Direct dyes from nongenotoxic diamines

This paper pertains to the synthesis and evaluation of direct dyes in which 2,2'-dimethyl 5,5'-dipropoxybenzidine and 5,5'-dipropoxybenzidine are used as potential alternatives to benzidine, an established human carcinogen. The two benzidine analogs were diazotized and coupled with widely used dye intermediates to generate a group of direct dyes giving red and blues shades on cotton. Dye structures were confirmed using negative ion electrospray mass spectrometry (ESMS). A summary of the ESMS data and fastness properties of the new direct dyes are reported.