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Preparation method of 2,4-difluoroacetophenone

A technology of difluoroacetophenone and difluoroaniline, applied in 2 fields, can solve problems such as difficult industrialization, difficult source of raw materials, harsh reaction conditions, etc.

Inactive Publication Date: 2012-07-04
SHANGHAI SINOFLUORO SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Method (1)~(3) raw material source is difficult, risk is big, and reaction condition is harsher, is difficult for industrialization; And method (4) is easier industrialization, but its small test yield only reaches about 42%

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] Add 660 g of water and 150 g of 98% sulfuric acid into the three-necked flask, then slowly add 129.4 g of 99.7% 2,4-difluoroaniline dropwise therein, stir evenly, make it fully salt, and then cool with a cold salt bath. Maintain the temperature between -5 and 5 degrees Celsius, add 138 g of 50% sodium nitrite solution dropwise to the reaction solution, and let it stir under this condition for 40 minutes after the addition, to make the diazotization reaction complete.

Embodiment 2

[0014] Add hydroxylamine hydrochloride and distilled water into a four-necked flask equipped with an electric stirrer, a thermometer, a condenser and a dropping funnel, stir and dissolve, add ammonia water to adjust the pH value to 4, and add acetaldehyde dropwise. During this process, the temperature must not be controlled. Over 25 degrees Celsius, after the dropwise addition, react at 20-25 degrees Celsius for about 1 hour, add ammonia water to adjust the pH value to 4, then add strong acid and weak base salt, distill the neutralized reaction product, collect 95-112 degrees Celsius Fraction (purity 96.2%). This cut is the acetaldehyde oxime needed later.

[0015] Add 120g of water, 16g of copper sulfate, and 25g of acetic acid into another three-necked bottle, and stir until completely dissolved. At room temperature, add 75g of the acetaldehyde oxime we just prepared, and stir for 10 minutes. It was slowly added dropwise into the diazotization reaction solution, and reacted...

Embodiment 3

[0017] Put the organic phase obtained in the previous example into a three-necked bottle, then add 130 g of water and 190 g of hydrochloric acid, heat and reflux at 90 to 95 degrees Celsius for 2 to 3 hours, control its pH at 5 to 6, cool to 40 to 45 degrees Celsius, and separate the organic phase. The phase was neutralized with 5% NaOH and washed with water to neutrality, the toluene was recovered by distillation under reduced pressure, and the fraction at 96 to 99 degrees Celsius was collected to obtain 2,4-difluoroacetophenone with a yield of 79% (with 2,4-difluoro Aniline), content 95%~99.2% " ethyl ketone, its reaction yield 79%.

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PUM

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Abstract

The invention provides a preparation method of 2,4-difluoroacetophenone. The 2,4-difluoroacetophenone is synthesized by using 2,4-difluoroaniline, acetaldoxime and copper sulfate; the pH is adjusted to 3-6 in a reacting process, and is preferably equal to 4; after a reaction, a product is distilled by using water vapor; and after benzene extraction, post-treatment is performed by using a reduced-pressure rectification method. Reaction conditions are mild, operation is simple, and the yield is high.

Description

technical field [0001] The invention relates to the field of fluorine chemical industry, in particular to a synthesis method of 2,4-difluoroacetophenone. Background technique [0002] 2,4-Difluoroacetophenone is an important pesticide and pharmaceutical intermediate, and aryl-alkyl ketones are usually synthesized by Friedel-Crafts reaction very conveniently. However, since this reaction belongs to the electrophilic reaction process, if there are substituent groups with strong electron-withdrawing effects such as nitro and fluorine groups on the aromatic ring, the Friedel-Crafts reaction cannot react. Before this paper, the synthetic methods of 2,4-difluoroacetophenone mainly include: (1) Grignard reaction of 2,4-difluorobenzocyanide and methyl iodide; (2) 2,4-difluorobenzoic acid through acid chloride Reaction of cadmium reagent with methyl iodide; (3) reaction of 2,4-difluorobenzaldehyde with diazomethane; (4) reaction of 2,4-difluorophenylbromobenzene with Grignard reagen...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C49/807C07C45/42
Inventor 闾肖波江静
Owner SHANGHAI SINOFLUORO SCI
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