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Process for preparing 2,2'-dichloro-hydrazobenzene

A technology of dichlorohydroazo and o-nitrochlorobenzene, which is applied in 2 fields, can solve the problems of catalyst separation and recovery and regeneration yield affecting production costs, precious metal catalysts are expensive, and labor-intensive, etc., to achieve recovery and mechanical application Convenience, low cost, and production cost reduction effects

Inactive Publication Date: 2005-03-16
JIANGSU YANGNONG CHEM GROUP
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Catalytic hydrogenation is a relatively advanced process, which has the advantages of high yield, good product quality, and less "three wastes" pollution, but the use of noble metal catalysts is expensive, and the separation and recovery of catalysts and the yield of regeneration greatly affect production costs
At the same time, the batch tank type hydrogenation has low charging coefficient, high labor intensity, and there are certain safety hazards in the production batch conversion.

Method used

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  • Process for preparing 2,2'-dichloro-hydrazobenzene
  • Process for preparing 2,2'-dichloro-hydrazobenzene
  • Process for preparing 2,2'-dichloro-hydrazobenzene

Examples

Experimental program
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Effect test

Embodiment 1

[0017] Example 1 Preparation of 2,2'-dichlorohydroazobenzene by batch hydrogenation reduction

[0018] In a 1-liter autoclave, add 120 grams of o-nitrochlorobenzene, 200 milliliters of toluene, 150-200 milliliters of pre-prepared methanol / sodium hydride solution (12 grams of solid alkali dissolved in 100 milliliters of methanol), 10 grams of nickel Catalyst, 0.5-1 gram of cocatalyst, 2 grams of dechlorination inhibitor ethanolamine. After the feeding is completed, the autoclave is closed, and the air is replaced with nitrogen and hydrogen respectively, and 0.6Mpa hydrogen is introduced, stirring and heating are started, and hydrogenation reduction reaction is carried out at 40-50°C.

[0019] In the initial stage, it is advisable to keep the hydrogen absorption rate at 0.05Mpa for every 0.05Mpa drop in hydrogen pressure. As time goes on, the hydrogen absorption rate will gradually slow down. It takes more than 30 minutes to drop by 0.05Mpa, and the reaction ends at this moment...

Embodiment 2

[0022] Example 2 Preparation of 2,2'-dichlorohydroazobenzene by continuous hydrogenation reduction in kettle

[0023] Three 1-liter high-pressure reactors and one 5-liter pressure receiving tank are connected in series, and the liquid material flows through the three reactors in sequence according to the liquid level difference, and finally reaches the receiving tank. The receiving tank discharges the material intermittently, but it does not affect the continuous input and output of the material, thus realizing the continuous hydrogenation process. Each reactor has a double-valve feeding port to add catalyst intermittently, and the balance pipe is used to balance the pressure between each reactor so that the material overflows.

[0024] To prepare the toluene solution of o-nitrochlorobenzene, add 600 grams of o-nitrochlorobenzene and 3 grams of promoters in every liter of toluene and stir evenly. Prepare a methanol solution of sodium hydroxide, add 120 grams of solid alkali t...

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Abstract

The invention discloses a process for preparing 2,2'-dichloro-hydrazobenzene by using ortho-nitrochlorobenzene as raw material, nickel system as catalyst, mixed solvent of alcohols and aromatic hydrocarbons as reaction medium for reaction under alkaline condition. The method can be used not only for intermittent hydrogenation reduction, but also for continuous hydrogenation preparation of 2, 2'-dichloro-hydrazobenzene.

Description

technical field [0001] The invention relates to a preparation method in the technical field of fine chemical products, in particular to a preparation method of 2,2'-dichlorohydroazobenzene. Background technique [0002] 2,2'-dichlorohydroazobenzene is an intermediate for the production of 3,3'-dichlorobenzidine, and 3,3'-dichlorobenzidine is a very important pigment intermediate. Currently, 3 , The methods of 3'-dichlorobenzidine (DCB) mainly include zinc powder method, formaldehyde-hydrazine hydrate method and catalytic hydrogenation method. Among them, the zinc powder method and the formaldehyde-hydrazine hydrate method are the main methods for producing 3,3'-dichlorobenzidine in my country. U.S. Patent 3,156,724, European Patent 0,391,606, introduced the use of noble metal catalysts such as Pd / c, Pt / c, etc. and 1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone or 2-hydroxy anthraquinone or 2,6-Hydroxyanthraquinone is used as a cocatalyst, and an appropriate amount of ...

Claims

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Application Information

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IPC IPC(8): C07C245/08
Inventor 丁克鸿许金来顾志强薛守兆龚连明牛鹏远茅爱梅
Owner JIANGSU YANGNONG CHEM GROUP
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