Process for preparing beta-halogen-alpha-phenyl ethyl alcohol compounds

A compound, phenylethyl alcohol technology, applied in the field of preparation of β-halogenated-α-phenylethyl alcohol compounds, can solve the problems of reduced reaction selectivity and yield, difficult separation and purification, low reaction efficiency, etc., reaching the reaction temperature range Wide, high yield, high selectivity effect

Inactive Publication Date: 2005-03-02
ZHEJIANG UNIV
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AI Technical Summary

Problems solved by technology

Someone used solid potassium borohydride to reduce 2-chloro-1-(2',4'-dichlorophenyl)-ethanone in methanol or DMF under ice-water bath, room temperature or heating under reflux [Liu Shangzhong et al., Pesticides, 1995, 34(10), 13-14] [Jiang Cailing, Zhang Guohong, China Journal of Pharmaceutical Industry, 1997, 28(5), 231-232], [Ye Baohui et al., China Journal of Pharmaceutical Industry, 1990, 21(2), 56-57 ], in the reaction process, the heat release is large, strong gas is generated, and the operation of adding solid borohydride is difficult to control, which is easy to cause the reaction liquid to overflow due to the violent reaction and danger occurs, and the reaction is accompanied by the substitution reaction of α-halogen atoms Produce a large number of various by-products such as phenyl oxirane, α-halo-β-phenylethanol, α-phenylethanol, β-phenylethanol, phenylethyl alcohol, etc., which reduces the selectivity and yield of the reaction. Difficulties in subsequent separation and purification
Inefficient Reduction of α-Halo-Acetophenones with Aluminum Isopropoxide

Method used

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  • Process for preparing beta-halogen-alpha-phenyl ethyl alcohol compounds
  • Process for preparing beta-halogen-alpha-phenyl ethyl alcohol compounds

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Embodiment 1: Synthesis of 1-(2,4-dichlorophenyl)-2-chloro-ethanol

[0024] Add 0.2mol (22.2g) of calcium chloride, 0.1mol (22.35g) of 2,2',4'-trichloroacetophenone, and 90ml of methanol into a 250ml three-necked flask, and stir at 25°C for 0.5 hours. Dissolve 0.12mol (4.8g) of 96% sodium borohydride in a solution made of 10ml of methanol + 10ml of 1% aqueous sodium hydroxide solution. Under ice bath and stirring, sodium borohydride solution was added dropwise. After the dropwise addition, the stirring reaction was continued at room temperature for 20 minutes, and a white solid was produced as the reaction progressed. Add 50ml (1+2) of hydrochloric acid solution to decompose. Most of the methanol was distilled off under reduced pressure. Cool to room temperature, separate the organic layer, extract the aqueous phase with ether (20ml×2), combine the extract into the organic phase, and dry over anhydrous magnesium sulfate. Ethyl ether was distilled off to obtain 22 g ...

Embodiment 2

[0026] Embodiment 2: Synthesis of 1-(2,4-dichlorophenyl)-2-chloro-ethanol

[0027] 0.20mol (39.58g) manganese dichloride (MnCl 24H2O), 0.10mol (22.35g) 2,2', 4'-trichloroacetophenone, 100ml95% ethanol, join in the 250ml there-necked flask, and stir at 25°C for 0.5 hour. Dissolve 0.15mol (5.70g) of 96% sodium borohydride in 10ml of 1% aqueous sodium hydroxide solution, and slowly add the sodium borohydride solution dropwise at room temperature with stirring. After the dropwise addition, the stirring reaction was continued for 30 minutes under heating in a water bath at 70° C., and the following treatment was the same as in Example 1. 22 g of a yellow oily liquid product was obtained, and white crystals were precipitated upon standing. Analysis by gas chromatography showed that the product 1-(2,4-dichlorophenyl)-2-chloro-ethanol had a purity of 99.8%. 20 g of white needle-like crystals were obtained by recrystallization with 20 ml of petroleum ether, with a yield of 88.7%.

Embodiment 3

[0028] Embodiment 3: Synthesis of 1-(2,4-dichlorophenyl)-2-chloro-ethanol

[0029] Add 0.1mol zinc chloride (13.63g) or 0.1mol zinc nitrate (29.75g), 0.05mol (11.175g) 2,2',4'-trichloroacetophenone, 50ml methanol into a 250ml three-necked flask, Stir at 25°C for 0.5 hours. Dissolve 0.075mol (2.85g) of 96% sodium borohydride in 5ml of methanol + 8ml of 1% aqueous sodium hydroxide solution, and slowly add the sodium borohydride solution dropwise in an ice-water bath with stirring. After the dropwise addition, the stirring reaction was continued for 30 minutes under heating in a water bath at 50°C. The following treatment was the same as in Example 1. 12 g of a yellow oily liquid product was obtained, and white crystals were precipitated upon standing. Analysis by gas chromatography showed that the product 1-(2,4-dichlorophenyl)-2-chloro-ethanol had a purity of 98.5%.

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Abstract

The present invention discloses the preparation process of beta-halogeno-alpha-phenyl ethyl alcohol compound. With sodium or potassium borohydride as reductant and in the presence of metal ion of Ca, Mg, Sr, Mn, Ln, Zn or Cu in the stoichiometric value or greater than the stoichiometric value, alpha-halogeno-acetophenone compound is reduced into beta-halogeno-alpha-phenyl ethyl alcohol compound in methanol or ethanol medium. Owing to that the metal ion and alpha-halogeno-acetophenone compound form stable compound, the halogen atom in the alpha-position is not substituted or reduced to raise the reaction selectivity greatly. The reaction has wide temperature range, may be performed at normal temperature in high selectivity and yield.

Description

technical field [0001] The invention relates to a preparation method of β-halogenated-α-phenethyl alcohol compounds. Background technique [0002] β-halogenated-α-phenylethanol compounds are important fine chemical intermediates such as medicines and dyes, which can be prepared by reducing corresponding α-halogenated-acetophenone compounds. The methods for reducing ketones to alcohols mainly include: catalytic hydrogenation, reduction of metal hydride lithium aluminum hydride, sodium borohydride or potassium borohydride, borane and their partial hydrogen substitutes such as tri(methoxy) lithium aluminum hydride, etc. method, aluminum isopropoxide reduction method. Catalytic hydrogenation generally requires pressure-resistant equipment, and the equipment structure is complex and expensive. Catalysts are usually made of precious metals such as platinum, rhodium, rhenium, etc., and copper-based catalysts are also available (as the patent publication nu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C29/143C07C33/46
Inventor 杨立荣吴坚平王明慧
Owner ZHEJIANG UNIV
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