Synthetic method of 5-bromo-2-chlorobenzoic acid
A technology of chlorobenzoic acid and synthesis method, applied in chemical instruments and methods, preparation of carboxylate, preparation of organic compounds, etc., can solve the problems of cumbersome post-processing, high production cost, poor post-processing effect, etc., and achieve a synthesis route The effect of novelty, less environmental pollution and low production cost
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Embodiment 1)
[0052] The present embodiment is the preparation of 2-hydroxyl-5-bromo-benzoic acid, and the specific method is as follows:
[0053] Add 138.0g of salicylic acid (1.0mol), 6.68g of aluminum trichloride (0.05mol), and 1.0L of 1,2-dichloroethane into a three-necked flask, heat to 45°C, and dropwise add 176.0g of Bromine (1.1mol), the temperature was raised to reflux after dropping, and reacted for 15h.
[0054] The reaction controlled by HPLC was completed, and the ratio of 2-hydroxy-5-bromo-benzoic acid to 2-hydroxy-3-bromo-benzoic acid was about 6:1.
[0055] The reacted system was cooled to 0°C with ice water, and then saturated aqueous sodium bisulfite solution was added to the system with stirring until it was colorless, left to stand for liquid separation, the organic layer was washed with water and saturated brine successively, concentrated under reduced pressure, Then add ethanol / tetrahydrofuran mixed solvent (volume ratio 1:5), heat up to 70°C and stir to dissolve, and...
Embodiment 2)
[0057] The present embodiment is the preparation of 2-hydroxyl-5-bromo-benzoic acid, and the specific method is as follows:
[0058] Add 138.0g of salicylic acid (1.0mol) and 1.5L of acetic acid into a three-necked flask, heat to 80°C, add 300.0g of dibromohydantoin (1.05mol) in batches, and keep stirring at this temperature to react 12h.
[0059] The reaction controlled by HPLC was completed, and the ratio of 2-hydroxy-5-bromo-benzoic acid to 2-hydroxy-3-bromo-benzoic acid was about 7.5:1.
[0060] Cool the reacted system to room temperature, then pour it into 2L of ice water at one time, precipitate a yellow solid, filter, dry, then add ethanol / tetrahydrofuran mixed solvent (volume ratio 1:5), heat up to 70°C and stir to dissolve, Finally, it was slowly cooled to room temperature, stirred and crystallized, filtered and dried to obtain 156.0 g of white solid 2-hydroxy-5-bromo-benzoic acid with a yield of 71.9% and a purity of 96.5% (HPLC).
Embodiment 3)
[0062] The present embodiment is the preparation of 2-hydroxyl-5-bromo-benzoic acid, and the specific method is as follows:
[0063] Add 12.2g of sodium metavanadate (0.1mol), 26.7g of aluminum tribromide (0.1mol) and 338.0g of tetrabutylammonium bromide (1.05mol) to a 5L three-necked flask, then fill with oxygen, and then add 138.0g of salicylic acid (1.0mol), 2L of 1,4-dioxane, and 1.8g of water (0.1mol), heated to 80°C and stirred for 8h, supplemented with oxygen during the reaction.
[0064] The reaction controlled by HPLC was completed, and the ratio of 2-hydroxy-5-bromo-benzoic acid to 2-hydroxy-3-bromo-benzoic acid was about 24:1.
[0065] The reacted system was cooled to room temperature, then 1N hydrochloric acid was added, and then extracted with ethyl acetate (1L×2). The organic layers were combined and washed with water and saturated brine in turn. The solvent was evaporated under reduced pressure, and then ethanol / tetrahydrofuran was added to mix Solvent (volume ...
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