Chemoenzymatic epoxidation of Karanja oil: an alternative to chemical epoxidation?

In light of increasing concern about diminishing fossil fuel reserve, a lot of research is being focussed on the production of chemicals using renewable feedstock. Vegetable oils provide this valuable renewable feedstock as they offer a large number of possibilities. One of the interesting possibilities offered is epoxidized vegetable oil, which can be used as a plasticizer, polyvinyl chloride stabilizer, diluent, etc. Hence, a chemoenzymatic method for epoxidation of Karanja oil was investigated. The enzyme reusability, the important criteria for commercial exploitation of the technique, was also investigated. Three commercially available immobilized lipase enzymes were screened and Novozyme 435 was found to be best for chemoenzymatic epoxidation of Karanja oil. The study revealed that epoxide conversion of 80% (equivalent to chemical methods) was obtained at room temperature in the absence of any side reactions. Maximum epoxide conversion was obtained in 8-9 h at 30 degrees C as compared with 6 h for conventional methods at 80 degrees C. The reaction could also be carried out in the absence of any solvent to an extent of 56% oxirane conversion. The catalyst was found to be strongly affected by temperature and H2O2 and denatured after repeated runs, showing a maximal reusability of four runs. The enzymatic method is beyond doubt a cleaner and greener technology compared with conventional method. The advantages of energy efficiency along with 100% selectivity make it a method for the future. Copyright (C) 2016 Curtin University of Technology and John Wiley & Sons, Ltd.