Prepn process of malonic ester

A technology of malonate and cyanoacetic acid, which is applied in the field of malonate preparation, can solve the problems of difficulty in realizing large-scale industrial production, high recovery cost of extractant toluene, large amount of extractant toluene, etc. The effect of reducing the amount of feed to the kettle, low production cost, and reducing the cost of environmental protection treatment

Inactive Publication Date: 2007-11-07
CHONGQING UNISPLENDOUR CHEM
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Problems solved by technology

But all there is following defective in above-mentioned method: 1, the addition consumption of extractant toluene is big, and the add-on of toluene is more than 2.5 times of mole of sodium cyanoacetate, makes the recovery cost of extractant toluene high, significantly increases operating cost, increases production total at last cost, thus leading to an increase in input and output ratio (i.e. low space-time yield), it is difficult to realize large-scale industrial production; There is always a dynamic balance between the reactant malonate and the product malonate in the reaction system. After the esterification reaction is completed, water-soluble salt is added, and part of the malonate and malonate will be lost with the acid water. , resulting in a decrease in the yield of malonate

Method used

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Embodiment 1: the preparation method of dimethyl malonate, its steps are as follows:

[0021] 725g of industrial chloroacetic acid with a weight percentage content of 98% (calculated as 7.5 moles), add 500g of water to dissolve, stir, and neutralize to pH=6.5~7.0 with aqueous sodium carbonate solution under cooling conditions to obtain sodium chloroacetate aqueous solution.

[0022] Mix the above-mentioned sodium chloroacetate aqueous solution with a liquid sodium cyanide solution with a concentration of 30% by weight, raise the temperature to 50°C, and initiate the cyanation reaction. When the cyanation reaction temperature reaches 85-90°C, stop heating and start cooling. When the cyanidation reaction temperature reached 105-115°C, the reaction was over, and then cooled down to below 60°C to obtain 4000g of sodium cyanoacetate solution, which was sampled and analyzed as CN-qualified. The obtained sodium cyanoacetate solution is divided into 5 equal parts, which are re...

Embodiment 2

[0033] Embodiment 2: the preparation method of diethyl malonate, its steps are as follows:

[0034] With the step in embodiment 1, carry out neutralization reaction and cyanation reaction with industrial chloroacetic acid as raw material, obtain sodium cyanoacetate solution 4170g. The obtained sodium cyanoacetate solution is divided into 5 equal parts, which are respectively used in the circulation reactions of the following circulation 1) to circulation 5).

[0035] Loop 1):

[0036]Get above-mentioned gained sodium cyanoacetate solution 1 / 5 namely 834g, add the industrial hydrochloric acid 185g that weight percentage concentration is 31% and carry out acidification, obtain the mixed aqueous solution of cyanoacetic acid and sodium chloride. Heating and evaporative desalination under vacuum conditions, the temperature is controlled at 60-85°C, when most of the sodium chloride is precipitated, cool to 50°C, filter, and wash the solid sodium chloride with a small amount of wate...

Embodiment 3

[0045] Embodiment 3: the preparation method of diisopropyl malonate, its steps are as follows:

[0046] With the step in embodiment 1, carry out neutralization reaction and cyanation reaction with industrial chloroacetic acid as raw material, obtain sodium cyanoacetate solution 4125g. Gained sodium cyanoacetate solution is divided into 5 equal parts, carries out circulation experiment with the step of embodiment 1, and wherein esterification is replaced methyl alcohol with Virahol (100%) 200g, and all the other are with embodiment 1.

[0047] The experimental data of the above cycles are shown in Table 3.

[0048] cycle batch

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Abstract

The present invention provides preparation process of malonic ester. Malonic ester is prepared with chloroacetic acid as material and through a neutralization reaction, a cyanidation, an acidification, a dewatering step, a hydrolysis and twice esterification. The preparation process with twice esterification has total malonic ester yield as high as 90 %, obviously reduced consumption of extractant toluene, high apparatus utilizing rate and lowered production cost.

Description

technical field [0001] The invention relates to a method for preparing malonate, in particular to a method for preparing malonate using chloroacetic acid as a raw material. Background technique [0002] Malonate products such as dimethyl malonate are industrial raw materials widely used in medicine, pesticides and cosmetics. The traditional production process is to use chloroacetic acid as raw material, through the steps of neutralization, cyanation, acidification, dehydration, esterification, etc., 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 of cyanoacetic acid into...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C69/38C07C67/08
Inventor 郑伯川徐洪罗延谷唐玉平
Owner CHONGQING UNISPLENDOUR CHEM
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