4511-42-6Relevant articles and documents
Method for catalytically synthesizing lactide
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Paragraph 0023-0055; 0077-0080; 0085-0094; 0098-0100, (2021/01/29)
The invention discloses a method for catalytically synthesizing lactide. According to the method, a mixture of stannous lactate and a urea substance is used as a composite catalyst, L-lactic acid (orD-lactic acid) with the lactic acid content of 90% is used as a raw material, and a reduced pressure distillation technology is adopted to synthesize the L-lactide (or D-lactide). Compared with independent use of onecatalyst, by adopting the composite catalyst, the yield can be effectively increased, under the same experimental conditions, the crude yields of lactide synthesized by independently using stannous lactate or urea catalysts are 69%-72% and 23%-30% respectively, and the yield can be increased to 90% or above by using the composite catalyst of the two. Compared with a traditional tincatalyst or zinc catalyst and other composite catalytic components, the composite catalytic reaction system is low in reaction temperature (150-180 DEG C), short in reaction time (0.5-2 h), high in lactide yield (90% or above), capable of saving more energy and increasing the yield and beneficial to industrial production.
Method for synthesizing rod-like long L-lactide crystal with high optical purity
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Paragraph 0017-0035, (2019/01/17)
The invention discloses a method for synthesizing a rod-like long L-lactide crystal with high optical purity, namely the method for synthesizing the rod-like long L-lactide crystal with the high optical purity by utilizing a decompression method with lactic acid as a raw material. A synthesis technology of the rod-like long L-lactide crystal with the high optical purity comprises the following conditions: the amount of a certain amount of the lactic acid is 10-50mL, the volume of a proper amount of catalyst stannous octoate is 1-10mL, the gradually rising temperature range from 90 to 190 DEG C, and the pressure of a reduced pressure distillation reaction is minus 0.10MPa to 0.10MPa, and a certain time is 1-10h. A synthesis method of the rod-like long L-lactide crystal with the high opticalpurity comprises the following steps: 1), taking a certain amount of the lactic acid, adding into a three-necked bottle of 250mL, then adding a proper amount of stannous octoate, gradually heating, and performing a reduced pressure distillation reaction for a certain time to obtain a white lactic acid oligomer; 2), gradually heating the white lactic acid oligomer in a device, and performing the reduced pressure distillation reaction for a certain time until no obvious distillate appears, and collecting the distillate, that is a lactide product, wherein the product is a mixture of D-type lactide and L-type lactide.
Catalytic Gas-Phase Cyclization of Glycolate Esters: A Novel Route Toward Glycolide-Based Bioplastics
De Clercq, Rik,Makshina, Ekaterina,Sels, Bert F.,Dusselier, Michiel
, p. 5649 - 5655 (2018/12/04)
A catalytic process to produce glycolide, the cyclic dimer of glycolic acid (GA), is proposed. Glycolide is the key building block of the biodegradable plastic polyglycolic acid. Instead of the current industrial two-step route, which involves the polycondensation of GA and a subsequent backbiting reaction, a new route based on the gas-phase transesterification of methyl glycolate (MGA) over a fixed catalyst bed is presented. With specific supported TiO2 catalysts, a high glycolide selectivity of 75–78 % can be achieved at the thermodynamically-limited equilibrium conversion of MGA (54 % at 300 °C, 5.6 vol% MGA, 1 atm). The absence of solvent and the continuous nature of the process should allow for easy product separation and recycling of unconverted esters, while the few side-products, i. e. linear alkyl glycolate dimers and trimers seem recoverable via methanolysis. The reaction is compared to the cyclization of other α-hydroxy esters, such as methyl lactate to lactide, over the same catalysts, in terms of kinetics and thermodynamics. The absence of a methyl substitution on the α-carbon seems to lead to faster cyclization kinetics of MGA when compared to methyl lactate or the double-substituted methyl-2-hydroxy-isobutyrate. Contrarily, glycolide production is less favored thermodynamically compared to lactide. The absence of glycolide decomposition at temperatures up to 300 °C however allows to increase equilibrium conversion by taking the endergonic reaction to higher temperatures.