Nanjing University

Na Cheng

Hong Li

Wei Jiang

Quanxing Zhang

Wei Huang

Bingcai Pan

Tianrong Zhang

Aimin Li

Jiaye Sheng

A method of purifying a cyclic ester, the method including: granulating a crude cyclic ester, an average particle size of resulting granules being 0.05-1.00 mm; adding the granules to 0-4&#xb0; C. water to yield a mixture, a mass ratio of the water to the granules being (0.5-2):1; stirring the mixture, and performing solid-liquid separation on the mixture; repeating the stirring and solid-liquid separation for 1-4 times, to yield a purified cyclic ester; drying the purified cyclic ester at 0-4&#xb0; C. and at an absolute pressure of less than or equal to 10 pascal for 4-6 hours, and continually drying the purified cyclic ester at 40-60&#xb0; C. and at an absolute pressure of less than or equal to 5 pascal for 1-2 hours.

Method of purifying cyclic ester

A technological method for synthesizing optically pure L-/D-lactide by using a biogenic guanidine catalysis method. The method of the present invention comprises: by using biogenic guanidine creatinine (CR) as a catalyst and L-/D-lactic acid (90% of mass content) as a raw material, synthesizing optically pure L-/D-lactide by using a reactive reduced pressure distillation catalysis method. The method of the present invention has advantages that the used catalyst is biogenic guanidine creatinine and free of toxicity, metal, and cytotoxicity; the synthesized lactide is high in optical purity (the specific rotation of the L-lactide [&#x3b1;]25D=&#x2212;276&#x2dc;&#x2212;280, and the specific rotation of the D-lactide [&#x3b1;]25D=280), and does not contain any metal; the amount of the catalyst used in reaction is low, the technological process is simplified (a process for rectifying and purifying a crude lactide product by using a conventional method is avoided); and the technological method is simple and convenient to operate and easy in industrial implementation.

Technological method for synthesis of optically pure L-/D-lactide catalyzed by biogenic guanidine

A method for synthesizing poly(butylene succinate-co-butylene adipate) (PBSA), including: a) adding raw materials including succinic acid, adipic acid, and 1,4-butanediol into a reaction still; increasing the temperature in the reaction still to 130&#xb0; C., and stirring the raw materials, then keeping the temperature in the reaction still at 170-200&#xb0; C., and dehydrating for 1-3 hours at atmospheric pressure, to yield an oligomer of PBSA; and b) decreasing the temperature of the reaction still to 100&#xb0; C., and adding a composite catalyst system, the total addition of the composite catalyst system accounting for one ten-thousandth to one ten-millionth of a total weight percentage of the raw materials; uniformly stiffing and mixing the composite catalyst system and reactants, slowly vacuum pumping the reaction still, heating the reaction still to a temperature of 200-240&#xb0; C. and allowing the composite catalyst system and the reactants to react for 10-20 hrs.

Method for synthesizing poly(butylene succinate-co-butylene adipate)

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Nanjing, China

Na Cheng