Solid-State and Solution Photolyses of Tetracyanobenzene with Benzyl Cyanides or Benzyl Alcohols

Intermolecular photoreactions of tetracyanobenzene (TCNB) with benzyl cyanide (BzCN), benzyl alcohol (BzOH) and various others were investigated in the solid state (cocrystal) and in solution. The new solid-state photocoupling reaction found for the cocrystal TCNB·BzCN, giving a stilbene derivative followed by the solution isomerization into an isoindole derivative, is a very limited reaction. On the other hand, its solution photocondensation to give products of the diphenylmethane type occurred quite generally, probably under acidic conditions.