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A method for synthesizing 2,5-dimethylphenol

A technology of dimethylphenol and dimethylbenzenesulfonic acid, applied in organic chemistry, ether preparation, bulk chemical production, etc., can solve the problem of reducing the yield and purity of sulfonated products, high feeding temperature and reaction temperature, and increasing The three wastes and production costs, etc., achieve the effect of shortening the reaction time, reducing the synthesis cost and high conversion rate

Active Publication Date: 2021-02-23
THE NORTHWEST RES INST OF CHEM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, there are still some problems in this process. The feeding temperature and reaction temperature are too high during sulfonation, which will easily lead to the occurrence of side reactions such as multiple sulfonation, and reduce the yield and purity of sulfonation products; a large amount of KOH is used during alkali fusion And the pH value of the acidification is very low, although the alkali fusion yield is increased to about 85%, but the three wastes and the production cost are greatly increased

Method used

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  • A method for synthesizing 2,5-dimethylphenol
  • A method for synthesizing 2,5-dimethylphenol
  • A method for synthesizing 2,5-dimethylphenol

Examples

Experimental program
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Embodiment 1

[0025] The synthetic method of the present embodiment is:

[0026] Step 1, the preparation of 2,5-dimethylbenzenesulfonic acid: add 2.0mol p-xylene to a 500mL four-necked flask with a water separator, then add 2.0mol mass concentration of concentrated sulfuric acid with a mass concentration of 98%. Under atmosphere, heat and reflux at 140°C for 3h, after cooling, distill under reduced pressure to remove excess p-xylene to obtain 56mL brown viscous liquid, then add 30mL distilled water to it, precipitate a large amount of solid, filter to obtain a filter cake, the filter cake is in 2,5-dimethylbenzenesulfonic acid was obtained by vacuum drying for 24 hours at a pressure of 3kPa and a temperature of 30°C;

[0027] After testing, the conversion rate of concentrated sulfuric acid in step 1 was 87.4%, and the yield rate of 2,5-dimethylbenzenesulfonic acid was 83.9%;

[0028] Step 2, oxidative hydrolysis of 2,5-dimethylbenzenesulfonic acid: 0.25mol of 2,5-dimethylbenzenesulfonic ac...

Embodiment 2

[0032] The synthesis method of this embodiment is the same as that of Example 1, except that the molar weight of concentrated sulfuric acid in step 1 is 1.5 mol.

[0033]After testing, the conversion rate of concentrated sulfuric acid in step 1 of this example is 96.3%, and the yield of 2,5-dimethylbenzenesulfonic acid is 88.6%; the 2,5-dimethylbenzenesulfonic acid described in step 2 The conversion rate is 90.5%, the yield of the pure 2,5-dimethylphenol in step 3 is 88.6%, and the purity of the pure 2,5-dimethylphenol is 99.04%.

Embodiment 3

[0035] The synthesis method of this embodiment is the same as that of Example 1, except that the molar weight of concentrated sulfuric acid in step 1 is 2.66 mol.

[0036] After testing, the conversion rate of concentrated sulfuric acid in step 1 of this example is 90.9%, and the yield of 2,5-dimethylbenzenesulfonic acid is 85.3%; the 2,5-dimethylbenzenesulfonic acid described in step 2 The conversion rate is 91.1%, the yield of the pure 2,5-dimethylphenol in step 3 is 86.6%, and the purity of the pure 2,5-dimethylphenol is 99.02%.

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Abstract

The invention discloses a method for synthesizing 2,5-dimethylphenol. The method comprises: using 2,5-dimethylbenzenesulfonic acid as a raw material, supercritical distilled water as a reaction medium, and sodium hydroxide as a catalyst. Oxygen is the oxidizing agent, and the crude product of 2,5-dimethylphenol is obtained after the reaction, and finally, the pure product of 2,5-dimethylphenol is obtained after successively filtering, refining with ethanol, and filtering and drying. The present invention uses supercritical hydration to synthesize 2,5-dimethylphenol, which is the most suitable method at present, reduces reaction steps, shortens the process flow, fundamentally solves the problem of environmental pollution, and produces no three wastes. Therefore, the present invention adopts the technique of supercritical hydration to synthesize 2,5-xylenol, which has very remarkable effect.

Description

technical field [0001] The invention belongs to the technical field of pharmaceutical intermediates, and in particular relates to a method for synthesizing 2,5-dimethylphenol. Background technique [0002] 2,5-Dimethylphenol is an important chemical raw material and pharmaceutical intermediate. It is the main raw material for the preparation of gemfibrozil. It is widely used in the production of trimethylphenol, an intermediate of vitamin E, and is often used as a disinfectant Agents, solvents, drugs, plasticizers and wetting agents, etc. [0003] At present, the methods for synthesizing 2,5-dimethylphenol mainly include sulfonation alkali fusion method, nitration reduction method, and direct catalytic hydroxylation method. When Wang Xiao et al. used 1-nitroso-2-naphthol-6-sulfonic acid sodium iron salt as a catalyst, the conversion rate of p-xylene reached 55.9%; but the selectivity of 2,5-dimethylphenol was only 18.1 %, the yield is only 10.1%, and the catalyst is dissol...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C41/01C07C43/205
CPCC07C41/01C07C303/06C07C43/205C07C309/30Y02P20/54
Inventor 王宪沛刘卫涛张立龙李小安张辉辉雷东卫闫俊
Owner THE NORTHWEST RES INST OF CHEM IND