Electrochemistry of 1,1,4,4-tetraphenyl-1,3-butadiene, 1,1,4,4-tetraphenyl-1,2-butadiene, and 1,1,4,4-tetraphenyl-1-butene in dimethylformamide

Abstract

In dimethylformamide containing tetra-n-butylammonium perchlorate, 1,1,4,4-tetraphenyl-1-butene exhibits a single polarographic wave; preparative-scale reduction of the starting material produces 1,1,4,4-tetraphenylbutane.A polarogram for 1,1,4,4-tetraphenyl-1,3-butadiene consists of three waves. Large-scale electrolysis of 1,1,4,4-tetraphenyl-1,3-butadiene at potentials corresponding to either the first or second wave yields 1,1,4,4-tetraphenyl-1-butene in the absence of a proton donor and a mixture of 1,1,4,4-tetraphenyl-2-butene and 1,1,4,4-tetraphenyl-1-butene in the presence of excess glacial acetic acid. If 1,1,4,4-tetraphenyl-1,3-butadiene is electrolyzed at a potential on the third polarographic wave, one obtains 1,1,4,4-tetraphenylbutane in the absence of a proton donor but a mixture of 1,1,4,4-tetraphenyl-2-butene and 1,1,4,4-tetraphenylbutane in the presence of glacial acetic acid. Reduction of 1,1,4,4-tetraphenyl-1,2-butadiene gives two polarographic waves. At potentials on the first wave, electrolysis of 1,1,4,4-tetraphenyl-1,2-butadiene yields 1,1,4,4-tetraphenyl-1-butene when no proton donor is present and a mixture of 1,1,4,4-tetraphenyl-1-butene and 1,1,4,4-tetraphenyl-2-butene when a proton donor is added; at potentials on the second wave, 1,1,4,4-tetraphenylbutane is formed in the absence of a proton donor and a mixture of 1,1,4,4-tetrphenyl-2-butene and 1,1,4,4-tetraphenylbutane is produced in the presence of glacial acetic acid. In the absence of a proton source, a facile, elecrolytically induced isomerization of 1,1,4,4-tetraphenyl-1,2-butadiene to 1,1,4,4-tetraphenyl-1,3-butadiene occurs.