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Method for preparing 5-bromomethyl-2,3-dimethyl pyridine dicarboxylate through ultraviolet light catalysis

A technology for the preparation of dimethyl picidinedicarboxylate and catalysis, which is applied in the direction of organic chemistry, can solve the problems of low conversion rate, excessive raw materials, difficulties in purification and quality control of the original drug, etc., and achieve high conversion rate and high selectivity Effect

Inactive Publication Date: 2020-04-14
中化安全科学研究(沈阳)有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Though the generation of dibromo product can be controlled, the transformation efficiency of reaction is lower, and raw material remains more than 30%, and hydrobromic acid charging amount is 5-bromomethyl-2, twice of 3-pyridinedicarboxylic acid dimethyl ester, Too much raw material
[0005] In summary, the bromination methods in the existing reports have shortcomings in the conversion rate of raw materials and impurity control. The unreacted raw materials and the generated dibrominated by-products will bring difficulties to the purification and quality control of the original drug.

Method used

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  • Method for preparing 5-bromomethyl-2,3-dimethyl pyridine dicarboxylate through ultraviolet light catalysis
  • Method for preparing 5-bromomethyl-2,3-dimethyl pyridine dicarboxylate through ultraviolet light catalysis

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Experimental program
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Effect test

Embodiment 1

[0024] Add 4.1g of 5-methyl-2,3-pyridinedicarboxylate (0.0196mol) and 55g of 1,2-dichloroethane into a reactor that can transmit ultraviolet light, and heat to 70°C, Turn on the ultraviolet lamp, let the reactor be within the radiation range of the ultraviolet lamp light, put 2.7g of N-bromosuccinimide (0.0152mol) into the bottle, add it in about 2 hours, and raise the temperature to 85°C after feeding. Keep it warm for 1 hour. HPLC detected the remaining 23% of dimethyl 5-methyl-2,3-pyridinedicarboxylate and 2% of the dibromo by-product.

Embodiment 2

[0026] Add 4.1g of 5-methyl-2,3-pyridinedicarboxylate dimethyl (0.0196mol) and 100g of chlorobenzene into a reactor that can transmit ultraviolet light, heat to 85°C, turn on the ultraviolet lamp, and let the reaction In the UV lamp radiation range, add 4.18g of hypobromous acid (0.0215mol) dropwise into the bottle, and add it in about 3 hours. After feeding, keep 85°C for 0.5 hour. HPLC detected the remaining 8% of dimethyl 5-methyl-2,3-pyridine dicarboxylate and 5% of the dibromo by-product.

Embodiment 3

[0028] Add 4.1g of 5-methyl-2,3-pyridinedicarboxylate (0.0196mol) and 120g of chloroform to a reactor that can transmit ultraviolet light, heat to 55°C, turn on the UV lamp, and let Put 5.6g of dibromohydantoin (0.0182mol) into the bottle in the reactor within the radiation range of the ultraviolet lamp, and the filling is completed in about 4 hours. After the feeding, the temperature is maintained at 65°C and the temperature is kept for 0.5 hours. HPLC detected the remaining 12% of dimethyl 5-methyl-2,3-pyridinedicarboxylate and 3% of the dibromo by-product.

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Abstract

The invention relates to preparation of an intermediate compound, particularly to a method for preparing 5-bromomethyl-2,3-dimethyl pyridine dicarboxylate through ultraviolet light catalysis. The method comprises the following steps: carrying out a bromination reaction by using 5-methyl-2,3-dimethyl pyridine dicarboxylate as a starting raw material in an organic solvent under the catalytic initiation of ultraviolet light to prepare 5-bromomethyl-2,3-dimethyl pyridine dicarboxylate. According to the invention, by using ultraviolet light as catalytic initiation effect, the conversion rate of theraw materials can be increased and is up to 90%; and a reaction is performed under the catalytic initiation of ultraviolet light, so that the selectivity is high, and only 5% of dibromo products aregenerated when the conversion rate reaches 90%.

Description

Technical field [0001] The invention relates to the preparation of intermediate compounds, in particular to a method for preparing dimethyl 5-bromomethyl-2,3-pyridinedicarboxylate by ultraviolet photocatalysis. Background technique [0002] Dimethyl 5-bromomethyl-2,3-pyridinedicarboxylate is a key intermediate for the preparation of imazamox. The published information shows that its synthesis method is mainly based on 5-methyl-2,3-pyridinedicarboxylate. Dimethyl formate is used as a raw material, and the target product is obtained by halogenation. Such as US2011224433, EP0747360, US5288866 and so on. [0003] Patent US5288866A and WO2010055042A1 both disclose the preparation method of 5-bromomethyl-2,3-pyridinedicarboxylate dimethyl, starting with 5-methyl-2,3-pyridinedicarboxylate dimethyl It is prepared by bromination with NBS or sodium hypobromite in the presence of azodiisobutyronitrile in an organic solvent, but the patent also reports that the bromination process will produ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/80C07D213/803
CPCC07D213/80C07D213/803
Inventor 程春生马晓华刘玄魏振云李全国杨兆国
Owner 中化安全科学研究(沈阳)有限公司