Sulfuric Acid → Sulfuric Acid

Participants

Reaction Steps

16.6 parts of 3-amino-5-nitro-2,1-benzisothiazole are introduced into 130 g of sulphuric acid (96% strength) at 25° C. After 90 minutes' stirring a clear solution has been obtained, to which 31 parts of 50% strength sulphuric acid and 25.8 parts of 42.5% strength nitrosylsulphuric acid are added at an interval of 30 minutes. After a further 30 minutes, the mixture is cooled to 5° C and a solution of 17.6 parts of N-ethyl-N-β-caboxyethyl-m-toluidine in 60 parts of glacial acetic acid is added dropwise at this temperature. After a further 30 minutes, the reaction mixture is poured out onto an ice-water mixture and this mixture is stirred for 4 hours. The dyestuff which has precipitated is filtered off, washed until the wash waters are neutral and then dried. The dyestuff of the formula ##SPC13##

Provenance & Evidence