Formation of Aromatic Nitriles by Direct Replacement of the Nitro Groups of Dinitrotetrachlorobenzenes

Direct replacement of nitro by cyano groups has been effected by treatment of the dinitrotetrachlorobenzenes in refluxing chloroform with aqueous cyanide ion in the presence of a phase transfer catalyst. Esters, amides and nitriles derived from tetrachlorobenzene dicarboxylic acids are useful as herbicides, bactericides and fungicides 1 Generally these compounds have been prepared from chlorine-free precursors by reaction with chlorine at high temperatures 2 . Alternative syntheses were sought starting from the various tetrachloroben-zenes, which are accessible cheaply from by-products of other manufacturing processes. It has been found that the dinitrotetrachlorobenzenes, formed by nitration of the corresponding tetrachlorobenzenes 3 , react with aqueous solutions of alkali metal cyanides with replacement of one or more of the nitro groups by cyanide (Table).