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.
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
9.
Occupational safety and health
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These terms of course also refer to the goals of this field, so their use in the sense of this article was originally an abbreviation of occupational safety and health program/department etc. The goals of occupational safety and health programs include to foster a safe, OSH may also protect co-workers, family members, employers, customers, and many others who might be affected by the workplace environment. In the United States, the occupational health and safety is referred to as occupational health and occupational and non-occupational safety. In common-law jurisdictions, employers have a common law duty to take care of the safety of their employees. As defined by the World Health Organization occupational health deals with all aspects of health, Health has been defined as a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity. Occupational health is a field of healthcare concerned with enabling an individual to undertake their occupation. Health has been defined as It contrasts, for example, with the promotion of health and safety at work, since 1950, the International Labour Organization and the World Health Organization have shared a common definition of occupational health. It was adopted by the Joint ILO/WHO Committee on Occupational Health at its first session in 1950, the concept of working culture is intended in this context to mean a reflection of the essential value systems adopted by the undertaking concerned. Such a culture is reflected in practice in the systems, personnel policy, principles for participation, training policies. Professionals advise on a range of occupational health matters. The research and regulation of safety and health are a relatively recent phenomenon. As labor movements arose in response to concerns in the wake of the industrial revolution. The initial remit of the Inspectorate was to police restrictions on the hours in the textile industry of children. The commission sparked public outrage resulted in the Mines Act of 1842. Otto von Bismarck inaugurated the first social insurance legislation in 1883, similar acts followed in other countries, partly in response to labor unrest. Although work provides many economic and other benefits, an array of workplace hazards also present risks to the health. Personal protective equipment can protect against many of these hazards. Physical hazards affect many people in the workplace, Falls are also a common cause of occupational injuries and fatalities, especially in construction, extraction, transportation, healthcare, and building cleaning and maintenance
10.
Organophosphorus compound
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Organophosphorus compounds are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environment, organophosphorus chemistry is the corresponding science of the properties and reactivity of organophosphorus compounds. Phosphorus, like nitrogen, is in group 15 of the periodic table and these compounds are highly effective insecticides, though some are also lethal to humans at minuscule doses and include some of the most toxic substances ever created by man. The definition of organophosphorus compounds is variable, which can lead to confusion, in industrial and environmental chemistry, an organophosphorus compound need contain only an organic substituent, but need not have a direct phosphorus-carbon bond. Thus a large proportion of pesticides, are included in this class of compounds. In a descriptive but only intermittently used nomenclature, phosphorus compounds are identified by their coordination number δ, in this system, a phosphine is a δ3λ3 compound. Phosphate esters have the general structure P3 feature P, such species are of technological importance as flame retardant agents, and plasticizers. Lacking a P−C bond, these compounds are in the technical sense not organophosphorus compounds, many derivatives are found in nature, such as phosphatidylcholine. Phosphate ester are synthesized by alcoholysis of phosphorus oxychloride, a variety of mixed amido-alkoxo derivatives are known, one medically significant example being the anti-cancer drug cyclophosphamide. Also derivatives containing the group include the pesticide malathion. The organophosphates prepared on the largest scale are the zinc dithiophosphates, several million kilograms of this coordination complex are produced annually by the reaction of phosphorus pentasulfide with alcohols. In the environment, these compounds break down via hydrolysis to eventually afford phosphate, phosphonates are esters of phosphonic acid and have the general formula RP2. Phosphonates have many applications, a well-known member being glyphosate. With the formula 2PCH2NHCH2CO2H, this derivative of glycine is one of the most widely used herbicides, bisphosphonates are a class of drugs to treat osteoporosis. The nerve gas agent sarin, containing both C–P and F–P bonds, is a phosphonate, phosphinates feature two P–C bonds, with the general formula R2P. A commercially significant member is the herbicide Glufosinate, similar to glyphosate mentioned above, it has the structure CH3PCH2CH2CHCO2H. The Michaelis–Arbuzov reaction is the method for the synthesis of these compounds. For example, dimethylmethylphosphonate arises from the rearrangement of trimethylphosphite, which is catalyzed by methyl iodide, in the Horner–Wadsworth–Emmons reaction and the Seyferth–Gilbert homologation, phosphonates are used in reactions with carbonyl compounds
11.
