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Method for preparing 2-chloro-5-substituted pyridine

A technology for pyridine and chlorination reagents, applied in the field of preparation of 2-chloro-5-substituted pyridines, which can solve the problems of high energy consumption, low yield, complicated operation, etc., and achieve simplified operation procedures, reduced production costs, and shortened reaction time Effect

Active Publication Date: 2013-10-09
SHENYANG SINOCHEM AGROCHEMICALS R&D CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a new method for preparing 2-chloro-5-substituted pyridine and separating by-product chlorides, so as to overcome the problems of complex operation, high energy consumption and low yield in the prior art, so that It successfully realized industrial scale production

Method used

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  • Method for preparing 2-chloro-5-substituted pyridine
  • Method for preparing 2-chloro-5-substituted pyridine
  • Method for preparing 2-chloro-5-substituted pyridine

Examples

Experimental program
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Effect test

Embodiment 1

[0037] In 50ml chlorobenzene, add 45.4g (0.24mol) N-benzyl-N-(1-propenyl) acetamide (self-made, method is referred to Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972 -1999) (1984), (6), 1173-82) and 24.1 g (0.33 mol) of N, N-dimethylformamide, and the temperature was controlled at 15° C. during the addition. After the addition of the materials, the temperature was raised to 30° C., and 71.3 g (0.24 mol) of bis(trichloromethyl)carbonate in chlorobenzene was slowly added dropwise to the system within 1 hour. After the addition, start the distillation reaction at a pressure of 60 mbar, and basically steam the chlorobenzene at 70 ° C, then continue heating to steam the mixture of benzyl chloride and 2-chloro-5-picoline, the distillation reaction process is about 60 minutes to the basic No distillate was evaporated, and the reaction was completed to obtain 63.0 g of the mixture.

[0038] Add 50 g of 35% concentrated hydrochloric acid t...

Embodiment 2

[0040] Add 45.4g (0.24mol) N-benzyl-N-(1-propenyl) acetamide and 24.1g (0.33mol) N,N-dimethylformamide to 50ml chlorobenzene at 15°C to keep the internal The temperature was 15°C, and 71.3 g (0.24 mol) of bis(trichloromethyl)carbonate in chlorobenzene was slowly added dropwise to the system within 1 hour. After the addition, keep the pressure at 20mbar and distill the reaction until the solvent is basically distilled at 50°C, then continue to heat to distill the mixture of benzyl chloride and 2-chloro-5-picoline, and distill for about 30 minutes until there is basically no distillate. , the reaction was completed, and 68.0 g of the mixture was obtained.

[0041] Add 50 g of 35% concentrated hydrochloric acid to the above mixture, stir vigorously for 15 minutes, and then let stand to separate layers. The upper layer (oil layer) was separated to obtain 29.5 g of benzyl chloride, and the content of GC analysis was 97.5%; the acid solution in the lower layer was adjusted to pH 9 ...

Embodiment 3

[0043] Addition operation is with embodiment 1. After the addition, the distillation reaction was carried out under normal pressure. When the temperature of the reaction solution reaches 140° C., the chlorophenyl is basically evaporated and removed. Continue heating to distill out the mixture of benzyl chloride and 2-chloro-5-picoline. Distill the reaction for about 90 minutes until almost no distillate comes out. After the reaction is completed, 58.0 g of the mixture is obtained.

[0044] The operation of separating product and by-product from the mixture is the same as in Example 2. 22.0 g of the product 2-chloro-5-methylpyridine was obtained, with a content of 97.8%, and a yield of 70.3%; 23.3 g of by-product benzyl chloride, with a content of 97.9% by GC analysis.

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Abstract

The invention belongs to the field of organic synthesis, and discloses a method for preparing 2-chloro-5-substituted pyridine (I), which comprises the following steps: 1) preparing 2-chloro-5-substituted pyridine by ethylidene amide compound (III) and dialkyl methanamide (IV) under the action of a chlorination reagent, continuously evaporating a mixture of the product of 2-chloro-5-substituted pyridine (I) and the by-product chloride (II) from the reaction system during the reaction; 2) acidifying the mixture of the product and the by-product to obtain two phases of an oil phase and a water phase, separating the oil phase to obtain the by-product chloride; 3) adjusting the pH value of the water phase to 8-14 by adding an alkali, directly separating or adding an extractant to extracting and separating 2-chloro-5-substituted pyridine. The general formulae and definitions of various groups are in the specification. The method of the invention has low energy consumption, less equipment investment, and few three waste amounts, and the obtained product has high purity; meanwhile, the high-purity by-product which can be used directly is obtained; and the method is applicable to industrial large-scale production.

Description

technical field [0001] The invention belongs to the field of organic synthesis, and in particular relates to a method for preparing 2-chloro-5-substituted pyridine. Background technique [0002] Patents US5304651 and EP 722934 disclose methods for preparing 2-chloro-5-substituted pyridine compounds. Although both technical proposals use ethylene amide compounds, dialkyl amide compounds and chlorinating reagents as raw materials to prepare 2-chloro-5-substituted pyridine compounds, the processes are different. Patent US5304651 puts three kinds of raw materials into the reactor, and reacts for more than 10 hours at 100-140°C; after the reaction, pour the reaction liquid directly into a large amount of ice water, then extract it with an organic solvent, and then concentrate and rectify it to obtain product. Patent EP 722934 proposes an improved preparation method: after adding three raw materials, react at low temperature first, then add the reaction liquid to the boiling sol...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D213/61C07C22/04C07C17/093
Inventor 耿丽文丁亚伟杨春河杨丙连
Owner SHENYANG SINOCHEM AGROCHEMICALS R&D CO LTD
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