Microwave-assisted NaHSO4-catalyzed synthesis of ricinoleic glycol ether esters

The synthesis of several ricinoleic acid glycol ether esters by high-pressure microwave radiation is described. Ricinoleic acid which is from castor oil reacted fastly with glycol ethers in the presence of NaHSO4 · H2O and dichloromethane (DCM) in special microwave reactor. The influences of reaction factors such as catalyst and solvent type, reaction temperature, and time were investigated and the optimal reaction conditions were obtained. The activity of catalyst had a higher performance up to the 10th cycle and the excellent values of turnover numbers and turnover frequency were obtained. Compared with the traditional esterification in reflux heating systems., the microwave-assisted process has many advantages such as shorter reaction time, less side effects, higher yield, which is a great potential for the development of green chemistry.