N-BENZYLHYDROXYLAMINE HYDROCHLORIDE

Preparation

(a) Preparation of a-phenyl-N-benzylnitrone. To a flask equipped with a stirrer and condenser and containing 17.6 gm (0.0827 mole) of N,N-dibenzylhydroxylamine is added 36.8 gm (0.17 mole) of yellow mer­curic oxide and 100 ml of ether. The mixture is stirred and the resulting exothermic reaction causes the ether to reflux for 1 hr. After a total of 3 hr reaction time the reaction mixture is filtered and concentrated to afford 15.7 gm (90%), m.p. 81.5-83.5°C (recrystallized from acetone-ligroin). Jones and Sneed [12a] earlier reported that air-KOH can also be used to effect this oxidation.
(b) Hydrolysis of a-phenyl-N-benzylnitrone to N-benzylhydroxylamine [12a]. To a flask containing 17.0 gm (0.0806 mole) of the above nitrone is added 34 ml of concentrated hydrochloric acid solution. Then the mixture is steam-distilled to remove the formed benzaldehyde. After the benzal­dehyde is removed the hydrochloric acid is removed by heating over a low flame. To the cool residue is added a cold solution of sodium carbonate to neutralize the mixture. The mixture is filtered, and the filtrate, after being cooled to 0°C, is made alkaline. After 1 hr N-benzylhydroxylamine pre­cipitates from the cold filtrate and is filtered to afford 6.0 gm (61%), m.p. 57°C (recrystallized from benzene-petroleum ether). Yields as high as 88% have been reported for this preparation.