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Preparation of 2-bromo-4-methylphenol

A technology of methylphenol and p-cresol, which is applied in the synthesis field of preparing 2-bromo-4-methylphenol, can solve the problems of prolonging the reaction time, and achieve the effect of reducing the reaction time and increasing the yield

Inactive Publication Date: 2010-07-21
JIAXING ZHONGHUA CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In order to ensure that the reaction is carried out at a lower temperature, the titration rate of bromine needs to be controlled to ensure that the heat generated by the reaction can be transferred in time, thereby prolonging the reaction time

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] Add 370 grams of dichloroethane and 108 grams (1.00mol) of p-cresol into a 500ml three-necked bottle, and cool it to -10~-5°C with an ice-salt bath; Ethyl chloride and 156.8 grams of bromine (0.98 mol) were also cooled to -10 to -5°C in an ice-salt bath for use. Add the above-mentioned cooled p-cresol solution at a rate of 47.8 grams per minute, and the bromine solution at a rate of 52.7 grams per minute into a tubular reactor with an internal diameter of 5 mm and a length of 500 mm. The end of the reactor is connected to a 1000ml three-port Reaction bottle, use three-necked reaction bottle to receive the reaction solution. The three-necked flask is equipped with a reflux condenser and a thermometer. The hydrogen bromide gas discharged through the reflux condenser is absorbed, and the temperature of the reaction liquid entering the three-necked flask can be measured at 10-20°C. After the reaction finished, the hydrogen bromide generated by the reaction was reclaimed by...

Embodiment 2

[0018] Add 3700 grams of dichloroethane and 1080 grams (10.0mol) of p-cresol into a 5000ml three-necked bottle, and cool it to -20~-15°C with an ice-salt bath; Ethyl chloride and 1608 grams of bromine (10.05 mol) were also cooled to -10 to -5°C in an ice-salt bath for use. Add the above-mentioned cooled p-cresol solution at a rate of 478 grams per minute, and the bromine solution at a rate of 283.8 grams per minute into a tubular reactor with an inner diameter of 10 mm and a length of 500 mm. The end of the reactor is connected to a 10000ml three-port reaction A three-necked reaction bottle is used to receive the reaction solution. The three-necked flask is equipped with a reflux condenser and a thermometer, and the hydrogen bromide gas discharged is absorbed through the reflux condenser, and the temperature of the reaction liquid entering the three-necked flask can be measured at 0-15°C. After the reaction finished, the hydrogen bromide generated by the reaction was reclaime...

Embodiment 3

[0020] Add 5940 grams of chloroform and 1080 grams (10.0 mol) of p-cresol in a 5000ml three-necked flask, and cool it to -20~-15°C with an ice-salt bath; add 2970 grams of chloroform and 513ml bromine (10.0mol, 1600g), also cooled to -20~-15°C with an ice-salt bath for later use. Add the above-mentioned cooled p-cresol solution at a rate of 702 grams per minute, and the bromine solution at a rate of 457 grams per minute into a tubular reactor with an inner diameter of 10 mm and a length of 500 mm. The end of the reactor is connected to a 10000ml three-port reaction A three-necked reaction bottle is used to receive the reaction solution. The three-necked flask is equipped with a reflux condenser and a thermometer, and the hydrogen bromide gas discharged is absorbed through the reflux condenser, and the temperature of the reaction liquid entering the three-necked flask can be measured at -5 to 10°C. After the reaction finished, the hydrogen bromide generated by the reaction was...

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Abstract

The invention provides a synthetic method utilizing the paracresol continuous bromination method to prepare a 2-bromine-4-methylphenol, which measures the reaction material bromine and the paracresol accurately according to the reaction and mixes the materials evenly for being added to a reactor, the mixture is maintained in the reactor for a proper period of time for reaching the full reaction, then a reaction solution is transferred and separated to obtain the 2-bromine-4-methylphenol. The 2-bromine-4-methylphenol generated by the method of the invention will not contact with the bromine, thereby greatly reducing the side reaction and improving the selectivity of monobromination, as well as reducing the reaction time and increasing the yield.

Description

technical field [0001] The present invention relates to a method for preparing 2-bromo-4-methylphenol, more specifically to a method for preparing 2-bromo-4-methylphenol by continuous bromination of p-cresol and bromine. Background technique [0002] The bromination reaction of p-cresol is generally in the presence of an inert solvent, bromine and p-cresol are mixed and then reacted, but most of them are carried out intermittently. The selectivity of this bromination reaction is better at low temperature, and the general reaction temperature is controlled at about 0°C or at a lower temperature. However, this reaction is an exothermic reaction. In order to ensure that the reaction is carried out at a lower temperature, it is necessary to transfer the heat of the reaction process in time through a refrigerant. In order to ensure that the reaction is carried out at a lower temperature, it is necessary to control the titration rate of bromine to ensure that the heat generated b...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C39/26C07C37/62
Inventor 毛海舫曹钟林邹炳其
Owner JIAXING ZHONGHUA CHEM
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