Ligand
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In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the electron pairs. The nature of bonding can range from covalent to ionic. Furthermore, the bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic ligand, metals and metalloids are bound to ligands in virtually all circumstances, although gaseous naked metal ions can be generated in high vacuum. Ligands in a complex dictate the reactivity of the atom, including ligand substitution rates, the reactivity of the ligands themselves. Ligand selection is a consideration in many practical areas, including bioinorganic and medicinal chemistry, homogeneous catalysis. Ligands are classified in many ways, including, charge, size, the identity of the atom. The size of a ligand is indicated by its cone angle, the composition of coordination complexes have been known since the early 1800s, such as Prussian blue and copper vitriol. The key breakthrough occurred when Alfred Werner reconciled formulas and isomers and he showed, among other things, that the formulas of many cobalt and chromium compounds can be understood if the metal has six ligands in an octahedral geometry. The first to use the term ligand were Alfred Stock and Carl Somiesky, the theory allows one to understand the difference between coordinated and ionic chloride in the cobalt ammine chlorides and to explain many of the previously inexplicable isomers. He resolved the first coordination complex called hexol into optical isomers, in general, ligands are viewed as electron donors and the metals as electron acceptors. This is because the ligand and central metal are bonded to one another, bonding is often described using the formalisms of molecular orbital theory. The HOMO can be mainly of ligands or metal character, ligands and metal ions can be ordered in many ways, one ranking system focuses on ligand hardness. Metal ions preferentially bind certain ligands, in general, soft metal ions prefer weak field ligands, whereas hard metal ions prefer strong field ligands. According to the orbital theory, the HOMO of the ligand should have an energy that overlaps with the LUMO of the metal preferential. Metal ions bound to strong-field ligands follow the Aufbau principle, whereas complexes bound to weak-field ligands follow Hunds rule. Binding of the metal with the results in a set of molecular orbitals, where the metal can be identified with a new HOMO and LUMO
12.
Ferrocene
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Ferrocene is an organometallic compound with the formula Fe2. It is the prototypical metallocene, a type of chemical compound consisting of two cyclopentadienyl rings bound on opposite sides of a central metal atom. Such organometallic compounds are known as sandwich compounds. The rapid growth of organometallic chemistry is often attributed to the excitement arising from the discovery of ferrocene, in 1951, Pauson and Kealy at Duquesne University reported the reaction of cyclopentadienyl magnesium bromide and ferric chloride with the goal of oxidatively coupling the diene to prepare fulvalene. Instead, they obtained a light orange powder of remarkable stability, a second group at British Oxygen also unknowingly discovered ferrocene. Miller, Tebboth and Tremaine were trying to synthesise amines from hydrocarbons such as cyclopentadiene and they published this result in 1952 although the actual work was done three years earlier. The stability of the new compound was accorded to the aromatic character of the negatively charged cyclopentadienyls. Robert Burns Woodward and Geoffrey Wilkinson deduced the structure based on its reactivity, independently Ernst Otto Fischer also came to the conclusion of the sandwich structure and started to synthesize other metallocenes such as nickelocene and cobaltocene. The structure of ferrocene was confirmed by NMR spectroscopy and X-ray crystallography, in 1973 Fischer of the Technische Universität München and Wilkinson of Imperial College London shared a Nobel Prize for their work on metallocenes and other aspects of organometallic chemistry. The carbon–carbon bond distances are 1.40 Å within the rings. The staggered conformation is believed to be most stable in the condensed phase due to crystal packing, the point group of the staggered conformation is D5d and the point group of the eclipsed conformation is D5h. The Cp rings rotate with a low barrier about the Cp–Fe–Cp axis, as observed by measurements on substituted derivatives of ferrocene using 1H, for example, methylferrocene exhibits a singlet for the C5H5 ring. In terms of bonding, the center in ferrocene is usually assigned to the +2 oxidation state. Each cyclopentadienyl ring is then allocated a single charge, bringing the number of π-electrons on each ring to six. These twelve electrons are shared with the metal via covalent bonding. When combined with the six d-electrons on Fe2+, the complex attains an 18-electron configuration, the first reported syntheses of ferrocene were nearly simultaneous. Pauson and Kealy synthesised ferrocene using iron chloride and a Grignard reagent, iron chloride is suspended in anhydrous diethyl ether and added to the Grignard reagent, which is prepared by reacting cyclopentadiene with magnesium and bromoethane in anhydrous benzene. The other early synthesis of ferrocene was by Miller et al. who reacted metallic iron directly with gas-phase cyclopentadiene at elevated temperature, an approach using iron pentacarbonyl was also reported
13.
