The selective aerobic oxidation of ethyl lactate to ethyl pyruvate mediated by a trace of HBr with visible light

The selective aerobic oxidation of ethyl lactate (EL) is considered as a green protocol for producing ethyl py-ruvate (EP) in chemical industry. In this work, a mild, low-cost and efficient approach has been developed, in which 99.2% EL conversion and 99% EP yield was obtained in the presence of O-2 by using a trace of HBr with blue light. Also, a more than 94.6% yield of EP could be obtained even in air. Meanwhile, about 90.3% yield of EP was attained when the reaction was further amplified by 20 times. Based on the radical trapping and control experiments, a possible reaction mechanism is proposed. Therein, the generation of the Br center dot radical and center dot O-2(-) plays a crucial role in the EL oxidation.