Process for the production of substituted acetonitriles

A process for the production of an aromatic or heteroaromatic substituted acetonitrile of the formula ##STR2## where R.sub.1 is hydrogen, phenyl, thienyl, pyridyl, quinolyl or isoquinolyl and R.sub.2 is thienyl, pyridyl, quinolyl or isoquinolyl or R.sub.2 is a substituted thienyl, pyridyl, quinolyl or isoquinolyl group having at least one substituent wherein the substituent is lower alkyl, halogen, hydroxy, cyano, phenoxy or methoxy and n is 0 or 1 comprising reacting a substituted methane of the formula R.sub.1 --CH.sub.2 --R.sub.2, toluene or hydroxytoluene with cyanogen chloride in the gas phase by feeding the substituted methane and cyanogen chloride separately from each other and in gaseous form into the reactor at a temperature close to the reaction temperature and carrying out the reaction at a temperature between 550.degree. and 850.degree. C., cooling the reaction mixture immediately after leaving the reactor to a temperature below 100.degree. C. and treating the reaction mixture with an aqueous base.