Epoxidation of vietnam rubber seed oil by using peroxophosphatotungstate catalyst complex based on Na2WO4/H3PO4/H2O2 with the presence of phase-transfer catalyst

Abstract

Abstract Rubber seed oil (RSO) with a high acid value was esterified under mild conditions with methanol to convert the free fatty acids in the RSO into methylesters in the esterified rubber seed oil (RSOE) and minimize the acid value as well. The peroxophosphatotungstate complexes were formed in the aqueous phase from the reaction between Na2WO4, H3PO4, and H2O2. Thanks to a cation exchange reaction with the phase-transfer catalyst (PTC), the catalytic complexes moved from phase to phase to perform their catalytic role. By studying a variety of factors influencing the epoxidation via the determination of oxirane oxygen, yield, conversion, and catalytic selectivity, the optimum conditions are found. They are as DB (double bond)/H2O2/Na2WO4 ratio of 1/2/0.0065, Na2WO4/PTC/H3PO4 ratio of 1/0.55/3 with RSOE, and 1/0.25/3 with RSO at 60°C for just one hour. The epoxidized rubber seed oil (ERSO) had an oxirane oxygen of 6.36% when 92.97% of the double bonds in the RSO were broken and 75.09% of the double bond was converted to the epoxide. These parameters would be 7.53%, 91.82%, and 88.91%, respectively for epoxidized esterified rubber seed oil (ERSOE). The catalyst selectivity for these reactions was significantly different, which was 0.81 for the high acid value RSO but 0.97 for the low acid value RSOE. Through the FTIR and NMR study, the success of the epoxidation has been shown.