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Preparation method of p-fluoroaniline

A technology for p-fluoroaniline and Raney nickel, which is applied in the field of preparation of p-fluoroaniline, can solve the problems of serious defluorination side reactions, defluorination side reactions, and high production costs, and achieves reduction of reaction temperature and reaction pressure, and reduction of defluorination. The formation of fluorine by-products, the effect of reducing the generation of waste water and waste residue

Active Publication Date: 2018-12-21
SHANGYU SUNFIT CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] When adopting two-step method to prepare p-fluoroaniline, the second step reaction is the reduction method of p-fluoronitrobenzene. In the early stage, iron powder is generally used for reduction. This method has high reduction efficiency, but it will produce a large amount of waste water and waste residue, which is not good for the environment. friendly
[0005] In recent years, there have been many literature reports that the method of metal-catalyzed hydrogenation is used to synthesize p-fluoroaniline. The catalyst used is generally Raney nickel for catalysis. There are two problems. First, the price of the catalyst is relatively expensive, the service life is not long enough, and the cost of industrial production is too high; second, under the condition of catalytic hydrogenation, the side reaction of defluorination will occur, especially under the condition of large feeding amount. Defluorination side reactions are more serious

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Add 2000g of p-fluoronitrobenzene, 5g of modified nickel catalyst and 3L of methanol into a 10L reactor, then replace with nitrogen and hydrogen for three times in sequence, and finally pressurize the hydrogen to 0.5MPa, and stir at 40°C for reaction. After 1 hour, it was filtered, the filter cake was washed with methanol, and 1520.8 g of the product was collected by distillation under reduced pressure, with a yield of 95.78%, a GC purity of 99.2%, and a defluorinated by-product of 0.06%.

[0024] Wherein, the preparation method of modified nickel catalyst is as follows:

[0025] (1) Slowly add 100 g of aluminum-nickel alloy (50:50) into 500 mL of aqueous solution containing 150 g of sodium hydroxide within 1 hour, stir while adding, and cool with an ice bath. After the addition, the reaction mixture was heated to 115-120° C. under stirring, and reacted for 3 hours until no foaming occurred. Then add 1L of water, pour out the supernatant after standing, and repeat thre...

Embodiment 2

[0028] Add 2000g of p-fluoronitrobenzene, 5g of modified nickel catalyst and 3L of methanol into a 10L reactor, then replace with nitrogen and hydrogen for three times in sequence, and finally pressurize the hydrogen to 0.5MPa, and stir at 40°C for reaction. After 1 hour, it was filtered, the filter cake was washed with methanol, and 1496.7 g of the product was collected by distillation under reduced pressure, with a yield of 91.8%, a GC purity of 96.6%, and a defluorinated by-product of 3.1%.

[0029] Wherein, the preparation method of modified nickel catalyst is as follows:

[0030] (1) Slowly add 100 g of aluminum-nickel alloy (50:50) into 500 mL of aqueous solution containing 150 g of sodium hydroxide within 1 hour, stir while adding, and cool with an ice bath. After the addition, the reaction mixture was heated to 115-120° C. under stirring, and reacted for 3 hours until no foaming occurred. Then add 1L of water, pour out the supernatant after standing, and repeat three ...

Embodiment 3

[0033] Add 2000g of p-fluoronitrobenzene, 5g of modified nickel catalyst and 3L of methanol into a 10L reactor, then replace with nitrogen and hydrogen for three times in sequence, and finally pressurize the hydrogen to 0.5MPa, and stir at 40°C for reaction. After 1 hour, it was filtered, the filter cake was washed with methanol, and 1505.3 g of the product was collected by distillation under reduced pressure, with a yield of 92.8%, a GC purity of 97.1%, and a defluorinated by-product of 2.2%.

[0034] Wherein, the preparation method of modified nickel catalyst is as follows:

[0035] (1) Slowly add 100 g of aluminum-nickel alloy (50:50) into 500 mL of aqueous solution containing 150 g of sodium hydroxide within 1 hour, stir while adding, and cool with an ice bath. After the addition, the reaction mixture was heated to 115-120° C. under stirring, and reacted for 3 hours until no foaming occurred. Then add 1L of water, pour out the supernatant after standing, and repeat three ...

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Abstract

The invention discloses a preparation method of p-fluoroaniline. The preparation method comprises the steps: under the catalysis of modified Raney nickel, a hydrogenation reduction reaction occurs ina hydrogen atmosphere in the p-fluoronitrobenzene, and after the reaction is finished, the p-fluoroaniline is obtained through post-treatment; the modified Raney nickel is Raney nickel modified by Moand Cr. The preparation method effectively reduces the occurrence of defluorination side reaction and improves the reaction yield by using the modified Raney nickel as a catalyst, and has industrial application prospects.

Description

technical field [0001] The invention belongs to the field of preparation of chemical intermediates, and in particular relates to a preparation method of p-fluoroaniline. Background technique [0002] P-Fluoroaniline is an important fine chemical product, mainly used in pharmaceutical, dyestuff and pesticide industries, for example, it can be used in the synthesis of plant growth regulators, herbicides, and various pharmaceutical intermediates. [0003] According to comprehensive literature reports, the synthesis method of p-fluoroaniline can be divided into one-step method and two-step method. The one-step method usually uses azidobenzene or N-phenylammonium hydroxide or p-chloronitrobenzene as raw materials to directly synthesize p-fluoroaniline through one-step reaction. The one-step method is limited by the source of raw materials or needs to use hydrofluoric acid, etc., so there is no industrialization report yet. The two-step method usually uses fluorobenzene or p-chl...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C209/36C07C211/52B01J25/02
CPCB01J25/02C07C209/36C07C211/52
Inventor 黄生建李文陈炯明李东平常鹏胡金铬梁旭华
Owner SHANGYU SUNFIT CHEM
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