Nitroso Dyes:-
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Nitroso Dyes:-
Nitroso dyes consist of a small number of dyestuffs group, nitroso group being the chromophore and generally hydroxy (phenolic) group being an auxochrome. Nitroso dyes are derived from resorcinol (214) and a-nitroso-b-naphthol. Examples are the iron complex of bis nitroso resorcinol and iron complex of a-nitroso-b-naphthol-6-sulphonic acid called as Fast Green O and Naphthol Green B respectively.
Fast Green O iron complex is prepared by addition of ferrous ammonium sulphate solution to ammoniacal solution of the dinitroso resorcinol, and was one time important in calico printing. Naphthol Green B, preparede by the treatment of ferrous sulphate, lime and sodium carbonate on a-nitroso-b-naphthol-6-sulphonic acid is one of the fastest acid green dyes for wool,.
