THE PHOTOCHEMISTRY OF 1-NAPHTHYLMETHYL CARBONATES AND CARBAMATES

The photochemistry in methanol of 1-naphthylmethyl phenyl carbonate (3 ) and 1-naphthylmethyl benzyl carbonate (4) has been studied. Products resulting from both the 1-naphthylmethyl cation and the 1-naphthylmet hyl radical are obtained for 3, but only from the cation for 4. Simila r results were obtained for the corresponding 1-naphthylmethyl derivat ives 5 and 6 of N-phenyl and N-benzyl carbamic acids. The product yiel ds for all four compounds can be explained by a mechanism of initial h omolytic cleavage of the 1-naphthylmethyl carbon-oxygen bond from the excited singlet state. The radical pair generated then partitions betw een the two pathways: electron transfer to form the ion pair or decarb oxylation. For PhO-CO-O' and PhNH-CO-O', decarboxylation is rapid and competitive with electron transfer. For PhCH(2)O-CO-O' and PhCH(2)NH-C O-O', decarboxylation is slower, electron transfer dominates, and only products from the ion pair are obtained.