A method for separating and purifying m-cresol from m-p-mixed cresol

Abstract

The invention relates to a method for separating and purifying m-cresol from a mixture of m-cresol and p-cresol by using a complex crystallization method. The method comprises the following steps: 1) complex crystallization: adding a mixture of m-cresol and p-cresol into a reactor, adding urea and heating to 70-95 DEG C to completely dissolve the urea in the mixture of m-cresol and p-cresol; cooling, adding petroleum ether when the mixture is cooled 50-60 DEG C, wherein the adding amount of petroleum ether is 1-2 times the volume of the raw material of the mixture of m-cresol and p-cresol, and crystallizing at 0 DEG C-8 DEG C for 2-4 h; 2) solid-liquid separation washing to obtain white needlelike m-cresol complex crystals and a filtrate 1; 3) decomplexation: pumping the complex crystal and adding of toluene, decomplexing at 50-60 DEG C under the, and filtering while hot to obtain a solid urea and a filtrate 2, wherein the filtrate 2 is a mixture of m-cresol and toluene; and 4) distillation: separating m-cresol and toluene in the mixture filtrate 2 through vacuum distillation to obtain pure m-cresol and toluene.

Description

technical field

[0001] The invention belongs to the field of separation and purification of chemical industry, and specifically relates to a method for separating and purifying m-cresol from m-p-mixed cresol by using a complex crystallization method. Background technique

[0002] Cresol is an important fine chemical intermediate, and its three isomers (o-cresol, m-cresol and p-cresol) are all fine chemical products that are in short supply in China, especially m-cresol, which is seriously insufficient in domestic supply , needs to import about 6,000 tons per year to meet the domestic market demand. The main application fields of m-cresol are: synthesis of VE, preparation of pyrethroid pesticides, synthesis of spices, plastic antioxidants, etc.

[0003] m-cresol and p-cresol are difficult to separate by ordinary distillation due to their very close boiling points. The separation methods of m-cresol and p-cresol can be divided into two categories: physical methods and chemic...

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