Hydrochloric Acid → 2,3-Dichlorophenylglyoxal aldoxime

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Reaction Steps

2,3-Dichloroacetophenone (20.00 g, 0.104 mol) was dissolved in dry diethyl ether (200 ml) and hydrogen chloride bubbled through the solution for half an hour. Amyl nitrite (24.36 g, 0.238 mol) was added dropwise, with stirring, so that the solution was maintained at a gentle reflux. The solution was then gently refluxed for 3 hours with continued passage of hydrogen chloride. The solution was allowed to stand at room temperature overnight. The reaction mixture was poured into 2N sodium hydroxide solution (200 ml) with extreme caution (very vigorous reaction), and separated. The organic phase was extracted with 2N sodium hydroxide solution (2×100 ml). The alkaline phases were combined, poured onto ice (200 ml) and Concentrated hydrochloric acid (100 ml) added with stirring. The resulting acid mixture was allowed to stand at room temperature overnight and the precipitate which formed was filtered at the pump. 2,3-Dichlorophenylglyoxal aldoxime was afforded as a cream solid (10.4 g, 46% yield). T.l.c. (SiO2CHCl3) showed no impurities, therefore no further purification was attempted.

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