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Synthesis method of N-methyl-2-fluoroaniline

A synthesis method and technology of fluoroaniline, applied in the field of synthesis of N-methyl-2-fluoroaniline, can solve the problems of unfavorable industrial production, unfriendly environment, high cost, etc., achieve high selectivity, cheap and easy-to-obtain reaction raw materials, good quality effect

Active Publication Date: 2018-12-21
JIANGSU FLAG CHEM IND
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] Chinese patent CN 107973721A discloses a synthesis method of N-methyl-o-fluoroaniline, using o-fluoroaniline as a raw material, through two steps of enamination and hydrogenation The reaction obtains N-methyl o-fluoroaniline, but this method needs to use a metal catalyst, the cost is high, the environment is not friendly, and it is not conducive to industrial production

Method used

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  • Synthesis method of N-methyl-2-fluoroaniline
  • Synthesis method of N-methyl-2-fluoroaniline
  • Synthesis method of N-methyl-2-fluoroaniline

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Embodiment 1

[0024] Step 1, diazotization reaction

[0025] Add 27.8g of 2-fluoroaniline and 90g of 30% hydrochloric acid into a 250mL four-necked bottle, stir for 30min, place the system in an ice-salt bath to cool down to the internal temperature of -10°C, and dropwise add sodium nitrite solution (19g of sodium nitrite Dissolve in 50mL water), keep the internal temperature below 5°C, and drop it in about 1 hour; after the dropwise addition, keep it warm for 30 minutes and blow out the residual HCl with nitrogen, and the system is ready for use.

[0026] Step 2, methylation reaction

[0027] Heat 60 g of methylamine 40% aqueous solution to 50° C., add dropwise the above-prepared 2-fluoroaniline diazonium salt solution into the reaction flask, a large amount of gas is released, and the dropwise addition is completed in about 2 hours. After the dropwise addition, stir until the reaction is complete, about 30 minutes. After the reaction was completed, the organic solvent ethyl acetate (EA)...

Embodiment 2

[0029] Prepare the synthetic method of N-methyl-2-fluoroaniline with the method of embodiment 1, difference is:

[0030] Group A: In the step 1, before adding the sodium nitrite solution, the system was cooled to -15°C; the yield of N-methyl-2-fluoroaniline was 95%;

[0031] Group B: in the step 1, before adding the sodium nitrite solution, the system was cooled to -5°C; the yield of N-methyl-2-fluoroaniline was 88%;

[0032] Group C: in the step 1, before adding the sodium nitrite solution, the system was cooled to 0°C; the yield of N-methyl-2-fluoroaniline was 78%;

Embodiment 3

[0034] Prepare the synthetic method of N-methyl-2-fluoroaniline with the method of embodiment 1, difference is:

[0035] Group A: In the step 1, the temperature of the heat preservation reaction is: -10°C, and the reaction time is 2 hours; the yield of N-methyl-2-fluoroaniline is 94%;

[0036] Group B: In the step 1, the temperature of the heat preservation reaction is: 15° C., and the reaction time is 2 hours; the yield of N-methyl-2-fluoroaniline is 45% (GC yield);

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Abstract

The invention belongs to the technical field of organic synthesis and particularly relates to a synthesis method of N-methyl-2-fluoroaniline. The synthesis method comprises the following steps: step one, mixing 2-fluoroaniline with concentrated hydrochloric acid, adding a sodium nitrite solution and carrying out thermal reaction to obtain 2-fluoroaniline diazonium salt; step two, adding the 2-fluoroaniline diazonium salt into a methylamine aqueous solution, and carrying out thermal reaction and post treatment to obtain the N-methyl-2-fluoroaniline. According to the method, the N-methyl-2-fluoroaniline with high yield and high selectivity can be obtained by taking the 2-fluoroaniline as a raw material, carrying out diazotization reaction on the 2-fluoroaniline and then carrying out high temperature reaction on the methylamine aqueous solution and a reactant; reaction raw materials are cheap and easily obtained; the process is reasonable, advanced and feasible; the obtained N-methyl-2-fluoroaniline has the advantages of high purity, good quality and capability of being industrially produced on a large scale.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, in particular to a synthesis method of N-methyl-2-fluoroaniline. Background technique [0002] The monomethylation reaction of primary amines is widely used in organic synthesis, and the monomethylation reagents are also diverse. The classic method is the Eschweiler-clark methylation reaction, which is a reductive methylation reaction with formaldehyde and formic acid, in which formic acid is used as a reducing agent and a hydrogen donor. The reagents used in this method are cheap and easy to obtain, and the experimental operation is simple. However, after the secondary amine is formed in this reaction, it will continue to interact with HCOOH / HCHO, and then generate a tertiary amine compound, which makes it difficult to control the reaction in the monomethyl substitution stage. [0003] [0004] There is also the use of dimethyl sulfate as a methylation reagent, which is a relative...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C245/20C07C209/22C07C211/52
CPCC07C209/22C07C245/20C07C211/52
Inventor 陈文新张烽张棹然张璞王凤云侯远昌
Owner JIANGSU FLAG CHEM IND
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