Method for microwave synthesis of 2-nitro-3',4',5'-trifluoro-1,1'-biphenyl
A microwave synthesis and nitro technology is applied in the synthesis field of 2-nitro-3',4',5'-trifluoro-1,1'-biphenyl, an important intermediate of amide fungicide Xemium, It can solve the problems of high cost and long time, and achieve the effect of fast reaction speed, mild reaction conditions and high yield.
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[0015] Specifically, the synthesis method may include the following steps:
[0016] Step 1: In a microwave reaction tube, the raw materials o-nitrochlorobenzene and 3,4,5-trifluorophenylboronic acid are dissolved in a solvent, and a catalyst and a base are added;
[0017] Step 2: place in a microwave reactor, stir the reaction until the end;
[0018] Step 3: remove catalyst, the organic phase of extraction;
[0019] Step 4: Obtain 2-nitro-3',4',5'-trifluoro-1,1'-biphenyl by silica gel column chromatography.
[0020] Wherein, the solvent may include any one or more combinations of ethanol, ethylene glycol, tetrahydrofuran, N,N-dimethylpropanamide, methanol and water, preferably ethylene glycol, but not limited thereto.
[0021] Wherein, the catalyst is a palladium / graphene catalyst. In the present invention, microwaves are used for selective heating, and graphene with strong microwave absorption is used as a carrier to make the metal particle catalyst generate local high tem...
Embodiment 1
[0039] Example 1: In a 10ml microwave reaction tube, add 158mg (1mmol) o-nitrochlorobenzene, 176mg (1.2mmol) 3,4,5-trifluorophenylboronic acid, 415mg (3mmol) potassium carbonate, catalyst palladium / graphite Add 5mol% ethylene glycol, 2ml of ethylene glycol as the reaction solvent, and then add a stirring magnet and a certain amount of trimethylbenzene as the internal standard. After the addition, the microwave reaction tube was placed in a microwave reactor, the reaction temperature was 100°C, and the reaction time was 1.5 hours. After that, the reaction mixture was centrifuged several times to remove the catalyst, and extracted with ethyl acetate, and then the organic phase was treated with a silica gel column layer. The eluent used is ethyl acetate or petroleum ether, and the purified product is a light yellow crystalline solid with a yield of 90%, a melting point of 78.1-78.3°C, and a liquid phase content of 90%. The characterization data are as follows :
[0040] 1 HNMR ...
Embodiment 2
[0041] Example 2: In a 10ml microwave reaction tube, add 158mg (1mmol) o-nitrochlorobenzene, 176mg (1.2mmol) 3,4,5-trifluorophenylboronic acid, 415mg (3mmol) potassium carbonate, catalyst palladium / graphite Add 5mol% ethylene glycol, 2ml of ethylene glycol as the reaction solvent, and then add a stirring magnet and a certain amount of trimethylbenzene as the internal standard. After the addition, the microwave reaction tube was placed in a microwave reactor with a reaction temperature of 90° C. and a reaction time of 1.5 hours. The reaction product was purified referring to the same scheme as in Example 1. After the product was detected by liquid chromatography, it was found that the yield was about 76%.
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