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Preparation method of diphenhydramine

A technology for diphenhydramine and benzhydryl alcohol, which is applied in the field of preparation of diphenhydramine, can solve the problems that toluenesulfonic acid cannot be recycled and the production cost is high, and achieves easy industrial production, simple operation and high product yield. Effect

Inactive Publication Date: 2015-09-09
JIAXING UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

A large amount of p-toluenesulfonic acid is used in this process and cannot be recycled, resulting in relatively high production costs

Method used

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  • Preparation method of diphenhydramine
  • Preparation method of diphenhydramine
  • Preparation method of diphenhydramine

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Add 36.8 grams (0.2mol) of diphenylmethanol, 26.7 grams (0.3mol) of dimethylaminoethanol, 2.9 grams (accounting for 8% of the mass of diphenylmethanol) of dibutyltin oxide and ionic liquid N bromide in a 250mL one-mouth bottle - 1.1 grams of n-propylpyridine (accounting for 3% of the mass of diphenylmethanol), the reaction mixture was stirred and reacted under reflux. The progress of the reaction was detected by gas chromatography. After reacting for 10 hours, the reaction was completed, and the excess dimethylaminoethanol (which can be recycled) was removed by distillation under reduced pressure, and then the temperature was raised to carry out distillation under reduced pressure to obtain 49.0 grams of diphenhydramine, with a yield of 96.0%, gas phase analysis 99.5% purity.

Embodiment 2

[0026] Add 36.8 grams (0.2mol) of diphenylmethanol, 26.7 grams (0.3mol) of dimethylaminoethanol, 1.1 grams (accounting for 3% of the mass of diphenylmethanol) of dibutyltin oxide and ionic liquid N bromide in a 250mL one-mouth bottle - 1.1 grams of n-propylpyridine (accounting for 3% of the mass of diphenylmethanol), the reaction mixture was stirred and reacted under reflux. The progress of the reaction was detected by gas chromatography. After reacting for 20h, the reaction was completed, and the excess dimethylaminoethanol (which can be recycled) was removed by distillation under reduced pressure, and then the temperature was increased to carry out distillation under reduced pressure to obtain 48.6 grams of diphenhydramine, with a yield of 95.1%, gas phase analysis 99.0% purity.

Embodiment 3

[0028] Add 36.8 grams (0.2mol) of diphenylmethanol, 35.6 grams (0.4mol) of dimethylaminoethanol, 3.68 grams (accounting for 10% of the mass of diphenylmethanol) of dibutyltin oxide and ionic liquid bromide 1 in a 250mL one-port bottle. - 1.8 g of methyl-3-ethylimidazolium salt (accounting for 5% of the mass of benzhydryl alcohol), and the reaction mixture was stirred and refluxed for reaction. The progress of the reaction was detected by gas chromatography. After reacting for 8 hours, the reaction was completed, and the excess dimethylaminoethanol (which can be recycled) was removed by distillation under reduced pressure, and then the temperature was raised to carry out distillation under reduced pressure to obtain 49.5 grams of diphenhydramine, with a yield of 97.0%, gas phase analysis 99.6% purity.

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Abstract

The invention relates to a preparation method of diphenhydramine, which takes benzhydrol and dimethylaminoethanol as raw materials, under existence of dibutyltin oxide and ion liquid compound, benzhydrol and dimethylaminoethanol are subjected to an intermolecular dehydration reaction to obtain diphenhydramine. The method has the advantages of simple preparation technology, mild reaction condition, low cost, high product yield and high purity.

Description

technical field [0001] The invention relates to a preparation method of diphenhydramine, which belongs to the field of chemical synthesis. Background technique [0002] Diphenhydramine is a key pharmaceutical intermediate for the synthesis of antihistamines diphenhydramine, diphenhydramine hydrochloride and diphenhydramine citrate (diphenhydramine citrate), which has a large demand in domestic and foreign markets and has a good market prospect . [0003] There are few synthetic routes of reported diphenhydramine at present, and the following three synthetic routes are mainly used for synthesis: [0004] (1) Diphenylchloromethane or diphenylbromomethane is used as raw material to carry out nucleophilic substitution reaction with dimethylaminoethanol to prepare diphenhydramine. During the reaction process, the quaternization of the dimethylamino position will occur, resulting in complicated purification process and low product yield. [0005] (2) Carry out etherification wi...

Claims

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Application Information

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IPC IPC(8): C07C217/10C07C213/06
Inventor 宗乾收汪剑波宋熙熙邱观音生包琳缪程平张洋
Owner JIAXING UNIV
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