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Method for preparing metacresol by directly hydrolyzing meta-aminotoluene

A technology for toluidine and m-methylamine, which is applied in the field of directly hydrolyzing m-toluidine to prepare m-cresol, can solve the problems of large pollution, limited resources, large amount of waste acid, etc., so as to reduce production costs, shorten reaction steps, and reduce waste water. Effect

Inactive Publication Date: 2009-12-02
NANJING UNIV OF SCI & TECH
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  • Summary
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AI Technical Summary

Problems solved by technology

However, resources are limited and the process is complex
At present, the synthesis techniques include toluene sulfonation alkali fusion method, isopropyl toluene oxidation method, and toluene chlorination hydrolysis method (Xu Kexun. Handbook of Fine Organic Chemical Raw Materials and Intermediates. Beijing: Chemical Industry Press, 1998, 3-83~3- 85), these methods exist either because the process is simple, the amount of waste acid is too large, and the pollution is large; or the process flow is long, the product contains m- and p-cresol, the separation is difficult, and the cost of distillation and purification is high; m-toluidine diazo hydrolysis is also m-toluidine. An important method for the production of cresol (Hao Yanxia, ​​Chen Shusen. Process research on the preparation of m-cresol from m-toluidine. Journal of Explosives, 2002, (1): 64-66)
Due to the instability of diazonium salt and the thermal decomposition of diazonium salt in aqueous acid solution, a large amount of waste water leads to low yield and difficult treatment of 20% dilute acid

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] In a 1L zirconium reactor equipped with a stirrer, thermocouple, and pressure gauge, add 0.75mol (80.0g) m-methylamine, 98% concentrated H 2 SO 4 74.8g, 540mL distilled water. The reactor was filled with nitrogen, heated to 200°C, the reaction solution was stirred at 200°C for 6h, and then gradually cooled to room temperature. The solution was extracted with 50mL toluene, the mother liquor was hydrolyzed and extracted under the same conditions twice and three times, and the combined extracts were washed with 5% Na 2 CO 3 After washing with 10mL and 10mL of water, 61.4g m-cresol was obtained by distillation. The purity of the product detected by GC was 99.2%, and the yield was 76.1%. Using 36.5% HCl instead to react under the same conditions can obtain a yield of 79.2%.

Embodiment 2

[0020] Carry out in the zirconium alloy reactor, the same as embodiment 1. Change the acid to 85% phosphoric acid and add 154 g and 400 mL of distilled water. The reactor was filled with nitrogen, heated to 290°C, the reaction solution was stirred at 290°C for 12h, and then gradually cooled to room temperature. The solution was extracted with 50mL cyclohexane, and the extract was extracted with 5% Na 2 CO 3 After washing with 10mL and 10mL of water, 69.6g m-cresol was obtained by distillation. The conversion rate detected by GC was 100%, the purity of the product was 99.4%, and the yield was 86.2%.

[0021] After separation of the mother liquor, 80 g of m-methylamine, 70 g of 85% phosphoric acid and 10 g of water were added, and the above-mentioned experimental operation was repeated at 290° C. for 12 h, and then gradually cooled to room temperature. The solution was extracted with 50mL cyclohexane, and the extract was extracted with 5% Na 2 CO 3 After washing with 10m...

Embodiment 3

[0023] The reaction was carried out in a titanium alloy reactor, the same as in Example 1. Change the acid to α-zirconium phosphate (α-ZrP) and add 40 g and 400 mL of distilled water. The reactor was filled with nitrogen, heated to 280°C, the reaction solution was stirred at 280°C for 8h, and then gradually cooled to room temperature. Sulfuric acid was added to adjust the pH to 5-6, the solution was extracted with 50mL of dichloromethane, the mother liquor was hydrolyzed and extracted three times under the same conditions, the extracts were combined, and 73.3g of m-cresol was obtained by distillation. The purity of the product detected by GC was 99.1%, and the yield was 90.8%.

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Abstract

The invention discloses a method for preparing metacresol by directly hydrolyzing meta-aminotoluene. The method comprises the following steps: acid, meta-aminotoluene and water are made into a solution which is put into a reactor; nitrogen is introduced into the reactor; heating and stirring are carried out, so that the hydrolysis reaction is carried out fully; when the reaction is finished, the temperature is cooled to room temperature, the material is extracted by an organic solvent to obtain the metacresol crude product. The hydrolysis of the invention is carried out by one step or multiple steps of continuous reactions, the method is simple and practicable with low cost, the product of primary hydrolysis is removed, a plurality of hydrolyses of the mixture can improve the yield; after metacresol is extracted, the residual mixed liquor is added with reactant which are heated to hydrolysis temperature, and multiple times of hydrolysis reactions are carried out, which is capable of effectively reducing waste water; the reaction processes are shortened, the treatment of waste water is greatly reduced, the conversion rate of the reaction is up to 100%, and the yield is up to above 80%; the invention is a new method for synthesizing metacresol and can remarkably reduce the production cost of metacresol.

Description

technical field [0001] The invention belongs to the technology for preparing m-cresol by hydrolyzing m-toluidine, in particular to a method for directly hydrolyzing m-toluidine to prepare m-cresol. Background technique [0002] m-cresol is an intermediate for the production of spices, high-efficiency and low-toxicity pesticides, an important raw material for making film, and can also be used to make resins. The traditional method of m-cresol preparation is natural separation, that is, rectification from coal tar. But the resources are limited and the process is complicated. At present, the synthesis techniques include toluene sulfonation alkali fusion method, isopropyl toluene oxidation method, and toluene chlorination hydrolysis method (Xu Kexun. Handbook of Fine Organic Chemical Raw Materials and Intermediates. Beijing: Chemical Industry Press, 1998, 3-83~3- 85), these methods exist either because the process is simple, the amount of waste acid is too large, and the pollu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C39/06C07C37/01
Inventor 李斌栋吕春绪崔小刚
Owner NANJING UNIV OF SCI & TECH
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