Preparation method of 3-bromo-N, N-dimethylaniline

A technology of dimethylaniline and bromoaniline, which is applied in the field of preparation of 3-bromo-N,N-dimethylaniline, can solve the problems of not reaching the scale-up production stage, increasing cost expenditure, low atom utilization rate, etc., reaching Low cost, less waste, and high controllability

Pending Publication Date: 2022-06-03
BEIJING GREENCHEM TECH
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

The problem that this method exists is that the atom utilization rate is low, and the yield is too low, only about 25%
If you want to increase the yield, you must add a catalyst, which can increase the yield to about 85%, but it increases the cost, and the method is still in the laboratory stage and has not reached the scale-up production stage.

Method used

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  • Preparation method of 3-bromo-N, N-dimethylaniline
  • Preparation method of 3-bromo-N, N-dimethylaniline

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preparation example Construction

[0023] Specifically, the preparation method of 3-bromo-N,N-dimethylaniline of the present invention comprises: heating m-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 3-Bromo-N,N-dimethylaniline shown in (I).

[0024] 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

[0037] Add 1kg of industrial pure m-bromoaniline (commercially available) and 1.5L of mesitylene into the reaction flask, heat under stirring and control the temperature at 130~150°C, add 896g of trimethyl phosphate dropwise, and the dropwise addition ends. Then, under the condition of 140 ℃, stirring for 4h, dropping 20% ​​NaOH aqueous solution to adjust the pH to be alkaline, extracting with 0.5L dichloromethane, separating the dichloromethane phase, then carrying out the precipitation of the dichloromethane phase, and finally carrying out rectification 626 g of light yellow oily liquid was obtained, the calculated yield was 54.0%, and the purity of 3-bromo-N,N-dimethylaniline obtained by gas chromatography was 98.0%. The molar ratio of trimethyl phosphate to m-bromoaniline in the present embodiment is 1.1, which is less than 1.3, and the yield is low.

Embodiment 2

[0039] Add 1kg of industrial pure m-bromoaniline (commercially available) and 1.5L of mesitylene into the reaction flask, heat under stirring and control the temperature at 130~150℃, add 1.06kg of trimethyl phosphate dropwise, the reaction process Alleviate, after the dropwise addition is completed, stir at 140°C 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 desolvate the dichloromethane phase , and finally rectified to obtain 1.055kg of light yellow oily liquid, the calculated yield was 90.9%, and the purity of 3-bromo-N,N-dimethylaniline obtained by gas chromatography was 98.0%. figure 1It is the nuclear magnetic spectrum of 3-bromo-N,N-dimethylaniline prepared in Example 2. The molar ratio of trimethyl phosphate to m-bromoaniline in the present embodiment is 1.3, and the yield is higher.

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Abstract

The invention relates to a preparation method of 3-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 m-bromoaniline to prepare the 3-bromo-N, N-dimethylaniline. According to the preparation method disclosed by the invention, a high-yield and high-quality product is obtained, harsh reaction conditions of an existing process are avoided, the reaction conditions are mild, the safety is high, the controllability is high, the whole process is small in pollution, few in three wastes, few in side reaction, simple in post-treatment, easy in product separation, simple in process operation and low in cost, and the preparation method is particularly suitable for large-scale industrial production.

Description

technical field [0001] The invention relates to a preparation method of 3-bromo-N,N-dimethylaniline, and belongs to the technical field of organic synthesis. Background technique [0002] 3-Bromo-N,N-dimethylaniline is a kind of organic synthesis intermediate and pharmaceutical intermediate, mainly used in laboratory research and development process and chemical production process. At present, there are mainly two methods for preparing 3-bromo-N,N-dimethylaniline. The first one is obtained by methylation of m-bromoaniline under the conditions of formaldehyde, sulfuric acid and sodium borohydride. Although this method has high yield, the reaction conditions are harsh and the danger is high; at the same time, a large amount of three wastes are produced. The second preparation method uses m-bromoaniline as a raw material, uses methyl iodide as a methylating reagent, and obtains through methylation. The problem with this method is that the atom utilization rate is low and the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C211/52C07C209/22
CPCC07C209/22C07C211/52Y02P20/582
Inventor 宫宁瑞
Owner BEIJING GREENCHEM TECH
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