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Method for preparing mixture of 2-hydroxy-5-methyl-3-hexanone and 3-hydroxy-5-methyl-2-hexanone

A technology of mixture and methyl, 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 difficult industrial production, long reaction time, cumbersome operation, etc., and achieve convenient operation and low cost of raw materials , The effect of simple preparation process

Inactive Publication Date: 2011-08-31
SHANGHAI INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The present invention solves the above-mentioned preparation method of 2-hydroxy-5-methyl-3-hexanone and 3-hydroxy-5-methyl-2-hexanone with complicated operation, long reaction time, low yield and difficult industrial production etc. Existing technical problems provide a kind of preparation 2-hydroxyl-5-methyl-3-hexanone and 3-hydroxyl-5-methyl-2-hexanone with 3-methylbutyraldehyde and acetaldehyde as raw material The method of ketone mixture, the method is pollution-free, simple to operate and cheap in raw material cost, and is suitable for industrialized production

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0017] The preparation method of the thiazole salt catalyst used in the present invention: refer to the literature Organic Synthesis, 1984, 7: 95-100.

[0018] Apparatus used in the present invention:

[0019] GC-1690 gas chromatograph, produced by Hangzhou Kexiao Chemical Equipment Co., Ltd.;

[0020] WHF-0.5 high-pressure reactor, produced by Weihai Automatic Control Reactor Co., Ltd.;

[0021] SHZ-D(Ⅲ) circulating water vacuum pump, produced by Shanghai Dayan Instrument Co., Ltd.;

[0022] ZNHW type electronic energy-saving temperature controller, produced by Shanghai Dayan Instrument Co., Ltd.;

[0023] AV-400 Nuclear Magnetic Resonance Apparatus, produced by Bruker, Germany.

[0024] All the reagents used in the present invention are of domestic analytical grade and purchased from Sinopharm Chemical Reagent Co., Ltd.

Embodiment 1

[0026] In a three-necked flask equipped with magnetic stirring and a thermometer, add 14.3g (0.1mol) of 5-(2-hydroxyethyl)-4-methyl-1,3-thiazole, 12.7g (0.1mol) of freshly distilled Benzyl chloride and 50 ml of dry acetonitrile. The solution was refluxed and stirred for 24 hours, cooled to room temperature, filtered with suction, washed with acetonitrile until colorless, and dried under vacuum at 100°C / 20mmHg for 5 hours to obtain catalyst 1, namely N-benzyl-5-(2-hydroxy Ethyl)-4-methyl-1,3-thiazole chloride salt 19g, yield 70%;

[0027] Add 86g (1mol) of 3-methylbutyraldehyde, 44g (1mol) of acetaldehyde, and catalyst 1, namely N-benzyl-5-(2-hydroxyethyl)-4-methyl, into a 0.5L autoclave -1.3g of 1,3-thiazole chloride salt (1wt%) and 130g of ethanol, heated and stirred, controlled the reaction temperature at 80°C, reacted for 2 hours, and rectified under reduced pressure (78-84°C / 1mmHg), finally 36.5g of 2 -Hydroxy-5-methyl-3-hexanone and 3-hydroxy-5-methyl-2-hexanone mixture...

Embodiment 2

[0036] In a 0.5L autoclave, add 3-methylbutyraldehyde 86g (1mol), acetaldehyde 88g (2mol), the catalyst 1 obtained in Example 1, that is, N-benzyl-5-(2-hydroxyethyl base)-4-methyl-1,3-thiazole chloride salt 0.87g (0.5wt%) and 170g ethanol. Heat up and stir, control the reaction temperature to 140°C, react for 4 hours, rectify under reduced pressure (78-84°C / 1mmHg), and finally obtain 77g of 2-hydroxy-5-methyl-3-hexanone and 3-hydroxy-5 -Methyl-2-hexanone mixture.

[0037] Through gas chromatography analysis, the conversion rate of acetaldehyde is 98%, the conversion rate of 3-methylbutyraldehyde is 85%, and the selectivity of 2(3)-hydroxyl-5-methyl-3(2)-hexanone is 52%. %, the resulting 2-hydroxyl-5-methyl-3-hexanone and 3-hydroxyl-5-methyl-2-hexanone mixture has a relative 3-methylbutyraldehyde molar yield of 69.6%.

[0038] The molar ratio of 2-hydroxy-5-methyl-3-hexanone to 3-hydroxy-5-methyl-2-hexanone in the resulting mixture, i.e. 2-hydroxy-5-methyl-3-hexanone: 3-hydr...

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Abstract

The invention discloses a method for preparing a mixture of 2-hydroxy-5-methyl-3-hexanone and 3-hydroxy-5-methyl-2-hexanone. Under the catalysis of thiazole salt, 3-methyl butyraldehyde and aldehyde are taken as initial materials, ethanol is taken as a solvent, and the mixture is synthesized in a high pressure reactor. A molar ratio of the 3-methyl butyraldehyde to the aldehyde is 1:(1-5); a mass ratio of the raw materials, namely the 3-methyl butyraldehyde and the aldehyde, to the thiazole salt is (10-1,000):1; and the reaction temperature is 80 to 160DEG C and the reaction time is 2 to 6 hours. The 3-methyl butyraldehyde and the aldehyde are taken as raw materials, the mixture of the 2-hydroxy-5-methyl-3-hexanone and the 3-hydroxy-5-methyl-2-hexanone is synthesized by a one-step synthesis method in the presence of the thiazole salt catalyst, and the molar yield relative to the 3-methyl butyraldehyde is 65 to 72 percent, so the preparation method has the characteristics of low raw material cost, simple preparation process, high yield, no pollution in the production process, convenience of operation and the like.

Description

technical field [0001] The invention relates to a preparation method of a mixture of 2-hydroxy-5-methyl-3-hexanone and 3-hydroxy-5-methyl-2-hexanone. Background technique [0002] The mixture of 2-hydroxy-5-methyl-3-hexanone and 3-hydroxy-5-methyl-2-hexanone is a very valuable food flavoring, widely used in food and beverage additives. 3-Hydroxy-5-methyl-2-hexanone has been reported to be found in milk with an aroma similar to that of melted cheese. Zeiningen, M G (US6123974) and others reported the preparation method of 2-hydroxy-5-methyl-3-hexanone and 3-hydroxy-5-methyl-2-hexanone mixture, using 5-methyl-2- Hexanone and sulfonyl chloride react to generate 3-chloro-5-methyl-2-hexanone intermediate, and then react with sodium acetate and sodium iodide under nitrogen protection to obtain 3-acetoxy-5-methyl-2 -hexanone, followed by hydrolysis under basic conditions to give a mixture of 2-hydroxy-5-methyl-3-hexanone and 3-hydroxy-5-methyl-2-hexanone. The method is cumbersom...

Claims

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Application Information

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IPC IPC(8): C07C49/17C07C45/73
Inventor 王之建梁立冬贾卫民赵延伟
Owner SHANGHAI INST OF TECH
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