4-halogenated-2-methyl-2-ethyl crotonate preparing method

A technology of ethyl crotonate and ethyl pyruvate, which is applied in the field of chemical intermediate synthesis, can solve the problems of low total reaction yield and long process route, and achieves good reaction selectivity, simple overall process and no equipment requirements. harsh effect

Active Publication Date: 2015-04-15
SHANGYU NHU BIOCHEM IND +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] The method process route is lon...

Method used

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  • 4-halogenated-2-methyl-2-ethyl crotonate preparing method

Examples

Experimental program
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Effect test

Embodiment 1

[0032] A. Preparation of Hydroxyl Compound (V)

[0033] Add 23.43g of ethyl pyruvate (99% purity) and 80ml of toluene into a 250ml four-neck flask, stir to cool down to -10°C, and start to drop 91ml of vinylmagnesium chloride Grignard reagent (content: 2.2mol / L, commercially available product, the solvent is tetrahydrofuran), the dripping is completed in about 60 minutes, and the heat preservation reaction is 1 hour. After the heat preservation is completed, the resulting product is a condensate.

[0034] The condensate was slowly added dropwise to 150ml of dilute sulfuric acid (10% concentration by mass), and the reaction temperature was kept within 50°C during the dropping process, and the reaction was continued for 10 minutes after the dropping. The layers were separated, the upper organic phase was separated, and the lower aqueous phase was extracted twice with toluene, each time the amount of toluene was 30ml. Combine and extract toluene to the organic phase, neutralize...

Embodiment 2

[0038] A. Preparation of Hydroxyl Compound (V)

[0039] Add 23.43g of ethyl pyruvate (purity: 99%) and 80ml of toluene into a 250ml four-neck flask, stir and cool down to -10°C, start to drop 87ml of vinylmagnesium bromide Grignard reagent (content: 2.3mol / L, Commercially available products, the solvent is tetrahydrofuran), the dripping is completed in about 60 minutes, and the reaction is kept for 1 hour. After the heat preservation is completed, the resulting product is a condensate. The condensate was slowly added dropwise to 150ml of dilute sulfuric acid (10% concentration by mass), and the reaction temperature was kept within 50°C during the dropping process, and the reaction was continued for 10 minutes after the dropping. The layers were separated, the upper organic phase was separated, and the lower aqueous phase was extracted twice with toluene, each time the amount of toluene was 30ml. Combine and extract toluene to the organic phase, neutralize with 100ml saturate...

Embodiment 3

[0043] A. Hydroxy compound (V) is prepared in the same way as in Example 1

[0044] B. Preparation of Bromocarbapentamate (I)

[0045] Add 22.85g of hydroxyl compound (V) (purity: 94.5%) and 60ml of dichloromethane into a 250ml four-neck flask, stir and cool the reaction mixture to 0°C, start to drop 32.0g of hydrobromic acid (mass percentage concentration: 57%) , After about 30 minutes of dripping, keep warm for 20 minutes. The layers were separated, the organic phase was separated, and the aqueous phase was extracted with 20ml of dichloromethane and combined into the organic phase. The organic phase was neutralized with 80ml of saturated sodium bicarbonate and then washed once with 80ml of saturated sodium chloride. After washing, dichloromethane was recovered to obtain 28.7g of a concentrate, which was compared and analyzed by commercially available standard bromocarbon pentaester (I) GC , the purity is 91.8%, and the yield is 84.8%.

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Abstract

The invention discloses a 4-halogenated-2-methyl-2-ethyl crotonate preparing method which includes following steps: (1) performing a Grignard reaction to ethyl pyruvate (II) and a vinyl magnesium halide Grignard reagent (III) to obtain a condensation compound (IV) after the reaction finished, and carrying out a hydrolysis reaction to the condensation compound (IV) to obtain a hydroxyl compound (V); and (2) performing a halogenating reaction to the hydroxyl compound and a haloid acid to obtain the 4-halogenated-2-methyl-2-ethyl crotonate (I). The 4-halogenated-2-methyl-2-ethyl crotonate preparing method is simple in total technology, allows raw materials to be obtained easily, is good in reaction selectivity, is less in by-products and is high in yield. The employed raw materials are all low-toxic or toxic-free and are all corrosiveness-free so that the method is not rigorous in requirement of devices, is environmental-friendly and is suitable for industrialized production.

Description

technical field [0001] The invention relates to the field of synthesis of chemical intermediates, in particular to a preparation method of ethyl 4-halo-2-methyl-2-butenoate. Background technique [0002] 4-halo-2-methyl-2-butenoic acid ethyl ester (hereinafter referred to as halocarbon pentaester), which is the key intermediate for the synthesis of 8'-apo-β-carotinic acid ethyl ester, the current The main synthetic methods are vinyl propionitrile method, methyl vinyl ketone method and dimethoxyacetone method. [0003] Patent documents US4937308 and DE3244273 describe the method for preparing halogenated carbopentamate by vinylpropionitrile method, and its reaction process is shown in the following formula: [0004] The method uses hydrogen chloride gas and bromine, the toxicity and corrosion of hydrogen chloride gas and bromine are increased, the requirements for equipment are high, and the overall reaction yield is not ideal. [0005] Patent documents US4596889 and US57...

Claims

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Application Information

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IPC IPC(8): C07C69/65C07C67/327
CPCC07C67/31C07C67/327C07C69/65C07C69/732
Inventor 张明锋黄国东吕国锋曾庆宇李小军
Owner SHANGYU NHU BIOCHEM IND
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