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Synthesis method of N-methyl o-fluoroaniline

A technique for the synthesis of methyl o-fluoroaniline, which is applied in the preparation of pharmaceutical intermediates and the field of pesticides, can solve problems such as poor selectivity, poor product quality, and difficult separation, and achieve high selectivity, good product quality, and low output of three wastes Effect

Active Publication Date: 2021-05-28
JIANGSU FLAG CHEM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method involves a diazotization reaction, uses a large amount of concentrated hydrochloric acid, and has extremely strict temperature requirements of -15 to -10°C. Once the reaction temperature is too high, a large amount of organic tar will be produced, and a large amount of acidic wastewater will be produced, and the intermediate Difficult to preserve, directly affects the yield and quality of the methylated product in the next step
[0013]The above five routes belong to the methylation reaction, but they have a common disadvantage, which is poor selectivity and the content of N,N-dimethyl-o-fluoroaniline as a by-product Higher, leading to separation difficulties or poorer product quality

Method used

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  • Synthesis method of N-methyl o-fluoroaniline
  • Synthesis method of N-methyl o-fluoroaniline
  • Synthesis method of N-methyl o-fluoroaniline

Examples

Experimental program
Comparison scheme
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Embodiment 1

[0028] Add 100 g of dimethyl carbonate, 15 g (0.1351 mol) of o-fluoroaniline, and 0.75 g of alkaline montmorillonite catalyst into a 250 ml reaction bottle, stir and heat up to reflux under normal pressure, and the reflux time is 10 to 15 hours. The reaction process was followed by GC until the disappearance of the raw materials, and the reaction was considered to be over. Afterwards, the material was cooled to room temperature and filtered to remove the catalyst. The filtrate was rectified by a 20-30cm rectification column under normal pressure, and the main fraction at 85°C-88°C was collected to obtain 16.03g of N-methyl-o-fluoroaniline with a GC purity of 98.79%. The yield after rectification is 96.89%, and the by-product N,N-dimethyl-o-fluoroaniline is 0.21%.

Embodiment 2

[0030] Add 100 g of dimethyl carbonate, 15 g (0.1351 mol) of o-fluoroaniline, and 1.5 g of alkaline montmorillonite catalyst into a 250 ml reaction bottle, stir and heat up to reflux under normal pressure, and the reflux time is 10 to 15 hours. The reaction process was followed by GC until the disappearance of the raw materials, and the reaction was considered to be over. Afterwards, the material was cooled to room temperature and filtered to remove the catalyst. The filtrate passed through a 20-30 cm rectification column, rectified under normal pressure, and collected the main fraction at 85-88 ° C to obtain 16.21 g of N-methyl-o-fluoroaniline with a GC purity of 98.95%. The yield after distillation is 97.97%, and the by-product N,N-dimethyl-o-fluoroaniline is 0.15%.

Embodiment 3

[0032] Add 100 g of dimethyl carbonate, 15 g (0.1351 mol) of o-fluoroaniline, and 1.00 g of alkaline kaolin as a catalyst into a 250 ml reaction flask, stir and heat up to reflux under normal pressure, and the reflux time is 10 to 15 hours. The reaction process was followed by GC until the disappearance of the raw materials, and the reaction was considered to be over. Afterwards, the material was cooled to room temperature and filtered to remove the catalyst. The filtrate passed through a 20-30cm rectification column, rectified at normal pressure, and collected the main fraction at 85-88°C to obtain 16.59g of N-methyl-o-fluoroaniline with a GC purity of 98.53%. The yield after distillation is 96.2%, and the by-product N,N-dimethyl-o-fluoroaniline is 1.17%.

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Abstract

The invention relates to the field of preparation of pesticide and medical intermediates, and in particular, relates to a preparation method of N-methyl o-fluoroaniline, wherein the preparation method comprises the following steps: by taking o-fluoroaniline as a raw material and dimethyl carbonate as a reaction raw material and a reaction solvent, carrying out heat preservation reaction under the action of a basic catalyst; and after the reaction is finished, filtering to remove the catalyst, carrying out rectification separation on filtrate, and separating the solvent dimethyl carbonate from the product. Compared with the prior art, the novel synthesis method of N-methyl o-fluoroaniline provided by the invention has the following effective effects: only one-step reaction is needed, the selectivity is extremely high, the product quality is good, the selected methylation reagent dimethyl carbonate is low in toxicity, green and safe, the output of three wastes is low, and the novel synthesis method of N-methyl o-fluoroaniline is a green chemical process with extremely competitive power.

Description

technical field [0001] The invention belongs to the field of preparation of pesticides and pharmaceutical intermediates, in particular to a method for synthesizing N-methyl-o-fluoroaniline. Background technique [0002] N-methyl-o-fluoroaniline belongs to fluorine-containing N-alkylarylamines. It is a very important organic raw material and fine chemical intermediate, widely used in the fields of fuel, plastics, medicine and pesticides. With the continuous development of the dye and rubber industries, the dosage of pesticides and medicines has been increasing, and the demand for N-methyl-o-fluoroaniline has grown rapidly, and the corresponding synthesis development has also attracted much attention. [0003] Specifically, there are many synthetic methods for N-methyl-o-fluoroaniline, which can be divided into the following according to different reaction routes: [0004] ① Patent No. CN107973721A discloses a kind of o-fluoroaniline as raw material, adding toluene, paraforma...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C209/18C07C211/52
CPCC07C209/18C07C211/52Y02P20/584
Inventor 张璞王豪吴耀军陈文新张烽侯远昌
Owner JIANGSU FLAG CHEM IND