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Method for preparing benzyl bromide with substituent groups

A technology of substituent and benzyl bromide, applied in the field of preparation of benzyl bromide, can solve problems such as serious equipment corrosion, accelerated decomposition process, hidden dangers, etc. Effect

Inactive Publication Date: 2019-03-19
YONGNONG BIOSCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Although this method realizes the rebirth of bromine and improves the utilization rate of bromine, hydrogen peroxide will accumulate during the reaction process, and it is unstable in strong acid and easy to decompose. There is a phenomenon of self-acceleration during the decomposition process. A large amount of heat and gas are released, which poses a safety hazard
High-concentration hydrobromic acid (concentration is 48%) is volatile and highly corrosive, which seriously corrodes equipment and has a risk of leakage. Therefore, there is still room for improvement

Method used

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  • Method for preparing benzyl bromide with substituent groups
  • Method for preparing benzyl bromide with substituent groups

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] A preparation method of o-nitrobenzyl bromide:

[0022] The reaction formula is as follows:

[0023]

[0024] 100g of o-nitrotoluene, 200g of dichloroethane, 60g of sodium bromide, 5g of anhydrous sodium sulfate, 2.2g of acetonitrile, 4.5g of azobisisobutyronitrile, and 150ml of water were successively put into a 500ml four-necked bottle, and stirred and heated to 70°C, at 55-70°C, blow chlorine gas into the bottle through the air guide tube, adjust the flow rate of chlorine gas, control the color of the reflux liquid to be reddish, and after aeration for about 3.5 hours, the sampling gas phase tracking shows that the raw material is 30.8%, and benzyl bromide is 63.3%. Dibromobenzyl is 4.2%, and benzyl chloride is 1.7%. Stop the reaction, lower the temperature to 35°C, separate layers, add 60ml of water to the organic phase, add 10g of liquid caustic soda dropwise, adjust the pH value to 10-11, let stand and separate the layers to obtain 355g of the organic phase, a...

Embodiment 2

[0026] A preparation method of o-nitrobenzyl bromide:

[0027] In a 50L model glass kettle, put 10kg of o-nitrotoluene, 20kg of industrial dichloroethane, 6kg of sodium bromide, 0.5kg of anhydrous sodium sulfate, and 15L of deionized water in sequence, and stir for half an hour until the materials are all dissolved, then put in 0.22 kg of industrial acetonitrile and 0.45kg of azobisisobutyronitrile, turn on the condenser cooling water and exhaust gas absorption system, heat the jacket to 65°C, start to pass chlorine gas, and pass 3.95kg of chlorine gas under the liquid surface through the air guide within 4 hours , control the reddish reflux liquid. After aeration finishes, sampling analysis, gas chromatogram shows raw material 33.6%, benzyl bromide is 60.5%, dibromide 4.1%, and benzyl chloride is 1.8%. Add 5L of deionized water to cool down to 30°C, let it stand for stratification, return the organic phase to the kettle, add 6L of water, add 1k of industrial liquid caustic s...

Embodiment 3

[0029] A preparation method of (E)-2-(2-bromomethylphenyl)-2-methoxyiminoacetic acid methyl ester:

[0030] The reaction formula is as follows:

[0031]

[0032] In a 1L three-necked reaction flask, add 200g (E)-2-(2-methylphenyl)-2-methoxyiminoacetic acid methyl ester (content 95%), 400g dichloroethane, 100g sodium bromide, 9.7 g anhydrous sodium sulfate, 4.4g acetonitrile, 190ml water, 5.9g azobisisobutyronitrile, raise the temperature to 55-70°C, pass chlorine gas into the reaction bottle through the gas guide tube, adjust the flow rate of chlorine gas, and control the reflux liquid to be reddish . After ventilating for 3 hours, sampling gas phase tracking, the spectrum shows that the monobromide content is 82.2%, the raw material is 9.2%, the dibromide is 6.8%, and the benzyl chloride is 1.8%. Stop the reaction, cool down to room temperature, add 50ml of water, let stand to separate layers, extract the water layer once with 20ml of dichloroethane, combine the organic ...

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Abstract

The invention relates to the technical field of chemical engineering, and provides a method for preparing benzyl bromide with substituent groups. By the aid of the method, the problem of severe corrosion on equipment can be pertinently solved. The technical scheme includes that bromide is used as a bromine source at the temperature of 55-70 DEG C under two-phase conditions, chlorine is used as anoxidizing agent, azodiisobutyronitrile is used as an initiator, methylbenzene with substituent groups is brominated to obtain substituted benzyl bromide in the presence of auxiliaries and catalysts, materials are cooled until the temperatures of the materials reach 20-40 DEG C, are allowed to stand still to be layered at the temperatures of 20-40 DEG C, and then are neutralized, and substituted benzyl bromide solution can be obtained after secondary layering is carried out. The method has the advantages that the nonvolatile bromide with extremely low irritation is used as the bromine source, the chlorine is oxidized, accordingly, bromine can be regenerated, the utilization rate of bromine elements can be increased, reaction can be quickly carried out, accumulation phenomena can be prevented, corrosion on equipment can be reduced, risks of industrial production can be decreased, and production procedures are safe.

Description

technical field [0001] The invention relates to the technical field of chemical engineering, in particular to a preparation method of benzyl bromide containing substituents. Background technique [0002] At present, the commonly used bromination method of substituted toluene to prepare substituted benzyl bromide is NBS, dibromohydantoin and other brominated imines. The reaction is characterized by fast reaction speed, but the atom utilization rate is very low, and the produced butane It is difficult to directly recycle solids such as imide and hydantoin. In addition, benzylic bromide substances are very irritating, and it is difficult to avoid great harm to the human body during the solid discharge process. Sodium bromate or potassium bromate can also be brominated under sulfuric acid system, but the price is relatively expensive; a part of hydrogen bromide will be produced during the direct bromination reaction of bromine, and the utilization rate of bromine element is only...

Claims

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Application Information

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IPC IPC(8): C07C201/12C07C205/06C07C249/02C07C251/24
CPCC07C201/12C07C249/02C07C205/06C07C251/24
Inventor 吴承骏魏兴辉毛春晖许健杰罗中华许春林
Owner YONGNONG BIOSCI