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Environment-friendly clean method for preparing dimethyl malonate

A dimethyl malonate, clean technology, applied in the preparation of carboxylate, the preparation of organic compounds, chemical instruments and methods, etc., can solve the problems of easy decomposition of cyanoacetic acid, consumption of sulfuric acid acid waste water, etc., to avoid cyanoacetic acid The effect of decomposition and reduction of waste water generation

Inactive Publication Date: 2013-12-04
CHONGQING UNISPLENDOUR CHEM
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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
[0009] This method also has the same disadvantages as method 1
[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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  • Environment-friendly clean method for preparing dimethyl malonate
  • Environment-friendly clean method for preparing dimethyl malonate
  • Environment-friendly clean method for preparing dimethyl malonate

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Embodiment Construction

[0026] The following will refer to figure 1 , further illustrate the present invention by embodiment:

[0027] (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;

[0028] (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;

[0029] (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) h...

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Abstract

The invention discloses an environment-friendly clean method for preparing dimethyl malonate. The method comprises steps of neutral reaction, cyaniding reaction, acidizing reaction, steaming water desalination, esterification reaction and the like, wherein inorganic salt in a cyanoacetic acid aqueous solution is removed in the step of steaming water desalination, and the preferable technical scheme of steaming water desalination is carried out twice. The inorganic salt-sodium chloride mixed in cyanoacetic acid is removed through steaming water desalination before the esterification reaction, the reaction of sulfuric acid and sodium chloride are avoided in the esterification process, and the consumption of sulfuric acid and the waste water generating capacity are reduced, so that the method for preparing the dimethyl malonate is environment-friendly and clean. The steaming water desalination is carried out twice, so that the phenomenon that cyanoacetic acid is decomposed due to local overtemperature caused by large salt content in the later stage of one-time steaming concentration is avoided.

Description

technical field [0001] The invention relates to a method for preparing malonate, in particular to an environmentally friendly and clean method for preparing dimethyl malonate using chloroacetic acid and sodium cyanide as raw materials. 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 esterification re...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C69/38C07C67/22C07C67/08
Inventor 丁永良刘佳龙晓钦张飞屈洋吴传隆郑道敏姚如杰罗延谷李朝全
Owner CHONGQING UNISPLENDOUR CHEM
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