Synthesis method of metaldehyde

A synthetic method, metaldehyde technology, applied in the direction of organic chemistry, etc., can solve the problems of low product yield and high energy consumption, and achieve the effects of mild reaction conditions, easy industrialization, and increased selectivity

Inactive Publication Date: 2015-12-30
方光华
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Metaldehyde is usually prepared by acetaldehyde polymerization, but in the prior art, a large amount of paraldehyde is obtained in the reaction process
People have done a lot of research, but problems such as low product yield, high energy consumption, and environmental protection have not been effectively resolved

Method used

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  • Synthesis method of metaldehyde
  • Synthesis method of metaldehyde
  • Synthesis method of metaldehyde

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] The first embodiment of the present invention provides a method for synthesizing metaldehyde. The synthesis method includes catalyst preparation, polymerization reaction and depolymerization reaction.

[0028] Catalyst preparation: Add 4 g of furan hydrobromide under stirring with 6 g of hydrobromic acid (49%), stir and dissolve for later use.

[0029] Polymerization: Stir 200ml of acetaldehyde down to -15°C, add 0.6g of the above-mentioned catalyst dropwise to the acetaldehyde, control the rate of addition, and ensure the temperature of the reaction solution. Heat and stir for 1 hour, then filter, wash the solid phase with water, and dry to obtain 20.5 g of white crystal metaldehyde, with a yield of 13.1%. Content>99%. The results of gas chromatography were as attached figure 1 , peak time: 5.372min, 9.833min; Area%: 0.153, 99.847.

[0030] Depolymerization reaction: Take 160ml of the filtrate, add 5 grams of phosphoric acid: sulfuric acid (V:V=50:50) composite c...

Embodiment 2

[0032] The second embodiment of the present invention provides a method for synthesizing metaldehyde. The synthesis method includes catalyst preparation, polymerization reaction and depolymerization reaction.

[0033] Catalyst preparation: Add 4 g of piperazine hydrobromide under stirring with 6 g of hydrobromic acid (49%), stir and dissolve for later use.

[0034] Polymerization: Stir 200ml of acetaldehyde down to -15°C, add 0.6g of the prepared catalyst dropwise to the acetaldehyde, control the rate of addition, and ensure the temperature of the reaction solution, the highest is not higher than 10°C, after the catalyst is added, it will be at -5-5 Stir at ℃ for 1 hour, then filter, wash the solid phase with water, and dry to obtain 22.3 g of white crystal metaldehyde, with a yield of 14.3% and a content of >99%. The results of gas chromatography were as attached figure 2 , peak time: 1.458min, 9.830min; Area%: 0.229, 99.771.

[0035] Depolymerization reaction: Add 5 gra...

Embodiment 3

[0037] The third embodiment of the present invention provides a method for synthesizing metaldehyde. The synthesis method includes catalyst preparation, polymerization reaction and depolymerization reaction.

[0038] Catalyst preparation: Add 4 g of pyridine hydrobromide under stirring with 6 g of hydrobromic acid (49%), stir and dissolve for later use.

[0039] Polymerization: Stir 200ml of acetaldehyde down to -15°C, add 0.6g of the prepared catalyst dropwise to the acetaldehyde, control the rate of addition, and ensure the temperature of the reaction solution, the highest is not higher than 10°C, after the catalyst is added, it will be at -5-5 Stir at ℃ for 1 hour, then filter, wash the solid phase with water, and dry to obtain 23.5 g of white crystal metaldehyde, with a yield of 15.1% and a content of >99%. Gas chromatography test results like image 3 , peak time: 1.470min, 9.828min; Area%: 0.268, 99.732.

[0040] Polymerization reaction: add 5 grams of phosphoric aci...

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Abstract

The invention provides a synthesis method of metaldehyde. The method comprises a polymerization reaction of acetaldehyde in an acidic condition; a compound with the following general formula in the reaction is adopted as a catalyst: HY:CPHSNM.HY; wherein P is an integer from 1 to 8; S is an integer from 1 to 16; M is an integer from 1 to 4; and Y is F, Cl or Br. The synthesis method is mild in reaction, economical, environmentally friendly, and easy to industrialize.

Description

technical field [0001] The invention relates to the technical field of organic synthesis, in particular to a method for synthesizing metaldehyde. Background technique [0002] Metaldehyde is a white needle-like crystal, which is unstable when exposed to heat, insoluble in water, and easily soluble in ethanol, ether, acetone and benzene. It is a special drug for eliminating snails, slugs and other mollusc pests with lungs. It can be used for artificial rainfall, making safety matches, colored candles and fireworks. Metaldehyde is usually prepared by acetaldehyde polymerization, but in the prior art, a large amount of paraldehyde is obtained during the reaction. Due to harsh reaction conditions, it needs to be prepared in a low-temperature environment, and the yield is low, so that the cost of metaldehyde remains high. To this end, people have done a lot of research, and there are many synthetic literature reports. [0003] Metaldehyde is synthesized from acetaldehyde by ca...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D323/00
CPCC07D323/00
Inventor 方光华
Owner 方光华
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