Method for preparing lactide by catalytic method under reduced pressure
A lactide and catalyst technology, which is applied in the field of lactide preparation by decompression catalytic method, can solve the problems of increased cost, high distillation temperature, waste of raw materials, etc.
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Embodiment 1
[0021] L-lactic acid is used as raw material to prepare lactide by vacuum catalytic distillation. First, put 200ml of lactic acid into a three-necked flask, and remove the free water in the lactic acid at 75°C and 0.085MPa vacuum for 1 hour;
[0022] Add catalyzer namely reactant mass percent 0.5% zinc oxide, reactant volume percent 0.5% stannous octoate and reactant volume percent 0.5% Tween 80 surfactant;
[0023] Then keep warm at 0.085MPa vacuum degree and 125°C, and decompose water for 5 hours;
[0024] Stir and heat up to 168°C, lactide is distilled out, and the temperature is gradually raised to collect lactide, the highest temperature is 200°C, distillation is 8h, and the crude yield reaches 86%.
Embodiment 2
[0026] L-lactic acid is used as raw material to prepare lactide by vacuum catalytic distillation. First, put 300ml of lactic acid into a three-necked flask, and remove the free water in the lactic acid at 90°C and 0.090MPa vacuum for 2 hours;
[0027] Add catalyzer namely the zinc oxide of reactant mass percent 1%, the stannous octoate of reactant mass percent 1% and the sodium dodecylsulfonate of reactant mass percent 1%;
[0028] Then keep warm at 0.090MPa vacuum degree and 135°C for dehydration reaction for 5h;
[0029] Stir and heat up to 165°C, lactide is distilled out, and the temperature is gradually raised to collect lactide, the highest temperature is 190°C, distillation is 8h, and the crude yield reaches 91%.
[0030] Such as figure 1 As shown, the measurement data of lactide prepared by adding zinc oxide, stannous octoate and sodium dodecylsulfonate after dehydration: infrared spectrum, melting point: 125.4-126.5 ° C, can reduce the lactide production process The...
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