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Preparation method of 2,3,6-trichloropyridine

A technology of trichloropyridine and pyridine, which is applied in the field of preparation of 2,3,6-trichloropyridine, can solve problems such as difficult separation, low selectivity, and low yield, and achieve short process flow, high purity, and post-processing Handle simple effects

Active Publication Date: 2019-04-02
CHONGQING ZHONGBANG TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method also has low selectivity to 2,3,6-trichloropyridine, difficult separation and low yield

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] The catalyst HZSM-5 raw powder (Tianchang Runyuan Catalyst Co., Ltd.) with a silicon-aluminum ratio of 80 was pressed into tablets and sieved to obtain a uniform size of 10-20 mesh. Weigh 25 g of the catalyst and load it into a quartz reaction tube with a diameter of 2.4 cm and a length of 60 cm. The 20% pyridine aqueous solution is first pumped into the preheater with a flow rate of 60g / h for gasification (the weight hourly space velocity of pyridine should be 0.48h -1 ), followed by N 2 The mixed gas is sent to the fixed bed reactor as the carrier gas to react with chlorine gas, Cl 2 The molar ratio with pyridine was 7:1, reacted at 350°C for 2h, and collected the reaction solution. Use 20% NaOH solution to adjust the pH of the reaction solution to 11, then extract with dichloromethane, and rotate the organic phase to obtain the crude product of 2,3,6-trichloropyridine (the product composition is 2,3,6-trichloropyridine 86.5 %, 2,6-dichloropyridine 8.2%, 2,3,5-tric...

Embodiment 2

[0027] The catalyst HZSM-5 raw powder (Tianchang Runyuan Catalyst Co., Ltd.) with a silicon-aluminum ratio of 260 was pressed into tablets and sieved to obtain a uniform size of 10-20 mesh. Weigh 25 g of the catalyst and load it into a quartz reaction tube with a diameter of 2.4 cm and a length of 60 cm. The 20% pyridine aqueous solution is first pumped into the preheater with a flow rate of 60g / h for gasification (the weight hourly space velocity of pyridine should be 0.48h -1 ), followed by N 2 The mixed gas is sent to the fixed bed reactor as the carrier gas to react with chlorine gas, Cl 2 The molar ratio with pyridine was 8:1, reacted at 350°C for 2h, and collected the reaction solution. Use 20% NaOH solution to adjust the pH of the reaction solution to 11, then extract with dichloromethane, and rotate the organic phase to obtain the crude product of 2,3,6-trichloropyridine (the product composition is 2,3,6-trichloropyridine 95.8 %, 2,6-dichloropyridine 3.2%, 2,3,5-tri...

Embodiment 3

[0029] The catalyst HZSM-5 raw powder (Tianchang Runyuan Catalyst Co., Ltd.) with a silicon-aluminum ratio of 260 was pressed into tablets and sieved to obtain a uniform size of 10-20 mesh. Weigh 25 g of the catalyst and load it into a quartz reaction tube with a diameter of 2.4 cm and a length of 60 cm. The 20% pyridine aqueous solution is first pumped into the preheater with a flow rate of 60g / h for gasification (the weight hourly space velocity of pyridine should be 0.48h -1 ), followed by N 2 The mixed gas is sent to the fixed bed reactor as the carrier gas to react with chlorine gas, Cl 2 The molar ratio with pyridine was 5:1, reacted at 350°C for 2h, and collected the reaction solution. Use 20% NaOH solution to adjust the pH of the reaction solution to 11, then extract with dichloromethane, and rotate the organic phase to obtain the crude product of 2,3,6-trichloropyridine (the product composition is 2,3,6-trichloropyridine 94.2 %, 2,6-dichloropyridine 3.8%, 2,3,5-tri...

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Abstract

The invention discloses a preparation method of 2,3,6-trichloropyridine. The method comprises the following steps: taking a pyridine solution as a raw material, carrying out preheating and gasifying,and sending the gasified pyridine solution to a fixed bed reactor by using a carrier gas, and carrying out a reaction on pyridine with chlorine under the action of a molecular sieve catalyst to generate the 2,3,6-trichloropyridine, wherein the molecular sieve catalyst is an HZSM-5 molecular sieve, the molar ratio of the pyridine to the chlorine is 1:(3-12), the weight hourly space velocity of thepyridine is 0.12-2 h<-1>, and the reaction temperature is 200-450 DEG C. The method disclosed by the invention is short in technological process, low in raw material cost and simple in post-treatment;the highest selectivity of the 2,3,6-trichloropyridine can reach 95% or above; and the highest yield can reach 90% or above.

Description

technical field [0001] The invention belongs to the field of chemical industry and relates to a preparation method of 2,3,6-trichloropyridine. technical background [0002] 2,3,6-Trichloropyridine is an important chemical synthesis intermediate, which is widely used in the fields of medicine and pesticides. For example, in the field of pesticides, it is the key raw material for the synthesis of chlorantraniliprole insecticide. [0003] At present, 2,3,6-trichloropyridine is synthesized mainly by chlorination of 2,6-dichloropyridine through chlorine gas under the catalytic action of Lewis acid. US Patent No. 3,538,100 discloses the use of 2,6-dichloropyridine as a raw material, ferric chloride as a catalyst, and the addition of a small amount of iodine can increase the reaction rate of 2,3,5,6,-tetrachloropyridine. US4281135 proposes to use an autoclave, under the conditions of 220 ° C, 0.35 MPa, and alumina ball catalyst, 2,6-dichloropyridine is basically completely convert...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/61
CPCC07D213/61
Inventor 薛谊慕灯友陈洪龙李雪永钱勇王平
Owner CHONGQING ZHONGBANG TECH CO LTD
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