In this work, we focus on oxidations mediated by singlet oxygen. These reactions are easily performed with a visible light source, require inexpensive photosensitizers, and have a widespread application . We specifically investigate the oxidation of α-terpinene to ascaridole, a benchmark reaction to characterize photoreactor performance . Ascaridole has applications as a pharmaceutical drug due to its anthelmintic properties and antitumor activity . The photosensitizer of choice for this reaction, is the organic dye Rose Bengal (RB). The overall scheme of the reaction is presented in Fig 1 . The primary product of the photooxygenation is ascaridole; however, side reactions can result in the formation of various products such as p-cymene, isoascaridole, allylic epoxides, as well as enals .