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A kind of method for preparing 2,3-dihydroxybenzaldehyde by removing the methyl group of o-vanillin

A technology of dihydroxybenzaldehyde and o-vanillin, which is applied to the preparation of carbon-based compounds, the preparation of organic compounds, chemical instruments and methods, etc., can solve the problems of low yield, high preparation cost, and inconvenient operation. Achieve the effects of simple reaction purification operation, wide range of sources and low price

Active Publication Date: 2021-05-18
美迪森(荆门)生物医药科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

First of all, boron tribromide is expensive, the preparation cost is high, and it is difficult to realize industrial production; secondly, the yield of hydrogen bromide demethylation is relatively low, and the operation is inconvenient
[0004] Aluminum trichloride is also a commonly used demethylation reagent. For example, Lange developed a method for removing o-hydroxyanisole, using aluminum trichloride-pyridine system to remove the methylation of vanillin in halogenated alkanes or aromatics. group (US3256336), but this method cannot be used for the demethylation reaction of o-vanillin (The Journal of Organic Chemistry 1962,27,2037-2039)
[0005] In addition, the reagent system of the combination of aluminum triiodide and various Lewis bases is also used to remove the methyl group of o-vanillin, such as CN106278825A discloses a method for cracking ether bonds with aluminum triiodide-pyridine, and CN106866377A discloses A method for cracking ether bonds with aluminum triiodide-carbodiimide is disclosed, and CN107473916 discloses a method for cracking ether bonds with aluminum triiodide-inorganic bases or metal oxides, although these three methods can be used to remove adjacent The methyl group of vanillin was used to prepare 2,3-dihydroxybenzaldehyde, but the yields of these three methods were not high

Method used

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  • A kind of method for preparing 2,3-dihydroxybenzaldehyde by removing the methyl group of o-vanillin

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Experimental program
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Effect test

Embodiment 1

[0020]

[0021] Acetonitrile (40ml), aluminum chloride (0.804g, 6.03mmol, 1.1eq), NaI (2.464g, 16.44mmol, 3.0eq) and o-vanillin (0.417g, 2.74mmol) were added to a 100ml eggplant-shaped flask ), heated to 80°C, stopped stirring after 18 hours of reaction, added 2mol / L dilute hydrochloric acid (10ml) to the eggplant-shaped bottle after cooling to room temperature to acidify, extracted with ethyl acetate (50ml×3), combined the organic phases, First wash with a saturated aqueous solution of sodium thiosulfate (10ml), then wash with saturated brine (10ml), dry over anhydrous magnesium sulfate, filter, and the filtrate is evaporated to dryness with a rotary evaporator, and the residue is subjected to flash column chromatography (eluent Purified by ethyl acetate / petroleum ether=1:4, volume ratio) to obtain 0.322g of 2,3-dimethoxybenzaldehyde (yellow solid, yield 85%).

[0022] R f =0.58 (petroleum ether / ethyl acetate=1:3), mp106-108°C.

[0023] 1 H NMR(400MHz,DMSO-d6)δ10.22(s,1...

Embodiment 2

[0025] Add acetonitrile (40ml), aluminum chloride (0.752g, 5.64mmol, 1.1eq), NaI (2.305g, 15.38mmol, 3.0eq) and o-vanillin (0.780g, 5.13mmol) to a 100ml eggplant-shaped flask ), heated to 80°C, stopped stirring after 18 hours of reaction, added 2mol / L dilute hydrochloric acid (10ml) to the eggplant-shaped bottle after cooling to room temperature to acidify, extracted with ethyl acetate (50ml×3), combined the organic phases, First wash with a saturated aqueous solution of sodium thiosulfate (10ml), then wash with saturated brine (10ml), dry over anhydrous magnesium sulfate, filter, and the filtrate is evaporated to dryness with a rotary evaporator, and the residue is subjected to flash column chromatography (eluent Ethyl acetate / petroleum ether=1:4, volume ratio) was purified to obtain 0.620 g of 2,3-dimethoxybenzaldehyde (yellow solid, yield 87%).

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Abstract

The invention discloses a method for preparing 2,3-dihydroxybenzaldehyde by removing the methyl group of o-vanillin, comprising the following steps: in an organic solvent, in the presence of aluminum trichloride and iodide, O-vanillin undergoes an ether bond cleavage reaction at a temperature of -20°C to reflux to generate 2,3-dihydroxybenzaldehyde. The method has mild conditions, simple operation and high yield.

Description

Background technique [0001] The invention relates to the technical field of intermediate synthesis of medicines and chemical raw materials, in particular to a method for preparing 2,3-dihydroxybenzaldehyde by removing the methyl group of o-vanillin. Background technique [0002] 2,3-Dihydroxybenzaldehyde is an important chemical intermediate, such as a key intermediate 2,2-difluoro-1,3-benzodioxol that can be used to prepare the insecticide fludioxonil -4-formaldehyde (CN106699722), and an important raw material for the synthesis of 3'-formyl benzocrown intermediate 3'-formyl benzocrown derivatives (Journal of Zhengzhou Institute of Light Industry 1995, 10, 61-62). [0003] 2,3-Dihydroxybenzaldehyde can be obtained by demethylation of o-vanillin. For example, Potisek et al. reported a preparation of 2,3-dihydroxybenzaldehyde by demethylation of o-vanillin with boron tribromide in dichloromethane. -The method of dihydroxybenzaldehyde (Journal of the American Chemical Society...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C45/64C07C47/565
CPCC07C45/64C07C47/565
Inventor 桑大永涂小东田娟
Owner 美迪森(荆门)生物医药科技有限公司
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