Study On Synthesis Of Dicarboxylic Anhydride

Nowadays the anhydride was widely used in some field, such as pharmaceuticals, pesticides,resins, power eletronics, surface active agent and food processing, especially dicarboxylic anhydride, becouse the special structle of the cyclic anhydride, not only be used as ordinary anhydride, but also play an important part in curing agent, modifying agent and other auxiliary products. But due to the backwarded production, some dicarboxylic anhydride were hard to product, so lead to low production efficiency, high energy consumption, so the prices of dicarboxylic anhydride were so high, so finding a suitable method for producing dicarboxylic anhydride has great research value. Therefore, in this paper, the alkali metal salt or alkaline earth salts were used as catalysts for the synthesis of citraconic anhydride, succinic anhydride and glutaric anhydride.Firstly, the synthesis of citraconic anhydride in the presence of catalyst was studied in this paper. The effects of factors, such as kind and dosage of catalyst, kind and dosage of solvent, and reaction time, were examined. The optimum conditions were obtained as follows: the reaction used itaconic acid, barium hydroxide as catalyst and water carrying agent dimethylbenzene,reaction time 6.0 h. Under the above reaction conditions, the yield and the purity of citraconic anhydride were more than 83% and 98.9%, respectively. The structle of the product was characterized by the 1HNMR、13CNMR and FT-IR. And the results showed that the synthesized product wascitraconic anhydride.Secondly, the synthesis of succinic anhydride in the presence of catalyst was studied in this paper. The effects of factors, such as kind and dosage of catalyst, kind and dosage of solvent, and reaction time, were examined. The optimum conditions were obtained as follows: the reaction used succinic acid, magnesium oxide as catalys and water carrying agent 1,2,3,4-tetrahydronaphthalene, reaction time 4.0 h. Under the above reaction conditions, the yield and the purity of succinic anhydride were more than 93.1% and 99.8 %, respectively. The structle of theproduct was characterized by the 1HNMR、13CNMR and FT-IR. And the results showed that the synthesized product was succinic anhydride.Finally, the synthesis of glutaric anhydride in the presence of catalyst was studied in this paper. The effects of factors, such as kind and dosage of catalyst, kind and dosage of solvent, and reaction time, were examined. The optimum conditions were obtained as follows: the reaction used glutaric acid, sodium dihydrogen phosphate as catalyst and water carrying agent 1,2,3,4-tetrahydronaphthalene, reaction time 8.0 h. Under the above reaction conditions, the yield and the purity of glutaric anhydride were more than 63.3% and 97.6 %, respectively. The struct. of the product was characterized by the 1HNMR、13CNMR and FT-IR. And the results showed that the synthesized product was glutaric anhydride.In summary, in the synthesis process of the dicarboxylic anhydride, alkali metal salt or the alkaline earth salt catalysts have showed good catalytic activity and selectivity. Compare to the technology of traditional synthesis methods, the new method have the advantage of the catalyst alkali metal salt and alkaline earth salt source, low price, solvent recycling reuse convenient and dehydration reaction speed fast and high conversion rate and other advantages, to achieve low cost synthetic dicarboxulic anhydride provides support and basis.