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Process for producing methyl benzoic acid by paraxylene

A technology of p-toluic acid and p-xylene, which is applied in the preparation of carboxylate, the preparation of organic compounds, chemical instruments and methods, etc., can solve the problems of difficult separation and purification, high melting point, and achieves no three wastes and low production costs. , the effect of high production stability and safety

Inactive Publication Date: 2008-05-14
YANGZHOU LIUSHI CHEM
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Problems solved by technology

Because terephthalic acid and p-carboxybenzaldehyde have a high melting point and are almost insoluble in any organic solvent, it brings many difficulties to the separation and purification of p-toluic acid products.

Method used

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  • Process for producing methyl benzoic acid by paraxylene

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Embodiment Construction

[0019] The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

[0020] As shown in the figure, the process of producing p-toluic acid with p-xylene uses p-xylene as the raw material, and the equipment to be used is a catalytic reactor, a solid-liquid separator, a distillation and debenzene distillation device, and a scraper-type cooling crystallization device etc.

[0021] Its process steps are as follows:

[0022] (1) Use p-xylene 1500kg, catalyst cobalt isooctanoate 6kg, and compressed air at a reaction temperature of 100-130°C and an operating pressure of 0.2-0.3MPa in a tower-type bubbling reactor for oxidation reaction of p-xylene and oxygen 5-6hr, generate p-toluic acid product and by-products such as p-tolualdehyde, p-carboxybenzaldehyde, terephthalic acid and water;

[0023] (2) Solid-liquid separation, at an operating temperature of 130-140°C, use a pipeline filter for solid-liquid separation op...

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Abstract

The invention relates to a production process for methyl benzol methanoic acid using paraxylene;, comprising following steps: a selective catalyze oxidation reaction is implemented on the paraxylene and the oxygen in the air; solid-liquid separation is implemented on the reactant, so that methyl benzaldehyde, carboxyl benzaldehyde, terephthalic acid and other high-melting and crystallizable subsidiary products can be removed; the paraxylene of the reactant is removed in the paraxylene distillation apparatus; a vacuum distillation is implemented on the material in a gap rectifying tower; so that the light-component impurities can be removed further; in the rectifying tower of methyl benzol methanoic acid crude product, the top of the tower is implemented on an impurity removal separation for refining the methyl benzol methanoic acid; the refined methyl benzol methanoic acid liquidoid is arranged into a cooling crystallizer for cooling and crystallization so as to get methyl benzol methanoic acid crystallization product with uniform particles. The invention has the advantages of safety and reliability, high yield, low production cost and environmental friendliness.

Description

technical field [0001] The invention relates to a process for producing p-toluic acid from p-xylene, which belongs to the technical field of fine chemicals. Background technique [0002] P-toluic acid can be used as an intermediate of medicine, pesticide, organic pigment, etc. Its preparation methods mainly include p-xylene or p-methylcumene nitric acid oxidation method, p-xylene air oxidation method, toluene carbonylation-oxidation method, etc. During the air oxidation process of p-xylene, a small amount of by-products such as p-tolualdehyde, p-carboxybenzaldehyde and terephthalic acid will inevitably be produced. Because terephthalic acid and p-carboxybenzaldehyde have a high melting point and are almost insoluble in any organic solvent, it brings many difficulties to the separation and purification of p-toluic acid products. Contents of the invention [0003] The purpose of the present invention is to aim at the deficiencies in the current production process, and to p...

Claims

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Application Information

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IPC IPC(8): C07C63/04C07C51/265
Inventor 刘顺兆
Owner YANGZHOU LIUSHI CHEM
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