Photochemistry of cyclododecanone

Abstract

Quantitative measurements of the photolytic reactions of cyclododecanone gave quantum yields of reaction and of intersystem crossing as 0.56 and 0.88 respectively, and a triplet lifetime of 1.7 x 10-⁷ s. Cyclobutanol formation accounts for most of the reaction with only a low yield of the Norrish II cleavage product; this contrasts markedly with the opposite behaviour of acyclic ketones of similar size. The results may be explained by the apparent restriction of rotation in cyclododecanone molecules.