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Method for preparing high purity solid cyanoacetic acid

A cyanoacetic acid and high-purity technology, applied in the field of preparation of high-purity cyanoacetic acid, can solve problems such as application limitation, and achieve the effects of easy recovery and reuse, simple process and cost reduction

Inactive Publication Date: 2008-09-24
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But the content of the cyanoacetic acid product obtained by this method is only about 90%, wherein the water content and salt content are all high, so that its application is limited

Method used

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  • Method for preparing high purity solid cyanoacetic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] (1) Preparation of cyanoacetic acid aqueous solution:

[0019] Add sodium hydroxide to chloroacetic acid for neutralization, add sodium cyanide for cyanation to obtain sodium cyanoacetate aqueous solution, then add hydrochloric acid for neutralization to obtain a mixed solution of cyanoacetic acid and sodium chloride:

[0020] ClCH 2 COOH+NaOH→ClCH 2 COONa +H 2 o

[0021] ClCH 2 COONa +NaCN→CNCH 2 COONa+NaCl

[0022] CNCH 2 COONa+HCl→CNCH 2 COOH+NaCl

[0023] (2) At 50°C, extract the mixed solution prepared in step (1) with ethyl formate, the volume ratio of the mixed solution prepared in said step (1) to ethyl formate is 1:3, and the number of extractions is 5 times , each extraction time is 10min;

[0024] (3) Concentrating the extract by evaporating under reduced pressure to obtain solid cyanoacetic acid with a content of more than 98%, while reclaiming the extractant ethyl formate;

[0025] (4) Recovery of salt

[0026] Extract the inorganic salts in the...

Embodiment 2

[0028] (1) Sodium hydroxide aqueous solution is added in the chloroacetic acid, neutralizes to neutrality below 45 ℃, obtains sodium chloroacetate solution; The neutralization solution is added in the sodium cyanide aqueous solution that mass percent concentration is 30%, react Control the temperature at 105-115°C and keep it warm for 30 minutes to obtain an aqueous solution of sodium cyanoacetate; after cooling down to below 50°C, add hydrochloric acid to neutralize to obtain a mixed solution of cyanoacetic acid and sodium chloride, and measure the content of cyanoacetic acid; (this step It is a traditional process, and a mixed solution of cyanoacetic acid and sodium chloride can also be obtained under other conditions)

[0029] (2) Take the mixed solution of cyanoacetic acid and sodium chloride as the water phase (W), ethyl acetate (O) as the oil phase, and extract with intermittent stirring, in a there-necked flask equipped with a stirrer, a thermometer and a condenser Add ...

Embodiment 3

[0032] (1) with embodiment 2;

[0033] (2) Compared with O / W=3, the ester solvent is propyl formate, which is extracted by intermittent stirring, the extraction temperature is 50°C, and the extraction time is 10 minutes;

[0034] (3) After phase separation, the organic phase was distilled under reduced pressure to obtain solid cyanoacetic acid, and the yield of one extraction of cyanoacetic acid was 20%.

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Abstract

The present invention discloses a preparation method of high-purity solid cyano acetic acid. The preparation method comprises the following steps: (1) chloroactic acid and sodium hydroxide have the reaction of neutralization and cyanidation to prepare sodium chloroacetate aqueous solution; hydrochloric acid is added for neutralization; then the mixed solution of cyano acetic acid and sodium chloride can be prepared; (2) at the temperature of 20 to 90 DEG C, ester solvents are used for extracting the mixed solution prepared in the first step; the volume ratio of the mixed solution and the ester solvents is 1 : 1 to 5; the time of extraction is 4 to 10; the time of each extraction step is 5 to 15 minutes; (3) the extract is condensed through vacuum evaporation to prepare the high-purity solid cyano acetic acid. The preparation method has the advantages of simple process and low investment. The extractant is stable, cheap and easily available; and the extractant can be recycled and reused. More importantly, the preparation method can be used for preparing the high-purity solid cyano acetic acid and can satisfy the requirements for refining the high-purity solid cyano acetic acid in the industry.

Description

technical field [0001] The invention belongs to the technical field of organic chemical synthesis, and relates to a preparation method of high-purity cyanoacetic acid. Background technique [0002] Cyanoacetic acid is an important intermediate in the production of medicines, dyes, and pesticides. It is used in the production of methyl α-cyanoacrylate and n-butyl ester, vitamin B6, caffeine, etc., and is also used in the production of the fungicide cymoxanil. [0003] The traditional production process uses chloroacetic acid, sodium carbonate, and sodium cyanide as raw materials. It is obtained through neutralization, cyanation, acidification, and dehydration under reduced pressure. However, the content of the cyanoacetic acid product obtained by this method is only about 90%, and the water content and salt content are relatively high, which limits its application. Contents of the invention [0004] The purpose of the invention is to overcome the deficiencies in the prior ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C255/19C07C253/14
Inventor 王学花高俊超姜申德
Owner TIANJIN UNIV
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