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A method for preparing 2,5-dimethoxy-2,5-dihydrofuran

A technology of dihydrofuran and dimethoxy, applied in the direction of organic chemistry, can solve the problems of high replacement cost, troublesome replacement, unpleasant odor sensitivity, etc., and achieve the effect of reducing production cost and improving yield

Active Publication Date: 2021-04-30
ZHEJIANG MEDICINE CO LTD XINCHANG PHAMACEUTICAL FACTORY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The reaction system adopted by this method is too complicated, complex impurities are easy to be produced during the reaction process, and the addition of organic amines is particularly sensitive to unpleasant odors in the production environment; in addition, the fixed bed catalytic reaction has catalysts that are easy to deactivate, troublesome to replace, and replacement costs advanced questions

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Put 80g of furan, 0.2g of sodium bromide, and 420g of 30% mass fraction of sodium methoxide methanol solution into a 1000ml three-neck flask, stir and cool down to 0~5°C, then slowly introduce chlorine gas to maintain a stable reaction, and judge the end point by gas phase , when the furan remaining about 3%, stop the chlorine gas, and continue to stir to remove the remaining chlorine gas and HCl. After the reaction, let stand to separate layers, filter to remove sodium chloride, and separate solvent methanol, furan and product 2,5-dimethoxy-2,5-dihydrofuran 141.3g from the filtrate through rectification, with a yield of 92.4% , content 99.3%.

Embodiment 2

[0025] Put 80g of furan, 0.2g of sodium bromide, 130g of solid sodium methoxide, and 320g of methanol into a 1000ml three-necked flask, stir and cool down to 0~5°C, then slowly introduce chlorine gas to maintain a stable reaction, judge the end point by the gas phase, when the furan When the remaining 3% is left, the chlorine gas is stopped, and the stirring is continued to remove the remaining chlorine gas and HCl. After the reaction, stand and separate layers, filter to remove sodium chloride, the filtrate is separated by rectification solvent methanol, furan and product 2,5-dimethoxy-2,5-dihydrofuran 137.9g, yield 90.2% , content 99.2%.

Embodiment 3

[0027] Put 80g of furan, 0.2g of potassium bromide, and 420g of 30% mass fraction of sodium methoxide methanol solution into a 1000ml three-necked flask, stir and cool down to 0~5°C, then slowly introduce chlorine gas to maintain a stable reaction, and judge the end point by gas phase , when the furan remaining about 3%, stop the chlorine gas, and continue to stir to remove the remaining chlorine gas and HCl. After the reaction, let stand to separate layers, filter to remove sodium chloride, and separate solvent methanol, furan and product 2,5-dimethoxy-2,5-dihydrofuran 133.2g from the filtrate through rectification, yield 87.1% , content 99.1%.

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Abstract

The invention discloses a method for preparing 2,5-dimethoxy-2,5-dihydrofuran. In the current chemical synthesis method, furan and bromine are reacted at low temperature, and the by-product HBr produced in the reaction process is neutralized with alkali to obtain the product; the liquid bromine used in this method is extremely poisonous and corrosive, and produces a large amount of bromine. The three wastes seriously pollute the environment and are difficult to produce on a large scale. The present invention uses methanol and furan as raw materials, and under the condition of adding a catalyst, chlorine replaces bromine, and sodium methoxide is added as an alkali to neutralize the acid produced by the reaction, keeping the reaction temperature at -25~50°C; the catalyst is bromine One or more of sodium chloride, zinc bromide, and potassium bromide. In the present invention, by adding a catalyst, adopting a method of passing chlorine, and using sodium methoxide methanol solution as an acid-binding agent, the production cost is greatly reduced, and the market competitiveness is improved; the by-product is only sodium chloride, which is easy to handle and meets environmental protection requirements.

Description

technical field [0001] The invention relates to the field of organic synthesis, in particular to a method for preparing 2,5-dimethoxy-2,5-dihydrofuran. Background technique [0002] 2, 5-dimethoxy-2, 5-dihydrofuran is an important fine chemical intermediate, an intermediate for the synthesis of anisodamine and anticholinergic drug atropine sulfate, and also a raw material for the synthesis of carotenoids Important intermediate of 2,7-dimethyl-2,4,6-octatriene-1,8-dialdehyde; direct hydrolysis to 2-hydroxy-1,4-butanedialdehyde; catalytic reduction to 2,5 - Dimethoxytetrahydrofuran. [0003] There are three traditional methods for preparing 2,5-dimethoxy-2,5-dihydrofuran. (1), chemical synthesis method: react with furan and bromine simple substance at low temperature, and the by-product HBr produced in the reaction process is neutralized with alkali to obtain the product. The liquid bromine used in this method is highly toxic and corrosive, produces a large amount of three ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D307/32
CPCC07D307/32
Inventor 翟德伟刘冬邵斌
Owner ZHEJIANG MEDICINE CO LTD XINCHANG PHAMACEUTICAL FACTORY
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