Method for preparing parahydroxybenzaldehyde by catalytic oxidation of paracresol with metalloporphyrin

Abstract

The invention relates to a method for preparing parahydroxybenzaldehyde by catalytic oxidation of paracresol with metalloporphyrin; in the method, the paracresol is used as raw material, monohydric alcohol, dihydric alcohol or the mixing solution of the monohydric alcohol and water is used as solvent, any one or two of mononuclear metalloporphyrin with structures of a formula (I) and a formula (II) and binuclear metalloporphyrin are used as catalysts, under the existence of sodium hydroxide which accounts for 37.5-80 percent of raw materials, oxygen gas or air flows in under ordinary pressure, the reaction is carried out 6-13 hours at 50-90 DEG C of reaction temperature, the paracresol is catalytically oxidized to obtain the parahydroxybenzaldehyde. The method has the advantages of less using amount of the catalyst, no separation and recovery, being capable of degradation naturally, low environment pollution and mild reaction condition and having wide application prospect in industry.

Description

technical field [0001] The invention relates to a method for preparing p-hydroxybenzaldehyde by catalytic oxidation of p-cresol by metalloporphyrin Background technique [0002] At present, the preparation methods of p-hydroxybenzaldehyde mainly include Reimer-Tiemann method, Gattermann method, formaldehyde method, manganese trioxide method and Etard method. These methods have many reaction and separation steps, cause great environmental pollution, and some reactions even involve toxic reactants. The synthesis of p-hydroxybenzaldehyde by directly oxidizing p-cresol with air or oxygen has the advantages of short process, simple operation, high yield, high purity, and easy availability of raw materials, so it has broad industrial application prospects. [0003] Chinese patent CN 1319581A (disclosure date: October 31, 2001) discloses a preparation method of p-hydroxybenzaldehyde. The method uses p-cresol as raw material, cobalt chelate, specifically cobalt phthalocyanine (II)...

AI Technical Summary

Problems solved by technology

[0005] (1) The catalyst used is a supported catalyst, the preparation process is complicated, and the energy consumption is high, and the three wastes are discharged more

[0006] (2) The amount of catalyst used is large (accounting for 0.2-5.1% of the weight of raw materials), and it must be separated and recovered after use, and the cost of separating and recovering the catalyst is high, energy consumption is large, and three wastes are discharged;

[0007] (3) It is necessary to use transition metals and rare earth metal inorganic salts as cocatalysts, and the consumption is relatively large (accounting for 0.01 to 5% of the weight of raw materials), resulting in complicated subsequent separation and recovery processes, difficult treatment of saline wastewater, and serious environmental pollution. and high energy consumption;

[0008] (4) The solvent must be anhydrous monohydric alcohol, and the aqueous solution of alcohol cannot be used as the solvent;

[0009] (5) The amount of sodium hydroxide is relatively large (accounting for 55.6% to 222% of the weight of raw materials), and correspondingly more acid is required for neutralization in the subsequent separation process, and more saline wastewater is produced at the end, which is a waste of resources , causing environmental pollution

Images