|
Kolbe Nitrile Synthesis
The Kolbe nitrile synthesis is a method for the preparation of alkyl nitriles by reaction of the corresponding alkyl halide with a metal cyanide. A side product for this reaction is the formation of an isonitrile because the cyanide ion is an ambident nucleophile and according to Kornblum's rule is capable of reacting with either carbon or nitrogen. The reaction is named after Hermann Kolbe. :\underset + \underset -> \underset + \underset The ratio in which both isomers form depends on the solvent and the reaction mechanism. With the application of alkali cyanides such as sodium cyanide and polar solvents the reaction type is an SN2 reaction whereby the alkylhalide is attacked by the more nucleophilic carbon atom of the cyanide ion. This type of reaction together with dimethyl sulfoxide as a solvent is a convenient method for the synthesis of nitriles. The use of DMSO was a major advancement in the development of this reaction, as it works for more sterically hindered electrophi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermann Kolbe
Adolph Wilhelm Hermann Kolbe (27 September 1818 – 25 November 1884) was a major contributor to the birth of modern organic chemistry. He was a professor at Marburg and Leipzig. Kolbe was the first to apply the term synthesis in a chemical context, and contributed to the philosophical demise of vitalism through synthesis of the organic substance acetic acid from carbon disulfide, and also contributed to the development of structural theory. This was done via modifications to the idea of "radicals" and accurate prediction of the existence of secondary and tertiary alcohols, and to the emerging array of organic reactions through his Kolbe electrolysis of carboxylate salts, the Kolbe-Schmitt reaction in the preparation of aspirin and the Kolbe nitrile synthesis. After studies with Wöhler and Bunsen, Kolbe was involved with the early internationalization of chemistry through work in London (with Frankland). He was elected to the Royal Swedish Academy of Sciences, and won the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrile
In organic chemistry, a nitrile is any organic compound that has a functional group. The prefix ''cyano-'' is used interchangeably with the term ''nitrile'' in industrial literature. Nitriles are found in many useful compounds, including methyl cyanoacrylate, used in super glue, and nitrile rubber, a nitrile-containing polymer used in latex-free laboratory and medical gloves. Nitrile rubber is also widely used as automotive and other seals since it is resistant to fuels and oils. Organic compounds containing multiple nitrile groups are known as cyanocarbons. Inorganic compounds containing the group are not called nitriles, but cyanides instead. Though both nitriles and cyanides can be derived from cyanide salts, most nitriles are not nearly as toxic. Structure and basic properties The N−C−C geometry is linear in nitriles, reflecting the sp hybridization of the triply bonded carbon. The C−N distance is short at 1.16 Å, consistent with a triple bond. Nitriles a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organohalide
Halocarbon compounds are chemicals in which one or more carbon atoms are linked by covalent bonds with one or more halogen atoms (fluorine, chlorine, bromine or iodine – ) resulting in the formation of organofluorine compounds, organochlorine compounds, organobromine compounds, and organoiodine compounds. Chlorine halocarbons are the most common and are called organochlorides. Many synthetic organic compounds such as plastic polymers, and a few natural ones, contain halogen atoms; they are known as ''halogenated'' compounds or ''organohalogens''. Organochlorides are the most common industrially used organohalides, although the other organohalides are used commonly in organic synthesis. Except for extremely rare cases, organohalides are not produced biologically, but many pharmaceuticals are organohalides. Notably, many pharmaceuticals such as Prozac have trifluoromethyl groups. For information on inorganic halide chemistry, see halide. Chemical families Halocarbons are t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanide
Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms. In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom. In inorganic cyanides, the cyanide group is present as the anion . Soluble salts such as sodium cyanide (NaCN) and potassium cyanide (KCN) are highly toxic. Hydrocyanic acid, also known as hydrogen cyanide, or HCN, is a highly volatile liquid that is produced on a large scale industrially. It is obtained by acidification of cyanide salts. Organic cyanides are usually called nitriles. In nitriles, the group is linked by a covalent bond to carbon. For example, in acetonitrile (), the cyanide group is bonded to methyl (). Although nitriles generally do not release cyanide ions, the cyanohydrins do and are thus rather toxic. Bonding The cyanide ion is isoelectronic with carbon monoxide a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isonitrile
An isocyanide (also called isonitrile or carbylamine) is an organic compound with the functional group –. It is the isomer of the related nitrile (–C≡N), hence the prefix is ''isocyano''.IUPAC Goldboo''isocyanides''/ref> The organic fragment is connected to the isocyanide group through the nitrogen atom, not via the carbon. They are used as building blocks for the synthesis of other compounds. Properties Structure and bonding The C-N distance in isocyanides is 115.8 pm in methyl isocyanide. The C-N-C angles are near 180°. Akin to carbon monoxide, isocyanides are described by two resonance structures, one with a triple bond between the nitrogen and the carbon and one with a double bond between. The π lone pair of the nitrogen stabilizes the structure and is responsible of the linearity of isocyanides, although the reactivity of isocyanides reflects some carbene character, at least in a formal sense. Thus, both resonance structures are useful representations. They are sus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambident Nucleophile
