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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 m-cresol preparation from nitrogen oxide gas, can solve the problems of equipment selection, use, maintenance difficulties, and difficult treatment, so as to solve the problem of waste acid pollution, reduce cost and difficulty, and consume Falling effect

Inactive Publication Date: 2010-07-14
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-forming reaction: add 480 grams of sulfuric acid of mass concentration 40% in reactor, add 60 grams of m-toluidine in reactor under agitation condition, obtain m-toluidine sulfate aqueous solution;

[0048] (2), diazotization reaction: add the above-mentioned m-toluidine sulfate solution into the diazotization reaction kettle with cooling device, lower the temperature to 5°C, and slowly pass in the mixed gas of equimolar nitric oxide and nitrogen dioxide , the amount of nitrogen oxide is 6300ml, make it react to generate m-toluidine diazonium sulfate, 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 reactor and heat it to 70°C, add the above-mentioned diazonium salt dropwise below the liquid level, and the flow rate is 12mL / min. After completion, maint...

Embodiment 2

[0051] (1), salt-forming reaction: add 598 grams of sulfuric acid of mass concentration 37% in reactor, add 60 gram m-toluidines in reactor under agitation condition, obtain m-toluidine sulfate aqueous solution;

[0052] (2), diazotization reaction: add the above-mentioned m-toluidine sulphate aqueous solution into the diazotization reaction kettle with cooling device, cool down to 2° C., slowly feed the mixed gas of equimolar nitric oxide and nitrogen dioxide, The amount of nitrogen oxide is 6500ml, make it react to generate m-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: 195 grams of sulfuric acid solution with a mass concentration of 30% and 80 grams of xylene are added together in the reactor and heated to 75 ° C, and the above-mentioned diazonium salt is added dropwise below the liquid level, and the flow rate is 14 mL / min. After the ad...

Embodiment 3

[0055] (1), salt-forming reaction: add 440 grams of sulfuric acid (recycle acid of embodiment 1) of mass concentration 35% in reactor, add 60 grams of m-toluidine in reactor under stirring condition, obtain m-toluidine Sulfate solution;

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

[0057] (3), hydrolysis reaction: 200 grams of sulfuric acid solution with a mass concentration of 30% and 85 grams of toluene are added together in the reactor and heated to 80 ° C, and the above-mentioned diazonium salt is added dropwise below the liquid level, and the flow rate ...

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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 chemical manufacturing, and in particular 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, which 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 flammable liquid with phenol odor, it can be used in industries such as medicine, pesticide, dye, spice, barrel resin, plasticizer, film, antioxidant and reagent, mainly for synthesis Meprocarb, fenthion, antioxidant CA, tribromocresol, 4-nitro-m-cresol, 3-phenoxytoluene, m-cresol, m-methyldiphenylaldehyde, cresolsulfonic acid Calcium, disperse yellow SE-5R, chlorocresol m-cresyl, 2-chloro-5-cresol, 4-chloro-3-cresol, m-hydroxybenzaldehyde and other chemical raw materials and products. [0003] The current m-cresol preparation p...

Claims

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Application Information

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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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