Лако-красочные материалы — производство

The possibility of replacing all three phenyl rings in the triarylmethane lactone structure by heterocycles has also been exploited. The first com­pound to be described83 was the 3,3-bisindolyl-7-azaphthalide (18). This

compound was obtained directly by reaction of 2 mol of 1,2-dimethylindole with pyridine-2,3-dicarboxylic acid anhydride in acetic anhydride. However, the unambiguity of this 7-azaisomer would seem somewhat doubtful since a later report84 describes the preparation of 4- and 7-azaisomeric mixtures by sequential reaction of two differing 1,2-disubstituted indoles with the an­hydride. Further examples of asymmetric 7-azaphthalides with indoles and benzindoles have also been cited.85 These color formers give red to purple images with clay and phenolic resin developers with good light stability.

Mixtures of 4- and 7-azaphthalides carrying a wide variety of hetero­cycles such as carbozolyl, pyrrolyl, acridinyl, phenothiazinyl, thianaph — thenyl, and thienyl as well as indolyl of the general formulas 19 and 20 have also been described.86 Table 1 illustrates the variety of hues available with such compounds.

4-Azaphthalides carrying indolyl and indolizinyl substituents have been shown65 to produce blue color formers, while the combination of indoles

with imidazo[ 1,2-a]pyridines results in red images with clay developers.66 Pyrazine-2,3-dicarboxylic acid anhydride has been found85 to react analog­ously, producing red color formers on sequential reaction with benzindoles and pyrroles, while indoles and indolizines produce blue derivatives.65 Finally, quinoxaline-2,3-dicarboxylic acid anhydride has frequently been reacted with indoles, and the intermediate ketoacid then condensed with benzindoles,82 indolizines,65 and imidazo[ 1,2-a]pyridines to produce red, blue-black, and orange color formers, respectively.