2,2'-Dimethyl-4,4'-biphenyldiamine 2,2'-Dimethylbenzidine 2,2'-Tolidine 4,4'-Diamino-2,2'-dimethylbiphenyl 84-67-3 Benzidine, 2,2'-dimethyl- NSC1989 [1,1'-Biphenyl]-4,4'-diamine, 2,2'-dimethyl- m-Tolidine