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Continuous preparation of m-toluidine

A technology of m-cresol and cresol, which is applied in the field of continuous preparation of m-cresol, can solve the problems of hindering m-cresol reaction system, large amount of three wastes, long reaction cycle, etc. Low, shorten the effect of the reaction cycle

Inactive Publication Date: 2004-02-04
王林
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The viscous tar-like substance formed by the side reaction floats on the surface of the reaction liquid, which hinders m-cresol from being taken out of the reaction system with distillation, making the reaction cycle longer
In addition, the amount of sulfuric acid used in the above reaction is large, and the amount of three wastes to be treated is also large.

Method used

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  • Continuous preparation of m-toluidine
  • Continuous preparation of m-toluidine

Examples

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Effect test

Embodiment 1

[0015] Example 1: The diazonium salt solution of m-toluidine was alternately prepared with two or more reactors at 0-10°C in a conventional method. Referring to the figure, in a 500L reactor, add 281kg of 20wt% sulfuric acid, then add 25kg of m-toluidine, keep the reaction temperature at 0~10℃ under stirring, add 17.5kg of sodium nitrite dissolved in 35kg of water and pass the weight Nitridation reaction to prepare m-toluidine diazonium salt solution.

[0016] In a 500L hydrolysis reactor, add 300L of 30wt% sulfuric acid, and continuously add the m-toluidine diazonium salt solution prepared above to the hydrolysis reactor at 105-110°C; the m-cresol produced by the reaction will follow The steam is distilled and continuously taken out, and dilute sulfuric acid and tar-like by-products with m-cresol are continuously overflowed from the upper overflow port of the reactor.

[0017] The overflow liquid overflowing from the overflow port is separated into waste sulfuric acid and meta-cr...

Embodiment 2

[0020] Example 2: The diazotization of meta-toluidine is the same as that in Example 1; 50wt% sulfuric acid is used for the hydrolysis reaction, and the temperature of the hydrolysis reaction is 110~150℃; the steamed water is absorbed by the macroporous resin and discharged (the water contains meta Phenol <0.02 g / l). The crude m-cresol was recovered by elution with methanol. The waste sulfuric acid is used as a raw material to prepare m-toluidine diazonium salt solution after being adsorbed by resin. Use water vapor to elute the adsorbed organic substances on the resin. 24.04 kg of crude m-cresol with a content of 95-97 wt% is obtained. After the crude m-cresol is rectified, 21.69 kg of a finished product of m-cresol with a content of ≥99.5% is obtained, with a yield of 85.96%.

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Abstract

A process for continuously preparing meta-tolylphenol includes such steps as continuously adding the diazonium salt of meta-tolylamine to diluted sulfuric acid, and reacting at 106-150 deg.C while controlling the concentration of sulfuric acid to 25-64 wt.%. Its advantages are low cost, high output rate, small reactor volume, and cyclic use of sulfuric acid after treated by macroreticular resin.

Description

Technical field [0001] The invention relates to a method for continuously preparing m-cresol, which belongs to the field of fine chemicals. Background technique [0002] The conversion of m-toluidine to m-cresol through diazotization and hydrolysis reactions currently generally adopts an intermittent production method. This method uses sodium nitrite, sulfuric acid, and m-toluidine to diazotize at low temperature to generate a diazonium salt solution of m-toluidine, and then add the diazonium salt solution of m-toluidine to boiling dilute sulfuric acid for hydrolysis. The m-cresol produced by the reaction is distilled out with steam, and the m-cresol remaining in the reactor and the distilled m-cresol are extracted by solvent and then the solvent is distilled off. This method is intermittent, batch production, requires a very large equipment volume, uses a lot of solvents, and the yield is generally low, only about 70%. The viscous tar-like substance formed by the side reaction f...

Claims

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Application Information

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IPC IPC(8): C07C37/05C07C39/07
Inventor 刘仁培王林
Owner 王林
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