Лако-красочные материалы — производство

The starting products for reflux thionation in aqueous or solvent media are chiefly derivatives of indophenol (10, Y = OH) and indoaniline (10, Y = NH2). The starting compounds are often in the leuco form 11.

This class of compounds also includes phenazone, phenothiazone, and phe — noxazone derivatives (12), and so these polysulfide melt dyes are also referred to as quinoneimine or indophenol sulfur dyes.

Gnehm and Kaufler [4] showed that C. I. Sulphur Blue 9, 53430 [1327-56-6], which is prepared by sulfurization of the indophenol derivative 10 [Y = N(CH3)2], has the phenothiazone structure 12.

Zerweck et al. [2], on the other hand, subjected well-defined phenothiazone derivatives to successive sulfurizations, obtaining sulfur dyes whose colors and other properties largely matched those of the corresponding unchlorinated indo- phenols or diphenylamine derivatives 14. In the trichlorophenothiazones 13, the chlorine atoms were replaced by sulfur in stepwise reactions (Scheme 2.7).

In this way it was established that both thiazone and thianthrene structures are present in all the quinoneimine sulfur dyes studied (C. I. Vat Blue 43, 53630 [1327-79-3]; C. I. Sulphur Black 6, 53295 [1327-16-8], C. I. Sulphur Black 7, 53300 [1327-17-9]; C. I. Sulphur Black 11, 53290 [1327-14-6]; and C. I. Sulphur Red 5, 53820). The thianthrene structure was also found to contribute greatly to the sub — stantivity of the dyes.

The structure 15 can thus be regarded as the prototype of the polysulfide-melt dyes (quinoneimine or indophenol sulfur dyes) (Scheme 2.8).

The polysulfide melt dyes are similar to vat dyes by virtue of the quinonei — mine structure. Reducing agents also convert them to a leuco form with a change of hue. The agent not only reduces the quinoneimine group but also transforms the disulfide groups of the dye molecule to sodium thiolate groups. The reduction and the associated cleavage of the disulfide groups render the molecule consider­ably smaller.

Polysulfide melt dyes, which are applied chiefly with dithionite and commonly show a higher degree of fastness, are called sulfur vat dyes. They include such dyes as C. I. Vat Blue 43 and C. I. Sulphur Black 11.

The polysulfide melt process yields mainly reddish brown, violet, blue, green, and black sulfur dyes, depending on the intermediate.