A method for preparing o-nitrobenzoic acid by oxidation of o-nitrotoluene with catalyst-free oxygen

A technology for o-nitrobenzoic acid and o-nitrotoluene, which is applied in the field of preparing o-nitrobenzoic acid by oxidation of o-nitrotoluene without catalyst with oxygen, can solve the problems of difficulty in catalyst synthesis, industrial application limitation, explosion danger and the like, and achieves low cost The effect of recycling, easy recycling, and easy production control

Active Publication Date: 2021-02-02
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage of this type of method is that the use of anhydrous methanol or methanol-benzene as a solvent, anhydrous methanol operating (reaction or distillation) under pure oxygen conditions has a potential explosion hazard, and methanol is very toxic to the optic nerve; In addition, benzene has great blood toxicity and neurotoxicity, which is a potential threat to the health of laboratory or industrial operators.
In the above public reports, metal metal phthalocyanines or metal porphyrins are required as catalysts. Due to the problems of low yield, difficult separation and purification, and the need to consume a large amount of organic solvents in the synthesis of such catalysts, their industrial applications are limited.
[0004] To sum up, whether it is the traditional chemical oxidation method, catalytic oxidation method, or biomimetic catalytic oxidation method, there are still problems such as heavy metal pollution, environmental pollution, or difficulty in the synthesis of catalysts, which limit its industrial application. Especially for heavy metal residue requirements and its strict pharmaceutical and food industry fields

Method used

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  • A method for preparing o-nitrobenzoic acid by oxidation of o-nitrotoluene with catalyst-free oxygen

Examples

Experimental program
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Effect test

Embodiment 1

[0024]Example 1: Take o-nitrotoluene (823mg, 6mmol), sodium hydroxide (1.8g, 45mmol), put them into a 100ml autoclave, add 10ml methanol; after filling with oxygen three times, pass oxygen (pressure 1.8MPa), React in an oil bath at 25°C for 24h. After the reaction, methanol was added to dilute, the pH value of the reaction mixture was neutralized to 2-3, most of the solvent was removed under reduced pressure, ethyl acetate was added, and then dried and filtered. After chromatographic column separation, 263 mg (1.92 mmol) of o-nitrotoluene was recovered, the conversion rate of o-nitrotoluene was 68%, 130 mg (0.78 mmol) of o-nitrobenzoic acid was obtained, and the yield was 13%.

Embodiment 2

[0025]Example 2: Take o-nitrotoluene (823mg, 6mmol), sodium hydroxide (1.8g, 45mmol), put them into a 100ml autoclave, add 10ml methanol; after filling with oxygen three times, pass oxygen (pressure 1.8MPa), React in an oil bath at 40°C for 6h. After the reaction, methanol was added to dilute, the pH value of the reaction mixture was neutralized to 2-3, most of the solvent was removed under reduced pressure, ethyl acetate was added, and then dried and filtered. After chromatographic column separation, 247 mg (1.86 mmol) of o-nitrotoluene was recovered, the conversion rate of o-nitrotoluene was 69%, and 211 mg (1.26 mmol) of o-nitrobenzoic acid was obtained, and the yield was 21%.

Embodiment 3

[0026]Example 3: Take o-nitrotoluene (823mg, 6mmol), sodium hydroxide (1.8g, 45mmol), put them into a 100ml autoclave, add 10ml methanol, fill with oxygen three times, and then pass oxygen (pressure 1.8MPa). The reaction was carried out at 40°C for 24h in an oil bath. After the reaction, methanol was added to dilute, the pH value of the reaction mixture was neutralized to 2-3, most of the solvent was removed under reduced pressure, ethyl acetate was added, and then dried and filtered. After chromatographic column separation, 140 mg (1.02 mmol) of o-nitrotoluene was recovered, the conversion rate of o-nitrotoluene was 83%, and 401 mg (2.4 mmol) of o-nitrobenzoic acid was obtained, with a yield of 40%.

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Abstract

The invention discloses a method for preparing o-nitrobenzoic acid by oxidizing o-nitrotoluene with oxygen without a catalyst, and relates to a preparation method of o-nitrobenzoic acid. Under the condition of not adding any catalyst, take o-nitrotoluene as raw material, oxygen as oxidant, sodium hydroxide as alkali, reaction temperature is 25-85°C, react in solvent alcohol or its aqueous solution for 5-72 hours, after Treatment, separation and purification to obtain the o-nitrobenzoic acid. The method does not need a catalyst; the price of raw materials and solvents is low; and the reaction temperature is moderate; the production control is easy, the yield can be as high as 90%, and it is suitable for mass preparation and industrialization, and has broad application prospects.

Description

Technical field[0001]The invention relates to a preparation method of o-nitrobenzoic acid, in particular to a method for preparing o-nitrobenzoic acid by oxidation of o-nitrotoluene with oxygen without a catalyst.Background technique[0002]O-nitrobenzoic acid is an important organic synthesis intermediate, which is widely used in dyes, medicine, food, organic synthesis and other fields. At present, the methods for synthesizing o-nitrobenzoic acid are mainly potassium permanganate oxidation method, sodium dichromate oxidation method, NaClO oxidation method, nitric acid oxidation method or the addition of other transition metals and noble metal catalyst oxidation methods (Letters in Drug Design & Discovery, 2013, 10,369; Applied Organometallic Chemistry, 2015,29,276; Tetrahedron, 2012,68,9763; Catalysis Communications, 2012,27,124; Hangzhou Chemical Industry, 1996.2.44), the oxidants used in these methods are mostly high-valent manganese, chromium or chlorate. There are serious environ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C201/12C07C205/57
CPCC07C201/12C07C205/57
Inventor 佘远斌方坤李贵杰付海燕
Owner ZHEJIANG UNIV OF TECH
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