Method for separating and purifying m-cresol and p-cresol through complexation crystallization

A technology of p-cresol and crystallization method, which is applied in the field of separation and purification of m/p-cresol mixture by complex crystallization method, can solve the problems of expensive equipment and operation costs, waste of raw materials, high equipment requirements, etc., achieve mild temperature conditions and improve recovery The effect of low efficiency and equipment requirements

Inactive Publication Date: 2017-12-08
TIANJIN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Among them, the selection and preparation of high-efficiency adsorbents in the adsorption separation method are difficult, the adsorption capacity is limited and a large amount of desorbent is required; the extraction method needs to use a large amount of organic solvents, which is easy to pollute the environment; the high-pressure crystallization method and recrystallization method will produce harmful The problem of high equipment requirements or the use of a large amount of organic solvents; the technical process of the membrane permeation method is not mature enough to be applied to large-scale industrial production; although the alkylation method can achieve high-purity separation of m/p-cresol, it is also There are disadvantages of complicated process, exp

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  • Method for separating and purifying m-cresol and p-cresol through complexation crystallization
  • Method for separating and purifying m-cresol and p-cresol through complexation crystallization

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Experimental program
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Effect test

Embodiment 1

[0028] 1). P-cresol complex crystallization: mix the raw materials with m / p-cresol (60% m-cresol, 40% p-cresol) and add it into the reactor after weighing the volume. The volume ratio of the mixed cresol with the raw material is Add 2.0:1 solvent n-butyl ether into the reactor, and mix the two evenly to completely dissolve cresol in n-butyl ether. Then add the complexing agent DABCO·6H which is 0.9:1 with p-cresol molar ratio 2 O, heated in a water bath at 90°C and stirred vigorously for 2h. After the reaction is over, transfer the reaction solution into a crystallizer for cooling and crystallization. The cooling rate is 10°C / h, and the crystallization termination temperature is -10°C. After reaching -10°C, keep the constant temperature for 3 hours;

[0029] 2). Filtration, washing and rectification: Use a vacuum pump to filter the reaction solution after cooling and crystallization to obtain the filtrate and filter cake, and then use -10°C toluene as a detergent to wash and ...

Embodiment 2

[0040] Experimental device and operation process are the same as embodiment 1, just step 1) in, complexing agent DABCO 6H 2 O was replaced by DABCO, and the analysis results are shown in Table 1.

Embodiment 3

[0042] The experimental device and operation process are the same as in Example 1, except that in step 1), the volume ratio of the solvent n-butyl ether and the raw material mixed cresol is replaced by 2.5:1, and the added complexing agent DABCO 6H 2 The molar ratio of p-cresol in O and the raw material mixed cresol is changed to 0.8:1, the reaction time is changed to 3h, the cooling rate is 5°C / h, and after reaching -10°C, the constant temperature is kept for 2h; in step 2), each washing The quality of the toluene used is the same as the quality of the filter cake obtained after each suction filtration. The analysis results are shown in Table 1.

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Abstract

The invention relates to a method for separating and purifying m-cresol and p-cresol by a complex crystallization method; first, triethylenediamine is used as a complexing agent to obtain high-purity p-cresol through complex crystallization, and then the filtrate in this operation is As a reactant, sodium acetate is used as a complexing agent to purify m-cresol through complex crystallization. In order to improve the overall yield, the filtrate in the sodium acetate method is recycled back to the first step as a reactant to continue to use. The method can simultaneously obtain m-cresol and p-cresol products with a purity of more than 99.5%, and recycles the filtrate after rectification to maximize the use of raw materials, so that the overall yield of the process can reach more than 99%. The organic solvents and complexing agents used in the reaction process can be recycled in the process, without the discharge of "three wastes", achieving the goal of environmental protection. In addition, compared with the prior art, the complexing agent selected in the present invention requires milder temperature conditions for reaction and cooling crystallization, which greatly reduces energy consumption.

Description

technical field [0001] The invention belongs to the field of separation and purification of chemical industry. More specifically, it relates to the method of separating and purifying m / p-cresol mixture by complex crystallization, thereby obtaining high-purity m-cresol and p-cresol products simultaneously. Background technique [0002] Both high-purity m-cresol and p-cresol are important fine chemical intermediates, so the separation of m / p-cresol has been a hot topic in the chemical industry for a long time. m-cresol is an important raw material for the production of pesticides, antioxidants, fragrances, phenolic resins, vitamin E, dyes, fluorescent whitening agents, solvents, plasticizers and flame retardants. Since the downstream products produced using m-cresol as raw material have broad development prospects, the demand for m-cresol in my country maintains a high-speed growth at an annual growth rate of 8-10%. And p-cresol is widely used in the synthesis of drugs, herb...

Claims

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Application Information

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IPC IPC(8): C07C37/68C07C37/74C07C37/84C07C37/72C07C39/07
CPCC07C37/685C07C37/72C07C37/74C07C37/84C07C39/07
Inventor 王启纶唐忠利
Owner TIANJIN UNIV
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