Preparation of oximes from ketones and hydroxylamine hydrochloride

J. Org. Chem, 1974, 39, 2492


Ketone : 1 equivalent

Hydroxylamine : 2 eq

Triethylamine : 2.1 eq or excess

Methanol : solvent

Oxime : >90% t=yield expected


The ketone was dissolved in anhydrous methanol (4 mL/mmol) containing hydroxylamine hydrochloride (2 eq) and triethylamine (2.1 eq).  The solution was refluxed for 2 days and diluted with H2O containing conc. NH4OH until the pH was basic.  The aqueous layer was extracted with CHCl3 (3x).  The combined chloroform layers were washed with brine, dried over MgSO4, filtered, and concentrated in vacuo.  The solid was recrystallized by dissolving in CHCl3 followed by addition of hexane until the solution turned cloudy and let sit in cold.  If the product is not a solid, then the oxime is purified via silica gel chromatography. Yield = 90%.

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