Diphosphane
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Diphosphane is an inorganic compound with the chemical formula P2H4. This colourless liquid is one of several binary phosphorus hydrides and it is the impurity that typically causes samples of phosphine to ignite in air. Diphosphane adopts the gauche conformation with a P-P distance of 2.219 angstroms and it is nonbasic, unstable at room temperature, and spontaneously flammable in air. It is only soluble in water but dissolves in organic solvents. Its 1H NMR spectrum consists of 32 lines resulting from an A2XXA2 splitting system, diphosphane is produced by the hydrolysis of calcium monophosphide, which can be described as the Ca2+ derivative of P24−. According to a procedure, hydrolysis of 400 g of CaP at -30 °C gives about 20 g of product. Reaction of diphosphine with butyllithium affords a variety of condensed polyphosphine compounds, a variety of organic derivatives of diphosphane are known
14.
1,2-Bis(diphenylphosphino)ethane
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1, 2-Bisethane is a commonly used bidentate ligand in coordination chemistry. Dppe is almost invariably chelating, although there are examples of monodentate, selective mono-oxidation of dppe can be achieved by reaction with PhCH2Br to give dppeO. This is followed by purification and alkaline catalyzed hydrolysis of the mono-phosphonium salt, hydrogenation of dppe gives the ligand bisethane. Coordination complexes of dppe, and diphosphine ligands in general, are almost entirely used as catalysts for a wide range of reactions. Two simple coordination complexes of dppe include Pd2 and Ir2, Pd2 can be prepared by reduction of Pd with NaBH4. It is most conveniently prepared, however, in situ from Pd2
15.
Chlorodiphenylphosphine
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Chlorodiphenylphosphine is an organophosphorus compound with the formula 2PCl, abbreviated Ph2PCl. It is an oily liquid with a pungent odor that is often described as being garlic-like. It is useful reagent for introducing the Ph2P group into molecules, like other halophosphines, Ph2PCl is reactive with many nucleophiles such as water and easily oxidized even by air. Chlorodiphenylphosphine is produced on a scale from benzene and phosphorus trichloride. Benzene reacts with phosphorus trichloride at extreme temperatures around 600 °C to give dichlorophenylphosphine, redistribution of PhPCl2 in the gas phase at high temperatures results in chlorodiphenylphosphine. 2 PhPCl2 → Ph2PCl + PCl3 Alternatively such compounds are prepared by redistribution reactions starting with triphenylphosphine, synthesis of Ph2PCl by the direct reaction of phenylmagnesium bromide and phosphorus trichloride is not practiced. On the other hand, PCl3 can be converted to its monoamide. Chlorodiphenylphosphine hydrolyzes to give diphenylphosphine oxide, with amines, it forms the amides Ph2PNR2. Ph2PCl, along with other chlorophosphines, is used in the synthesis of various phosphines, chlorodiphenylphosphine is used in the synthesis of sodium diphenylphosphide via its reaction with sodium metal in refluxing dioxane. Ph2PCl +2 Na → Ph2PNa + NaCl Diphenylphosphine can be synthesized in the reaction of Ph2PCl and LiAlH4,4 Ph2PCl + LiAlH4 →4 Ph2PH + LiCl + AlCl3 Both Ph2PNa and Ph2PH are also used in the synthesis of organophosphine ligands. The quality of chlorodiphenylphosphine is often checked by 31P NMR spectroscopy
16.