In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are Lewis bases. ''Nucleophilic'' describes the affinity of a nucleophile to bond with positively charged atomic nuclei. Nucleophilicity, sometimes referred to as nucleophile strength, refers to a substance's nucleophilic character and is often used to compare the affinity of atoms. Neutral nucleophilic reactions with solvents such as alcohols and water are named solvolysis. Nucleophiles may take part in nucleophilic substitution, whereby a nucleophile becomes attracted to a full or partial positive charge, and nucleophilic addition. Nucleophilicity is closely related to basicity. History The terms ''nucleophile'' and ''electrophile'' were introduced by Christopher Kelk Ingold in 1933, replacing the terms ''anionoid'' and ''cationoid'' p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kornblum's Rule
HSAB concept is a jargon for "hard and soft (Lewis) acids and bases". HSAB is widely used in chemistry for explaining stability of compounds, reaction mechanisms and pathways. It assigns the terms 'hard' or 'soft', and 'acid' or 'base' to chemical species. 'Hard' applies to species which are small, have high charge states (the charge criterion applies mainly to acids, to a lesser extent to bases), and are weakly polarizable. 'Soft' applies to species which are big, have low charge states and are strongly polarizable. The theory is used in contexts where a qualitative, rather than quantitative, description would help in understanding the predominant factors which drive chemical properties and reactions. This is especially so in transition metal chemistry, where numerous experiments have been done to determine the relative ordering of ligands and transition metal ions in terms of their hardness and softness. HSAB theory is also useful in predicting the products of metathesis rea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Isomers do not necessarily share similar chemical or physical properties. Two main forms of isomerism are structural or constitutional isomerism, in which ''bonds'' between the atoms differ; and stereoisomerism or spatial isomerism, in which the bonds are the same but the ''relative positions'' of the atoms differ. Isomeric relationships form a hierarchy. Two chemicals might be the same constitutional isomer, but upon deeper analysis be stereoisomers of each other. Two molecules that are the same stereoisomer as each other might be in different conformational forms or be different isotopologues. The depth of analysis depends on the field of study or the chemical and physical properties of interest. The English word "isomer" () is a back-for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solvent
A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for polar molecules and the most common solvent used by living things; all the ions and proteins in a cell are dissolved in water within the cell. The quantity of solute that can dissolve in a specific volume of solvent varies with temperature. Major uses of solvents are in paints, paint removers, inks, and dry cleaning. Specific uses for organic solvents are in dry cleaning (e.g. tetrachloroethylene); as paint thinners (toluene, turpentine); as nail polish removers and solvents of glue (acetone, methyl acetate, ethyl acetate); in spot removers (hexane, petrol ether); in detergents ( citrus terpenes); and in perfumes (ethanol). Solvents find various applications in chemical, pharmaceutical, oil, and gas industries, including in chemical syn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reaction Mechanism
In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical change occurs. A chemical mechanism is a theoretical conjecture that tries to describe in detail what takes place at each stage of an overall chemical reaction. The detailed steps of a reaction are not observable in most cases. The conjectured mechanism is chosen because it is thermodynamically feasible, and has experimental support in isolated intermediates (see next section) or other quantitative and qualitative characteristics of the reaction. It also describes each reactive intermediate, activated complex, and transition state, and which bonds are broken (and in what order), and which bonds are formed (and in what order). A complete mechanism must also explain the reason for the reactants and catalyst used, the stereochemistry observed in reactants and products, all products formed and the amount of each. The electron or arrow pushing method is often used in i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Cyanide
Sodium cyanide is a poisonous compound with the formula Na C N. It is a white, water-soluble solid. Cyanide has a high affinity for metals, which leads to the high toxicity of this salt. Its main application, in gold mining, also exploits its high reactivity toward metals. It is a moderately strong base. Production and chemical properties Sodium cyanide is produced by treating hydrogen cyanide with sodium hydroxide: :HCN + NaOH → NaCN + H2O Worldwide production was estimated at 500,000 tons in the year 2006. Formerly it was prepared by the Castner process involving the reaction of sodium amide with carbon at elevated temperatures. : NaNH2 + C → NaCN + H2 The structure of solid NaCN is related to that of sodium chloride. The anions and cations are each six-coordinate. Potassium cyanide (KCN) adopts a similar structure. When treated with acid, it forms the toxic gas hydrogen cyanide: : NaCN + H+ → HCN + Na+ Because the salt is derived from a weak aci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SN2 Reaction
The SN2 reaction is a type of reaction mechanism that is common in organic chemistry. In this mechanism, one bond is broken and one bond is formed in a concerted way, i.e., in one step. The name SN2 refers to the Hughes-Ingold symbol of the mechanism: "SN" indicates that the reaction is a nucleophilic substitution, and "2" that it proceeds via a bi-molecular mechanism, which means both the reacting species are involved in the rate-determining step. The other major type of nucleophilic substitution is the SN1, but many other more specialized mechanisms describe substitution reactions. The SN2 reaction can be considered as an analogue of the associative substitution in the field of inorganic chemistry. Reaction mechanism The reaction most often occurs at an aliphatic sp3 carbon center with an electronegative, stable leaving group attached to it (often denoted X), which is frequently a halide atom. The breaking of the C–X bond and the formation of the new bond (often deno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
