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Pseudo Synthetic Sulfur Dyes

If NaSH is used in place of Ng S, alkali must be added to capture the H+ ions produced in reduction, because these would lead to evolution of H2S [Eq. (12)]  [Pg.225]

Pseudo sulfur dyes are not prepared by the classical sulfurization method. Instead, mercapto groups or their precursors are introduced into dye precursors or pigments by preparative means. [Pg.225]

In the case of the dye from copper phthalocyanine (C.I. Sulphur Green 25), the synthesis can follow one of two paths  [Pg.225]

1) Preparation of a tetranitro copper phthalocyanine by condensation of 4-nitrophthalimide with Cu2+ salts in, e.g., nitrobenzene, followed by reduction to the tetramino derivative with, e.g., NaSH, diazotization, and reaction with NaSCN (Sandmeyer reaction) to tetrathiocyanato copper phthalocyanine [6], [Pg.225]

2) Sulfochlorination of copper phthalocyanine with chlorosulfonic acid/thionyl chloride to yield the tetrasulfochloride, followed by reduction to the tetramer-capto compound (e.g., with Fe/HCl or thiourea) [7] [Eq. (13)]. [Pg.225]


The term pseudo (or synthetic) sulfur dyes refers to dyes that have application properties similar to those of sulfur dyes but are obtained by the insertion of mer-capto groups or their precursors into the dye precursors or pigments rather than by the classical sulfurization method. These dyes thus have some of the characteristics of sulfur dyes. [Pg.83]


See other pages where Pseudo Synthetic Sulfur Dyes is mentioned: [Pg.225]    [Pg.225]    [Pg.225]    [Pg.225]   


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