N-Butyllithium
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It is widely used as a polymerization initiator in the production of elastomers such as polybutadiene or styrene-butadiene-styrene. Also, it is employed as a strong base in the synthesis of organic compounds as in the pharmaceutical industry. Butyllithium is commercially available as solutions in such as pentane, hexanes. Solutions in diethyl ether and THF can be prepared, but are not stable enough for storage, annual worldwide production and consumption of butyllithium and other organolithium compounds is estimated at 1800 tonnes. Although butyllithium is colorless, n-butyllithium is usually encountered as a yellow solution in alkanes. Such solutions are stable indefinitely if properly stored, but in practice, fine white precipitate is deposited and the color changes to orange. N-BuLi exists as a cluster both in the state and in a solution. The tendency to aggregate is common for organolithium compounds, the aggregates are held together by delocalized covalent bonds between lithium and the terminal carbon of the butyl chain. In the case of n-BuLi, the clusters are tetrameric or hexameric, the cluster is a distorted cubane-type cluster with Li and CH2R groups at alternating vertices. An equivalent description describes the tetramer as a Li4 tetrahedron interpenetrated with a tetrahedron 4, bonding within the cluster is related to that used to describe diborane, but more complex since eight atoms are involved. Reflecting its electron-deficient character, n-butyllithium is highly reactive toward Lewis bases, due to the large difference between the electronegativities of carbon and lithium, the C-Li bond is highly polarized. The charge separation has been estimated to be 55-95%, for practical purposes, n-BuLi can often be considered to react as the butyl anion, n-Bu−, and a lithium cation, Li+. Solvents used for this preparation include benzene, cyclohexane, and diethyl ether, when BuBr is the precursor, the product is a homogeneous solution, consisting of a mixed cluster containing both LiBr and BuLi, together with a small amount of octane. BuLi forms a complex with LiCl, so that the reaction of BuCl with Li produces a precipitate of LiCl. The concentration of butyllithium in commercially available solutions tends to decrease over time as the BuLi reacts with air, subsequently, butyllithium is often titrated prior to use to ascertain its true concentration. The BuLi is added to an amount of a weakly acidic compound. Because butyllithium is a base, it quickly and quantitatively reacts with weak acids to give the corresponding lithium salts. An indicator, such as 1, 10-phenanthroline or 2, 2-bipyridine, is used to signal the endpoint of the titration
17.
Palladium-catalyzed coupling reactions
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Palladium-catalyzed coupling reactions comprise a family of cross-coupling reactions that employ palladium complexes as catalysts. It is an area of research and applications in homogeneous catalyst. In 2010, the Nobel Prize in Chemistry was awarded to Richard F. Heck, Ei-ichi Negishi, the reactions generally obey the following stoichiometry, X-R + M-R → MX + R-R Variations are based on the identity of X-R and M-R. For example, PdCl22 is reduced to a Pd complex or transmetalated to a Pd aryl complex before it participates in the catalytic cycle, unoptimized reactions typically use 10-15 mol% of palladium. In optimized reactions, catalyst loadings can be on the order of 0.1 mol % or below, many exotic ligands and chiral catalysts have been reported, but they are largely not available commercially, and do not find widespread use. Phosphines are labile, sometimes requiring additional ligand, for example, Pd4 would be supplemented with PPh3 to keep the palladium coordinated despite loss of the labile phosphine ligands. A concern with the use of palladium in the preparation of pharmaceuticals is that traces of the heavy metal will remain in the product. Column chromatography can be used, but solid-phase metal scavengers promise more efficient separation
18.
Palladium(II) chloride
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Palladium chloride, also known as palladium dichloride and palladous chloride, are the chemical compounds with the formula PdCl2. PdCl2 is a starting material in palladium chemistry – palladium-based catalysts are of particular value in organic synthesis. It is prepared by chlorination of palladium, two forms of PdCl2 are known. In both forms, the palladium centres adopt the square-planar coordination geometry that is characteristic of Pd, furthermore, in both forms, the Pd centres are linked by μ2-chloride bridges. The α-form of PdCl2 is a polymer, consisting of infinite slabs or chains, the β-form of PdCl2 is molecular, consisting of an octahedral cluster of six Pd atoms. Each of the edges of this octahedron is spanned by Cl−. PtCl2 adopts similar structures, whereas NiCl2 adopts the CdCl2 motif, palladium chloride is prepared by dissolving palladium metal in aqua regia or hydrochloric acid in the presence of chlorine. Alternatively, it may be prepared by heating palladium sponge metal with chlorine gas at 500 °C, even when dry, palladium chloride is able to rapidly stain stainless steel. Thus, palladium chloride solutions are used to test for the corrosion-resistance of stainless steel. Palladium chloride is used in carbon monoxide detectors. Palladium chloride can also be used for cosmetic tattooing of leukomas in the cornea
19.
