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Methyl 4-fluoro-5-hydroxy-2-nitrobenzoate

A technology of methyl nitrobenzoate and nitrobenzoic acid, which is applied in the field of preparation of methyl 4-fluoro-5-hydroxy-2-nitrobenzoate, can solve the problem of many side reactions and is not suitable for large-scale production , high energy consumption and other issues

Pending Publication Date: 2022-01-11
BAYECAO HEALTH IND RES INST (XIAMEN) CO LTD +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Although this method has high catalytic activity and is cheap and easy to obtain, it has the disadvantages of many side reactions, serious equipment corrosion, high energy consumption, and complicated treatment of reaction waste liquid. It is only suitable for a small amount of synthesis and is not suitable for large-scale production. scale production

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  • Methyl 4-fluoro-5-hydroxy-2-nitrobenzoate
  • Methyl 4-fluoro-5-hydroxy-2-nitrobenzoate
  • Methyl 4-fluoro-5-hydroxy-2-nitrobenzoate

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[0022] The invention provides a kind of preparation method of 4-fluoro-5-hydroxyl-2-nitrobenzoic acid methyl ester, comprising the following steps:

[0023] (1) Mix 4,5-difluoro-2-nitrobenzoic acid, an inorganic strong base and a polar solvent, and perform a substitution reaction to obtain 4-fluoro-5-hydroxyl-2-nitrobenzoic acid;

[0024] (2) Mix the 4-fluoro-5-hydroxyl-2-nitrobenzoic acid, methanol and a molecular sieve catalyst for esterification to obtain methyl 4-fluoro-5-hydroxyl-2-nitrobenzoate.

[0025] The invention mixes 4,5-difluoro-2-nitrobenzoic acid, inorganic strong base and polar solvent to carry out substitution reaction to obtain 4-fluoro-5-hydroxyl-2-nitrobenzoic acid. In the present invention, the strong inorganic base is preferably one or more of sodium hydroxide, potassium hydroxide, cesium hydroxide, lithium hydroxide and rubidium hydroxide. In the present invention, the molar ratio of the 4,5-difluoro-2-nitrobenzoic acid to the strong inorganic base is ...

Embodiment 1

[0053] (1) Synthesis of 4-fluoro-5-hydroxyl-2-nitrobenzoic acid

[0054]

[0055] 10 g of 4,5-difluoro-2-nitrobenzoic acid and 13 mL of water were added to the reaction kettle to form a suspension, and 20 mL of 30% NaOH aqueous solution was added dropwise. After the dropwise addition was completed, the mixture was heated to 80° C. for 30 minutes, and the reaction progress was monitored by TCL. Cool to room temperature after the reaction, adjust the pH to 1 with hydrochloric acid, extract with 25 mL of ethyl acetate, add 20 g of anhydrous sodium sulfate to dry the organic phase at the end of the extraction; perform rotary evaporation at 35 °C to remove the extractant to obtain a crude product. Recrystallize with 25 mL of toluene:cyclohexane (1:1) mixed solution to obtain 4-fluoro-5-hydroxy-2-nitrobenzoic acid. The yield was 95%, and the purity by HPLC was 99%.

[0056] The obtained 4-fluoro-5 hydroxy-2-nitrobenzoic acid 1 H-NMR picture as figure 1 shown.

[0057] (2) Sy...

Embodiment 2

[0062] (1) Synthesis of 4-fluoro-5-hydroxyl-2-nitrobenzoic acid

[0063]

[0064] Add 20g of 4,5-difluoro-2-nitrobenzoic acid and 30mL of methanol into the reaction kettle to mix, and add 40mL of 20% KOH aqueous solution dropwise. After the dropwise addition was completed, the mixture was heated to 85° C. for 20 minutes, and the reaction progress was monitored by TCL. Cool to room temperature after the reaction, adjust the pH to 3 with hydrochloric acid, extract with 70 mL of ethyl acetate, add 40 g of anhydrous magnesium sulfate to dry the organic phase after the extraction, and perform rotary evaporation at 37 ° C to remove the extractant to obtain a crude product. Recrystallize with 30 mL of toluene:cyclohexane (1:1) mixed solution to obtain 4-fluoro-5-hydroxy-2-nitrobenzoic acid. The yield was 93%, and the purity by HPLC was 98.6%.

[0065] (2) Synthesis of methyl 4-fluoro-5-hydroxy-2-nitrobenzoate

[0066]

[0067] Dissolve 15g of 4-fluoro-5-hydroxy-2-nitrobenzoi...

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Abstract

The invention provides a preparation method of methyl 4-fluoro-5-hydroxy-2-nitrobenzoate, belonging to the technical field of organic synthesis. The preparation method comprises the following steps: (1) mixing 4,5-difluoro-2-nitrobenzoic acid, inorganic strong base and a polar solvent, and carrying out a substitution reaction to obtain 4-fluoro-5-hydroxy-2-nitrobenzoic acid; and (2) mixing the 4-fluoro-5-hydroxy-2-nitrobenzoic acid, methanol and a molecular sieve catalyst, and carrying out an esterification reaction to obtain the methyl 4-fluoro-5-hydroxy-2-nitrobenzoate. The methyl 4-fluoro-5-hydroxy-2-nitrobenzoate obtained by using the method provided by the invention is relatively high in yield and purity, and is suitable for industrial production. The result of an embodiment shows that the yield of the methyl 4-fluoro-5-hydroxy-2-nitrobenzoate prepared by using the preparation method disclosed by the invention is 87.5 to 90 percent, and the purity of the methyl 4-fluoro-5-hydroxy-2-nitrobenzoate is 98.2 to 99.1 percent.

Description

technical field [0001] The invention relates to the technical field of organic synthesis, in particular to a preparation method of methyl 4-fluoro-5-hydroxy-2-nitrobenzoate. Background technique [0002] Methyl 4-fluoro-5-hydroxy-2-nitrobenzoate (C 8 h 6 FNO 5 ) is a widely used organic intermediate, mainly used in the pharmaceutical and dye industries. At present, the market supply of methyl 4-fluoro-5-hydroxy-2-nitrobenzoate is less, so there is an urgent need for new, efficient and green methods to prepare 4-fluoro-5-hydroxy-2-nitrobenzoic acid methyl ester. [0003] In the traditional preparation process of methyl 4-fluoro-5-hydroxy-2-nitrobenzoate, concentrated sulfuric acid, phosphoric acid, and p-toluenesulfonic acid are often used as catalysts to prepare the final product. Although this method has high catalytic activity and is cheap and easy to obtain, it has the disadvantages of many side reactions, serious equipment corrosion, high energy consumption, and com...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C201/12C07C205/59
CPCC07C201/12C07C205/59
Inventor 汤须崇赵应伟吴联浩曹丽平邓爱华
Owner BAYECAO HEALTH IND RES INST (XIAMEN) CO LTD
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