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Method for synthesizing 4-chloro-pyridine

A synthetic method, the technology of chloropyridine, which is applied in the field of synthesis of pharmaceutical and pesticide intermediates, can solve the problems of few manufacturers in the research of 4-chloropyridine synthesis, affect the continuous production of industrial reactions, and blockage of reactors, etc., and achieve the solution of pyridine coking , easy to industrialized production, the effect of mild conditions

Inactive Publication Date: 2013-10-23
SHANGHAI SYNCHES CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Both 2-chloropyridine and 4-chloropyridine are representative substances of monochloropyridine. Among them, 2-chloropyridine is widely used, and many manufacturers have carried out research and development. 4-Chloropyridine is also an important pharmaceutical intermediate in medicine. However, there are few manufacturers who have studied the synthesis of 4-chloropyridine
[0006] In addition, there is an obvious phenomenon of pyridine coking during the pyridine chlorination reaction using chlorine gas as the chlorination agent, which leads to blockage of the reactor, thus affecting the continuous production of industrial reactions

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  • Method for synthesizing 4-chloro-pyridine

Examples

Experimental program
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Effect test

Embodiment 1

[0031] Starting material: pyridine; organic solvent: ethyl acetate; chlorination reagent: thionyl chloride

[0032] Add 200g of anhydrous pyridine and 100-200mL of ethyl acetate in sequence in a 1000mL reaction flask, protect with nitrogen, cool in a cold water bath, slowly add 200g of thionyl chloride dropwise under stirring, and the temperature does not exceed 40°C. After the addition, the temperature was raised and kept at 70-75° C. for 5 hours. During this period, the color of the reaction mixture gradually became darker, and finally turned into a black oily substance. Cool down and let it stand, add 500ml ethanol to the reaction solution, heat it at 50-60°C and stir for 1 hour, cool down to about 10°C, filter, it is easier to filter with suction, the filtrate is dark, the solid is dark brown, soak in absolute ethanol Wash and dry to obtain 266.8 grams of tan solid powder, with a yield of about 70.2%. Its purity was 95.6% as determined by HPLC. The product was identifie...

Embodiment 2

[0034] Starting material: pyridine; Organic solvent: dichloromethane; Chlorinating reagent: phosphorus oxychloride

[0035] Add 200g of anhydrous pyridine and 150mL of dichloromethane to a 1000mL reaction flask in sequence, cool in a cold water bath, slowly add 160g of phosphorus oxychloride dropwise under stirring, and the temperature does not exceed 50°C. After the addition, the temperature was raised and kept at 70-75° C. for 5 hours. During this time, the color of the reaction mixture gradually became darker. Cool down and stand still, add 500ml ethanol to the residue in the lower layer, heat at 50-60°C and stir for 1 hour, cool down to about 10°C, filter, easy to filter with suction, the filtrate is dark, the solid is dark brown, use absolute ethanol Soak, wash, and dry to obtain 152 grams of tan solid powder, with a yield of about 52.4%. Its purity was 93.9% as determined by HPLC. The product was identified as 4-chloropyridine hydrochloride by NMR identification. The...

Embodiment 3

[0037] Starting material: pyridine; organic solvent: chlorobenzene; chlorination reagent: phosphorus pentachloride

[0038] Add 100g of anhydrous pyridine and 100mL of chlorobenzene in sequence in a 500mL reaction bottle, protect with nitrogen, cool in a cold water bath, slowly add 100g of phosphorus pentachloride dropwise under stirring, and the temperature does not exceed 30°C. After the addition, the temperature was raised and kept at 70-75° C. for 5 hours. During this time, the color of the reaction mixture gradually became darker. Cool down and let it stand, add 300ml n-butanol to the residue in the lower layer, heat it at 50-60°C and stir for 1 hour, cool down to about 10°C, filter, it is easier to filter with suction, the filtrate is dark, the solid is dark brown, dry it 116.2 g of tan solid powder was obtained, with a yield of about 61.3%. Its purity was 92.7% as determined by HPLC. The product was identified as 4-chloropyridine hydrochloride by NMR identification. ...

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Abstract

The invention provides a method for synthesizing 4-chloro-pyridine. According to the method, pyridine or N-(4-pyridyl) pyridinium chloride hydrochloride which serves as a starting raw material reacts with a chlorinating reagent in one pot to prepare the final product which is the 4-chloro-pyridine or the 4-chloro-pyridine hydrochloride, wherein the 4-chloro-pyridine hydrochloride can be neutralized continuously and treated through steam distillation or extraction or the like to obtain the 4-chloro-pyridine. The optimal process conditions are obtained and the common problems of pyridine coking and reactor plugging are solved by studying different reaction conditions and after-treatment processes, thus the continuous and safe production can be guaranteed through industrial reaction. In addition, the process route of the method provided by the invention is simple because the target product can be obtained through only one-step reaction and the step of separating intermediate products is not needed, the reaction conditions are mild, and the production safety is high, thus the method is suitable for industrial production. Moreover, the auxiliary and raw materials are low in cost and easily obtained, thus the cost can be reduced effectively.

Description

technical field [0001] The invention relates to a method for synthesizing medicine and pesticide intermediates, in particular to a method for synthesizing 4-chloropyridine. Background technique [0002] Pyridine chloride and its derivatives are important chemical raw materials, mainly used to prepare a series of pesticides and pharmaceutical intermediates with pyridine ring as the parent. Pyridine and its derivatives are widely distributed in nature, and are mainly used in the pharmaceutical industry to make sulfonamides, odorless ribocycin, vitamin A, cortisone, anthelmintics, local anesthetics, etc.; they are also used as stabilizers for high-grade calico, Synthetic rubber accelerator, paint solvent, condensing agent for synthetic resin; also used in the manufacture of vinylpyridine, agricultural pesticides, herbicides (paraquat), etc. [0003] Pyridine has various chlorinated derivatives. The representative substance of monochloropyridine, 2-chloropyridine, is used in t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/61
Inventor 夏永余王顺余
Owner SHANGHAI SYNCHES CO LTD
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