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Preparation method of 2-fluoro-3-nitrobenzoic acid

A technology of nitrobenzoic acid and fluoronitrobenzene, which is applied in the field of preparation of 2-fluoro-3-nitrobenzoic acid, can solve the problems of poor selectivity and low yield, achieve mild reaction conditions, high yield, Effects suitable for large-scale preparation

Pending Publication Date: 2021-12-31
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The reaction has poor selectivity, other by-products appear in the nitration process, and the yield is low
[0007] Lithium diisopropylamide (LDA) used in the present invention is a stable organometallic compound, widely used as a non-nucleophilic base in organic synthesis, so far, utilizing LDA to promote 2-fluoronitrobenzene The reaction for the synthesis of 2-fluoro-3-nitrobenzoic acid has not been reported

Method used

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  • Preparation method of 2-fluoro-3-nitrobenzoic acid
  • Preparation method of 2-fluoro-3-nitrobenzoic acid
  • Preparation method of 2-fluoro-3-nitrobenzoic acid

Examples

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Effect test

Embodiment 1

[0024] In a 250ml three-necked flask, dissolve 2-fluoronitrobenzene (1.41g, 0.01mol) in 2-methyltetrahydrofuran (100ml), replace it with a nitrogen atmosphere, and start to lower the temperature. When the temperature is -30°C, start A mixed solution of lithium diisopropylamide (2.14g, 0.02mol) and 2-methyltetrahydrofuran (40ml) was added dropwise. After the dropwise addition, the reaction was continued at this temperature for 6h. After the reaction was completed, under a nitrogen atmosphere, Dry ice (2.2 g, 0.05 mol) was added quickly to quench and stirring was continued for 2 h. Then the reaction liquid was naturally returned to room temperature, and the solvent was removed in vacuo, and 30 ml of water was added to the obtained residue, and the pH of the aqueous phase was adjusted to 2 with concentrated hydrochloric acid, and then extracted with ethyl acetate (30 ml×3). The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, filtere...

Embodiment 2

[0027] In a 250ml three-necked flask, dissolve 2-fluoronitrobenzene (1.41g, 0.01mol) in tetrahydrofuran (100ml), replace it with a nitrogen atmosphere, and start to lower the temperature. When the temperature is at -80°C, start to add diiso A mixed solution of lithium propylamide (8.57g, 0.08mol) and tetrahydrofuran (40ml) was added dropwise, and the reaction was continued at this temperature for 8h. After the reaction was completed, dry ice (2.2g, 0.05 mol), quenched and continued to stir for 2h. Then the reaction liquid was naturally returned to room temperature, and the solvent was removed in vacuo, and 30 ml of water was added to the obtained residue, and the pH of the aqueous phase was adjusted to 2 with concentrated hydrochloric acid, and then extracted with ethyl acetate (30 ml×3). The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, filtered with suction, and concentrated to obtain 1.64 g of 2-fluoro-3-nitrobenzoic acid wi...

Embodiment 3

[0029] In a 250ml three-necked flask, dissolve 2-fluoronitrobenzene (1.41g, 0.01mol) in ether (100ml), replace it with a nitrogen atmosphere, and then start to lower the temperature. When the temperature is at -80°C, start to drop tert-butyl Lithium (3.84g, 0.06mol) and ether (40ml) mixed solution, after the dropwise addition, continue to react at this temperature for 2h, after the reaction, under nitrogen atmosphere, quickly add dry ice (2.2g, 0.05mol) , was quenched and continued to stir for 2h. Then the reaction liquid was naturally returned to room temperature, and the solvent was removed in vacuo, and 30 ml of water was added to the obtained residue, and the pH of the aqueous phase was adjusted to 2 with concentrated hydrochloric acid, and then extracted with ethyl acetate (30 ml×3). The organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, filtered with suction, and concentrated to obtain 0.96 g of 2-fluoro-3-nitrobenzoic acid wi...

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Abstract

The invention discloses a preparation method of 2-fluoro-3-nitrobenzoic acid (II), which comprises the following steps: carrying out fluorine ortho-lithiation, dry ice carbonyl insertion reaction and acidic hydrolysis on 2-fluoronitrobenzene (I) by utilizing lithium diisopropylamide or tert-butyl lithium under a low-temperature condition to prepare the target product 2-fluoro-3-nitrobenzoic acid. The method has the advantages of mild reaction conditions, no need of transition metal catalysis, good selectivity, high yield, simple and efficient process, environmental protection, economy and suitableness for large-scale preparation;.

Description

technical field [0001] The invention relates to a preparation method of 2-fluoro-3-nitrobenzoic acid. Background technique [0002] 2-Fluoro-3-nitrobenzoic acid is an important synthetic intermediate raw material, which is widely used in the fields of pesticides and medicine, and can be used to synthesize drugs such as benzenesulfonamide thiazoles, quinolone derivatives and active biological enzymes. [0003] The synthetic method of the 2-fluoro-3-nitrobenzoic acid of literature report at present mainly comprises: [0004] (1) Use 2-fluoro-3-nitrotoluene as raw material to synthesize 2-fluoro-3-nitrobenzoic acid by direct oxidation of chromium trioxide and sulfuric acid system. The chromium trioxide used in this method has high environmental toxicity and is a non-environmentally friendly method. [0005] (2) Using o-cresol as raw material, nitrate to generate 2-methyl-6-nitrophenol, hydroxychloride to generate 2-chloro-3-nitrotoluene, and then fluorinate to generate 2-fluo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C201/12C07C205/58
CPCC07C201/12C07F1/02C07C205/58
Inventor 张国富韩泽伟丁成荣吕井辉
Owner ZHEJIANG UNIV OF TECH
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