The use of bisphthalonitriles in the synthesis of side-strapped 1,11,15,25-tetrasubstituted phthalocyanines

Nucleophilic aromatic substitution reactions of 3-nitrophthalonitrile yield 3-hydroxyphthalonitrile and 3-neopentoxyphthalonitrile, the latter of which condensed to 1,8,15,22-tetraneopentoxyphthalocyanine as a mixture of isomers. Bisphthalonitriles such as 1,3-bis(2',3'-dicyanophenoxy)-2,2-dipentylpropane, 1,3-bis(2',3'-dicyanophenoxy)-2,2-diethylpropane, 1,3-bis(2',3'-dicyanophenoxy)-2,2-dioctylpropane, and 1,3-bis(2',3'-dicyanophenoxy)-2-methyl-2-trityloxymethylpropane all gave bis-crown-like 1,11,15,25-tetrasubstituted phthalocyanines as pure compounds when treated with lithium octoxide in 1-octanol at 196 degrees C. A host of nine other bisphthalonitriles including 1,5-bis(2',3'-dicyanophenoxy)-3-oxapentane, 1,1 -bis(2',3'-dicyanophenoxymethyl)cyclohexane, 1,2-bis(2',3'-dicyanophenoxymethyl)benzene, and 2,5-bis(2',3'-dicyanophenoxymethyl)furan did not dimerize to mononuclear phthalocynaines. The ''gem dimethyl'' effect was suggested as a reason for the successful macrocyclizations.