Electrochemical Synthesis Of Epoxides From Vegetable Oils

Epoxidised vegetable oils can be used as new environmentally friendly lubricants, reactive toughening agents of epoxy resin, PVC plasticizers and stabilizers, etc. Therefore, the research and development of epoxidised vegetable oils has important significance. In this paper, the main content includes the following two aspects.In the first part, the paper put forward a novel and effective electrochemical synthesis method to prepare epoxidised castor oil. Firstly, the electrocatalytic property of Ag、Pt、Ti、Ti/Sn O2 + Sb2O4/Pb O2 was investigated. Secondly, reaction time、p H、reaction temperature、passing oxygen rate、current density、molar ratio of castor oil double bond to HCOOH and catalyst dosage(0.1 mol/L hydrochloride) were examined for epoxidation of castor oil. The parameters were optimized by orthogonal test. Finally, castor oil and its products were analyzed with FT-IR and TG. The results showed that: ① The oxygen evolution potential of Ti/Sn O2 + Sb2O4/Pb O2 was the highest, and the corrosion resistance was the best, and the exchange current density was the highest. The best electrocatalytic activity of Ti/Sn O2 + Sb2O4/Pb O2 suggested it was more suitable as anode. ② A better reaction condition of electrochemical epoxidation of castor oil by orthogonal test: 4 h reaction time, p H6.5, 30℃reaction temperature, 3 cm3·s-1 the passing oxygen rate, 0.3 A·cm-2 current density,8M ratio of castor oil double bonds to HCOOH, and 0.3 m L catalyst dosage(relative to 40 g vegetable oil). Relative epoxy yield of epoxidised castor oil was up to 53.7% under this reaction condition. The influence order of reaction condition: p H > reaction time > current density > reaction temperature > molar ratio of castor oil double bonds > passing oxygen rate > catalyst dosage. ③ The FT-IR and TG analysis showed that castor oil was epoxied into corresponding epoxidised castor oil.In the second part, Ti/Sn O2 + Sb2O4/Pb O2 and graphite were used as anode and cathode, respectively. Firstly, the fatty acid composition of different vegetable oils was compared. Secondly, different vegetable oils were epoxied with electrochemical synthesis, and analyzed with FT-IR and TG. Finally, the mechanical properties of resin cured film were examined with epoxidised vegetable oils as a reactive toughening agent. The results showed that: ①Unsaturated fatty acid of castor oil is primarily ricinoleic acid. Unsaturated fatty acids of soybean oil、corn oil、peanut oil、rice bran oil、sunflower oil and cotton seed oil are mainly oleic and linoleic acids. These vegetable oils contain unsaturated carbon-carbon double bonds and epoxidation reaction can be carried out. ② Under a better reaction condition of epoxidation of castor oil, the relative epoxy yield of soybean oil, corn oil, peanut oil, rice bran oil, sunflower oil, cotton seed oil was 30%, 31.1%, 31.7%, 23.7%, 21.3% and 19.9%, respectively. The FT-IR and TG analysis results showed various vegetable oils were translated into the corresponding epoxides. ③ The epoxy groups had a curing reaction with amine, and it can enhance the mechanical properties of resin cured film. The mechanical properties of the film were relatively good when epoxidised castor oil was added in an amount of 4% to 6%, and epoxidised soybean oil was added in an amount of 2% to 6%.In this paper, vegetable oils were epoxied with electrochemical synthesis method. It provided a new synthetic route for epoxidised vegetable oil.