Preparation and application of 2-bromoxynil_Kain Industrial Additive

Scenery and overview[1-4]

2-Bromobenzonitrile is an organic intermediate that can be prepared in one step from o-bromostyrene or o-bromobenzyl alcohol or o-bromobenzaldehyde. Can be used to prepare o-bromoacetophenone.

Preparation[1-3]

Synthesis of o-bromobenzonitrile

Add 0.4 mmol o-bromostyrene, 2 mmol sodium nitrite, 5 mg metallic iron(Ⅲ) porphyrin, and 4.5 ml acetonitrile solvent into the reaction tube. Heat and stir at 70°C for the first 0.5 hours in an air atmosphere. Add 0.5 ml of formic acid drop by drop. After 4 hours of reaction, stop heating and stirring, cool to room temperature, obtain the crude product through a rotary evaporator, and then separate and purify it through column chromatography to obtain the target product. The column chromatography eluent used is: Mixed solvent of petroleum ether and ethyl acetate. The compound is a white solid with a yield of 78.49%. Its nuclear magnetic data are as follows: 1H NMR (400MHz, CDCl3) δ7.62 (ddd, J=15.9, 9.3, 4.2Hz, 2H), 7.42- 7.35 (m, 2H) ; 13C NMR (101MHz, CDCl3) δ134.34,133.91,133.22,127.65,125.35, 118.78,117.15.

Add 0.1mol/L sodium perchlorate in acetonitrile solution (10mL), o-bromobenzyl alcohol (1mmol, 187mg), TEMPO (0.15mmol, 23mg) and ammonium acetate (3mmol, 231mg) into a 30ml beaker. Constant potential electrolysis at 25°C and 1.5V, the reaction ended after 10 hours. Add saturated sodium bisulfite solution to the reaction solution and stir, then extract with ethyl acetate, separate the organic layer, evaporate the solvent under reduced pressure, and then perform column chromatography separation, using an ethyl acetate/n-hexane volume ratio of 1:5. The mixed liquid was used as the eluent. The eluent containing the target compound was collected, and the solvent was evaporated to obtain 162.0 mg of 2-bromoxynil, with an isolation yield of 89%.

Add 0.1mol/L sodium perchlorate in acetonitrile solution (10mL), o-bromobenzaldehyde (1mmol, 184mg), TEMPO (0.1mmol, 16mg), HMDS (2.5mmol, 404mg) and Acetic acid (2.5mmol, 150mg). Constant potential electrolysis at 25°C and 1.5V, the reaction ended after 12 hours. Add saturated sodium sulfite solution to the reaction solution and stir, then extract with dichloromethane, separate the organic layer, evaporate the solvent under reduced pressure, and then perform column chromatography separation. Use a mixed solution of ethyl acetate/petroleum ether with a volume ratio of 1:200. eluent, collect the eluate containing the target compound, and evaporate the solvent to obtain 143.8 mg of 2-bromophenonitrile, with an isolation yield of 79%.

Application[4]

A method for synthesizing high-purity o-bromoacetophenone. o-bromoacetophenone is an important organic synthesis intermediate and is widely used in spices, medicines, pesticides, dyes, organic optoelectronics and other fields. It includes the following steps: add methylmagnesium bromide Grignard reagent in a container, and add dropwise a tetrahydrofuran solution of 2-bromobenzonitrile under normal temperature conditions. After the addition is completed, a large amount of white solid will appear; HPLC detects that there is no raw material , stop the reaction; drop it into the hydrochloric acid solution, separate the liquids, spin dry, and distill under reduced pressure to obtain a colorless liquid product, which is high-purity o-bromoacetophenone. The invention improves the production operating environment, can synthesize high-purity o-bromoacetophenone under normal temperature conditions, is easy to operate and control, shortens the reaction time, reduces the cost, and is beneficial to industrial production.

Main reference materials

[1] CN201710893797.6 A method for synthesizing aromatic nitriles from aromatic olefins catalyzed by metal porphyrins

[2] CN201710027754.X A method for the electrochemical catalytic synthesis of aromatic nitriles using alcohol as raw material

[3] [China invention, China invention authorization] CN201510947314.7 Electrochemical catalytic synthesis method of aromatic nitriles

[4] CN201410518187.4 Synthesis method of high-purity o-bromoacetophenone