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Purification method of lactic acid ester

A purification method and technology of lactic acid ester, applied in the direction of organic chemistry, reaction preparation of ester group and hydroxyl group, etc., can solve the problem of simultaneous hydrolysis of lactic acid ester, and achieve the effects of reducing production costs, simple operation, and high efficiency

Active Publication Date: 2009-06-17
南京枫华投资管理有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] The invention provides a method for purifying lactic acid esters, which can overcome the problem of simultaneous hydrolysis of lactic acid esters during the depolymerization of dimers or polymers in existing purification methods, and make dimers or Polymer conversion to lactate, more efficient purification of lactate

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  • Purification method of lactic acid ester
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  • Purification method of lactic acid ester

Examples

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Embodiment 1

[0034] Prepare and purify menthol lactate by the method of the present invention, comprise the following steps:

[0035] (1) Preparation of menthol lactate, dimerization and polymer mixture:

[0036] Put quantitative 50g menthol, 50g lactic acid (85%wt) and 50mL toluene respectively into the four-neck flask, slowly drop 0.35g concentrated sulfuric acid in the stirring state, heat and reflux in the oil bath for 2h, collect 15mL water in the water separator, and detect by GC Menthol content <8%wt, the reactant was cooled to room temperature, washed with 10mL of saturated saline, 10% aqueous sodium hydroxide solution to adjust the pH value to 6.5-7.5, and washed again with 10mL of saturated saline, and the solvent was recovered. It is a mixture of menthol lactate, dimer and polymer.

[0037] (2) Degradation of polymers:

[0038] At room temperature, dissolve the mixture obtained in the above steps in 70 mL of anhydrous methanol, add 0.6 g of solid potassium carbonate, stir for ...

Embodiment 2

[0040] Prepare and purify cyclohexanol lactate by the method of the present invention, comprise the following steps:

[0041] (1) Preparation of cyclohexanol lactate, dimerization and multimerization mixture:

[0042] The operation method is as in Example 1, 33g of cyclohexanol is added, the solvent is 50mL of benzene, the catalyst is 0.8g of p-toluenesulfonic acid, reflux for 3.5h, and the remainder is the same as in Example 1.

[0043] (2) Degradation of polymers:

[0044] At room temperature, dissolve the above-obtained mixture in 50 mL of absolute ethanol, add 1.0 g of solid sodium carbonate, stir for 2.5 h, GC detects dimers < 0.5%, filter with suction, and neutralize the filtrate with acetic acid to pH = 7.0, recover the solvent to obtain The oil was distilled under reduced pressure to obtain 45.3 g of the oil, and the purity of cyclohexanol lactate was 98.8% as detected by GC.

Embodiment 3

[0046] Prepare and purify lauryl lactate by the method of the present invention, comprise the following steps:

[0047] (1) Preparation of lauryl lactate, dimerization and multimerization mixture:

[0048] The operation method is as in Example 1, adding 60g of lauryl alcohol, the solvent is 50mL of petroleum ether (60-90°C), the catalyst is 5g of sodium bisulfate, reflux for 5.0h, and the remainder is the same as in Example 1.

[0049] (2) Degradation of polymers:

[0050] At room temperature, dissolve the above-obtained mixture in 75 mL of anhydrous methanol, add 0.6 g of solid potassium carbonate, stir for 2.5 h, GC detects that the dimer is <0.5%, filter with suction, and neutralize the filtrate with acetic acid to pH = 7.0, recover the solvent to obtain The oil was distilled under reduced pressure to obtain 75.2 g of the oil, and the purity of the lauryl lactate was 99.2% as detected by GC.

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Abstract

The invention discloses a method for purifying lactate. The method comprises: dissolving the lactate containing dimer and polymer in a solvent of lower alcohol, adding a catalytic amount of alkali, carrying out the ester exchange reaction at a temperature of between 0 and 80 DEG C, converting the dimer or polymer into lactate products and methyl lactate or ethyl lactate, and adding acid for neutralization or adopting cation resin for ion exchange so as to neutralize the reaction product; and recovering the solvent, and obtaining the finished product by recrystallization or reduced pressure distillation. The method has the advantages that the method can effectively lower hydrolysis of the lactate simultaneously carried out during depolymerization of the dimer or polymer in the purificationprocess, the reaction can be carried out at normal temperature, and the production cost can be effectively lowered, along with simple operation, safety and high efficiency; moreover, the purity of the obtained target product reaches more than 98 percent, so that the method has industrial application values.

Description

technical field [0001] The present invention relates to a method for purifying lactic acid esters, in particular to a method for depolymerizing polylactic acid esters produced during the esterification of lactic acid and alcohol. Background technique [0002] The usual preparation method of lactic acid ester is obtained by the esterification reaction of lactic acid and alcohol under the action of a catalyst. During the esterification reaction, it is easy to generate a by-product—a dimer or polymer of lactic acid ester, as follows Shown in formula I, this brings great difficulty to the separation and purification of lactate. There are a small amount of literature reports to provide the degradation method of its dimer or polymer while disclosing the preparation method of lactic acid ester, but most of the methods therein will regenerate lactic acid when the dimer or polymer is degraded. The conversion of ester products into raw materials is detrimental to the production of la...

Claims

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Application Information

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IPC IPC(8): C07C67/03C07C69/68
Inventor 史鲁秋李华山
Owner 南京枫华投资管理有限公司
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