The activation or functionalization of the saturated C-H is an extremely active field at present. We have explored the triplet state thioxanthone in reactivity of the hydrogen transfer reaction between donors and acceptors. In our works, two donors with quasi-inert sp3 C-H of skipped diene (3,6-nonadiene) and cyclic acetals (benzodioxole) reacted with type II photoinitiators (triplet state of thioxanthone series, TXs) as acceptors are investigated. The excited energies of TXs were obtained by time-dependent density functional theory (TD-DFT). TXs show obvious photosensibility based on their low reorganization energies (< 60 kcal mol-1). The isoentropy reactions had linear geometries of transition state (TS). The distortion/interaction model was used to probe the existence of interaction between acceptors and donors in saddle point. The distortion energy and activation barrier of benzodioxole are much higher than those of the corresponding 3,6-nonadiene. The lower bond dissociation energy noticeably affect the transition state. The reaction of triplet state of TXs with skipped dienes were found to have an anomalous low tunneling factors by using Wigner correction and early transition state by using the bond-energy-bond-order method. The triplet state of TXs photoinitiator can induced the hydrogen abstraction from saturated cyclic acetals and the skipped alkadienes. The hydrogen abstraction experiment are confirmed by UV and real-time FTIR.
Keywords: Hydrogen transfer; Thioxanthone; Triplet state.