Benzonitrile
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Benzonitrile is the chemical compound with the formula C6H5CN, abbreviated PhCN. This aromatic organic compound is a liquid with a sweet almond odour. It is mainly used as a precursor to the resin benzoguanamine and it is prepared by ammoxidation of toluene, that is its reaction with ammonia and oxygen at 400 to 450 °C. Benzonitrile is a solvent and a versatile precursor to many derivatives. It reacts with amines to afford N-substituted benzamides after hydrolysis and it is a precursor to Ph2C=NH via reaction with phenylmagnesium bromide followed by methanolysis. Benzonitrile forms coordination complexes with metals that are both soluble in organic solvents and conveniently labile. The benzonitrile ligands are readily displaced by stronger ligands, making benzonitrile complexes useful synthetic intermediates, benzonitrile was reported by Hermann Fehling in 1844. He found the compound as a product from the dehydration of ammonium benzoate. He deduced its structure from the already known analogue reaction of ammonium formate yielding formonitrile and he also coined the name benzonitrile which gave the name to all the group of nitriles
20.
Diphosphines
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Diphosphines, sometimes called bisphosphanes, are organophosphorus compounds used as ligands in inorganic and organometallic chemistry. They are identified by the presence of two groups linked by a backbone, and are usually chelating. Many widely used diphosphine ligands have the general formula Ar2PnPAr2, when the two phosphine substituents are linked by two to four carbon centres, the resulting ligands often chelate rings with a single metal. A common diphosphine ligand is dppe, which forms a five-membered chelate ring with most metals, some diphosphines, such as the extraordinary case of tBu2P10PtBu2, give macrocyclic complexes with as many as 72 atoms in a ring. To position phosphine donor groups trans on a sphere, several atoms are required to link the donor centres and long-chain diphosphines are typically floppy. This challenge has been resolved by the long but rigid diphosphine SPANphos, the bite angle of the diphosphine influences the reactivity of the metal center. Some examples of non-chelating diphosphine also exist, due to steric effect, these phosphorus atoms can not react with anything except a proton. Particularly common diphosphine ligands are shown in the table below
21.
Borrowing hydrogen
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Borrowing hydrogen catalysis, also called hydrogen autotransfer, is an important catalytic concept. Borrowing hydrogen can be seen as an example of Green chemistry, the method is highly atom economic, because is circumvents the activation of the alcohol. The method is not limited to the preparation of amines, it can also be used to form Carbon–carbon bonds, alcohols can be temporarily converted into carbonyl compounds by the metal-catalysed removal of hydrogen. The carbonyl compounds are reactive in a range of transformations than the precursor alcohols and can react in situ to give imines, alkenes. Nitroaromatics can also give this reaction, reducing nitro to amine and imine giving secondary amines, ruthenium dichloride dimer Dichlorotrisruthenium dppf Eschweiler-Clarke reaction
22.
Google Books
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Books are provided either by publishers and authors, through the Google Books Partner Program, or by Googles library partners, through the Library Project. Additionally, Google has partnered with a number of publishers to digitize their archives. The Publisher Program was first known as Google Print when it was introduced at the Frankfurt Book Fair in October 2004, the Google Books Library Project, which scans works in the collections of library partners and adds them to the digital inventory, was announced in December 2004. But it has also criticized for potential copyright violations. As of October 2015, the number of scanned book titles was over 25 million, Google estimated in 2010 that there were about 130 million distinct titles in the world, and stated that it intended to scan all of them. Results from Google Books show up in both the universal Google Search as well as in the dedicated Google Books search website, if Google believes the book is still under copyright, a user sees snippets of text around the queried search terms. All instances of the terms in the book text appear with a yellow highlight. The four access levels used on Google Books are, Full view, Books in the domain are available for full view. In-print books acquired through the Partner Program are also available for full view if the publisher has given permission, usually, the publisher can set the percentage of the book available for preview. Users are restricted from copying, downloading or printing book previews, a watermark reading Copyrighted material appears at the bottom of pages. All books acquired through the Partner Program are available for preview and this could be because Google cannot identify the owner or the owner declined permission. If a search term appears many times in a book, Google displays no more than three snippets, thus preventing the user from viewing too much of the book. Also, Google does not display any snippets for certain reference books, such as dictionaries, Google maintains that no permission is required under copyright law to display the snippet view. No preview, Google also displays search results for books that have not been digitized, in effect, this is similar to an online library card catalog. Google also stated that it would not scan any in-copyright books between August and 1 November 2005, to provide the owners with the opportunity to decide which books to exclude from the Project. It can let Google scan the book under the Library Project and it can opt out of the Library Project, in which case Google will not scan the book. If the book has already been scanned, Google will reset its access level as No preview and this information is collated through automated methods, and sometimes data from third-party sources is used. This information provides an insight into the book, particularly useful when only a view is available
23.
International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
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