As the free 4-aminophthalic acid is not readily obtained pure, on account of its instability, we used its dimethyl ester as the starting point for our experiments. This was prepared from phthalic anhydride by nitrating, esterifying the mixture of nitro acids which result; separating the neutral ester of the 4-nitrophthalic acid, and then reducing the nitro acid with alcoholic hydrochloric acid and zinc dust. By this method, the amino ester was obtained in ...
