Method for synthesizing 3-methyl-4-nitrobenzoic acid by using stepped heating method and indirect electrosynthesis method

A technology of nitrobenzoic acid and step heating, which is applied in the direction of chemical instruments and methods, preparation of organic compounds, electrolysis process, etc., can solve problems such as decline, achieve high yield, high selectivity, increase selectivity and conversion rate Effect

Inactive Publication Date: 2013-09-25
HUNAN UNIV OF SCI & TECH
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  • Abstract
  • Description
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Problems solved by technology

[0004] The object of the present invention is to provide a method for the synthesis of 3-methyl-4-nitrobenzoic acid by a stepwise heating method and an indirect electrosynthesis method. Chromium sulfate is electrolytically oxidized to chromium trioxide, and then chromium trioxide is used to selectively oxidize 2,4-dimethylnitrobenzene to 3-methyl-4-nitrobenzoic acid; ,The oxidation reaction rate of 4-dimethylnitrobenzene solves the problem that the reaction rate decreases due to the consumption of acid during the reaction process, significantly improves the selectivity and conversion rate of the reaction, and greatly saves the cost

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0014] (1) In 200 mL of 30% (wt%) H 2 SO 4 solution, add 20g Cr 2 (SO 4 ) 3 Solid, stirred to dissolve and used as anolyte; 80 mL 10 % (wt%) H 2 SO 4 solution as catholyte. The electrolytic cell is divided into an anode chamber and a cathode chamber by ceramics. The anolyte is poured into the anode chamber and the catholyte is poured into the cathode chamber. The anode is a lead dioxide plate and the cathode is a lead rod. During electrolysis, control the temperature of the electrolyte in the electrolyzer to be 30 0 C, cell voltage 3 V, current density 400 A m -2 . When the anolyte changes from dark green to brownish red, stop electrolysis. Subsequently, the anolyte was evaporated to obtain a red solid of chromium trioxide, and 8.5 g of chromium trioxide was obtained after filtration, with a yield of 85%, and the filtrate (referred to as A) was concentrated sulfuric acid containing a small amount of trivalent chromium and hexavalent chromium, It can be recycled and u...

Embodiment 2

[0019] (1) In 200 mL of 40% (wt%) H 2 SO 4 solution, add 20g Cr 2 (SO 4 ) 3 Solid, stirred to dissolve and used as anolyte; 80 mL 10 % (wt%) H 2 SO 4 solution as catholyte. The electrolytic cell is divided into an anode chamber and a cathode chamber by ceramics. The anolyte is poured into the anode chamber and the catholyte is poured into the cathode chamber. The anode is a lead dioxide plate and the cathode is a lead rod. During electrolysis, control the temperature of the electrolyte in the electrolyzer to be 35 0 C, cell voltage 4V, current density 500A m -2 . When the anolyte changes from dark green to brownish red, stop electrolysis. Subsequently, the anolyte was evaporated to obtain a red solid of chromium trioxide, and 9g of chromium trioxide was obtained after filtration, with a yield of 90%. The filtrate (referred to as A) was concentrated sulfuric acid containing a small amount of trivalent chromium and hexavalent chromium, which could Recycling, used for t...

Embodiment 3

[0024] (1) In 200 mL of 40% (wt%) H 2 SO 4 solution, add 20g Cr 2 (SO 4 ) 3 Solid, stirred to dissolve and used as anolyte; 80 mL 10 % (wt%) H 2 SO 4 solution as catholyte. The electrolytic cell is divided into an anode chamber and a cathode chamber by ceramics. The anolyte is poured into the anode chamber and the catholyte is poured into the cathode chamber. The anode is a lead dioxide plate and the cathode is a lead rod. During electrolysis, control the temperature of the electrolyte in the electrolyzer to be 40 0 C, cell voltage 5 V, current density 600 A m -2 . When the anolyte changes from dark green to brownish red, stop electrolysis. Subsequently, the anolyte was evaporated to obtain a red solid of chromium trioxide, which was filtered to obtain 9.5 g of chromium trioxide with a yield of 95%, and the filtrate (referred to as A) was concentrated sulfuric acid containing a small amount of trivalent chromium and hexavalent chromium, It can be recycled and used fo...

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PUM

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Abstract

The invention discloses a method for synthesizing 3-methyl-4-nitrobenzoic acid by using a stepped heating method and an indirect electrosynthesis method. The method is implemented by taking 2,4-dimethylnitrobenzene and chromium sulfate as main raw materials through the following steps of: firstly, carrying out electrolytic oxidation on chromium sulfate by using an electrolytic process so as to obtain chromium trioxide; then, selectively oxidizing 2,4-dimethylnitrobenzene into a 3-methyl-4-nitrobenzoic acid by using chromium trioxide through using the stepped heating method. According to the invention, through adopting the stepped heating method, the oxidation reaction rate of 2,4-dimethylnitrobenzene is controlled, and the selectivity and conversion rate of reaction are remarkably improved. The conversion rate of chromium trioxide obtained by using an electrolytic oxidation method is 85-95%, and the conversion rate of 3-methyl-4-nitrobenzoic acid obtained by using the stepped heating method can reach 65-86%. According to the invention, the problem that in the process of reaction, the reaction rate declines due to the consumption of acids is solved; through carrying out electrolytic oxidation on chromium sulfate produced after reaction, chromium trioxide is circularly produced, thereby not only avoiding the environment pollution, but also greatly saving the cost.

Description

technical field [0001] The invention belongs to the field of fine chemical industry and organic electrosynthesis, and specifically relates to the synthesis of 3-methyl-4- Nitrobenzoic acid method. [0002] First, chromium sulfate is electrolytically oxidized to chromium trioxide, and then 2,4-dimethylnitrobenzene is selectively oxidized to 3-methyl-4-nitrobenzoic acid with chromium trioxide; by adopting a stepwise heating method, Control the reaction rate of 2,4-dimethylnitrobenzene oxidation, significantly improve the selectivity and conversion rate of the reaction. The invention adopts an indirect electrosynthesis method, does not pollute the environment, and is a high-selectivity, high-yield and green-friendly 3-methyl-4-nitrobenzoic acid synthesis technology. Background technique [0003] 3-Methyl-4-nitrobenzoic acid is an important intermediate in the pharmaceutical industry and fine organic product industry. It can be used as a raw material to further synthesize many...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C205/57C07C201/12C25B1/00
Inventor 易清风张玉晖刘小平唐梅香
Owner HUNAN UNIV OF SCI & TECH
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