However, the 3-nitrobenzoic thiol acid may also be condensed direct with an alkyl halide Hal-A-Q, in which A, X and Q are as defined for formula I and Hal is a halogen atom, preferably chlorine or bromine, in the presence of a base. ##STR24## The resultant 3-nitrobenzoic acid thiol ester is then reduced with hydrogen, e.g. in the presence of Raney nickel, to give the 3-aminobenzoic acid ester.