| The Propyl Gallate Butyl Gallate and Dodecyl Gallate were synthesized by gallic acid with propyl alcohol butyl alcohol and dodecanol catalyzed by p-toluenesulfonic acid dehydration by molecular sieves 4A under microwave irradiation. We discussed the amount of catalysts, the molar ratio of alcohol to acid, reaction temperature and the reaction time on the yield of product. The technological conditions were confirmed by Orthogonal Design. Eventually yield respectively achieved 93.87%,91.25%,88.10%.Currently, on the gallic acid and alcohol synthesis of direct esterification of gallic acid alkyl ester dynamics has not been reported. Thus, gallic acid alkyl ester kinetics of very far-reaching significance. In this paper, the two oil bath and microwave heating synthesis of propyl gallate and discussion dynamics were studied, at the same temperature scale, Conventional heating activation energy is 201.75KJ·mol-1, microwave irradiation gallic acid bingzhi activation energy is 35.33KJ·mol-1under microwave irradiation the reaction rate was 11 times for conventional oil heating.The microwave reported in literature applications in recent years,while many but most studies only stay in the synthesis of a product, the optimization experiment conditions under the condition of microwave chemical reaction dynamics research and accelerate the reaction mechanism research report, a few seldom-reported reports of the correctness of the mechanism is needed to explain discussion, many explanations only stay in the surface, use microwave "non-thermal effect" general explanation, lack of theoretical research.This topic was studied under microwave radiation for the first time the esterification reactions to explore the dynamic equations of microwave heating mechanism are instructive. Proved "the existence of non-thermal effect" in this study, points out the existing the esterification of system, "fuel factor" and "the joint action of non-thermal effect". |
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