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A kind of preparation method of 2,3,6-trichloropyridine

A technology of trichloropyridine and picoline, which is applied in the field of preparation of 2,3,6-trichloropyridine, can solve the problems of low selectivity of target products, low conversion rate of raw materials, harsh equipment requirements, etc., and achieve good industrial application Foreground, source is cheap and easy to get, the effect of strong processing capacity

Active Publication Date: 2021-10-01
CHONGQING ZHONGBANG TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The existing 2,3,6-trichloropyridine synthesis methods generally have disadvantages such as low reaction efficiency, poor selectivity, low yield, and a large amount of waste water generated during the reaction process.
For example, U.S. Patent No. 4,515,953 uses the pyridine chlorination method to prepare 2,3,6-trichloropyridine. The disadvantages of this method are low yield, many side reactions, and harsh equipment requirements.
U.S. Patents US4281135, US4785112, and US4810797 use 2,6-dichloropyridine in liquid-phase chlorination or gas-phase chlorination to prepare 2,3,6-trichloropyridine. The conversion rate of raw materials is low, the reaction time is long, and the efficiency of obtaining the target product is low.
Chinese patent CN 107759512A uses 2,6-dichloropyridine as a raw material to prepare 2,3,6-trichloropyridine by gas-phase chlorination under the action of a catalyst. The preparation steps of the catalyst are cumbersome and the selectivity of the target product is low.
Chinese patent CN 108484492 A uses nicotinamide as a raw material to prepare 2,3,6-trichloropyridine through Hofmann degradation, chlorination and Sandmeyer reaction. The method has the purity and yield of 2,3,6-trichloropyridine The efficiency is above 90%, but the raw materials are expensive, the reaction steps are long, and a large amount of waste water is produced

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0031] Take 10g of hydrogen-type ZSM-5 powder with a silicon-aluminum ratio of 80, 30g of γ-Al 2 o 3 , 0.5g scallop powder, add 0.5g nitric acid (68wt%, the same below) and 10g water, mix uniformly, extrude and form through screw extruder, the catalyst after forming is dried at 120 DEG C for 5h, roasted at 550 DEG C for 6h, after roasting The catalyst was crushed and sieved to obtain a granular catalyst A of 20-40 mesh.

[0032] Get above-mentioned 10g catalyst A, pack in the cylindrical fixed-bed reactor of internal diameter 25mm, plunger pump pumps the carbon tetrachloride solution of 3-picoline, the mass ratio of 3-picoline to carbon tetrachloride is 1 :10, 3-methylpyridine weight hourly space velocity is 6h -1 , the weight hourly space velocity of water is 3h -1 , the chlorine gas flow rate is 2L / min, 3-picoline, water, and chlorine gas are vaporized by the preheating tube and then passed into the fixed-bed reactor at the same time. The fixed-bed reactor is heated by re...

Embodiment 2

[0034] Get catalyst A in 10g embodiment 1, pack in the cylindrical fixed-bed reactor of internal diameter 25mm, plunger pump pumps the carbon tetrachloride solution of 3-picoline, 3-picoline and carbon tetrachloride mass The ratio is 1:10, and the space velocity of 3-picoline is 6h -1 , the weight hourly space velocity of water is 3h -1 , the flow rate of chlorine gas is 2L / min, 3-picoline, water, and chlorine gas are vaporized by the preheating tube and then passed into the fixed bed reactor at the same time. Obtain 2866g of the reaction product mixture in the receiving tank, add ammonia water to neutral, and separate the liquid with a pear-shaped funnel to obtain an organic solution phase, add 30g of anhydrous magnesium sulfate, suction filter, and then rotate evaporate. Remove carbon tetrachloride to obtain white crystals, namely 2,3,6-trichloropyridine. After analysis and detection, the purity of 2,3,6-trichloropyridine is 87%, and the yield is 90%.

Embodiment 3

[0036] Referring to Example 1, catalyst B was prepared by replacing the hydrogen-form ZSM-5 raw powder with a silicon-aluminum ratio of 80 with the hydrogen-form ZSM-5 raw powder with a silicon-aluminum ratio of 230.

[0037] Get 10g catalyst B, pack in the cylindrical fixed-bed reactor of internal diameter 25mm, plunger pump pumps the carbon tetrachloride solution of 3-picoline, 3-picoline and carbon tetrachloride mass ratio are 1: 10,3-Methylpyridine has a weight hourly space velocity of 6h -1 , the weight hourly space velocity of water is 3h -1, the flow rate of chlorine gas is 2L / min, 3-picoline, water, and chlorine gas are vaporized by the preheating tube and then passed into the fixed bed reactor at the same time. Obtain 2890g of the reaction product mixture in the receiving tank, add ammonia water to adjust to neutrality, separate the liquid with a pear-shaped funnel, and obtain the organic phase, add 30g of anhydrous magnesium sulfate, suction filter, and then rotary ...

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Abstract

The invention discloses a preparation method of 2,3,6-trichloropyridine, which uses 3-picoline and chlorine gas as raw materials, and uses a molecular sieve catalyst to catalyze one-step gas phase chlorination and detrichlorination in the presence of water vapor Methyl preparation of 2,3,6‑trichloropyridine. The molecular sieve catalyst is prepared by using molecular sieve raw powder as an active component. The raw material 3-picoline used in the present invention is a by-product of pyridine synthesized by the aldehyde-ammonia method, and the source is cheap and easy to obtain. Molecular sieve catalyst has strong processing ability. Using 3-picoline and chlorine gas as raw materials, adding appropriate amount of water, under the action of molecular sieve acid center and water vapor molecules, gas-phase chlorination and detrichloromethylation reactions occur, and one-step synthesis of 2,3 , 6-trichloropyridine, the process is simple, the product is pure, the conversion rate is high, and the yield can generally be maintained at more than 85%, the highest can reach 95%, and it has a good industrial application prospect.

Description

technical field [0001] The invention belongs to the field of chemical industry and relates to a preparation method of 2,3,6-trichloropyridine. Background technique [0002] 2,3,6-Trichloropyridine is an important chemical intermediate, which is widely used in the field of pesticides and medicine, and can be used as the key raw material for the synthesis of new pesticide chlorantraniliprole, such as 2,3-dichloropyridine. [0003] The existing 2,3,6-trichloropyridine synthesis methods generally have disadvantages such as low reaction efficiency, poor selectivity, low yield, and a large amount of waste water generated during the reaction process. For example, US Pat. No. 4,515,953 uses the pyridine chlorination method to prepare 2,3,6-trichloropyridine. The disadvantages of this method are low yield, many side reactions, and harsh equipment requirements. U.S. Patents US4281135, US4785112, and US4810797 use 2,6-dichloropyridine to prepare 2,3,6-trichloropyridine by liquid-phase...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D213/61
Inventor 薛谊李雪永慕灯友陈洪龙钱勇
Owner CHONGQING ZHONGBANG TECH CO LTD
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