| 摘要 |
PROBLEM TO BE SOLVED: To produce 4,4'-dimethyl-6,6'-dichlorothioindigo in the state of a stable crystal modification I and in the state of an easily dispersible, brilliant pigment having a dark hue, directly from 3-hydroxy-4-methyl-6-chlorothionaphthene having a specified max. average particle size by oxidation. SOLUTION: 4,4'-Dimethyl-6,6'-dichlorothioindigo of formula I in the state of a stable crystal modification I having, in the X-ray diffration pattern (CuKαradiation), high-strength spectral lines at diffraction angles (2θ) of 25.99 deg. and 21.26 deg. and medium-strength spectral lines at diffraction angles of 10.27 deg., 12.48 deg., 22.39 deg., 23.91 deg., 24.82 deg., and 28.87 deg. is produced directly from 3-hydroxy-4-methyl-6- chlorothionaphthene of formula II having an average particle size D50 of at most 20μm. Examples of an oxidizing agent used are an iron (III) salt, a nitro compd., oxygen, ozone, a percarbonate, a perborate, and a polysulfide.
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