Aluminum phthalocyanines, preparation

Aluminum phthalocyanine (PcAlX) can be prepared from the phthalonitrile and aluminum trichloride either in refluxing quinoline138 13g or without a solvent under addition of ammonium molybdate(VI).137 The chloro compound can be transformed to a hydroxy derivative by treatment with sulfuric acid.58-140 Also, the insertion of aluminum in a metal-free phthalocyanine is possible, for example trialkylaluminum can be used.141,142... 

Thus (XX) reacts with phenol in pyridine to form diphenoxysilicon phthalocyanine (XXII), with benzyl alcohol to form (XXIII), and with triphenylsilanol to form (XXIV) (168,170, 200). These complexes sublime readily without decomposition (cf. corresponding aluminum derivatives). Bis(diphenylmethylsiloxy)silicon phthalocyanine, which melts before subliming, is one of the very few metal phthalocyanines which actually melt (873). The siloxy complex (XXIV) may also be prepared in benzyl alcohol, thus implying that the Si—O—Si(Pc)—0—Si backbone is more stable than C—O—Si(Pc)—O—C. The dibenzyloxy derivative (XXIII) reacts with diphenylsilanediol to form bis(benzyloxydiphenylsiloxy)silicon phthalocyanine (XXV). 

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