Photochemistry in Porous Materials, II / Photolysis of Benzoin Ethers in Silicalite

Abstract

Four benzoin ethers 1 (a: methyl-, b: ethyl-, c: isopropyl-, d: phenylether) were photolyzed inside the channel system of silicalite S- 115, a novel type of zeolite. Products which could be separated from the zeolite framework in various relative yields were pinacol ethers (from a, b, c), benzil (a–d), benzaldehyde (a–d), benzoates (a–d), and phenol (d). While the former three types of products clearly arise from Norrish type I cleavage of the parent molecules, a mechanism involving the enolic form of the benzoin ethers is proposed in order to explain the formation of benzoates and phenol.