Process of preparing malonic ester

A technology of malonate and dilute sulfuric acid, which is applied in the preparation of carboxylic acid esters, organic compounds, and nitriles. It can solve the problems of sampling and analysis of dehydration residues, the impact of esterification reaction balance, and the hydrolysis of cyanoacetic acid. Achieve the effects of accurate control of moisture content, avoiding hydrolysis or esterification reaction, and easy control of content

Inactive Publication Date: 2006-09-20
CHONGQING UNISPLENDOUR CHEM
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Problems solved by technology

For example, the Chinese patent CN1200368A discloses a method for preparing malonate in which hydrolysis, esterification, and extraction are carried out simultaneously. This method requires controlling the water content in the system after cyanoacetic acid dehydration is 6%, otherwise the water content in the system is too small. It will affect the hydrolysis of cyanoacetic acid, make the hydrolysis of cyanoacetic acid incomplete, and cause the product quality to

Method used

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Experimental program
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Effect test

Embodiment 1

[0017] 145g of industrial chloroacetic acid with a weight percentage content of 98% (the percentage is calculated as 1.5 moles), dissolved in 100g of water, stirred, and neutralized to pH=6.5 to 7.0 with aqueous sodium carbonate solution under cooling conditions to obtain sodium chloroacetate aqueous solution.

[0018] Mix the above-mentioned sodium chloroacetate solution with a liquid sodium cyanide solution with a concentration of 30% by weight, raise the temperature to 50°C to initiate the cyanation reaction, stop heating when the cyanation reaction temperature reaches 85-90°C, and when the cyanation reaction When the temperature reaches 105-115°C, cool down to below 60°C to obtain a sodium cyanoacetate solution, and take a sample to analyze the hydrogen cyanide ion content to be qualified.

[0019] Adding 190 g of industrial hydrochloric acid with a weight percentage concentration of 31% to the sodium cyanoacetate solution was acidified to obtain a mixed aqueous solution o...

Embodiment 2

[0021] It is that the industrial hydrochloric acid 190g that is 30% by weight percentage concentration is used to change the acidification reaction in embodiment 1 to use the dilute sulfuric acid 185g that is 75% by weight percentage concentration to be used for the acidification of sodium cyanoacetate solution, all the other operations are the same as embodiment 1, obtain propanedione Dimethyl malonate finished product 176g, the content of dimethyl malonate is 98.92% after analysis, and the yield of dimethyl malonate is 87.93%.

Embodiment 3

[0023] The weight percent concentration that embodiment 1 is used is that the dilute sulfuric acid of 75% is replaced with a kind of industrial by-product dilute sulfuric acid (wherein containing HCl1.54%, H 2 SO 4 74.5%), all the other operations are with embodiment 1, obtain dimethyl malonate finished product 177g, the content of dimethyl malonate is 99.12% after analyzing, and the yield of dimethyl malonate is 88.60%.

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Abstract

This invention relates to a method to synthesize malonate from chloroacetic acid, which includes neutralization, cyanidation, acidification, dehydration and esterification. It has the characteristics that dilute sulphuric acid is added after dehydration so that cyanoacetic acid is hydrolyzed into malonic acid which is then esterified to obtain malonate. This invention has the advantages of low cost, easily-controlled technique and high yield.

Description

technical field [0001] The present invention relates to the preparation method of malonate, specifically is the method for the synthesis of malonate with chloroacetic acid as raw material. Background technique [0002] Malonate products such as dimethyl malonate are widely used as industrial raw materials for medicine, pesticides and cosmetics. The traditional production process uses chloroacetic acid as raw material, through neutralization, cyanation, acidification, dehydration, esterification Such steps are realized, but the yield is relatively low. This is mainly because it is required to completely remove the water during dehydration, and as the amount of water decreases, the dehydration temperature will gradually rise above 110°C, which will intensify the decomposition of the intermediate product cyanoacetic acid, resulting in the yield of the final product malonate The rate is lower. Therefore, many improved malonate synthesis methods have adopted the hydrolysis proc...

Claims

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Application Information

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IPC IPC(8): C07C67/08C07C51/08C07C69/38
Inventor 龙晓钦赵碧郑伯川周垂龙
Owner CHONGQING UNISPLENDOUR CHEM
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