| 摘要 |
Process for preparing a strong, non-flocking and rheologically excellent 4,4',7,7'-tetrachlorothioindigo pigment in high yields and high purity, which comprises (a) reacting 2,5 -dichlorophenylthioglycoloyl chloride with Friedel-Crafts catalysts in inorganic acyl halides of medium oxidation state as diluent as temperatures of -20 DEG to +50 DEG C. to 4,7-dichloro-3-oxythionaphthene, (b) oxidizing the resulting 4,7-dichloro-3-oxythionaphthene in a conventional manner to crude 4,4',7,7'-tetrachlorothioindigo, and (c) treating the crude 4,4',7,7'-tetrachlorothioindigo obtained in moist form with an aromatic solvent at 80 DEG to 180 DEG C. in the presence of an aqueous alkali solution and a surface-active compound.
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