Method for refining and purifying lactide
A technology for refining and purifying lactide, applied in directions such as organic chemistry, can solve problems such as unsatisfactory yield of lactide, and achieve the effects of reducing the use of organic solvents, reducing costs, and reducing the impact of the environment
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Embodiment 1
[0028] The crude lactide used in this example is an L-type lactide prepared from L-lactic acid through polycondensation-depolymerization reaction using zinc oxide as a catalyst.
[0029] A method for refining and purifying lactide, the specific steps are as follows:
[0030] Take 5kg of crude lactide and add it to the water washing tank, add 5kg of distilled water to it, keep the temperature at 25°C, start stirring for water washing, and the washing time is 20min. Separation; the obtained filter cake was put into a vacuum drying oven for vacuum drying at 30°C. Then the preliminary dried crude lactide is added to the vacuum distillation unit, the controlled distillation temperature is 180°C, and the distillation pressure is 5kPa, and the crude lactide distilled passes through the water removal device (the desiccant is calcium chloride, and the temperature maintained 100° C.) to further remove water to finally obtain lactide with a purity of 97.5%, and the yield of lactide is 8...
Embodiment 2
[0032] The crude lactide used in this example is an L-type lactide prepared from L-lactic acid through polycondensation-depolymerization reaction using zinc lactate as a catalyst.
[0033] A method for refining and purifying lactide, the specific steps are as follows:
[0034] Take 5kg of crude lactide and add it to the water washing tank, add 5kg of distilled water to it, keep the temperature at 25°C, start stirring for water washing, and the washing time is 30min. After separation, the obtained filter cake was put into a vacuum drying oven for vacuum drying at 30°C. Then the crude lactide of preliminarily drying is joined in the vacuum distillation unit, and the control distillation temperature is 180 ℃, and distillation pressure is 5kPa, and the crude lactide that distills out passes through dewatering device (desiccant is calcium sulfate, and the temperature that maintains is 120°C) to further remove water to finally obtain lactide with a purity of 98.6%, and the yield of...
Embodiment 3
[0036] The treatment process and operating conditions of this example are the same as those of Example 1, except that the water is washed once and then dehydrated, and the mass ratio of the amount of water to the crude lactide after dehydration is 1:1. After testing, lactide with a purity of 99.3% is finally obtained, and the yield of lactide is 82.6%.
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