Photochemistry of Phenyl Alkyl Ketones Adsorbed on Zeolite Molecular Sieves. Observation of Pronounced Effects on Type I/Type II Photochemistry

摘要

The photolysis of phenyl alkyl ketones adsorbed on a number of commonly available zeolites(molecular sieves) can result in dramatic changes in Type I/Type II photochemistry. The photochemistry of ketones in ordered environments is topic of current interest. Environmental effects can have important influence on the conformational flexibility of organic molecules, which in turn can affect the outcome of photochemical reactions. Two recent reports on the Norrish Type II reaction in ordered media prompts us to report our initial studies of the photochemistry of a number of phenyl alkyl ketones adsorbed in zeolites. Zeolites are crystalline aluminosilicates of usually well-defined structure. Within the zeolite framework are a system of channels and cavities of varying dimensions(2 - 13A), some of which are capable of adsorption of large organic molecules (e.g., substituted benzenes). Thus the possibility that the internal spaces (or void volumes) of zeolites can exert topological control on organic photochemical reactions warrants investigation, since it is well-known that zeolites display shape-selective catalytic and adsorptive properties in important industrial chemical processes.