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Preparation method of p-anisidine

A technology for p-aminoanisole and p-nitroanisole, which is applied in the field of preparation of p-aminoanisole, can solve the problems of large amount of solvent methanol, difficult temperature control, increase of by-products and the like, and achieves an increase in the production capacity of a single kettle , The effect of the substrate reaction is complete and the daily production capacity is improved

Pending Publication Date: 2021-06-25
宁夏华御化工有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] In view of this, the present invention provides a kind of preparation method of p-aminoanisole, in order to solve the production process of p-aminoanisole existing in the prior art, solvent methanol consumption is large, the production capacity that causes is limited, temperature is difficult to control, Technical issues with increased by-products

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  • Preparation method of p-anisidine

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preparation example Construction

[0025] In a specific embodiment, a method for preparing p-aminoanisole comprises using p-nitroanisole as a raw material and performing hydrogenation in a hydrogenation kettle to prepare p-aminoanisole. Include the following steps:

[0026] S11. Add methanol and catalyst, and under the protection of inert gas, add methanol, catalyst and co-catalyst to the hydrogenation tank.

[0027] Under the protection of inert gas, preferably nitrogen, add methanol, catalyst and cocatalyst to the hydrogenation tank. The dosage of methanol is 1 / 12 to 2 / 5 of the maximum allowable liquid level of the hydrogenation tank. The catalyst is one of Pd-C catalyst, supported nickel catalyst or Raney nickel catalyst. The dosage of catalyst is: start The dosage of the first tank of production is 0.15 to 0.75 times of the theoretical mass of methanol, and the later production is supplemented according to the actual loss of the catalyst.

[0028] It is worth noting that before adding methanol and catalys...

Embodiment 1

[0053] Add methanol, catalyst and co-catalyst to the hydrogenation tank first. The amount of methanol added is 1 ton, the amount of catalyst (Raney-Ni) added is 80 kg, and the amount of co-catalyst added is 0.1 kg. After nitrogen replacement and hydrogen replacement to remove oxygen, the pressure was maintained at 1.0 MPa, the temperature was raised to 50 °C, and the catalyst was activated for 1 h. Add p-nitroanisole to the hydrogenation tank at a flow rate of 1.5 t / h, and carry out hydrogenation reaction at a hydrogen pressure of 1.2 MPa and a reaction temperature of 80 °C until the liquid level of the hydrogenation tank reaches 60% , stop adding p-nitroanisole, and carry out sampling analysis, until the content of p-nitroanisole in the reaction solution≤0.05%, the reaction is terminated. After the hydrogenation reaction is completed, the material is cooled and discharged, and the carried catalyst is removed by filtration, and methanol is distilled off to obtain p-aminoanisol...

Embodiment 2

[0055] Add methanol, catalyst and co-catalyst to the hydrogenation tank first. The amount of methanol added is 2 t, the amount of catalyst (Raney-Ni) added is 80 kg, and the amount of co-catalyst added is 0.1 kg. After nitrogen replacement and hydrogen replacement to remove oxygen, the pressure was maintained at 1.0 MPa, the temperature was raised to 50 °C, and the catalyst was activated for 1 h. Add p-nitroanisole to the hydrogenation tank at a flow rate of 1.8 t / h, and carry out hydrogenation reaction at a hydrogen pressure of 1.2 MPa and a reaction temperature of 80 °C until the liquid level of the hydrogenation tank reaches 60% , stop adding p-nitroanisole, and carry out sampling analysis, until the content of p-nitroanisole in the reaction solution≤0.05%, the reaction is terminated. After the hydrogenation reaction is completed, the material is cooled and discharged, and the carried catalyst is removed by filtration, and methanol is distilled off to obtain p-aminoanisole....

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Abstract

The invention provides a preparation method of p-anisidine, and belongs to the technical field of chemical synthesis. The method comprises the following steps: firstly, adding a predetermined amount of methanol and a catalyst into a hydrogenation kettle, replacing, removing oxygen and activating the catalyst, and dropwise adding a raw material p-nitroanisole into the hydrogenation kettle at a predetermined hydrogen pressure and a predetermined reaction temperature to carry out a hydrogenation reaction. According to the method, in the process of reducing the use amount of methanol and dropwise adding p-nitroanisole for hydrogenation reaction, the concentration of p-nitroanisole in a hydrogenation kettle is always kept at a lower level, the solvent and the catalyst are sufficient, p-aminoanisole which is continuously generated is utilized to play a role of the solvent, the substrate reaction is more thorough, the reaction time is greatly shortened, and the generation amount of byproducts is reduced. Experiments show that the single-kettle hydrogenation reaction time is shortened by 30%-47%, the single-kettle productivity can be improved by 33%-97%, meanwhile, the single-kettle reaction time is shortened, the daily productivity can be improved by 77%-125%, and the purity of p-anisidine in the product reaches 99.3%-99.7%.

Description

technical field [0001] The invention relates to the technical field of chemical synthesis, in particular to a preparation method of p-aminoanisole. Background technique [0002] P-aminoanisole has great application value in the fields of dyes, medicines, spices, etc. The traditional industrial preparation method of p-aminoanisole is to use sodium sulfide, iron powder, etc. as reducing agents, and p-nitroanisole For raw materials, reduction reaction in the system. This method has problems such as low raw material utilization rate, large amount of three wastes, long production cycle, and cumbersome post-processing. [0003] As an environmentally friendly and efficient technology, hydrogenation reduction has been widely used. Since the hydrogenation process uses hydrogen as a reducing agent, metal nickel as a catalyst, and methanol as a solvent for the reaction, the reduction products are only p-aminoanisole and water, and the amount of three wastes is greatly reduced, and th...

Claims

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Application Information

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IPC IPC(8): C07C213/02C07C213/10C07C217/84
CPCC07C213/02C07C213/10C07C217/84Y02P20/584
Inventor 顾家立顾行祥徐麟
Owner 宁夏华御化工有限公司
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