Dyes Derived from 4: 5 DiaryI Thiazoles

In the present investigation a number of variously substituted p-dialkylamino styryl dyes, their corresponding aza and diaza analogues have been prepared from 2-methyl and 2-methyl mercapto 4,5 diaryl thiazoles respectively to evaluate the effect of the replacement of —CH = CH— by —CH = N— and —N = N— on absorption of these dyes. The absorption data have been discussed in the light of Forster's rule. The relative basicity of the different 4 :  5-diaryl thiazoles have been evaluated by using Brooker's Deviation factor.

Besides this, a number of azo dyes very much similar to diaza analogues mentioned above have been prepared for dyeing synthetic fibres. The sensitising properties of p-dialkylamino styryl dyes, their aza and diaze, analogues have also been evaluated.