Synthesis and evaluation of organic pigments. 4. New monoarylide and diarylide pigments

The synthesis, characterization and mutagenicity of a series of diarylide p igments prepared using highly twisted nonmutagenic 2,2/-dimethyl-5,5'-dipro poxybenzidine and 2,2'-dimethoxy-5,5'-dipropoxybenzidine, and their monoary lide counterparts arylide counterparts are reported. Five pigments in which nitro groups were incorporated into either the 3- or 4-position of the ace toacetanilide coupling component were mutagenic in either the standard Salm onella mutagenicity assay (Ames test) or the Prival modification. The prese nce of 3-trifluoromethyl or 3-acetyl groups in the acetoacetanilide moiety led to nonmutagenic pigments. Despite the high dihedral angle across the bi phenyl linkage, the lambda (max) of the highly twisted diarylide pigments w as significantly bathochromic relative to the corresponding monoarylide pig ments. (C) 2001 Elsevier Science Ltd. All rights reserved.