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A kind of preparation method of high yield 2-methyl-4-acetoxy-2-butenal

A technology of acetoxy and crotonaldehyde, applied in the field of medicinal chemistry, can solve the problems of unsuitable and simple operation, low substrate activity, high equipment requirements, etc., and achieve the effect of suitable reactivity, easy operation and good stability

Active Publication Date: 2022-07-01
XINFA PHARMA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0029] Although the 7-atom economy of this synthetic route is high, the 1,4-diacetoxy-2-butene used in the hydroformylation reaction contains two ester functional groups, the substrate activity is low, and special ligands are required. The reaction process The pressure is high (the pressure is 130-150 standard atmospheric pressure), the equipment requirements are high, and it is not suitable for industrialized simple operation

Method used

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  • A kind of preparation method of high yield 2-methyl-4-acetoxy-2-butenal
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  • A kind of preparation method of high yield 2-methyl-4-acetoxy-2-butenal

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0076] Example 1: Preparation of 3-formyltetrahydrofuran (III)

[0077] To a 500 ml stainless steel autoclave with stirring and a thermometer, add 70.0 g (1.0 mol) 2,5-dihydrofuran (II), 140 g toluene, 0.5 g tris(triphenylphosphine) rhodium carbonyl hydride, 0.5 g g of triphenylphosphine, closed the autoclave, replaced the gas in the autoclave 3 times with nitrogen, and then introduced the synthesis gas CO / H 2 (volume ratio 1:1), keep the synthesis gas pressure at 4.0-5.0MPa, turn on stirring, be warming up to 90-95°C, react for 4 hours, cool down, replace with nitrogen 3 times, remove the reaction liquid, wash the reaction with 30 grams of toluene The catalyst was removed by filtration, the filtrate was distilled to recover toluene, and then distilled under reduced pressure (80-90°C / 1-2mmHg) to obtain 94.6 g of 3-formyltetrahydrofuran (III) with a yield of 94.6% and a gas-phase purity of 99.7%.

Embodiment 2

[0078] Example 2: Preparation of 3-formyltetrahydrofuran (III)

[0079] Into a 500 ml stainless steel autoclave with stirring and a thermometer, add 70.0 g (1.0 mol) 2,5-dihydrofuran (II), 180 g toluene, 0.5 g tris(triphenylphosphine) rhodium chloride, 0.6 g g of triphenylphosphine, closed the autoclave, replaced the gas in the autoclave 3 times with nitrogen, and then introduced the synthesis gas CO / H 2 (volume ratio 1:1), keep the synthesis gas pressure at 5.0-6.0MPa, turn on stirring, be warming up to 100-105°C, react for 4 hours, cool down, replace with nitrogen 3 times, remove the reaction liquid, wash the reaction with 30 grams of toluene The catalyst was removed by filtration, the filtrate was distilled to recover toluene, and then distilled under reduced pressure (80-90°C / 1-2mmHg) to obtain 93.8 g of 3-formyltetrahydrofuran (III) with a yield of 93.8% and a gas-phase purity of 99.6%.

Embodiment 3

[0080] Example 3: Preparation of 2-formyl-4-acetoxy-1-butene (IV)

[0081] Into a 500-milliliter four-necked flask connected with a stirring, thermometer and reflux condenser, add 200 g of toluene, 50.0 g (0.5 mol) of 3-formyltetrahydrofuran (III) prepared in Example 1, 48.0 g (0.8 mol) of acetic acid , 0.20 g of p-toluenesulfonic acid, and the reaction was stirred at 110-112 ° C for 5 hours. Cooled to 20 to 25°C, changed to a distillation system, first distilled to recover toluene and excess acetic acid, and then changed to high vacuum vacuum distillation (85-100°C / 1-2mmHg) to obtain 68.5 g of 2-formyl-4-acetoxy Base-1-butene (IV), the yield was 96.5%, and the gas-phase purity was 99.3%.

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Abstract

The invention provides a preparation method of 2-methyl-4-acetoxy-2-butenal (I) with high yield, and the invention utilizes 2,5-dihydrofuran (II) and synthesis gas as raw materials , prepare 3-formyltetrahydrofuran (III) through hydroformylation reaction under the action of a catalyst, and then react with an acetylating reagent under the action of a catalyst to prepare 2-formyl-4-acetoxy-1-butene (IV) , and then under the action of a catalyst, 2-methyl-4-acetoxy-2-butenal (I) is obtained through double bond isomerization. The method of the invention is cheap and easy to obtain raw materials and low in cost; the technological process is short, the reaction is easy to realize, the operation is safe and convenient, the amount of waste water is small, and the environmental protection; the reaction intermediate product is stable, the reaction activity is suitable, the reaction selectivity is high, the side reaction is few, and High rate, suitable for industrial production.

Description

technical field [0001] The invention relates to a preparation method of high-yield 2-methyl-4-acetoxy-2-butenal, and belongs to the technical field of medicinal chemistry. Background technique [0002] 2-Methyl-4-acetoxy-2-butenal (I) is a key intermediate for preparing vitamin A acetate and various carotenoids, and its structural formula is as follows: [0003] [0004] The synthetic method of 2-methyl-4-acetoxy-2-butenal is summarized as the following according to the difference of the main raw material used and the unit reaction involved: [0005] 1. 1,1-dimethoxyacetone method [0006] US patent documents US4256878 and US5453547 use 1,1-dimethoxyacetone as a raw material, 3-methyl-3-hydroxy-4,4-dimethoxy-1-butyne is obtained by ethynylation, and hydrogen is selected Sexual hydrogenation to obtain 3-methyl-3-hydroxy-4,4-dimethoxy-1-butene, and then esterification with acetic anhydride to obtain 3-methyl-3-acetoxy-4,4 -Dimethoxy-1-butene, then isomerized by double bo...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C67/24C07C69/145
CPCC07C67/24C07C67/293C07D307/12C07C69/145
Inventor 周立山戚聿新吕强三于大伟鞠立柱
Owner XINFA PHARMA
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