P-chloroaniline hydrochloride preparation method

A technology of chloroaniline hydrochloride and p-chloronitrobenzene, which is applied in the field of preparation of p-chloroaniline hydrochloride, can solve the problems of hydrogenation tank corrosion, low yield, low yield of hydrogenation reaction, etc. Mild and controllable conditions, simple operation and post-treatment, and the effect of inhibiting the formation of dechlorinated substances

Inactive Publication Date: 2019-11-19
辽宁顺通化工股份有限公司
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AI Technical Summary

Problems solved by technology

[0009] But still have the generation of part dechlorination thing (aniline), cause hydrogenation reaction yield on the low side, crude product purity is not up to standard (crude product purity about 90%), in addition, along with the generation of dechlorination side reaction, with dechlorination thing ( Aniline) and the generation of additional by-product HCl, which will cause certain corrosion to the hydrogenation tank
[0010] 2) In order to improve the purity of the prepared p-chloroaniline, the crude product p-chloroaniline needs to be further purified, and the purification of the existing crude product p-chloroaniline (purity about 90%) needs to be realized by rectification and purification in a ten-meter-high rectification tower, The purification operation of the rectification tower is complicated, the yield is low, waste of energy and man-hours, which virtually complicates the production process
The water content of concentrated hydrochloric acid is generally about 64%, and p-chloroaniline hydrochloride is very soluble in water. During the post-treatment process of the traditional industrial production process of p-chloroaniline hydrochloride, it is concentrated until a small amount of water remains in the later stage and remains p-chloroaniline hydrochloride. Salt has bigger solubility, causes product yield (yield is about 85%) on the low side

Method used

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Examples

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preparation example Construction

[0051] 1.5 Preparation of p-chloroaniline sample solution

[0052] Weigh 25mg of p-chloroaniline into a 25mL brown volumetric flask, add methanol to dissolve and dilute to the mark, mix well, oscillate in an ultrasonic generator, fully dissolve, and set aside.

[0053] 1.6 Determination steps

[0054] Turn on the chromatograph. After the operating conditions of the instrument are stable, use a micro-syringe to draw 5 μL of the sample solution and inject it into the injection valve. After the last component has flowed out, use a chromatographic workstation or an integrator to process the results.

[0055] 1.7 Calculation of results

[0056] The mass fraction of p-chloroaniline and the content of organic impurities are expressed in wi Calculated according to formula (1):

[0057]

[0058] where:

[0059] A i - the peak area of ​​p-chloroaniline and related impurities in the sample solution;

[0060] ∑A i - The sum of the peak areas of p-chloroaniline and related impuri...

Embodiment 1

[0109] The preparation method of embodiment 1 p-chloroaniline hydrochloride

[0110] Into a 1L autoclave, add 400 mL of toluene, 200 g of p-chloronitrobenzene, 0.6 g of 1% platinum carbon wet product (0.2 g dry basis, 66.7% moisture content of the wet product), 0.02 g of dicyandiamide, and 0.8 g of ammonia water. The autoclave was evacuated for 10 minutes, and the air was replaced by nitrogen for three times, and the nitrogen was replaced by hydrogen for three times. Then absorb hydrogen, cool the reaction solution to below 60°C, replace the hydrogen with nitrogen, filter out the catalyst (to be applied mechanically), collect the filtrate into a 1L reaction flask, add 2g of activated carbon for decolorization, add 212g of concentrated hydrochloric acid to the filtrate, and warm the reaction solution to 90 ℃ of insulation reaction for 1 hour, continued to raise the temperature to 100 ℃, refluxed through a water separator, and toluene with water until no more water was separated...

Embodiment 2

[0111] The preparation method of embodiment 2 p-chloroaniline hydrochloride

[0112] To the 100L autoclave, add 40L of toluene, 20kg of p-chloronitrobenzene, 60g of 1% platinum carbon wet product (20g dry basis, 66.7% moisture content of the wet product), 2g of dicyandiamide, 80g of ammonia water, closed the autoclave, pumped Vacuum for 10 minutes, introduce nitrogen to replace the air three times, continue to introduce hydrogen to replace the nitrogen three times, control the pressure of hydrogen to be introduced to 1.0 MPa, raise the temperature of the reaction solution to 90-100 ° C for hydrogenation reaction for 6 hours until the reaction solution no longer absorbs hydrogen, Cool the reaction solution to below 60°C, replace the hydrogen with nitrogen, filter the catalyst with nitrogen pressure filtration, collect the filtrate into a 100L enamel reaction kettle, add 200g of activated carbon for decolorization, add 21.2kg of concentrated hydrochloric acid to the filtrate, and...

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Abstract

The invention provides a p-chloroaniline hydrochloride preparation method, which comprises: in the presence of an organic solvent azeotropic with water, using p-chloronitrobenzene as a starting raw material, adding anti-dehalogenation agent and an acid binding agent, sealing, introducing hydrogen gas, carrying out a hydrogenation reaction under the catalysis of a platinum-carbon catalyst at a hightemperature under a high pressure, cooling, filtering to remove the catalyst, collecting the filtrate, adding concentrated hydrochloric acid to the filtrate, carrying out thermal insulation for 0.5-2h at a temperature of 80-95 DEG C, continuously heating to achieve a boiling state, refluxing by a water separator until no water is separated, filtering, and drying to obtain p-chloroaniline hydrochloride. According to the present invention, the preparation method has characteristics of mild and controllable reaction conditions, simple operation and low cost, performs the two steps through the one-pot method, and provides the advanced preparation method for industrial production.

Description

technical field [0001] The invention belongs to the field of synthesis of pharmaceutical intermediates, in particular to a preparation method of p-chloroaniline hydrochloride. Background technique [0002] p-Chloroaniline hydrochloride is an important organic chemical raw material and intermediate, and plays an important role in the fields of medicine, dyes, pesticides, rubber additives, synthetic resins, spices, photography, etc. [0003] p-Chloroaniline is generally prepared by reduction of p-chloronitrobenzene, the reaction equation is as follows: [0004] [0005] The reduction methods of nitro group mainly include iron powder reduction method, alkali sulfide reduction method, hydrazine hydrate reduction method and catalytic hydrogenation reduction method. The iron powder reduction method has the characteristics of relatively mature technology, easy production control, and few side reactions. It is the main method for producing p-chloroaniline, but there are difficul...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C209/00C07C209/86C07C211/52
CPCC07C209/00C07C209/365C07C209/86C07C211/52
Inventor 何镭李可军包万仁范德军李权赵立峰
Owner 辽宁顺通化工股份有限公司
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