiple synonyms for constitutional isomers, three categories of constitutional isomers are skeletal, positional, and functional isomers. Positional isomers are also called regioisomers, in chain isomerism, or skeletal isomerism, components of the skeleton are distinctly re-ordered to create different structures. Pentane exists as three isomers, n-pentane, isopentane and neopentane, in position isomerism a functional group or other substituent changes position on a parent structure. In the table below, the group can occupy three different positions on an n-pentane chain forming three different compounds. Many aromatic isomers exist because substituents can be positioned on different parts of the benzene ring, only one isomer of phenol or hydroxybenzene exists but cresol or methylphenol has three isomers where the additional methyl group can be placed on three different positions on the ring. Xylenol has one group and two methyl groups and a total of 6 isomers exist. Functional isomers are structural isomers that have the molecular formula. These groups of atoms are called groups, functionalities. Another way to say this is that two compounds with the molecular formula, but different functional groups, are functional isomers. For example, cyclohexane and 1-hexene both have the formula C6H12 and these two are considered functional group isomers because cyclohexane is a cycloalkane and hex-1-ene is an alkene. For two molecules to be functional isomers, they must contain key groups of atoms arranged in particular ways, some of the best examples come from organic chemistry. Depending on how the atoms are arranged, it can represent two different compounds dimethyl ether CH3-O-CH3 or ethanol CH3CH2-O-H, dimethyl ether and ethanol are functional isomers. The carbon chain-oxygen-carbon chain functionality is called an ether, the carbon chain-oxygen-hydrogen functionality is called an alcohol. If the functionalities stay the same, but their locations change, 1-Propanol and 2-propanol are structural isomers, but they are not functional isomers. The functional group is present in both of these compounds, but they are not the same, while some chemists use the terms structural isomer and functional isomer interchangeably, not all structural isomers are functional isomers. Functional isomers are most often identified in chemistry using infrared spectroscopy, infrared radiation corresponds to the energies associated primarily with molecular vibration. The alcohol functionality has a very distinct vibration called OH-stretch that is due to hydrogen bonding, all alcohols in liquid and solid form absorb infrared radiation at certain wavelengths
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Phthalate
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Phthalates, or phthalate esters, are esters of phthalic acid and are mainly used as plasticizers. Phthalates are manufactured by reacting phthalic anhydride with alcohol that range from methanol and ethanol up to tridecyl alcohol and they are divided into two distinct groups, with very different applications, toxicological properties, and classification, based on the number of carbon atoms in their alcohol chain. They are used primarily to soften polyvinyl chloride, lower-molecular-weight phthalates are being gradually replaced in many products in the United States, Canada, and European Union over health concerns. They are replaced by high-molecular-weight phthalates, Phthalates are used in a wide range of common products, and are released into the environment. There is no covalent bond between the phthalates and plastics, rather, they are entangled within the plastic as a result of the process used to make PVC articles. They can be removed by exposure to heat or with organic solvents, phthalate exposure may be through direct use or by indirect means through leaching and general environmental contamination. Diet is believed to be the source of di phthalate. Fatty foods such as milk, butter, and meats are a major source, in studies of rodents exposed to certain phthalates, high doses have been shown to change hormone levels and cause birth defects. Phthalates are also used in soft plastic fishing lures, caulk, paint pigments. Phthalates are used in a variety of applications such as shower curtains, vinyl upholstery, adhesives, floor tiles, food containers and wrappers. Personal-care items containing phthalates include perfume, eye shadow, moisturizer, nail polish, liquid soap, Phthalates are also found in modern electronics and medical applications such as catheters and blood transfusion devices. The most widely used phthalates are di phthalate, diisodecyl phthalate, DEHP was the dominant plasticizer used globally in PVC due to its low cost. Benzylbutylphthalate is used in the manufacture of foamed PVC, which is used mostly as a flooring material, Phthalates with small R and R groups are used as solvents in perfumes and pesticides. Approximately 8.4 million tonnes of plasticizers are consumed every year. Approximately 70% of those totals are phthalates, down from about 88% in 2005, the remaining 30% are alternative chemistries. Plasticizers contribute 10-60% of total weight of plasticized products, all of these mentioned phthalates are now regulated and restricted in many products. Analysis of such applications will involve studies on alternatives and, given the number of compounds that have been used as plasticizers. The development of cellulose nitrate plastic in 1846 led to the patent of castor oil in 1856 for use as the first plasticizer, in 1870, camphor became the more favored plasticizer for cellulose nitrate
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Chisholm, Hugh, ed. (1911). "Phthalic Acids". Encyclopædia Britannica. 21 (11th ed.). Cambridge University Press. pp. 545–546.
Chisholm, Hugh, ed. (1911). "