Synthesis and application of direct black dyes containing 4,4-diaminodiphenyl sulfonamide

4, 4ʹ-Diaminodiphenyl sulfonamide and black dyes based on this intermediate were synthesised. When mixtures of the black dyes were used to dye silk, the blackness at 5% shade depth was C. I. Direct of Black 38. Their exhaustion and fastness to light and washing was better than that of C. I. Direct Black 38.