100% Selective Oxygenation of Alkyl Substituted Benzenes

在汞灯（λ > 300 nm）光照射下，以邻-对二氰基苯为光敏剂，对甲苯腈为环上取代的甲苯，与分子氧发生氧化反应，生成相应的醛。在可见光照射下，使用10-甲基-9-苯基吖啶离子作为光敏剂实现对二甲苯100%选择性氧化为对甲基苯甲醛，导致仅产生对甲基苯甲醛作为最终氧化产物。这两种氧化反应都是通过光诱导电子从环取代的甲苯转移到光敏剂的单重激发态而引发的。基于光诱导电子转移机理，讨论了甲苯衍生物光催化氧化反应高选择性的原因。

A ring-substituted toluene with an electron-withdrawing substituent, p-tolunitrile, is oxygenated with molecular oxygen to yield the corresponding aldehyde using tetrafluoro-p-dicyanobenzene as a photosensitizer under photoirradiation with an Hg lamp (λ > 300 nm). The 100 % selective oxygenation of p-xylene to p-tolualdehyde is achieved using 10-methyl-9-phenylacridinium ion as a photosensitizer under visible light irradiation, leading to yield p-tolualdehyde exclusively as the final oxygenated product. Both oxygenation reactions are initiated by photoinduced electron transfer from the ring-substituted toluene to the singlet excited state of the photosensitizer. The reason for the high selectivity in the photocatalytic oxygenation of various toluene derivatives is discussed based on the photoinduced electron transfer mechanism.