Efficient metal-free oxidation of ethylbenzene with molecular oxygen utilizing the synergistic combination of NHPI analogues

A metal- and initiator-free catalytic system comprising N -hydroxyquinolinimide (NHQI) and 4-carboxyl- N -hydroxyphthalimide (Car-NHPI) was developed for the oxidation of ethylbenzene using molecular oxygen as the terminal oxidant. The catalytic activity of Car-NHPI/NHQI catalytic system was higher than that of Car-NHPI or NHQI alone. The high catalytic performance of Car-NHPI/NHQI catalytic system could be attributed to the dual interactions of radical exchange and acid-base neutralization, which resulted in the increment of the conversion of ethylbenzene up to 70% and the selectivity of acetophenone up to 66% at 120   °C under 1 atm O 2 for 15   h.