Preparation method of 2-bromo-N, N-dimethylaniline

A technology of dimethylaniline and o-bromoaniline, which is applied in the field of preparation of 2-bromo-N,N-dimethylaniline, can solve the problems of not reaching the scale-up production stage, low atom utilization rate, and increased cost expenditure. Achieve the effect of improving atom utilization rate, low cost and increasing yield

Pending Publication Date: 2022-06-10
BEIJING GREENCHEM TECH
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  • Abstract
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  • Application Information

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Problems solved by technology

However, this method has low atom utilization, high cost, and very low yield, only about 20%.
If you want to increase the yield, you must add additional catalysts, which can increase the yield to about 80%, but it increases the cost, and the method is still in the laboratory stage and has not reached the scale-up production stage

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  • Preparation method of 2-bromo-N, N-dimethylaniline
  • Preparation method of 2-bromo-N, N-dimethylaniline

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preparation example Construction

[0024] Specifically, the preparation method of 2-bromo-N,N-dimethylaniline of the present invention comprises: heating o-bromoaniline and mesitylene under stirring and controlling the temperature at 130-150° C., adding trimethyl phosphate dropwise , after the dripping is completed, after the incubation reaction for 3 to 6 hours, add an alkaline aqueous solution dropwise to the reaction solution to adjust the pH to be alkaline, extract with an extractant, separate the extractant, carry out desolvation of the extractant, and finally carry out rectification to obtain the formula 2-Bromo-N,N-dimethylaniline shown in (I).

[0025] The present invention uses mesitylene as the solvent of the methylation reaction, which can greatly reduce the violent exothermic phenomenon in the reaction process, effectively reduce the reaction temperature, and make the reaction milder. The reason may be that a large amount of The heat of reaction can be diluted by mesitylene, and the diluted heat is ...

Embodiment 1

[0038] 1kg of industrial pure o-bromoaniline (commercially available) and 1kg of mesitylene were added to the reaction flask, heated under stirring and temperature-controlled at 130~150 ℃, drip the trimethyl phosphate of 814g, after the dripping finishes. , under the condition of 140 ℃, stir for 4h, drop 20% NaOH aqueous solution to adjust the pH to be alkaline, extract with 0.5L dichloromethane, separate the dichloromethane phase, then carry out the precipitation of the dichloromethane phase, and finally carry out rectification to obtain The light yellow oily liquid was 569 g, the calculated yield was 49.1%, and the purity of 2-bromo-N,N-dimethylaniline obtained by gas chromatography was 98.0%. The molar ratio of trimethyl phosphate to o-bromoaniline in the present embodiment is 1, which is less than 1.5, and the yield is low.

Embodiment 2

[0040]Add 1kg of industrial pure o-bromoaniline (commercially available) and 1kg of mesitylene into the reaction flask, heat under stirring and control the temperature at 130~150°C, add 1.63kg of trimethyl phosphate dropwise, and the reaction process is relaxed , after the dropwise addition, under the condition of 140 ℃, stir for 4h, drop 20% NaOH aqueous solution to adjust the pH to be alkaline, extract with 0.5L dichloromethane, separate the dichloromethane phase, and then carry out the precipitation of the dichloromethane phase, Finally, rectification was carried out to obtain 938 g of light yellow oily liquid, the calculated yield was 80.9%, and the purity of 2-bromo-N,N-dimethylaniline obtained by gas chromatography was 98.0%. figure 1 It is the nuclear magnetic spectrum of 2-bromo-N,N-dimethylaniline prepared in Example 2. The molar ratio of trimethyl phosphate and o-bromoaniline in the present embodiment is 2, and the yield is higher.

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Abstract

The invention relates to a preparation method of 2-bromo-N, N-dimethylaniline, which is characterized in that mesitylene is used as a reaction solvent to participate in methylation reaction of trimethyl phosphate and o-bromaniline to prepare the 2-bromo-N, N-dimethylaniline. The use of bromine is avoided, and the whole process is small in pollution; the side reaction is few, the post-treatment is simple, the product is easy to separate, and the process operation is simple; meanwhile, compared with a bromination method under the condition of single bromine in the prior art, the yield is increased by 3 times, the yield is high, the product purity is high, the cost is lower, the reaction condition is mild, the controllability is high, the safety is high, and the method is particularly suitable for large-scale industrial production.

Description

technical field [0001] The invention relates to a preparation method of 2-bromo-N,N-dimethylaniline, and belongs to the technical field of organic synthesis. Background technique [0002] 2-Bromo-N,N-dimethylaniline is an important intermediate in the synthesis of mifepristones. At present, there are mainly two methods for preparing 2-bromo-N,N-dimethylaniline. The first one is obtained by bromination with N,N-dimethylaniline as raw material. The reaction conditions of this method are harsh and dangerous, and it is applied to the second type of precursor chemical, bromine. Due to the nature of bromine itself, the process is highly toxic, causing serious harm to the human body and high requirements for equipment. The second preparation method takes o-bromoaniline as a raw material, uses methyl iodide as a methylating reagent, and obtains a product through methylation. However, this method has low atom utilization, high cost, and very low yield, only about 20%. If you wan...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C209/16C07C211/52
CPCC07C209/16C07C211/52
Inventor 宫宁瑞
Owner BEIJING GREENCHEM TECH
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