The syntheses of mono- and disubstituted phthalocyanines using a dithioimide

Hydrolysis of 5-neopentoxy-1,3-diiminoisoindoline gave 5-neopentoxy-1H-isoindole-1,3(2H)-dione (4-neopentoxyphthalimide), which, on treatment with Lawesson's reagent, yielded the thiophthalimides, 5-neopentoxy-1H-isoindole-1,3(2H)-dithione, 2,3-dihydro-6-neopentoxy-3-thioxo-1H-isoindol-1-one, and 2,3-dihydro-5-neopentoxy-3-thioxo-1H-isoindol-1-one. Attempted S-alkylations of the thiophthalimides resulted in the formation of β-isoindigos and N-alkylation products. In a new phthalocyanine synthesis crossed condensations of 1,3-diiminoisoindoline with 5-neopentoxy-1H-isoindole-1,3(2H)-dithione yielded mixtures of phthalocyanines from which 2-neopentoxyphthalocyanine and 2,16-dineopentoxyphthalocyanine could be purified in part from other phthalocyanines.