Лако-красочные материалы — производство

One further example of this principle of bridging the aryl groups of a triarylmethane phthalide was reported in 1986.108 Thus, treatment of phthalide 27 with aluminum chloride results in the formation of the spirobenzanthracene 28 as shown in Scheme 11. These color formers also exhibit absorption in the near infrared spectral region, but no further […]

4.7.1. Spirofluorene Phthalides Fusion of the two arylamino groups of a triarylmethane phthalide color former results in the formation of spirofluorene phthalides. Due to the increased planarity of this system, a bathochromic shift results leading also to color formers showing infrared absorption when developed. This was first exemplified in 1983102 by preparation of phthalide 26 […]

One further example of this principle of extended conjugation to produce infrared-absorbing color formers is the introduction of the bu — tadienyl group at the 3-position of the phthalide ring.100 Thus, 2-(4- dimethylaminobenzoyl)benzoic acid was reacted with 1,1-bis(4-dimethyl — aminophenyl)buta-1,3-diene in acetic anhydride to yield the phthalide 24. This idea, however, does not appear to […]

Introduction of two diaminophenylethylene moieties at the 3-position of the phthalide ring naturally also produces color formers exhibiting infrared absorption. As in Section 4.6.1, the first report93 encompasses a vast number of compounds such as 22 which was prepared by treating phthalic anhydride with 2 mol of 1,1-bisdimethylaminophenylethylene in acetic an­hydride. (22) Reaction proceeds via […]

4.6.1. 3-Ethylenyl Phthalides Introduction of an ethylene bridge between the meso-carbon atom and one of the diaminophenyl groups of a triarylmethane-type phthalide results in a considerable bathochromic shift, thus producing color formers exhibi­ting absorption in the near infrared region of the electromagnetic spectrum.

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 (18) 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 […]

As in the previous section, one class of compounds, namely, the 3-dialkylaminophenyl-3-indolyl-4-azaphthalides, is of primary importance from a commercial viewpoint. The 7-azaisomer, the first dialkylamino- phenylindolylazaphthalide, has been prepared69 as shown in Scheme 8 (cf. Scheme 7). Heating pyridine-2,3-dicarboxylic acid anhydride with 1-ethyl-2- methylindole has been claimed to yield solely the pyridine-2-carboxylic acid, albeit in […]

4.4.1. 3,3-Bisheterocyclic Substituted Phthalides From a commercial viewpoint the most important compounds of this class are the 3,3-(bisindol-3-yl)phthalides. The first synthesis47 involved Route B as described in Scheme 7, in which a second indole derivative condenses with the indolylbenzoylbenzoic acid in acetic anhydride. How­ever, for the preparation of symmetrical derivatives it has been shown61 that […]

Another approach to improve the color formation properties of Mala­chite Green lactone has been the introduction of nitrogen atoms into the phthalide ring. Thus, condensation ofpyridine-2,3-dicarboxylic acid anhydr­ide with dimethylaniline in the presence of zinc chloride has been shown54 to yield a mixture of the 4- and 7-azaphthalides 11 and 12. Stepwise addition of the […]

4.3.1. 3-Heterocyclic Substituted Phthalides A different approach for the modification of the basic Malachite Green lactone structure has been the replacement of one 4-dimethylaminophenyl group by electron-rich heterocycles. The most thoroughly investigated heterocycle has been the 3-indolyl residue, which may be introduced by two different routes as shown in Scheme 7. The first compounds of […]