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One-step method for preparing alpha-halo acetophenone dimethyl ketal compounds

A technology of halogenated acetophenone dimethyl ketal and compound, which is applied in the field of preparation of fine chemical products, and can solve the problems of difficult product purification and low yield

Inactive Publication Date: 2010-01-13
EAST CHINA NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] Therefore, many α-halogenated acetophenone dimethyl ketal compounds have not been reported in the literature due to low yields and difficult purification of products

Method used

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  • One-step method for preparing alpha-halo acetophenone dimethyl ketal compounds
  • One-step method for preparing alpha-halo acetophenone dimethyl ketal compounds
  • One-step method for preparing alpha-halo acetophenone dimethyl ketal compounds

Examples

Experimental program
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Effect test

Embodiment 1

[0033] Preparation of α-chloro-p-methylacetophenone dimethyl ketal from p-methylacetophenone

[0034] Add 15mmol dichlorohydantoin, 10mmol p-toluophenone, 35ml anhydrous methanol, 15g molecular sieves, 5mmol hexahydropyridine into a 50ml three-necked flask, and heat to reflux for 12h. Filter out molecular sieves, then distill methanol off, then dissolve with 50ml methyl tert-butyl ether or dichloromethane and 40ml water, separate the liquid with a separatory funnel, wash twice with saturated saline, dry over anhydrous sodium sulfate, filter, and distill off the solvent The product α-chloro-p-methylacetophenone dimethyl ketal was obtained with a yield of 70%. Product IR(cm -1 ): 1118, 1060, 1040, 1001.

Embodiment 2

[0036] Preparation of α-chloroacetophenone dimethyl ketal from acetophenone

[0037] Add 15mmol of dichlorohydantoin, 10mmol of acetophenone, 35ml of anhydrous methanol, 10g of molecular sieves, and 2.5mmol of triethylamine into a 50ml three-necked flask, and heat to reflux for 10h. Filter out molecular sieves, then distill methanol off, then dissolve with 50ml methyl tert-butyl ether or dichloromethane and 40ml water, separate the liquid with a separatory funnel, wash twice with saturated saline, dry over anhydrous sodium sulfate, filter, and distill off the solvent The product α-chloroacetophenone dimethyl ketal was obtained with a yield of 80%. Product IR(cm -1 ): 1120, 1070, 1045, 1006.

Embodiment 3

[0039] Preparation of α-chloro-p-bromoacetophenone dimethyl ketal from p-bromoethanone

[0040] Add 15mmol dichlorohydantoin, 10mmol p-bromoacetophenone, 35ml anhydrous methanol, 15g molecular sieves, 3mmol n-butylamine into a 50ml three-necked flask, and react at room temperature for 24h. Filter out molecular sieves, then distill methanol off, then dissolve with 50ml methyl tert-butyl ether or dichloromethane and 40ml water, separate the liquid with a separatory funnel, wash twice with saturated saline, dry over anhydrous sodium sulfate, filter, and distill off the solvent The product α-chloro-p-bromoacetophenone dimethyl ketal was obtained with a yield of 90%. Product IR(cm -1 ): 1124, 1073, 1051, 1011.

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Abstract

The invention discloses a one-step method for preparing alpha-halo acetophenone dimethyl ketal compounds, and the method takes carbonyl compounds as reactants, takes a base as a catalyst, takes a dihalogenated hydantoin as a halogenating agent and takes methanol as a solvent for simultaneously carrying out alpha-site halogenating reaction and condensation reaction of the methanol in one step in the presence of a dewatering agent, thereby obtaining the alpha-halo acetophenone dimethyl ketal compounds. The method uses a variety of acetophenone compounds and 1,3-dichloro (bromo)-5,5-dimethyl hydantoin and adopts the one-step method to directly obtain the corresponding alpha-halo acetophenone dimethyl ketal which can be generally obtained by two steps of reaction, the reaction conditions are mild, and the yield is high, thereby having better industrial prospects.

Description

technical field [0001] The invention belongs to the technical field of preparation of fine chemical products, and in particular relates to a method for directly preparing alpha-halogenated acetophenone dimethyl ketal compounds in one step. Background technique [0002] The α-monochloro(bromo) products of various carbonyl compounds are important intermediates in organic synthesis, and are widely used in the synthesis of functional chemicals such as medicines and pesticides. In the further synthesis, since the carbonyl is an active group, it is often necessary to protect it. Converting the carbonyl of ketones into ketals is the most classic and effective way to protect carbonyls (He Jingwen, Wu Yikang, "New Developments in Carbonyl Protecting Groups", Organic Chemistry, 2007, 27, No. 5, 576 ~586). The most widely used in practice is the ketal formed with methanol or ethylene glycol, which is cheap and easy to get. Such as: [0003] [0004] (Tetrahedron Letters, 30(45),...

Claims

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Application Information

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IPC IPC(8): C07B41/04C07C43/313C07C41/56C07C205/34C07C201/12C07C255/54C07C253/30
Inventor 邹新琢周斌朱伟韩冰冰
Owner EAST CHINA NORMAL UNIV
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