Highly Efficient Oxidation of Ethyl Lactate to Ethyl Pyruvate Catalyzed by TS‑1 Under Mild Conditions

Highly efficient oxidation of ethyl lactate (ELA) to ethyl pyruvate (EP) was realized over TS-1 in the presence of aqueous H<sub>2</sub>O<sub>2</sub> (30 wt %) at low temperature without other solvent. A 100% ELA conversion and 97.8% EP yield were obtained at 50 °C after 9 h. The conversion rate of ELA is sensitive to the reaction temperature. High reaction temperature (70 °C) leads to an increase in conversion rate of ELA but causes the fast hydrolysis and decarboxylation of EP to form byproducts of acetic acid and CO<sub>2</sub>. On the basis of the characterization (pyridine-FTIR and UV–vis) and reaction results, active species of Ti­(OOH) were proven. In addition, a nonradical mechanism for conversion of ELA to EP for this catalytic system was proposed. By kinetic analysis, the formation of Ti­(OOH) is confirmed as the rate-determining step. The apparent activation energy (103.4 kJ mol<sup>–1</sup>) was also obtained. Furthermore, TS-1 was highly stable for the oxidation of ethyl lactate. There were almost no change in ELA conversion and EP yield throughout 10 reaction runs.