Method for catalytically synthesizing polylactic acid by utilizing ionic liquid
A technology of ionic liquid and polylactic acid, which is applied in the field of material chemistry, can solve the problems of poor catalyst selectivity, poor product crystallization performance, and low product optical activity, and achieve the effects of short degradation cycle, improved production efficiency, and thorough degradation cycle
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Embodiment 1
[0027]Firstly, the L-lactic acid to be reacted was dried with 5A molecular sieve for 3 hours, and then placed for use. In a 250 ml reaction bottle, add 200 g of preliminarily dried L-lactic acid, blow nitrogen to drive away oxygen, use an oil bath to control the temperature at 60°C, vacuumize and distill water for 1 hour, add 1,3-dimethylimidazole to 0.1 g of tosylate, the temperature was slowly raised to 100°C, and reacted for 2 hours, the product gradually became viscous, cooled to obtain a white oligomeric solid. Then add the oligomer and 0.15 g of 1,3-dimethylimidazole p-toluenesulfonate into the polymerization tube, heat and melt under the protection of nitrogen, control the reaction temperature at 140 ° C, the reaction pressure at 1000 Pa, stir for 6 hours, and then Slowly cool down to room temperature to obtain a light yellow solid, add 50 ml of chloroform solvent, stir and dissolve the reactant, then add dropwise while stirring with methanol, until turbidity appears, a...
Embodiment 2
[0029] Firstly, the L-lactic acid to be reacted was dried with 5A molecular sieves for 2 hours, and then placed for use. In a 500ml reaction bottle, add 300g of preliminarily dried L-lactic acid, blow nitrogen to drive away oxygen, use an oil bath to control the temperature at 60°C, vacuumize the water for 1 hour, add 1-butyl-3-methyl 0.1 g of pyridinium tetrafluoroborate, the temperature was slowly raised to 100° C., and reacted for 2 hours, the product gradually became viscous, cooled to obtain a white oligomeric solid. Then add the oligomer and 0.2 g of 1-butyl-3-picoline tetrafluoroborate into the polymerization tube, heat and melt under the protection of nitrogen, control the reaction temperature at 140 ° C, the reaction pressure at 800 Pa, and stir for 6 hour, then slowly cool down to room temperature to obtain a light yellow solid, add 100 ml of chloroform solvent, stir and dissolve the reactant, then add dropwise while stirring with methanol, until turbidity appears, a...
Embodiment 3
[0031] Firstly, the L-lactic acid to be reacted was dried with 5A molecular sieve for 3 hours, and then placed for use. In a 500ml reaction bottle, add 300g of pre-dried L-lactic acid, blow nitrogen to drive away oxygen, use an oil bath to control the temperature at 60°C, vacuumize and distill water for 1 hour, add N-methyl-propylpiperidine 0.15 g of hexafluorophosphate, the temperature was slowly raised to 105° C., and reacted for 2 hours, the product gradually became viscous, cooled to obtain a white oligomeric solid. Then add 0.15 g of oligomer and N-methyl-propylpiperidine hexafluorophosphate into the polymerization tube, heat and melt under the protection of nitrogen, control the reaction temperature at 140 ° C, and the reaction pressure at 1000 Pa, stir and react for 6 hours, and then Slowly cool down to room temperature to obtain a light yellow solid, add 100 ml of chloroform solvent, stir and dissolve the reactant, then add dropwise while stirring with methanol, until ...
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