C-Nucleophilic substitution in tetrachlorophthalonitrile — An approach to some new hexadecasubstituted phthalocyanines

Reaction of tetrachlorophthalonitrile with some C -nucleophiles was studied. Only one chlorine atom was substituted regioselectively in the position 4 of benzene ring with diethyl malonate and malononitrile; no reaction occurred in case of bulkier diethyl ethylmalonate and ethylmalononitrile. In case of dimedone the domino substitution of two chlorine atoms, first with C -nucleophile followed by enolate O -nucleophile led to the mixture of two dibenzofuran derivatives. Remaining chlorine aroms n malonate and dibenzofuran derivatives were substituted with thiols, but in malononitrile derivative high acidity of methine proton led to the formation of stable carbanion under basic conditions that prevents further substitution. Hexadecasubstituted zinc phthalocyanines were synthesized from some new phthalonitriles.