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Process for preparing m-cresol by nitrogen oxide gas

A nitrogen oxide and system technology, which is applied in the field of nitrogen oxide gas preparation of m-cresol, can solve the problems of equipment selection, use, maintenance, and treatment difficulties, so as to solve the problem of waste acid pollution, reduce costs and difficulties, and reduce consumption. falling effect

Inactive Publication Date: 2012-12-05
JIANGSU HUAIHE CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0026] In the above methods, a large amount of salt-containing waste acid will be produced, which is extremely difficult to deal with, and also brings difficulties to the selection, use, and maintenance of equipment

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] (1) Salt formation reaction: add 480 grams of sulfuric acid with a mass concentration of 40% to the reactor, and add 60 grams of m-toluidine to the reactor under stirring conditions to obtain an aqueous solution of m-toluidine sulfate;

[0048] (2) Diazotization reaction: add the above-mentioned m-toluidine sulfate aqueous solution into a diazotization reactor with a cooling device, cool to 5°C, and slowly pass in an equimolar mixed gas of nitrogen monoxide and nitrogen dioxide , The amount of nitric oxide is 6300ml, make it react to generate meta-toluidine diazosulfate, until the starch potassium iodide test paper turns blue, stop the reaction, and add urea to remove excess nitrous acid;

[0049] (3) Hydrolysis reaction: add 190 grams of sulfuric acid solution with a mass concentration of 25% and 70 grams of benzene into the reaction kettle and heat it to 70°C, drop the above diazonium salt below the liquid surface, and add dropwise to a flow rate of 12mL / min. After finishi...

Embodiment 2

[0051] (1) Salt formation reaction: Add 598 grams of sulfuric acid with a mass concentration of 37% to the reactor, and add 60 grams of m-toluidine to the reactor under stirring conditions to obtain an aqueous solution of m-toluidine sulfate;

[0052] (2) Diazotization reaction: add the above-mentioned m-toluidine sulfate aqueous solution to a diazotization reactor with a cooling device, cool to 2°C, and slowly introduce a mixed gas of equimolar nitric oxide and nitrogen dioxide, The amount of nitric oxide is 6500ml to make it react to produce meta-toluidine diazonium sulfate, until the starch potassium iodide test paper turns blue, stop the reaction, and add urea to remove excess nitrous acid;

[0053] (3) Hydrolysis reaction: add 195 grams of sulfuric acid solution with a mass concentration of 30% and 80 grams of xylene into the reaction kettle and heat to 75°C, drop the above-mentioned diazonium salt below the liquid surface with a flow rate of 14 mL / min, dropwise After the addi...

Embodiment 3

[0055] (1) Salt formation reaction: Add 440 grams of sulfuric acid with a mass concentration of 35% (the recycled acid in Example 1) to the reactor, and add 60 grams of m-toluidine to the reactor under stirring to obtain m-toluidine Aqueous sulfate solution;

[0056] (2) Diazotization reaction: add the above-mentioned m-toluidine sulfate aqueous solution to a diazotization reactor with a cooling device, cool to 2°C, and slowly introduce a mixed gas of equimolar nitric oxide and nitrogen dioxide, The amount of nitric oxide is 6500ml to make it react to generate meta-toluidine diazosulfate, until the starch potassium iodide test paper turns blue, stop the reaction, and add urea to remove excess nitrous acid;

[0057] (3) Hydrolysis reaction: add 200 grams of sulfuric acid solution with a mass concentration of 30% and 85 grams of toluene into the reaction kettle and heat to 80°C, drop the above-mentioned diazonium salt below the liquid surface, and add dropwise at a flow rate of 16 mL...

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Abstract

The invention discloses a process for preparing m-cresol by a nitrogen oxide gas, which comprises the following steps: infusing the nitrogen oxide gas in m-toluidine sulfate for carrying out diazotization, hydrolyzing in the presence of an organic solvent and under an acidic condition, carrying out flash evaporation on the acid phase under the condition of negative pressure, returning the acid phase to a salifying step, dehydrogenating and rectifying the organic phase to obtain m-cresol products. The invention uses the nitrogen oxide gas as a diazotizing agent and inorganic salts do not existin a waste acid so that the waste acid is possibly used industrially. The hydrolysis is carried out in the presence of the organic solvent, the m-toluidine generated by the hydrolysis is quickly dissolved in the organic phase, the side product tarry matters generated in the reaction is few, the yield of the m-toluidine is improved, the salt-free waste acid is subjected to the flash evaporation under the negative pressure at a certain temperature, organic matters are stripped while the reaction water is removed, sulfuric acid is used, the dosage of the sulfuric acid is reduced, the purity of the m-toluidine products prepared by the process of the invention is 99.7% and the yield is more than 90%.

Description

Technical field [0001] The invention belongs to the field of fine chemicals manufacturing, and specifically relates to a process for preparing m-cresol from nitrogen oxide gas. Background technique [0002] There are three isomers of cresol, namely o-cresol, m-cresol, and p-cresol. They are all important chemical raw materials. The chemical name of m-cresol is 3-hydroxytoluene, and the molecular formula is C. 7 H 8 O is a colorless to light yellow combustible liquid with a phenol odor. It can be used in medicine, pesticides, dyes, perfumes, barrel resins, plasticizers, film films, antioxidants and reagents and other industries. It is mainly used for synthesis Simacarb, fenthion, antioxidant CA, tribromocresol, 4-nitro-m-cresol, 3-phenoxytoluene, m-methyldiphenyl ether, m-methyldiphenyl aldehyde, cresol sulfonic acid Calcium, disperse yellow SE-5R, chlorocresol m-cresol, 2-chloro-5-cresol, 4-chloro-3-cresol, m-hydroxybenzaldehyde and other chemical raw materials and products. [00...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C39/07C07C37/045
Inventor 董云孙雅坤王廷锋陆龙崔迎祥杨辉万金方
Owner JIANGSU HUAIHE CHEM
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