Indigoid Vat Dyes of the Isatin series. Part XIII. 3-Indole-2'-(6'-bromo) thionaphthene-Indigos

3-Hydrory-6-bromo-thionaphthene was condensed with isatin and some of its different types of sub­stitution products. The resulting 3-indole-2'-(6'-bromo) thionaphtheneindigos are found lighter than those of the corresponding 7'-bromo compounds^I from a comparative study of their colour, dyed shade and absorption maxima data