Nitriles

Nitriles, or organic cyanides, are characterized by a CN group attached to a carbon radical (unlike isonitriles, or carbamimines, for which attachment of the radical to N is characteristic); e.g. CH₃-C≡N. Nitriles can be obtained by the action of KCN on halogen derivatives of hydrocarbons: CH₃J + KCN = CH₃CN + KJ; by the removal of water from ammonium salts and amides of fatty acids, and from aldoximes: CH₃.COONH₄ = CH₃CN + 2H₂O; CH₃.CONH₂ = CH₃CN + H₂O; R.CH:N.OH = R.CN + H₂O. By the action of cyanogen chloride on Mg - organic compounds: C₅H₁₁MgBr + ClCN = MgClBr + C₆H₁₁CN. Nitriles, starting with CH₃CN, are liquids insoluble in water, neutral, more or less toxic. Under the influence of acids and alkalis they are hydrolyzed, giving acid amides and then the acid: CH₃CN + H₂O = CH₃.CONH₂; CH₃CONH₂ + H₂O = CH₃.COOH + NH₃. Upon reduction, nitriles convert to amines: CH₃CN + 2H₂ = C₂H₅NH₂. Polymers of nitriles are known, e.g. from 2 and 3 molecules of propionitrile (ethyl cyanide): (C₂H₅CN)₂ and (C₂H₅CN)₃. Nitriles are formed upon oxidation of proteins with chromic mixture or potassium permanganate with sulfuric acid. According to some authors, the formation of amino acids in plants, from which proteins are subsequently synthesized, goes through the stage of aminonitriles; e.g. CH₂:O + HCN + NH₃ → CH₂(NH₂).CN → CH₂(NH₂).COOH. This inadequately substantiated hypothesis could explain the finding in plants and animals exclusively of α-isomers of amino acids. The first representative of nitriles is acetonitrile, CH₃CN (methyl cyanide); it boils at 81.5°.