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Method for preparing 4-methyl benzene anhydride

A technology of methyl phthalic anhydride and methyl, which is applied in the field of preparation of 4-methyl phthalic anhydride, can solve the problems of long reaction cycle, low yield, poor product quality, etc., and achieve less three wastes, high yield and simple synthesis process Effect

Inactive Publication Date: 2012-10-03
BEILI CHEM ZHANGJIAGANG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] The object of the present invention is to provide a The method for synthesizing 4-methylphthalic anhydride from raw materials overcomes the problems of long reaction cycle, poor product quality and low yield in the prior art

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] A kind of preparation method of 4-methylphthalic anhydride:

[0020] Add 740g of chlorobenzene, 282g of sodium oxalate and 0.83g of tetrabutylammonium bromide to 166g of raw material 4-MTPA, stir and heat to 80°C for 30 minutes, start to add 324g of bromine dropwise at 85°C, keep the temperature at 85-100°C and add dropwise . After the dropwise addition, heat up, keep warm at 90-115°C for 2 hours, cool and filter, recover chlorobenzene, and distill under reduced pressure to collect the fraction with a boiling point of 142-146°C / 8mmHg to obtain 143g of white powder 4-MPA, GC: 99.4%, yield 88.3 %.

Embodiment 2

[0022] Phase transfer catalyst is not used, and other conditions are reacted under the completely identical situation of embodiment 1, investigate reaction result.

Embodiment 3

[0024] The usage amount of phase-transfer catalyst tetrabutylammonium bromide is 1%, and other conditions are reacted under the completely identical situation with embodiment 1, investigate reaction result.

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Abstract

The invention discloses a method for preparing 4-methyl benzene anhydride. The method comprises utilizing 4-methyl-1,2,3,6-tetra hydro phthalic anhydride as raw materials, and performing dehydrogenation on raw materials through the bromine to prepare the 4-methyl benzene anhydride. RCOOM or R(COOM)2 is utilized in the dehydrogenation reaction to serve as an acid-binding agent, quaternary ammonium salt is utilized to serve as a phase transfer catalyzer, benzene, chlorobenzene, orthodichlorobenzene, dibutyl ether and diisopropyl ether are utilized to serve as solvents, and the feeding molar ratio of 4-methyl tetrahydrophthalic anhydride to the acid-binding agent to the bromine is 1:2-4.4:2-2.2. The method is simple in synthesis process, less in wastewater, few in waste gases and residues, high in yield and suitable for industrialization production.

Description

technical field [0001] The invention relates to a method for synthesizing organic compounds, in particular to a method for preparing 4-methylphthalic anhydride. Background technique [0002] Methyl phthalic anhydride (4-methyl phthalic 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] (1) Literature US Patent No. 4,559,405 introduces a method for producing 4-methylphthalic anhydride. It uses 4-MTPA as the raw material to react with bromine under the condition of pyridine, the temperature is 30-70°C, the reaction is 3-4 hours, and after washing, extraction, concentration and crystallization, the yield is 87%. Although this method has a higher yield, it has many steps, and the c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D307/89
Inventor 杨巧梅徐晓东张雯君程文峰陆伟
Owner BEILI CHEM ZHANGJIAGANG
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