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Method for preparing high-purity m-cresol by selectively oxidizing mixed m-cresol and p-cresol

A technology for mixing cresols and selectivity, which is applied in the field of preparing high-purity m-cresol and achieves the effects of low production cost, easy industrial production and simple reaction operation.

Pending Publication Date: 2020-07-31
厦门中坤化学有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It is difficult to obtain high-purity m-cresol at a lower cost by traditional separation methods

Method used

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  • Method for preparing high-purity m-cresol by selectively oxidizing mixed m-cresol and p-cresol

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] 1) Oxidation: Put m-p-mixed cresol (1080g, m-cresol: p-cresol=2:1, molar ratio), catalyst (2.5wt%), sodium hydroxide (1500g), solvent (methanol: 10000ml) into In the flask, the stirring was started, the temperature was raised to the reaction temperature (65° C.), and oxygen gas (2000 ml / min) was continuously fed in, and the reaction was carried out for 8 hours. After the reaction was completed, water was added, and the solvent was recovered by distillation.

[0032] The conversion rate was determined by gas chromatography: Agilent 6890N DB-5 quartz capillary column (30m×0.32mm) was used for gas chromatography, and a hydrogen flame ionization detector (FID) was used.

[0033] 2) Crystallization separation: acidify the mother liquor obtained in step 1), adjust the pH=10, cool down to crystallize, cool to 5°C, filter, and obtain the filter cake as p-hydroxybenzaldehyde sodium salt, and the mother liquor as m-cresol sodium salt solution.

[0034] 3) P-Hydroxybenzaldehyde ...

Embodiment 2～7

[0038] According to the reaction conditions in Example 1, the molar ratio of m-cresol and p-cresol was adjusted to investigate the selective oxidation effect. The test results are shown in Table 1.

[0039] Table 1

[0040]

[0041] According to the data of Examples 1-7, it can be seen that the selective oxidation catalyst can efficiently realize the conversion of p-cresol into p-hydroxybenzaldehyde, while retaining m-cresol, maximizing the benefit and facilitating industrial production.

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Abstract

The invention discloses a method for preparing high-purity m-cresol by selectively oxidizing mixed m-cresol and p-cresol. The method comprises the following steps: putting mixed m-cresol and p-cresol,a catalyst, sodium hydroxide and a solvent into a container, stirring, heating to a reaction temperature, continuously introducing oxygen to react, adding water, distilling to recover the solvent toobtain a mother solution, acidifying, adjusting the pH value, cooling, crystallizing, and filtering to obtain filter cake which is p-hydroxybenzaldehyde sodium salt and a mother solution which is a m-cresol sodium salt solution; dissolving and acidifying the p-hydroxybenzaldehyde sodium salt, adjusting the pH value, cooling, crystallizing and filtering to obtain filter cake that is a wet p-hydroxybenzaldehyde product, and drying to obtain a finished p-hydroxybenzaldehyde product with the purity of higher than 99.2%; acidifying the m-cresol sodium salt solution, adjusting the pH value, collecting an oil phase m-cresol crude product, and putting the oil phase m-cresol crude product into a tower kettle of a rectifying tower; starting magnetic stirring in the tower kettle for stirring, starting a high-vacuum mechanical pump for pressure reduction, starting tower kettle heating, and collecting a front distillate, a main distillate and a rear distillate. The obtained main distillate is an m-cresol finished product with the purity of higher than 99.5%.

Description

technical field [0001] The invention relates to the field of fine chemical industry, in particular to a method for preparing high-purity m-cresol by selective oxidation of m-p-mixed cresol. Background technique [0002] There are two main uses of m-cresol: organic synthesis and analytical reagent. It is an important raw material for synthetic cosmetics, antioxidants and pesticides, and it is used in synthetic adhesives, synthetic resins, and color film developers. With the pharmaceutical industry's need for vitamin preparation and the development of the spice industry, the demand for m-cresol, especially high-purity m-cresol, is increasing year by year. In the process of separating mixed cresols, since the difference between m-cresol and p-cresol is only 0.4°C in boiling point and 24.6°C in melting point, it is difficult to separate and purify them by ordinary distillation or rectification techniques. However, the application of mixed phenols is limited, and the added valu...

Claims

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Application Information

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IPC IPC(8): C07C37/68C07C37/86C07C39/08
CPCC07C37/685C07C37/86C07C39/08
Inventor 许志刚郑祎敏魏文达郑启航杨毅融
Owner 厦门中坤化学有限公司
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