Summary By reduction with cupro-ammonia ion in dilute ammonium hydroxide the diazotized forms of the following amines are converted to biaryls in yields of 20-90%: the nitroanilines, the nitrotoluidines, anthranilic acid, a variety of halogenoand nitroanthranilic acids, a number of aminonaphthalene carboxylic acids, o-aminobenzenesulfonic acid.