Solid state photodimerization of surfactant esters of cinnamic acid

Abstract

Numerous examples of solid state photodimerizations have been reported. Although many of these reactions are topochemically controlled and lead to a single dimeric product in high Yield, the general synthetic utility of these reactions has been limited by the inability to manipulate and control structures. The concept of crystal engineering has been advanced by Schmidt, Cohen and coworkers;' their approaches to controlling packing geometry have included introduction of a dichlorophenyl group into unsaturated systems and co-crystallization of mercuric chloride-organic mixtures. In the latter case, the packing of the mercuric chloride controls the type of lattice formed. In the course of our investigations of environmental and medium effects on photoreactions, we have investigated the photochemistry of several surfactant molecules. We were somewhat surprised to find that the p-chlorobenzenesulfonate salt of N-octadecyl-4-stilbazole undergoes clean solid state photodimerization to yield exclusively the syn-head-to-head dimer (l).' This is in contrast to the behavior of simple non-surfactant stilbatole salts and to that of other quaternary N-