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Method for synthesizing p-toluenesulfonic acid-catalyzed dimethyl malonate

A technology of dimethyl malonate and p-toluenesulfonic acid, which is applied in the field of malonate preparation, can solve the problems of easy decomposition of cyanoacetic acid and consumption of sulfuric acid acid waste water, etc., so as to reduce the amount of use, reduce the amount of use and the amount of waste water generated , avoid the effect of high salt content

Active Publication Date: 2013-12-04
CHONGQING UNISPLENDOUR CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The shortcoming that this method exists is: the reaction process of synthesizing cyanoacetic acid produces a large amount of inorganic salt sodium chloride, and the mixture of cyanoacetic acid and salt carries out esterification reaction after being concentrated, but cyanoacetic acid is easy to decompose after being concentrated, and because there is A large amount of sodium chloride, sulfuric acid reacts with sodium chloride during esterification, consumes a large amount of sulfuric acid and produces a large amount of acidic wastewater
[0010] In addition, there are methods to report the use of calcium cyanoacetate instead of sodium cyanoacetate, but the above problems cannot be solved

Method used

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  • Method for synthesizing p-toluenesulfonic acid-catalyzed dimethyl malonate
  • Method for synthesizing p-toluenesulfonic acid-catalyzed dimethyl malonate
  • Method for synthesizing p-toluenesulfonic acid-catalyzed dimethyl malonate

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Embodiment 1

[0034] (1) Neutralization reaction: add 900kg of chloroacetic acid (content 98%, 9.30kmol) to 620kg of water, stir and dissolve, neutralize with aqueous sodium carbonate to pH=6.5-7.0, and generate sodium chloroacetate;

[0035] (2) Cyanide reaction: transfer the sodium chloroacetate obtained in step (1) into the cyanide reaction kettle, raise the temperature to 50°C, then add 1530kg (4.69kmol) of 30% sodium cyanide aqueous solution dropwise, when the reaction temperature reaches 85 After -90°C, stop heating and start to cool. When the reaction temperature reaches 105°C, the reaction ends and is cooled to room temperature to obtain an aqueous solution of sodium cyanoacetate;

[0036] (3) Acidification reaction: transfer the sodium cyanoacetate aqueous solution obtained in step (2) into the acidification reaction kettle, stir, and slowly add 1000L (content, 31%, 10.14kmol) hydrochloric acid into the acidification reaction kettle from the metering tank, after acidification to gen...

Embodiment 2

[0043] Embodiment 2 is directly applying the p-toluenesulfonic acid that embodiment 1 reclaims, and its preparation process is:

[0044] (1) Esterification reaction: Take the malonic acid methanol solution prepared in Example 1, add 550 L of dichloroethane and the p-toluenesulfonic acid recovered in Example 1 to the esterification reaction kettle, and control the temperature of the kettle to 65-70°C Perform an esterification reaction to generate dimethyl malonate, and the water generated by the reaction is continuously taken out of the system through azeotropy, and 200L of methanol is added after 2 hours;

[0045] (2) Extraction and phase separation: After the esterification is completed, cool to room temperature, centrifuge, recover 69kg of p-toluenesulfonic acid, add 150L of water, stir for 30 minutes, let stand for 40-60 minutes, then separate the phases, and wash the organic phase with saturated sodium carbonate solution Then transfer to rectification tower, rectification ...

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Abstract

The invention discloses a method for synthesizing p-toluenesulfonic acid-catalyzed dimethyl malonate. Chloroacetic acid is taken as a raw material, dimethyl malonate is generated through a neutralization reaction, a cyanation reaction, an acidification reaction, a hydrolysis reaction and an esterification reaction, the esterification reaction is performed under the catalytic effect of p-toluenesulfonic acid, a catalyst is recovered after the reactions, and the recovered catalyst can be recycled, so that the usage amount of the catalyst can be greatly reduced and sulfuric acid-containing wastewater cannot be produced by selecting p-toluenesulfonic acid instead of sulfuric acid in a traditional process as the catalyst in the esterification reaction; meanwhile, dichloroethane is added in the esterification reaction, has a good dissolving property for dimethyl malonate, is easily separated from dimethyl malonate through rectification and forms a ternary azeotropic system along with methanol and water, and the water generated in the reactions is continuously discharged from the system through azeotropy, so that the esterification reaction can be more thoroughly produced.

Description

technical field [0001] The invention relates to a method for preparing malonate, in particular to a method for synthesizing dimethyl malonate with chloroacetic acid and sodium cyanide as raw materials and catalyzed by p-toluenesulfonic acid. Background technique [0002] Dimethyl malonate is an intermediate of medicines, pesticides and dyes. At present, there are many production methods at home and abroad. In China, cyanation esterification is mainly used, that is, chloroacetic acid, sodium cyanide and methanol are used as raw materials, and after neutralization , Cyanide, acidification and esterification processes to obtain dimethyl malonate. [0003] Common synthetic methods: [0004] 1. Direct esterification of cyanoacetic acid [0005] [0006] The shortcoming that this method exists is: the reaction process of synthesizing cyanoacetic acid produces a large amount of inorganic salt sodium chloride, and the mixture of cyanoacetic acid and salt carries out esterificat...

Claims

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Application Information

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IPC IPC(8): C07C69/38C07C67/08
CPCY02P20/584
Inventor 丁永良刘佳吴传隆范倩玉姚如杰张飞屈洋郑道敏冷方蓉李静何咏梅李朝全
Owner CHONGQING UNISPLENDOUR CHEM
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