Preparation process of 2-tolylhydrazine hydrochloride

A technology for the preparation of methylphenylhydrazine, which is applied in the fields of hydrazine preparation and organic chemistry, can solve the problems of difficult transportation and storage, high cost, and many equipments, and achieve shortened reduction reaction time, low production cost, and high product purity Effect

Inactive Publication Date: 2012-03-21
袁雪冲
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Problems solved by technology

The synthetic method of this traditional phenylhydrazine hydrochloride, the reaction time is as long as 3~4 hours, and the yield is only between 63~72%. In addition, when the reducing agent used is sodium sulfite, the cost is higher, and the Production cost; and when ammonium bisulfite and ammonium hydroxide are used as reducing agents, because they are liquid, it is not easy to transport and store
In addition, reduction kettle, pressure filter and acid analysis kettle are used in this process, which requires a lot of equipment and large investment.

Method used

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Embodiment Construction

[0015] A specific embodiment of the present invention will be described below, but it is not limited to this example.

[0016] According to the preparation method of the 2-methylphenylhydrazine hydrochloride of the present embodiment, comprises the steps:

[0017] (1), diazotization reaction

[0018] Add 150ml of water and 58.5g of 10N hydrochloric acid to a 600ml beaker, add 21.4g of o-toluidine under stirring, then add crushed ice and cool to 0°C, then slowly add sodium nitrite aqueous solution (made by dissolving 15g of sodium nitrite and 30ml of water) , the speed of adding sodium nitrite aqueous solution should be controlled to control the temperature of the material in the beaker not to exceed 5°C. After the sodium nitrite aqueous solution is added, the pH of the system is 1-2, and the temperature of the system is controlled at 0-5°C. Continue stirring for 20 Minutes, 400ml of the solution obtained by filtration is the benzene diazonium chloride solution.

[0019] (2),...

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Abstract

The invention relates to a preparation process of 2-tolylhydrazine hydrochloride, which comprises the following steps of: firstly, carrying out a diazo reaction on o-nitrotoluene as an initial raw material to obtain benzenediazonium chloride; secondly, further carrying out a reducing reaction on the benzenediazonium chloride obtained in the first step under the action of a reducing agent to obtain a reduzate; and thirdly, carrying out a hydrolytic reaction on the reduzate obtained in the second step under the action of hydrochloric acid to generate the 2-tolylhydrazine hydrochloride. Particularly, in the second step, sodium metabisulfite is used as the reducing agent in the reducing reaction; and the reducing reaction is carried out under the conditions that the temperature is 15-25DEG C and the pH value is 7-9. According to the method, the production period can be shortened and the production cost is reduced while high yield is obtained.

Description

technical field [0001] The invention relates to a preparation method of phenylhydrazine hydrochloride, in particular to a preparation process of 2-methylphenylhydrazine hydrochloride. Background technique [0002] 2-Methylphenylhydrazine hydrochloride is an important intermediate, mainly used to prepare indole and pyrazolone derivatives, and can also be used to prepare other chemical products. The traditional preparation process of 2-methylphenylhydrazine hydrochloride includes two-step process of diazotization of aniline and reduction of benzene diazonium chloride, wherein the diazotization of aniline is mostly in hydrochloric acid medium, under the condition of pH equal to 2, at 0 Sodium nitrite is added to react at a low temperature of ~5°C to generate benzenediazonium chloride. Sodium sulfite and sodium bisulfite are generally used as reducing agents for the reduction of diazobenzene chloride, and ammonium bisulfite and ammonium hydroxide are also used as reducing agent...

Claims

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Application Information

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IPC IPC(8): C07C243/22C07C241/02
Inventor 袁雪冲
Owner 袁雪冲
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