Nitro Dyes:-
by : Rahul Sharma
Nitro Dyes:-
A few use full dyes belonging to this class are known. Nitro group is the chromohore in these dyes. There are two types of dyes in this class, namely, acid dyes are disperse dyes. Acid dyes contain a solubilising group such as sulphonic acid and Naphthol Yellow S is the example. Disperse dyes contain no solubilising group and generally have ortho nitro diphenylamine structure, as in the disperse yellow dyes.
Naphthol Yellow S is obtained from 1-naphthol-2, 4, 7-tri-sulphonic acid by the action of nitric acid when sulphonic acid groups in 2 and 4 positions are smoothly replayed by nitro groups. Disperse Yellow is obtained by the condensation of 2, 4-dinitrochlorobenzene with para amino phenol or with paranisidine and demethylation.
