The Solid Acid Catalyst In The Synthesis Of Esters And Research

In this paper, the applications of the environmental friendly solid acid catalysts for esterification were studied and the activities of these catalysts were discussed, by which the solid acid ferric sulfate x-hydrate was used first as catalyst in the synthesis of dimethyl fumarate(DMF) and ethyl chloroacetate and solid super acid SO42-/Fe2O3 was used first as catalyst in the synthesis of ethyl p-nitrobenzoate. Through discussing the effects of catalyst content, raw material ratio, reaction time on the yield of products in detail, the optimum synthetic conditions of these esters were established.The best conditions of the synthesis of DMF are: molar ratio of fumaric acid to methanol is 1:17, the quantity of catalyst [Fe2(SO4)3 xH2O] is 10% of the mass of fumaric acid, reflux time is 70 minutes. At these conditions, the yield of DMF reaches 90.7%. The catalyst can be reused 4 times and the yield is over 89% every time. The results showed that Fe2(SO4)3 xH2O is an excellent catalyst for the synthesis of DMF. Compared with other synthetic methods, this one is characterized by short reaction time, high yield, low energy consumption, no pollution and reused catalyst.The optimum synthetic conditions of ethyl chloroacetate are: molar ratio of chloroacetic acid to ethanol is 1:8, the quantity of catalyst[Fe2(SO4)3 xH2O] is 10% of the mass of chloroacetic acid, reaction time is 1 hour, 5A zeolite was used as dehydrating agent. In these conditions, the yield of ethyl chloroacetate was up to 73%.A solid super acid SO42-/Fe2O3 catalyst was prepared and used in the synthesis of ethyl p-nitrobenzoate. The best conditions of the synthesis of ethyl p-nitrobenzoate are: molar ratio of p-nitrobenzoic acid to ethanol is 1:4.5, the quantity of catalyst is 1.2g (14% of the mass of p-nitrobenzoic acid), reaction time is 2 hours. The yield of ester reaches 95.6%. The catalyst can be reused 3 times and the yield is over 92% every time. It shows that the acidity and catalytic activity of the solid super acid SO42-/Fe2O3 were the strongest when it was calcined at 500C.The mechanism of the synthesis of DMF with Fe2(SO4)3 xH2O as catalyst was suggested first that the more steady the transition state that the Fe3+ ion combined with the carboxylic acid is, the more favorable the esterification processes. The reasonability of the mechanism was proved by the synthesis of ethyl chloroacetate and ethyl p-nitrobenzoate using Fe2(SO4)3 xH2O as catalyst.