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Preparation method for 5-bromomethyl-2,3-dimethylpyridine dicarboxylate

A technology of dimethyl picolinate and bromomethyl, applied in the field of preparation of herbicide intermediates, can solve the problems of many by-products, low conversion rate, and low yield, and achieve less side reactions, reduced production, and easy raw materials The effect

Active Publication Date: 2017-09-29
江苏省农用激素工程技术研究中心有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] U.S. patent document US5288866A discloses a kind of preparation method of 5-bromomethyl-2,3-pyridine dicarboxylic acid dimethyl ester, and it is to take 5-methyl-2,3-pyridine dicarboxylic acid dimethyl ester as starting raw material , in the presence of azobisisobutyronitrile, in a carbon tetrachloride solvent, obtained through bromination of N-bromosuccinimide; the disadvantage of this method is that the target product is only 57%, especially ( Dibromo) by-products are as high as 23%, resulting in low yields, even if the highest yield is not more than 75% by recycling
[0005] The world patent document WO2010055042A1 discloses a preparation method of 5-bromomethyl-2,3-pyridinedicarboxylate, which uses 5-methyl-2,3-pyridinedicarboxylate as the starting material , in the presence of azobisisobutyronitrile, in dichloroethane solvent, through liquid bromine bromination; the disadvantage of this method is: there are more by-products, in addition to dibromo by-products, there are also tribromine by-products , therefore, its conversion rate is only 50%, indicating that its yield is lower

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1）

[0016] The preparation method of the 5-bromomethyl-2,3-pyridinedicarboxylate of the present embodiment is as follows:

[0017] Add 50 g of dimethyl 5-methyl-2,3-pyridinedicarboxylate (0.24 mol), 128 g of dichloroethane, 14.5 g of sodium bromate (0.096 mol), and 3.92 g of azo Diisobutyronitrile (0.024mol) and 130g of water are heated to reflux, and 97g of hydrobromic acid (0.48mol) with a concentration of 40wt% is added dropwise, and the drop is completed in about 2 hours.

[0018] After the reaction, cool the reaction solution to room temperature (15-25°C, the same below), adjust the pH value of the reaction solution to 6.0±0.2 with 30wt% sodium hydroxide aqueous solution, stir and leave to separate layers, and wash the organic layer with water The solvent was removed under reduced pressure to obtain 68 g of a reddish-brown liquid.

[0019] HPCL showed that the reddish-brown liquid after the single reaction contained 65.8% of the target product, 31.3% of 5-methyl-2,3-pyridine...

Embodiment 2～ Embodiment 6）

[0022] The preparation method of each embodiment is basically the same as that of Example 1, and the differences are shown in Table 1.

[0023] Table 1

[0024]

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PUM

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Abstract

The invention discloses a preparation method for 5-bromomethyl-2,3-dimethylpyridine dicarboxylate. 5-bromomethyl-2,3-dimethylpyridine dicarboxylate is prepared with 5-methyl-2,3-dimethylpyridine dicarboxylate as a starting raw material though a bromination reaction in an organic solvent in the presence of azodiisobutyronitrile, wherein the bromination reaction is carried out on 5-methyl-2,3-dimethylpyridine dicarboxylate and hydrobromic acid in the presence of sodium bromated. The method provided by the invention employs hydrobromic acid as a bromination reagent and uses sodium bromate and azodiisobutyronitrile as initiators, so production of by-products can substantially reduced, only about 1% of by-products are produced in a single reaction, and only about 2% of by-products are produced in circular reactions; and thus, yield of 90% or above can be realized through cyclical and indiscriminate reactions.

Description

technical field [0001] The invention belongs to the technical field of preparation of herbicide intermediates, and in particular relates to a preparation method of dimethyl 5-bromomethyl-2,3-pyridinedicarboxylate. Background technique [0002] Imazethapyr is an imidazolinone herbicide developed by American Cyanamid (now BASF), which belongs to the inhibitors of acetolactate synthase (ALS) or acetate hydroxyacid synthase (AHAs), absorbed through leaves, It conducts and accumulates in the meristem, inhibits the activity of AHAS, causes the biosynthesis of branched-chain amino acids-xytine, leucine and isoleucine to stop, interferes with DNA synthesis, cell mitosis and plant growth, and eventually causes plant death. The development prospect of imazethapyr in China is good, the market space is huge, and the future development will maintain a gradual upward trend. [0003] Dimethyl 5-bromomethyl-2,3-pyridinedicarboxylate is the key intermediate for the preparation of imazamox. ...

Claims

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Application Information

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IPC IPC(8): C07D213/80C07D213/803
CPCC07D213/80C07D213/803
Inventor 孙永辉张元元孔繁蕾刘晓佳吴溧明周荣华
Owner 江苏省农用激素工程技术研究中心有限公司
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