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Synthetic method for 5-bromine-2-methylpyridine

A synthesis method and aminopyridine technology, applied in directions such as organic chemistry, can solve problems such as increased cost, wasted time, unsuitable for large-scale industrial production, etc., and achieve the effects of reducing waste, reducing load, and avoiding the generation of 3-position by-products.

Inactive Publication Date: 2009-08-26
NANJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, its main synthetic method is the direct bromination method. Due to the positioning effect of the substituent, there will be a 3-position isomer during the reaction. The ratio is 45:55, and the difference in boiling point is only 1.5°C. Separation and purification are carried out by traditional methods such as rectification, and most of the reports in the literature are purified by column chromatography to obtain pure products. This method is a waste of time, increases costs, and is not suitable for large-scale industrial production. [1～4]

Method used

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  • Synthetic method for 5-bromine-2-methylpyridine
  • Synthetic method for 5-bromine-2-methylpyridine
  • Synthetic method for 5-bromine-2-methylpyridine

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] In a 500mL three-necked flask equipped with a stirrer and a thermometer, add 320mL of absolute ethanol, and then add 25.6g (0.19mol) 6-methyl-3-picolinic acid, 20mLSOCl 2 , Install a reflux condenser, control the temperature of the oil bath at 50-60°C, and follow the reaction until the reaction is complete. Spin the solvent to dryness, pour the solid into 200mL saturated NaCO 3 In solution, use CH 2 Cl 2 Extract (100mL*2), combine the organic layers, dry with 20g anhydrous sodium sulfate, filter, spin-dry 28g of brown liquid ethyl 6-methyl-3-picolinate as the solvent, yield 91%, bp 116~117 ℃.

[0032] In a 250mL single-neck flask equipped with magnetic stirring, add 176mL ammonia (concentration 25%), 22g (0.13mol) ethyl 6-methyl-3-pyridinecarboxylate, put into the single-neck flask and stir at room temperature 10~15℃ After 6-7 hours, put in the refrigerator overnight, let the white crystals be fully analyzed, filtered, and washed with water (50 mL*2) to obtain 16.7 g of whi...

Embodiment 2

[0036] In a 500mL three-necked flask equipped with a stirrer and a thermometer, add 300mL of absolute ethanol, and then add 25.6g (0.19mol) 6-methyl-3-picolinic acid, 20mL of concentrated hydrochloric acid, and install a reflux condenser. The temperature of the bath is controlled at 70-80°C, and the reaction is followed until the reaction is complete. Spin the solvent to dryness, pour the solid into 200mL saturated NaCO 3 In solution, use CH 2 Cl 2 Extract (100mL*2), combine the organic layers, dry with 20g anhydrous sodium sulfate, filter, spin-dry 25g of brown liquid ethyl 6-methyl-3-pyridinecarboxylate as solvent, yield 81%, bp 116~117 ℃.

[0037] In a 250mL single-necked flask equipped with magnetic stirring, add 100mL ammonia (concentration 28%), 22g (0.13mol) ethyl 6-methyl-3-pyridinecarboxylate, put into the single-necked flask and stir at room temperature 0~10℃ Place in the refrigerator overnight for 4 to 5 hours, allow the white crystals to be fully analyzed, filter, and ...

Embodiment 3

[0041] In a 500mL three-necked flask equipped with a stirrer and a thermometer, add 350mL of absolute ethanol, and then add 25.6g (0.19mol) 6-methyl-3-picolinic acid, 15mLH 2 SO 4 , Install a reflux condenser, control the temperature of the oil bath at 70-80°C, and follow the reaction until the reaction is complete. Spin the solvent to dryness, pour the solid into 200mL saturated NaCO 3 In solution, use CH 2 Cl 2 Extract (100mL*2), combine the organic layers, dry with 20g of anhydrous sodium sulfate, filter, spin off 26g of brown liquid ethyl 6-methyl-3-picolinate as the solvent, yield 84.5%, bp 116~117 ℃.

[0042] In a 250mL single-neck flask equipped with magnetic stirring, add 200mL ammonia (concentration 25%), 22g (0.13mol) ethyl 6-methyl-3-pyridinecarboxylate, put into the single-neck flask and stir at room temperature 15~25℃ After 7-8 hours, put in the refrigerator overnight, allow the white crystals to be fully analyzed, filtered and washed with water (50mL*2) to obtain 17g...

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Abstract

The invention discloses a synthetic method for 5-bromine-2-methylpyridine: using 6-methyl-3-picolinic acid as the raw material to react with ethyl alcohol to generate 6-methyl-3-picolinic acid ethyl ester; carrying out ammonolysis reaction by aqueous ammonia on the 6-methyl-3-picolinic acid ethyl ester to generate 6-methyl-3-pyridine carboxamide; carrying out Hofmann degradation reaction to obtain 6-methyl-3-aminopyridine; and finally reacting the 6-methyl-3-aminopyridine with a bromizing reagent to generate 5-bromine-2-methylpyridine. In the method, the process reaction condition is mild, the yield is high, the raw material is available, the cost is lower, and no 3-subsidary products are generated in the whole process, the load of post separation is eliminated and the prospect of industrialization is good.

Description

Technical field [0001] The invention belongs to the technical field of chemical synthesis, and specifically relates to a method for synthesizing 5-bromo-2-methylpyridine. Background technique [0002] Pyridine and its derivatives are widely distributed in nature. Many plant ingredients such as alkaloids contain pyridine ring compounds in their structures. They have a wide range of uses and can be used to produce high value-added fine chemical products, and occupy an important position in the pharmaceutical industry, pesticide industry and chemical industry. They are the basis for the production of many important compounds, and are indispensable and important raw materials in the production of medicines, pesticides, fuels, surfactants, rubber additives, feed additives, food additives, adhesives, and synthetic materials. 5-Bromo-2-methylpyridine is an important pharmaceutical intermediate. It has broad prospects in the production of cardiovascular drugs and respiratory drugs, and h...

Claims

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Application Information

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IPC IPC(8): C07D213/61
Inventor 郭成唐拾贵刘柏年李浩源张国华唐建国周义鑫毕胜
Owner NANJING UNIV OF TECH
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