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Method for preparing 3,4,5-trimethoxybenzoyl hydrazine

A technology for trimethoxybenzoic hydrazide and trimethoxybenzoic hydrazide finished products is applied in the field of preparing 3,4,5-trimethoxybenzoic hydrazide, and can solve the problems of low total yield, complicated process and environmental problems. It can reduce the discharge of waste, shorten the process steps and reduce the production cost.

Inactive Publication Date: 2018-08-24
重庆丽澄环保科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantages of the prior art are: (1) Concentrated sulfuric acid is used as a catalyst in the esterification reaction, which is highly corrosive, requires high equipment, and produces a large amount of acidic organic wastewater, which becomes salty after neutralization with alkali. High organic wastewater, high environmental hazards, high difficulty in wastewater treatment and high cost; (2) There are still many steps in the preparation of 3,4,5-trimethoxybenzoic hydrazide by two-step reaction, the process is cumbersome, and the process is complicated , high energy consumption, many impurities in side reactions, low total yield (only 80-90%), high production cost, etc.

Method used

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  • Method for preparing 3,4,5-trimethoxybenzoyl hydrazine

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0013] Put 212g of 3,4,5-trimethoxybenzoic acid, 265g of hydrazine hydrate with a content of 80%, and 42g of dicyclohexylcarbodiimide into a four-necked flask equipped with a stirring, thermometer, and rectifying column, and start stirring , heat up to reflux, when the steam enters the rectification column, extract water vapor at the column top temperature of 95°C to 100°C, react at the reflux temperature for 4 to 6 hours, and end the reaction when no condensed water flows out from the rectification column top, Use vacuum distillation to distill the remaining hydrazine hydrate and dicyclohexylcarbodiimide catalyst together to recover in the flask. After dissolution, filtration, recrystallization and drying, 216.5 g of the finished product of 3,4,5-trimethoxybenzoic hydrazide was obtained.

Embodiment 2

[0015] Put 212g of 3,4,5-trimethoxybenzoic acid, 295g of hydrazine hydrate with a content of 90%, and 53g of dicyclohexylcarbodiimide into a four-necked flask equipped with a stirring, thermometer, and rectifying column, and start stirring , heat up to reflux, when the steam enters the rectification column, extract water vapor at the column top temperature of 95°C to 100°C, react at the reflux temperature for 4 to 6 hours, and end the reaction when no condensed water flows out from the rectification column top, Use vacuum distillation to distill the remaining hydrazine hydrate and dicyclohexylcarbodiimide catalyst together to recover in the flask. After dissolution, filtration, recrystallization and drying, 218.8 g of 3,4,5-trimethoxybenzoic hydrazide was obtained.

Embodiment 3

[0017] Put 212g of 3,4,5-trimethoxybenzoic acid, 324g of hydrazine hydrate with a content of 98%, and 63g of dicyclohexylcarbodiimide into a four-necked flask equipped with a stirring, thermometer, and rectifying column, and start stirring , heat up to reflux, when the steam enters the rectification column, extract water vapor at the column top temperature of 95°C to 100°C, react at the reflux temperature for 4 to 6 hours, and end the reaction when no condensed water flows out from the rectification column top, Use vacuum distillation to distill the remaining hydrazine hydrate and dicyclohexylcarbodiimide catalyst together to recover in the flask. After dissolution, filtration, recrystallization and drying, 220.6 g of the finished product of 3,4,5-trimethoxybenzoic hydrazide was obtained.

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Abstract

The invention provides a method for preparing 3,4,5-trimethoxybenzoyl hydrazine. The method comprises the steps of: adopting 3,4,5-trimethoxybenzoic acid and hydrazine hydrate as raw materials, adopting dicyclohexyl carbodiimide (DCC) as a catalyst, and carrying out a hydrazide reaction at a certain temperature to obtain the 3,4,5-trimethoxybenzoyl hydrazine. The hydrazine hydrate is kept in excess in the reaction system, and water generated by the reaction is continuously separated from the reaction system, so that the hydrazine reaction is promoted effectively, the reaction time is shortened, and the reaction yield is improved. Compared with the prior art, the method has a simple process, can be completed through the one-step reaction, and has high yield, and the catalyst can be recycledand used repeatedly; besides, an esterification reaction is omitted, the process steps are shortened, the production cost is reduced, no acidic wastewater and salt-containing organic wastewater are generated, waste discharge is less, and therefore the method is a green and environment-friendly production process.

Description

technical field [0001] The invention belongs to the technical field of chemical synthesis, and in particular relates to a method for preparing 3,4,5-trimethoxybenzoic hydrazide. Background technique [0002] 3,4,5-Trimethoxybenzoylhydrazide is a white crystalline solid with a melting point of 159-160°C and is easily soluble in water and organic solvents. 3,4,5-Trimethoxybenzohydrazide is an intermediate in the synthesis of heterocyclic compounds such as trimethoprim, and is also a raw material for the synthesis of various drugs such as antihypertensive drugs (reserpine). [0003] At present, the preparation method of 3,4,5-trimethoxybenzoic hydrazide is mainly based on 3,4,5-trimethoxybenzoic acid, methanol and hydrazine hydrate as raw materials, through two-step reactions (esterification and hydrazine Decomposition reaction) to obtain 3,4,5-trimethoxybenzoic hydrazide: the first step of esterification reaction is to use 3,4,5-trimethoxybenzoic acid and methanol as raw mate...

Claims

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Application Information

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IPC IPC(8): C07C241/04C07C243/38
CPCC07C241/04C07C243/38Y02P20/584
Inventor 不公告发明人
Owner 重庆丽澄环保科技有限公司