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Improved 2-chlorine-5-chloromethyl pyridine synthesis process

A kind of chloromethylpyridine and synthesis technology technology, applied in the direction of organic chemistry, etc., can solve problems such as environmental impact, no recovery method, etc., to achieve the effect of overcoming a large amount of waste water

Inactive Publication Date: 2012-06-13
NANJING UNIV OF TECH +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the chlorination and cyclization process of the cyclopentadiene method needs to use a large amount of N,N-dimethylformamide, referred to as DMF, and there is no effective recovery method, and a large amount of waste water is generated at the same time, which has a serious impact on the environment.
In 2011, the Chinese invention patent CN101948424A disclosed a cyclization process in which solid phosgene or dimer phosgene or phosgene was used instead of phosphorus oxychloride and other phosphorus chlorination reagents, which can greatly reduce the amount of DMF, but the cyclization A large amount of waste water will still be produced during post-reaction treatment
[0012] Compared with prior art, the beneficial effect of the present invention: the purpose of this invention is to provide a kind of synthetic technique of improved 2-chloro-5-chloromethylpyridine, and this technique has carried out the cyclization reaction technique of cyclopentadiene method Improvement, the use of trialkylamine salification method in the post-treatment process of the cyclization reaction overcomes the shortcomings of the original technology to produce a large amount of waste water, and is a clean method for the production of 2-chloro-5-chloromethylpyridine

Method used

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  • Improved 2-chlorine-5-chloromethyl pyridine synthesis process

Examples

Experimental program
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Effect test

Embodiment 1

[0026] Example 1 Chlorination addition reaction

[0027] 2-methenyl-4-cyanobutyraldehyde (109 g, 1.00 mol) and toluene (300 g) were successively put into a 1000 ml three-necked flask. Control the temperature at -5-2°C, and feed chlorine gas. When the content of 2-methenyl-4-cyanobutyraldehyde is less than 1% as detected by gas chromatography, stop the chlorine gas flow. Raise the temperature to 30°C, and remove excess chlorine under reduced pressure. When the material turns from dark yellow to light yellow and transparent, stop the gas removal to obtain a toluene solution of 2-chloro-2-chloromethyl-4-cyanobutyraldehyde.

Embodiment 2

[0028] Example 2 Cyclization reaction

[0029] DMF (21.9g, 0.3mol) was added to the reaction solution in Example 1, and the temperature was raised to 90°C to start dropwise addition of a toluene (300g) solution containing triphosgene (100g, 0.340mol). The dropping time was 2h, and the temperature was controlled at 90 ~100°C, keep warm for 3-6h after the dropwise addition, gas chromatography detects that the content of 2-chloro-2-chloromethyl-4-cyanobutyraldehyde is less than 1.0%, and the content of 2-chloro-5-chloromethylpyridine reaches 97.0% %, stop the reaction. At 55° C., triethylamine (212 g, 2.09 mol) was added dropwise, then vacuum filtered while hot, and the filter cake was rinsed with hot toluene (50 ml×2 times). The toluene layers were combined, the toluene was distilled off, and then distilled under reduced pressure to collect fractions at 110-115°C / 1600kPa to obtain refined 2-chloro-5-chloromethylpyridine (118g, 0.727mol) with a yield of 72.7%.

Embodiment 3

[0030] Example 3 Cyclization reaction

[0031] DMF (21.9g, 0.3mol) was added to the reaction solution in Example 1, and the temperature was raised to 85°C, and a toluene (300g) solution containing triphosgene (100g, 0.340mol) was added dropwise for 2 hours, and the temperature was controlled at 90°C. ~100°C, keep warm for 3-6 hours after the dropwise addition, the content of 2-chloro-2-chloromethyl-4-cyanobutyraldehyde is less than 1.0% and the content of 2-chloro-5-chloromethylpyridine reaches 97.0% as detected by GC , stop the reaction. At 45° C., tri-n-propylamine (299 g, 2.09 mol) was added dropwise, then vacuum filtered while hot, and the filter cake was rinsed with hot toluene (50 ml×2 times). The toluene layers were combined, the toluene was distilled off, and then distilled under reduced pressure to collect fractions at 110-115°C / 1600kPa to obtain refined 2-chloro-5-chloromethylpyridine (114g, 0.704mol) with a yield of 70.4%.

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Abstract

The invention provides an improved 2-chlorine-5-chloromethyl pyridine synthesis process, which is characterized in that after reaction of toluene solution of 2-chlorine-2-chloromethyl-4-cyano butyraldehyde and triphosgene toluene solution is completed, a certain amount of trialkylamine is added in dropwise mode at 0 to 90 DEG C, trialkylamine hydrochloride is isolated by filtration, and filtrate is desolventized through distillation and then is decompressed and distilled to obtain products of the 2-chlorine-5-chloromethyl pyridine. The trialkylamine is one of triethylamine, tripropyl amine and tributylamine, quantity ratio of the triphosgene and the trialkylamine is 1:6.0 to 1:8.0, and the preferential ratio is 1:6.0 to 1:7.0. In the improved synthesis process, toluene obtained by distillation can be recycled, the main ingredients of a filter cake is the trialkylamine hydrochloride which can be sold as by-products after refining, and substrate after distillation is sent to a combustion furnace for treatment, thereby overcoming the shortcoming that the original technology generates a large amount of waste water, and achieving cleaner production of cyclization reaction.

Description

technical field [0001] The invention relates to an industrial production of organic industrial raw materials, in particular to an improved synthesis process of 2-chloro-5-chloromethylpyridine. technical background [0002] 2-Chloro-5-chloromethylpyridine is an important pesticide intermediate, which can be reacted with N-nitroiminoimidazolidine to synthesize imidacloprid. 2-Chloro-5-chloromethylpyridine is also an important intermediate of nitenpyram, thiacloprid and other neonicotinoid pesticides. [0003] At present, there are three main routes for synthesizing 2-chloro-5-chloromethylpyridine by ring method, which are benzylamine method, cyclopentadiene method and morpholine method. [0004] The benzylamine method takes propionaldehyde and benzylamine as raw materials, and obtains 2-chloro-5-chloromethylpyridine through four-step reaction synthesis, and the total yield (in benzylamine) of this method is about 31% (DE4446338, JP5178835, US5442072). The reaction equation ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/61
Inventor 朱红军刘山于国权杜刚吕良忠黄仁钧王锦堂王建荣周兴军马辉丁华平
Owner NANJING UNIV OF TECH
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