Preparation of glycollic acid from oxalaldehyde by intramolecular disproportionation method

A technology of glycolic acid and glyoxal, applied in carboxylate preparation, carboxylate preparation, organic chemistry, etc., can solve the problems of cumbersome process, high production cost, and low product purity, and achieve high reaction selectivity, The effect of less impurities and high purity of the product

Active Publication Date: 2013-10-30
WUHAN INSTITUTE OF TECHNOLOGY +1
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

[0006] Liao Chuanping once reported a new method of synthesizing glycolic acid from glyoxal via Cannicharro reaction under the catalysis of sodium hydroxide [Synthetic Chemistry, 2008,16(4):470-471], but the process requires both Reaction at low temperature and concentration at high temperature; at the same time, it is necessary to use strong acidic ion exchange resin to treat metal cations. The process is cumbersome and the production cost is high. After repeated experiments, it is found that there are many by-products and the product purity is low.

Method used

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  • Preparation of glycollic acid from oxalaldehyde by intramolecular disproportionation method

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Embodiment 1

[0029]Add 40g of calcium hydroxide and 500ml of water into a 1000ml three-necked reaction flask (the mass percent concentration of the calcium hydroxide solution is 7.4%), take a water bath, stir mechanically, and drop 145g of glyoxal with a mass concentration of 40% from the dropping funnel Solution, the rate of addition is preferably to control the reaction temperature not to exceed 25°C, and after the dropwise addition is completed, keep the reaction at 20-25°C for 1 hour to obtain a suspended calcium glycolate precipitation mixture. While stirring, add 55g of concentrated sulfuric acid (0.54mol) to the suspended calcium glycolate precipitation mixture through the dropping funnel for acidification, filter out the calcium sulfate precipitate, and when the filtrate is vacuum concentrated to no water, a small amount of calcium sulfate dissolved in the filtrate precipitates out , separated by filtration, the filtrate was diluted with deionized water until the mass concentration ...

Embodiment 2

[0031] Add 40g of calcium hydroxide and 300ml of water (mass percentage concentration is 11.8%) in 1000ml three-necked reaction flask, water bath, mechanical stirring, dropwise add 145g of mass concentration to be 40% glyoxal solution from the dropping funnel, the rate of addition is It is advisable to control the reaction temperature not to exceed 25°C. After the dropwise addition is completed, keep the reaction at 20-25°C for 1 hour to obtain a suspended calcium glycolate precipitation mixture. The reaction mixture was filtered, and the filter cake was washed with deionized water to obtain a precipitate of calcium glycolate. The precipitate is acidified with 108g mass concentration of 50% sulfuric acid solution, the calcium sulfate precipitate is filtered out, and the filtrate is removed with a mass concentration of 10% barium acetate solution to remove trace SO 4 2- ions until no new BaSO 4 until precipitation occurs. Add 1g of powdered wood activated carbon for decolori...

Embodiment 3

[0033] The glycolic acid solution obtained in Example 1 was concentrated by rotary evaporation until the mass concentration of glycolic acid was above 85%, the rotary evaporation temperature was 50-65°C, the vacuum degree was 0.080-0.095MPa, and cooled to room temperature, that is, crude glycolic acid crystals were precipitated. Filter, wash the crystals twice with a glycolic acid solution with a mass concentration of 60% as a detergent, and dry under reduced pressure in vacuum to obtain refined glycolic acid crystals. HPLC detection shows that the content of glycolic acid has a purity of more than 99%, and the yield of crystal glycolic acid is more than or equal to 75%.

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Abstract

The invention relates to a preparation method of glycollic acid from oxalaldehyde by intramolecular disproportionation. The preparation method comprises the following steps of: 1) performing disproportionation on calcium hydroxide solution and aqueous solution of oxalaldehyde and preserving heat to obtain a suspended calcium hydroxyl-acetate precipitate mixture; 2) performing acidulation precipitation with sulfuric acid on the mixture to obtain glycollic acid and calcium sulfate precipitate, filtering, concentrating the filtrate until the filtrate contains no water, and then filtering again; and 3) diluting the filtrate in step 2) with water, completely removing SO4(2-) ions by adding barium acetate or barium hydroxide into the filtrate, filtering out barium sulfate precipitate and active carbon, and concentrating the filtrate to obtain the glycollic acid solution. The preparation method has the advantages of: 1) low environmental pollution; 2) no special requirement on equipment, simplicity of operation, comprehensive usage of by-products and capability of realizing clean production during disproportionation at a normal temperature and under a normal pressure; and 3) high selectivity of reaction, few product impurities and high purity. The method provides the preparation of high-purity glycollic acid crystal with convenient conditions.

Description

technical field [0001] The invention relates to a preparation method of glycolic acid, in particular to a preparation method of glycolic acid by intramolecular disproportionation of glyoxal. Background technique [0002] Glycolic acid (hydroxyacetic acid; glycolic acid), also known as glycolic acid or glycolic acid, is the simplest molecular structure α - Hydroxy acids. Glycolic acid is widely used in chemical cleaning, household chemicals, biomedical materials and fungicides and other fields. Glycolic acid molecules contain both highly reactive hydroxyl and carboxyl groups, which have unique metal chelating ability and effective neutralization performance, and are less corrosive, so its 70% aqueous solution is commonly used in industry as cleaning for pipes, boilers, etc. agent to remove the precipitates formed by calcium and magnesium ions; glycolic acid has good water solubility and strong permeability, and can be absorbed by the skin through the stratum corneum to prom...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C59/06C07C51/02C07C51/41
Inventor 袁华段小六杜治平丁一刚吴元欣王维华马彦赵林林
Owner WUHAN INSTITUTE OF TECHNOLOGY
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