Surface Photochemistry: The CdS-Mediated Reactions of 1,1-Di-p-anisyletylene

Article abstract of DOI:10.1021/jo00230a019

The CdS-photomediated reaction of 1,1-di-p-anisylethylene (1b) leads to the formation of two cyclized (2 + 4) and two open chain dimeric products.All for reactions were quenched by 1,2,4,5-tetramethoxybenzene.Comparision of the product distribution in the CdS-induced reaction with those obtained by using cyanoaromatic sensitizers showed that the CdS distribution fell within the range found in the homogeneous systems by varying the nature of the sensitizer and of the solvent.It can be concluded that in this system, at least, the fact of adsorption on the semiconductor surface plays a minor role in directing the nature of the products.One sample of CdS used, which was of high purity, appeared able, even when washed, to induce the acid-catalyzed "dark" dimerization of 1b.This sample yielded, on irradiation, the same four dimeric materials obtained previously, together with 1,2-dimethyltetra-p-anisylethane.