Preparation method of 2-nitro-4-trifluoromethylbenzoic acid and its isomers
A technology of trifluoromethylbenzoic acid and trifluoromethylbenzonitrile is applied in the field of preparation of 2-nitro-4-trifluoromethylbenzoic acid and isomers thereof, and can solve the problems of low yield, 2 -Nitro-4-trifluoromethylbenzoic acid and its isomers have problems such as expensive raw materials, and achieve the effects of high yield, cheap raw materials and short reaction steps
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[0020] Concrete, the preparation method of 2-nitro-4-trifluoromethylbenzoic acid and its isomers, the method comprises: with 4-trifluoromethylbenzonitrile raw material, under the action of nitrating agent, one-step reaction obtains 2-nitro-4-trifluoromethylbenzoic acid and 3-nitro-4-trifluoromethylbenzoic acid.
[0021] Reaction formula of the present invention is as follows:
[0022]
[0023] The present invention is with 4-trifluoromethyl benzonitrile as raw material, because there is reaction selectivity problem, cyano group is hydrolyzed to be carboxyl group in acidic condition and is usually comparatively difficult, promptly obtains the mixture of amide and carboxylic acid under normal circumstances, and To improve the selectivity of carboxylic acid formation, harsh hydrolysis conditions, such as high concentration of strong acid or high temperature, are required. Experiments have found that if 4-trifluoromethylbenzonitrile and concentrated sulfuric acid are reacted u...
Embodiment 1
[0037] Add 5g of 4-trifluoromethylbenzonitrile and 30mL of dichloromethane to the three-necked flask, then dropwise add 10mL of nitrating agent, raise the temperature to 40°C, stir magnetically for 7h, and end the reaction; add 30mL of water, separate the liquids, and take the organic layer, The aqueous layer was extracted once with 30 mL of ethyl acetate, the organic phases were combined, dried over anhydrous sodium sulfate, and rotary evaporated to obtain 5.2 g of viscous liquid, which was detected at 215 nm in the liquid phase, and the content of 2-nitro-4-trifluoromethylbenzoic acid was 14 %, 3-nitro-4-trifluoromethylbenzoic acid content 10%.
Embodiment 2
[0039] Add 5g of 4-trifluoromethylbenzonitrile and 30mL of 1,2-dichloroethane to the three-necked flask, then dropwise add 10mL of nitrating agent, raise the temperature to 40°C, stir for 7h with magnetic force, and end the reaction; add 30mL of water, separate the liquid , the organic layer was taken, the aqueous layer was extracted once with 30 mL of ethyl acetate, the organic phases were combined, dried over anhydrous sodium sulfate, and rotary evaporated to obtain 5.3 g of viscous liquid, which was detected at 215 nm in the liquid phase, and 2-nitro-4-trifluoroform The content of benzoic acid is 15%, and the content of 3-nitro-4-trifluoromethylbenzoic acid is 11%.
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