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Preparation method of o-nitrobenzyl bromide

A technology of o-nitrobenzyl bromide and o-nitrotoluene, which is applied in the field of chemical synthesis of the fungicide pyraclostrobin intermediate, can solve the problem that there is no report on the purification process of the product o-nitrobenzyl bromide, and it is difficult to achieve high selectivity bromination reaction, unable to obtain solid crude products and other problems, to achieve the effect of cheap and easy-to-obtain raw materials, stable and controllable yield, and improve bromination selectivity

Pending Publication Date: 2022-04-19
JIANGSU FENGSHAN GROUP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, it has been found through confirmatory experiments that it is difficult to achieve a highly selective bromination reaction with this feeding method, and a large amount of by-products and bromides still exist, and there are residual raw materials.
Due to the existence of raw materials and by-products, the bromination reaction liquid can only be evaporated to dryness to obtain an oily product, and the solid crude product cannot be obtained, so it is also difficult to purify the product by elution.
[0007] The yield of the current industrialized o-nitrotoluene bromination reaction is basically 70%, and there are almost no reports on the purification process of the product o-nitrobenzyl bromide

Method used

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  • Preparation method of o-nitrobenzyl bromide
  • Preparation method of o-nitrobenzyl bromide

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] Add 1739L of chlorobenzene and 86.9kg of azobisisobutyronitrile into a 2500L stock preparation kettle, stir at room temperature for 30-60 minutes until completely dissolved, and pump the solution into the high-level tank for later use. Put 699kg of 27.5% hydrogen peroxide from the storage tank into another elevated tank for standby.

[0032] In a 5000L bromination kettle, add 602.1kg of o-nitrotoluene and 967.3kg of 40% hydrobromic acid in sequence, turn on the stirring, and the internal temperature rises to 75°C. Then add the azobisisobutylnitrile dichloroethane solution and hydrogen peroxide in the head tank at a uniform speed at the same time, and drop it in 4 hours. The temperature of the dropping process is controlled at 75-80 ° C, and then keep warm for 1 hour, then cool down to room temperature. During the reaction, the content of the by-product dibromo product was monitored to be 3%.

[0033] The reaction solution was unloaded into a 5000L separatory tank, and ...

Embodiment 2

[0036] Add 1739L of dichloroethane and 86.9kg of azobisisobutyronitrile into a 2500L stock preparation kettle, stir at room temperature for 30-60 minutes until completely dissolved, and pump the solution into the high level tank for later use. Put 699kg of 27.5% hydrogen peroxide from the storage tank into another elevated tank for standby.

[0037] In a 5000L bromination kettle, add 602.1kg of o-nitrotoluene and 967.3kg of 40% hydrobromic acid in sequence, turn on the stirring, and the internal temperature rises to 75°C. Then, the azobisisobutylnitrile dichloroethane solution and hydrogen peroxide in the overhead tank were added dropwise at a uniform speed at the same time, and the drop was completed in 4 hours. The temperature of the dropwise addition process was controlled at 75-80° C., and then kept for 1 hour, and then cooled to room temperature.

[0038] The reaction solution was unloaded into a 5000L separatory tank, and left to stand at room temperature for 2 hours, and ...

Embodiment 3

[0041] Add 1739L of dichloroethane and 86.9kg of azobisisobutyronitrile into a 2500L stock preparation kettle, stir at room temperature for 30 minutes until completely dissolved, and pump the solution into the overhead tank for later use. Put 699kg of 27.5% hydrogen peroxide from the storage tank into another elevated tank for standby.

[0042] In a 5000L bromination kettle, add 602.1kg of o-nitrotoluene and 967.3kg of 40% hydrobromic acid in sequence, turn on the stirring, and the internal temperature rises to 75°C. Then, the azobisisobutylnitrile dichloroethane solution and hydrogen peroxide in the overhead tank were added dropwise at a uniform speed at the same time, and the drop was completed in 4 hours. The temperature of the dropwise addition process was controlled at 75-80° C., and then kept for 1 hour, and then cooled to room temperature.

[0043] The reaction solution was unloaded into a 5000L separatory tank, and left to stand at room temperature for 2 hours, and the...

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Abstract

The invention relates to a preparation method of o-nitrobenzyl bromide, which comprises the following steps: by taking o-nitrotoluene and hydrobromic acid as substrates, a chlorobenzene solution of azodiisobutyronitrile as a dropwise adding substance 1 and hydrogen peroxide as a dropwise adding substance 2, dropwise adding the azodiisobutyronitrile solution and the hydrogen peroxide into the substrates at the same time, and ending at the same time; after dropwise adding, carrying out bromination reaction at 75-80 DEG C; after the reaction is finished, cooling to room temperature, standing for layering, taking an organic phase, quenching residual hydrogen peroxide by using a sodium sulfite aqueous solution, stirring, standing for layering, transferring and heating a lower-layer organic phase, and removing the solvent through reduced pressure distillation; and transferring the distilled liquid substrate while the liquid substrate is hot, adding a crystallization solvent, cooling and crystallizing to obtain slurry, separating and drying to obtain a white o-nitrobenzyl bromide solid product. The conversion rate and selectivity of the bromination reaction are improved, the process yield is high, the recovery rate in the crystallization and purification process is high, the total yield can reach 85%, raw materials are cheap and easy to obtain, operation is easy, environment protection and green are achieved, the comprehensive cost is low, and the method is suitable for large-scale production.

Description

technical field [0001] The invention belongs to the field of chemical synthesis of a fungicide pyraclostrobin intermediate, and in particular relates to a preparation method of o-nitrobenzyl bromide. Background technique [0002] Pyraclostrobin is also known as pyraclostrobin, and its chemical name is N-[2-[1-(4-chlorophenyl)-1H-pyrazol-3-yloxymethyl]phenyl](N- Methoxyl) methyl carbamate was listed in Germany, Britain and France in 2001 by BASF, Germany. [0003] At present, there are two routes for the synthesis of pyraclostrobin, both of which start from o-nitrotoluene to obtain products through five-step reactions. The difference between the two routes is mainly reflected in the first bromination or post bromination. Lan Shilin et al. (Research on the synthesis of o-nitrobenzyl bromide, Fine Chemical Intermediates, 2006, 36, 2, 24-25) disclosed a post-bromination route for the synthesis of o-nitrobenzyl bromide. Although the conditions are mild, However, due to the dif...

Claims

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Application Information

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IPC IPC(8): C07C201/12C07C201/16C07C205/11
CPCC07C201/12C07C201/16C07C205/11
Inventor 饶镇吴豆豆姚金莉陈宝明王晋阳单永祥殷凤山
Owner JIANGSU FENGSHAN GROUP