Studies on Some Thioindigoid Dyestuffs

Department of Chemistry, Bhagalpur University, Bhagalpur-812 007 Manuscript received 29 January 1976; revised 23 July 1976; accepted 28 July 1978 4-Bromo-3-hydroxy-thionaphthene was synthesised and condensed with isatin and its 5-chloro-, 5-bromo-, 5-iodo-, 5-nitro-, 5 :7-dibromo-, 5-bromo-7-nitro- and 5:7-dinitro derivatives. These newly prepared 3-indole-2' (4`-bromo) thionaphthene indigos were compared with the previously known corresponding 5'-bromo-, 6'-bromo- and 7'-bromo- dyes with respect to their colour and absorption maxima. The depth of colour was found to run asunder 5'-bromo dye > 7'-lbrosno dye > 4'-brorno dye > 6'-bromo dye