In a process for producing a nitrile compound from a corresponding aldehyde exhibited by the general formula (I) and a hydroxylamine inorganic acid salt or from an aldoxime exhibited by the general formula (II), (in the general formulas shown hereinabove, R.sup.1 represents an aryl group having 6 to 9 carbon atoms and R.sup.2 represents an alkyl or alkenyl group having 1 to 9 carbon atoms or an aryl group having 6 to 9 carbon atoms), a process, wherein water produced in the reaction is azeotropically distilled out of the reaction system with the aid of a solvent which makes an azeotropic mixture with water. The nitrile compound is useful as an important intermediate for the synthesis of pharmaceuticals or pesticides.

In preparing trifluoromethylbenzonitrile by reaction of trifluoromethylbenzaldehyde with hydroxylamine, the rate of reaction is enhanced and formation of trifluoromethylbenzamide is suppressed by carrying out the reaction in an organic solvent which is immiscible with water and has a sufficiently high boiling point, e.g. nitrotoluene, and continuously distilling by-produced water from the reaction system. The solvent can easily and almost entirely be recovered and reused.

Disclosed is a novel process for the preparation and separation of cyclopropanecarbonitrile (CPCN) from cyclopropropanecarboxaldehyde (CPCA) using a combination of three process steps. The process involves the steps of (1) reacting (CPCA) with hydroxylamine base in the presence of water to obtain CPCA oxime, (2) contacting the CPCA oxime of step (1) with formic acid to obtain CPCN, and (3) contacting the mixture comprising CPCN formed in step (2) with a base to obtain a mixture comprising an organic phase containing CPCN and an aqueous phase. The reactants and intermediates involved in each step are used within certain defined ratios.

A process for the preparation of a nitrile of formula ##STR1## wherein R is hydrogen, C.sub.1 -C.sub.4 alkyl or phenyl, by reaction of an aldehyde of formula ##STR2## wherein R is as defined above, with hydroxylamine sulfate and subsequent dehydration, which process comprises carrying out the reaction in propionic acid in the presence of a salt of propionic acid by heating to an external temperature in the range from 140.degree. to 165.degree. C., preferably from 150.degree. to 160.degree. C., for 2 to 6 hours, preferably for 3 to 5 hours, under atmospheric pressure, and simultaneously distilling the mixture of propionic acid and water from the system until a solution forms, and thereafter removing the mixture of propionic acid and water at 100.degree.-130.degree. C., preferably 110.degree.-120.degree. C., by vacuum distillation, and then isolating the resultant nitrile by standard procedures.

New process for the synthesis of the .alpha.-(1-m.ethylethyl)-3,4-dimethoxyacetonitrile of formula (I): ##STR1## which is known as an intermediate in the synthesis of the drug internationally known as verapamil. The process starts from the isobutyryl-3,4-dimethoxybenzene of formula (II): ##STR2## which, by means of the Darzens condensation, gives an epoxyester which, by alkaline hydrolysis and subsequent decarboxylation, gives the .alpha.-(1-methylethyl)-3,4-dimethoxybenzeneacetaldehyde. This product is reacted with hydroxylamine to obtain the corresponding oxime that, by dehydration, gives the nitrile of formula I.