Dyes derived from aminothiophenes .4. Synthesis of some nitro-substituted thiophene-based azo disperse dyes

A series of thienylazo dyes has been prepared from nitro-substituted 2- and 3-aminothiophenes; colorants front the former were reddish-blue to green, whereas those from the latter were yellow to orange. The 2-aminothiophenes were obtained either by the amination of an activated chlorothiophene or by the functionalisation of thiophenes synthesised using the Gewald reaction. The thienyl-3-azo dyes were prepared from derivatised 3-amino-2-methoxycarbonylthiophenes. The C-13 NMR chemical shifts of a nitrothienyl-2-azo dye ave reported together with those of a 5-nitrothiazolyl-2-azo analogue. (C) 1997 Elsevier Science Ltd.