Method for preparing p-cresol into p-hydroxy benzaldehyde by catalytic oxidation of metalloporphyrin-metal salt composite catalyst

Abstract

The invention relates to a method for preparing p-cresol into p-hydroxy benzaldehyde by the catalytic oxidation of a metalloporphyrin-metal salt composite catalyst. The method comprises the following steps: taking the p-cresol as a raw material, taking methanol or methanol water solution as a solvent, taking a combination of metalloporphyrin and metal salt as a catalyst or taking a combination of any two or three in a formula (1), a formula (II) or a formula (III) as a catalyst or taking a combination of the formula (1) and the formula (I), a combination of the formula (II) and the formula (II) and a combination of the formula (III) and the formula (III) as a catalyst, wherein the concentration of metalloporphyrin is 5-100 ppm, the concentration of the metal salt is 5-200 ppm, and the dosage of sodium hydroxide is 1-2.5 times of the molar dosage of the p-cresol; introducing oxygen of 0.1-1.0 MPa; and reacting for 1-12 hours at a temperature of 50-90 DEG C to obtain the p-hydroxy benzaldehyde. The method has the advantage that while a target product with high yield is obtained, the dosage of the catalyst is extremely less, and the alkali dosage is also remarkably reduced, so that not only can resources be effectively saved, and can the environment pollution be reduced, but also the purpose of reducing energy consumption can be achieved, and further, the effects of energy conservation and emission reduction can be completely realized.

Description

technical field [0001] The invention relates to a method for preparing aromatic aldehydes, in particular to a method for preparing p-hydroxybenzaldehyde by catalyzing the oxidation of p-cresol with a metalloporphyrin-metal salt composite catalyst. Background technique [0002] p-Hydroxybenzaldehyde is an important organic synthesis intermediate, widely used in medicine, pesticide, dyestuff and other fields. Although there are many methods for synthesizing p-hydroxybenzaldehyde from p-cresol at present, the biomimetic catalytic oxidation of metalloporphyrins is relatively superior. European patent EP330036A1 (disclosure date: August 30, 1989) discloses a method for preparing p-hydroxybenzaldehyde by biomimetic catalytic oxygen oxidation of p-cresol, which uses metalloporphyrin or metalloporphyrin-metal salt as a catalyst, The problem of environmental pollution caused by the use of a large amount of cobalt chloride catalyst in the traditional method (EP0012939A1, publication ...

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Problems solved by technology

European patent EP330036A1 (disclosure date: August 30, 1989) discloses a method for preparing p-hydroxybenzaldehyde by biomimetic catalytic oxygen oxidation of p-cresol, which uses metalloporphyrin or metalloporphyrin-metal salt as a catalyst, Solved the problem of environmental pollution caused by the use of a large amount of cobalt chloride catalyst in the traditional method (EP0012939A1, publication date: July 9, 1980), but this method still has the problem of a large amount of catalyst

Chinese patent CN101759536A (disclosure date: June 30, 2010) and literature (Chinese Journal of Chemical Engineering, 2012, 20: 262-266.) reported a metalloporphyrin-catalyzed oxidation of p-cresol to prepare p-hydroxybenzaldehyde method, the method adopts a small amount of metalloporphyrin as a catalyst, which further solves the problem that the amount of catalyst used in the above method is large, but the method still has the problem that the yield is not high

[0006] (3) When a higher yield is desired (55% to 81.0%), the amount of alkali used is large, and the molar ratio of alkali to p-cresol is 3 to 6:1, and a high amount of alkali will lead to later separation A large amount of acid is needed for neutralization, and the salt generated after neutralization makes wastewater treatment difficult, increases energy consumption for later separation, and greatly increases operating costs

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