Нитрилдер: Құрамы, қасиеттері және қолданылуы

Organic compound with a −C≡N functional group
the class of organic compounds

In organic chemistry, a nitrile is any organic compound that has a |\sC\tN functional group. The name of the compound is composed of a base, which includes the carbon of the |\sC\tN, suffixed with "nitrile", so for example |CH3CH2C\tN is called "propionitrile" (or propanenitrile). 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 |\sC\tN 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.

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 are polar, as indicated by high dipole moments. As liquids, they have high relative permittivities, often in the 30s.

The first compound of the homolog row of nitriles, the nitrile of formic acid, hydrogen cyanide was first synthesized by C. W. Scheele in 1782. In 1811 J. L. Gay Lussac was able to prepare the very toxic and volatile pure acid. Around 1832 benzonitrile, the nitrile of benzoic acid, was prepared by Friedrich Wöhler and Justus von Liebig, but due to minimal yield of the synthesis neither physical nor chemical properties were determined nor a structure suggested. In 1834 Théophile Jules Pelouze synthesized propionitrile, suggesting it to be an ether of propionic alcohol and hydrocyanic acid. The synthesis of benzonitrile by Hermann Fehling in 1844 by heating ammonium benzoate was the first method yielding enough of the substance for chemical research. Fehling determined the structure by comparing his results to the already known synthesis of hydrogen cyanide by heating ammonium formate. He coined the name "nitrile" for the newfound substance, which became the name for this group of compounds.

Industrially, the main methods for producing nitriles are ammoxidation and hydrocyanation. Both routes are green in the sense that they do not generate stoichiometric amounts of salts.

Two salt metathesis reactions are popular for laboratory scale reactions. In the Kolbe nitrile synthesis, alkyl halides undergo nucleophilic aliphatic substitution with alkali metal cyanides. Aryl nitriles are prepared in the Rosenmund von Braun synthesis. In general, metal cyanides combine with alkyl halides to give a mixture of the nitrile and the isonitrile, although appropriate choice of counterion and temperature can minimize the latter. An alkyl sulfate obviates the problem entirely, particularly in nonaqueous conditions (the Pelouze synthesis).

Nitriles can be prepared by the dehydration of primary amides. Common reagents for this include phosphorus pentoxide (|P2O5) and thionyl chloride (|SOCl2). In a related dehydration, secondary amides give nitriles by the von Braun amide degradation. In this case, one C N bond is cleaved.

The conversion of aldehydes to nitriles via aldoximes is a popular laboratory route. Aldehydes react readily with hydroxylamine salts, sometimes at temperatures as low as ambient, to give aldoximes. These can be dehydrated to nitriles by simple heating, although a wide range of reagents may assist with this, including triethylamine/sulfur dioxide, zeolites, or sulfuryl chloride. The related hydroxylamine O sulfonic acid reacts similarly. In specialised cases the Van Leusen reaction can be used. Biocatalysts such as aliphatic aldoxime dehydratase are also effective.

Nitrile groups in organic compounds can undergo a variety of reactions depending on the reactants or conditions. A nitrile group can be hydrolyzed, reduced, or ejected from a molecule as a cyanide ion.

Nitriles are susceptible to hydrogenation over diverse metal catalysts. The reaction can afford either the primary amine (|RCH2NH2) or the tertiary amine (|(RCH2)3N), depending on conditions. In conventional organic reductions, nitrile is reduced by treatment with lithium aluminium hydride to the amine. Reduction to the imine followed by hydrolysis to the aldehyde takes place in the Stephen aldehyde synthesis, which uses stannous chloride in acid.

Alkyl nitriles are sufficiently acidic to undergo deprotonation of the C H bond adjacent to the CN group. Strong bases are required, such as lithium diisopropylamide and butyl lithium. The product is referred to as a nitrile anion. These carbanions alkylate a wide variety of electrophiles. Key to the exceptional nucleophilicity is the small steric demand of the CN unit combined with its inductive stabilization. These features make nitriles ideal for creating new carbon carbon bonds in sterically demanding environments.

Nitriles are precursors to transition metal nitrile complexes, which are reagents and catalysts. Examples include tetrakis(acetonitrile)copper(I) hexafluorophosphate (|[Cu(MeCN)4]+) and bis(benzonitrile)palladium dichloride (|PdCl2(PhCN)2).

Cyanamides are N cyano compounds with general structure |R^{1}R^{2}N\sC\tN and related to the parent cyanamide.

Nitrile oxides have the chemical formula |RCNO. Their general structure is |R\sC\tN+\sO The R stands for any group (typically organyl, e. g., acetonitrile oxide |CH3\sC\tN+\sO−, hydrogen in the case of fulminic acid |H\sC\tN+\sO−, or halogen, e. g., chlorine fulminate |Cl\sC\tN+\sO−). They and are used in 1,3 dipolar cycloadditions. They undergo type 1 dyotropic rearrangement to isocyanates. They can be used to synthesise isoxazoles. Over 30 nitrile containing pharmaceuticals are currently marketed for a diverse variety of medicinal indications with more than 20 additional nitrile containing leads in clinical development. The types of pharmaceuticals containing nitriles are diverse, from vildagliptin, an antidiabetic drug, to anastrozole, which is the gold standard in treating breast cancer. In many instances the nitrile mimics functionality present in substrates for enzymes, whereas in other cases the nitrile increases water solubility or decreases susceptibility to oxidative metabolism in the liver. The nitrile functional group is found in several drugs.