A kind of preparation method of lipoic acid oxidation impurity
A technology for oxidizing impurities and lipoic acid, applied in organic chemistry and other directions, can solve problems such as separation and purification
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Embodiment 1
[0026] A preparation method for lipoic acid oxidized impurities, characterized in that it comprises the following steps:
[0027] (1) Dissolve lipoic acid (1.00g, 4.9mmol, 1) in dichloromethane (5ml), then add N,N'-dicyclohexylcarbodiimide (0.95g, 4.9mmol), 4- Dimethylaminopyridine (0.60g, 4.9mmol) and methanol (0.47g, 14.7mmol) were stirred at room temperature for 4 hours. After the reaction was complete, the reaction solution was filtered. The filtrate was washed with 5% aqueous citric acid (10 ml), saturated sodium bicarbonate (10 ml), and saturated brine (10 ml), and dried over anhydrous sodium sulfate. The organic solvent was distilled off under reduced pressure to obtain 0.90 g of a light yellow oily liquid, namely methyl lipoic acid (2i).
[0028] The reaction equation is:
[0029]
[0030] (2) Dissolve the crude lipoic acid methyl ester (2i, 0.90g, 4.1mmol) obtained in step (1) in dichloromethane (4.5ml), add m-chloroperoxybenzoic acid (0.83g, 4.1mmol, 85 %) stir...
Embodiment 2
[0037] (1) Lipoic acid (1.00g, 4.9mmol, 1) was dissolved in acetonitrile (10ml), and then 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride ( 0.94g, 4.9mmol), 4-dimethylaminopyridine (0.60g, 4.9mmol), benzyl alcohol (0.59g, 5.5mmol), stirred at room temperature for 4 hours, the reaction was completed, and the reaction solution was filtered. The filtrate was washed with 5% aqueous citric acid (10 ml), saturated sodium bicarbonate (10 ml), and saturated brine (10 ml), and dried over anhydrous sodium sulfate. The organic solvent was distilled off under reduced pressure to obtain 1.30 g of benzyl lipoic acid (2ii) as a light yellow oily liquid.
[0038] The reaction equation is:
[0039]
[0040] (2) Dissolve the crude lipoic acid benzyl ester (2ii, 1.30g, 4.4mmol) obtained in step (1) in N,N-dimethylformamide (13ml), add tert-butyl hydroperoxide solution (1.6 ml, 8.8mmol, 5.5mmol / ml) was stirred at room temperature for 8 hours, the reaction was completed, and conce...
Embodiment 3
[0047] A preparation method for lipoic acid oxidized impurities, characterized in that it comprises the following steps:
[0048](1) Dissolve lipoic acid (1.0g, 4.9mmol, 1) in N,N-dimethylformamide (20ml), and then add N,N'-bis(2,6-diisopropylbenzene Base) carbodiimide (1.78g, 4.9mmol), 4-dimethylaminopyridine (0.60g, 4.9mmol), isopropanol (0.88g, 14.7mmol), stirred at room temperature for 4 hours, after the reaction was completed, filtered The reaction solution. The filtrate was washed with 5% aqueous citric acid (10 ml), saturated sodium bicarbonate (10 ml), and saturated brine (10 ml), and dried over anhydrous sodium sulfate. The organic solvent was distilled off under reduced pressure to obtain 1.05 g of isopropyl lipoic acid (2iii) as a yellow oily liquid.
[0049] The reaction equation is:
[0050]
[0051] (2) The crude product of lipoic acid isopropyl ester (2iii, 1.05g, 4.2mmol) obtained in step (1) was dissolved in acetonitrile (21ml), added peracetic acid (8.9...
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