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Vapor phase method for preparing 4-methylphthalic anhydride

A technology of methylphthalic anhydride and methyltetrahydrophthalic anhydride, which is applied in the field of gas phase preparation of 4-methylphthalic anhydride, can solve the problems of low yield and achieve the effects of increased yield and improved preparation process

Inactive Publication Date: 2015-10-28
BEILI CHEM ZHANGJIAGANG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the limitation of the process, the yield is not high

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] 1) Add 4-methyl-1,2,3,6-tetrahydrophthalic anhydride to the solvent to fully dissolve;

[0025] 2) adding the quaternary ammonium salt phase transfer catalyst and the acid-binding agent to the solution prepared in step 1) and stirring evenly;

[0026] 3) Heat bromine to bromine vapor in a closed reaction tank and keep it at 140°C;

[0027] 4) Spray the mixed solution obtained in step 2) in a closed reaction tank through a sprayer, and keep the reaction temperature at 60° C. for 2 hours and then cool it down;

[0028] 5) The product obtained in step 4) is filtered and then distilled under reduced pressure to obtain a white powder.

[0029] The molar ratio of 4-methyltetrahydrophthalic anhydride, acid-binding agent and bromine is 1:2:2.

[0030] The dosage of the quaternary ammonium salt phase transfer catalyst is 0.1% of the weight of 4-methyltetrahydrophthalic anhydride.

[0031] The yield of the product obtained was calculated to be 89%.

Embodiment 2

[0033] 1) Add 4-methyl-1,2,3,6-tetrahydrophthalic anhydride to the solvent to fully dissolve;

[0034] 2) adding the quaternary ammonium salt phase transfer catalyst and the acid-binding agent to the solution prepared in step 1) and stirring evenly;

[0035] 3) Heat bromine to bromine vapor in a closed reaction tank and keep it at 60°C;

[0036] 4) Spray the mixed solution obtained in step 2) in a closed reaction tank through a sprayer, and keep the reaction temperature at 60° C. for 2 hours and then cool it down;

[0037] 5) The product obtained in step 4) is filtered and then distilled under reduced pressure to obtain a white powder.

[0038] The molar ratio of 4-methyltetrahydrophthalic anhydride, acid-binding agent and bromine is 1:4.4:2.2.

[0039] The dosage of the quaternary ammonium salt phase transfer catalyst is 5% of the weight of 4-methyltetrahydrophthalic anhydride.

[0040] The product was obtained in a calculated yield of 93%.

Embodiment 3

[0042] 1) Add 4-methyl-1,2,3,6-tetrahydrophthalic anhydride to the solvent to fully dissolve;

[0043] 2) adding the quaternary ammonium salt phase transfer catalyst and the acid-binding agent to the solution prepared in step 1) and stirring evenly;

[0044] 3) Heat bromine to bromine vapor in a closed reaction tank and keep it at 100°C;

[0045] 4) Spray the mixed liquid obtained in step 2) in a closed reaction tank through a sprayer, and maintain the reaction temperature at 100° C. for 2 hours and then cool it down;

[0046] 5) The product obtained in step 4) is filtered and then distilled under reduced pressure to obtain a white powder.

[0047] The molar ratio of 4-methyltetrahydrophthalic anhydride, acid-binding agent and bromine is 1:3:2.

[0048] The dosage of the quaternary ammonium salt phase transfer catalyst is 2% of the weight of 4-methyltetrahydrophthalic anhydride.

[0049] The product was obtained in a calculated yield of 92%.

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PUM

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Abstract

The invention discloses a vapor phase method for preparing 4-methylphthalic anhydride. The method comprises 1, fully dissolving 4-methyl-1,2,3,6-tetrahydrophthalic anhydride in a solvent, 2, adding a quaternary ammonium salt phase-transfer catalyst and an acid binding agent into the solution prepared by the step 1 and carrying out stirring to obtain a uniform solution, 3, heating bromine in an enclosed reaction pot to obtain bromine vapor and keeping the temperature in a range of 60-140 DEG C, 4, spraying the mixed solution obtained by the step 2 in the enclosed reaction pot by a sprayer, keeping the reaction temperature in a range of 60-140 DEG C for 1-2h and carrying out cooling and 5, filtering the product obtained by the step 4 and carrying out reduced pressure distillation to obtain white powder.

Description

technical field [0001] The invention relates to a gas-phase method for preparing 4-methylphthalic anhydride, which belongs to the field of organic chemical synthesis. Background technique [0002] 4-methylphthalic anhydride (4-MPA for short) is mainly used as an important intermediate in the synthesis of herbicides, especially in the synthesis of several cereal herbicides, and can also be used as an intermediate in the synthesis of dyes. [0003] The methods of synthesizing 4-methylphthalic anhydride in foreign countries mainly contain the following: [0004] A method for the production of 4-methylphthalic anhydride is described in the document US Pat. No. 4,559,405. It uses 4-MTPA as raw material to react with bromine under the condition of pyridine, the temperature is 30-70°C, the reaction is 3-4 hours, and then washed with water, extracted, concentrated and crystallized, and the yield is 87%. Although this method has a higher yield, it has many steps, and the cost of py...

Claims

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Application Information

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IPC IPC(8): C07D307/89
CPCC07D307/89C07C51/56
Inventor 徐晓东
Owner BEILI CHEM ZHANGJIAGANG
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