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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  • Summary
  • 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 ...

Method used

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

Examples

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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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