A kind of method for preparing p-nitrobenzoic acid by oxygen oxidation of p-nitrotoluene without catalyst

Abstract

The invention discloses a method for preparing p-nitrobenzoic acid by oxidizing p-nitrotoluene with oxygen without catalyst, and relates to a preparation method of p-nitrobenzoic acid. Under the condition of not adding any catalyst, use p-nitrotoluene as raw material, 0.1-2.0MPa oxygen as oxidant, sodium hydroxide as alkali, reaction temperature is 25-65°C, react in alcohol or its aqueous solution, after post-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 is as high as over 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 p-nitrobenzoic acid, in particular to a method for preparing p-nitrobenzoic acid by oxygen oxidation of p-nitrotoluene without a catalyst. Background technique [0002] p-Nitrobenzoic acid is an important intermediate in organic synthesis, widely used in dyes, medicine, food, organic synthesis and other fields. At present, the methods for synthesizing p-nitrobenzoic acid are mainly potassium permanganate oxidation, sodium bicarbonate oxidation, NaClO oxidation, nitric acid oxidation or adding other pre-transition metals and noble metal catalyst oxidation (Letters inDrug 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 strong oxidants, and there are heavy metals that seriously pollute the environment At the same time, it als...

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