ChemInform Abstract: Azo Disperse Dyes Derived from 3-Amino-7-nitro-2H-1,2-benzothiazine 1,1-Dioxide.

ChemInform Abstract

The sulfonamide (I) undergoes cyclocondensation with urea (II) to produce the benzothiazine (III) mentioned in the title. Diazotization of (III) with nitrosylsulfuric acid (IV) and subsequent coupling with the anilines (V) afford the azo dyes (VI) which are methylated with dimethyl sulfate (VII), forming the disperse dyes (VIII). Bromination of (VIIIa) and subsequent reaction with cupric cyanide (IX) give the cyanation product (X). The 4-bromo-2-methylbenzothiazine dioxide (XI), prepared by methylation and bromination of (III), is diazotized and then coupled with the aniline (Va); subsequent cyanation yields the disperse dye (XIII).