Preparation method of p-nitrobenzaldehyde

Abstract

The invention discloses a preparation method of p-nitrobenzaldehyde. The preparation method comprises the following steps: p-nitrotoluene, which is used as a raw material, undergoes bromine bromination under the catalysis of azo-dialkyl nitrile, so as to generate 4-nitrobenzyl bromide and hydrogen bromide; hydrolysis of 4-nitrobenzyl bromide is catalyzed by an aqueous carbonate solution to obtain p-nitrobenzyl alcohol; and hydrogen peroxide oxidation of p-nitrobenzyl alcohol is catalyzed by sodium hydroxide so as to generate a target product, namely p-nitrobenzaldehyde. According to the invention, the azo-dialkyl nitrile solid catalyst replaces a peroxycarbonate liquid phase catalyst to catalyze the bromination reaction, so as to raise operational safety of the industrial preparation reaction; by using aryl halide as a solvent medium, use of a haloalkane solvent medium is avoided, and pollution of volatile organic solvents with low boiling point is avoided; and by the hydrogen peroxide oxidation method, cleanliness of the industrial preparation reaction is raised, and environmental pollution is reduced. According to the invention, product yield is increased; yield is raised by about 3% in comparison with yield of existing traditional industrial methods; overall yield reaches 76%; and product purity reaches 99% and above.

Description

technical field [0001] The present invention relates to a kind of preparation method of known compound, is exactly a kind of industrial clean preparation method of p-nitrobenzaldehyde. Background technique [0002] p-Nitrobenzaldehyde is a light yellow crystalline powder with a melting point of 105-107°C. It is slightly soluble in water and soluble in organic solvents such as alcohols, aromatics, halogenated hydrocarbons, and carboxylates. Vapor volatility properties. Molecular formula is C 7 h 5 NO 3 , relative molecular mass 151.1. Its structural formula is: [0003] [0004] p-Nitrobenzaldehyde is used as an important intermediate in the synthesis of fine organic functional materials such as medicines, dyes, and pesticides. It has a wide range of uses and can derive many important functional chemicals. In the field of important intermediates used in the synthesis of pesticides, medicines, dyes, photosensitive materials and liquid crystal materials, such as the p...

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Problems solved by technology

Liu Changchun and others applied this method to the synthesis of p-nitrobenzaldehyde, using RuHAP as a catalyst, oxygen oxidation of p-nitrobenzyl alcohol under normal pressure to prepare p-nitrobenzaldehyde, this method can significantly improve the synthesis of p-nitrobenzaldehyde Selectivity and increase product yield, but the catalyst is expensive and difficult to recycle and recycle

Peng Xinhua et al. used p-nitrotoluene as a raw material, reacted with bromine to form p-nitrobenzyl bromide, then catalyzed hydrolysis by sodium carbonate to form p-nitrobenzyl alcohol, and further synthesized p-nitrobenzene by oxygen oxidation catalyzed by metal-organic complexes. Formaldehyde, although significantly improved reaction selectivity, has improved productive rate, but the organic peroxide liquid catalyst of bromination reaction procedure, its thermal stability of industrial application is poor; The used metal organic complex catalyst of the 3rd step oxidation reaction procedure is difficult Regeneration, and oxygen oxidation is a gas-liquid phase reaction system, which needs to be reacted under certain pressure conditions. Therefore, there is no obvious advantage in production costs and industrial operations.

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