Estudo da reação de epoxidação do óleo de tungue em reatores sonoquímicos

Abstract

Epoxidation reactions of vegetable oils have gained visibility as a viable and eco-friendly alternative for the synthesis of epoxides instead of petroleum-based epoxides. Previous studies did not address the formation of the high value-added by-products or explore some potential pathways of the process optimization. Therefore, the present work evaluates the epoxidation of tung oil using hydrogen peroxide as an oxidizing reagent and variations of organic acid as intermediates in addition to the use of sonochemical reactors to enhance these reactions. The effects of various parameters such as ultrasonic pulse duration, ultrasonic power, quantity of reagents and reactor configuration type were investigated regarding the degree of yield of epoxides and the formation of by-products. Industrially, the traditional epoxidation process for some vegetable oils, such as soybeans, has a cycle ranging from 8 to 12 hours, reaching about an 85% yield of epoxides. In this case, the use of tung oil instead of soybean was observed to be interesting, since in chemical reactors as well as in the traditional process, it gives almost a 91% yield of epoxides, with a selectivity near 100% in 3 hours of experiment. The reaction with tung oil in a sonochemical reactor showed yield levels of epoxides near 76%, also in 3 hours. In addition, two aldehydes of high commercial value, the 2,4-nonadienal and hexanal, were obtained as by-products in these reactions, which demonstrates that the commercial use of this technology results in the formation of more advantageous products. In the reactions in which the intermediate component was not used, the yield of epoxide reached almost 75%, attesting the performance of the ultrasonic in the formation of free radicals and consequent increase in the reaction rate.