(E)-2-oxopropanal oxime

To a well-stirred, ice-cooled solution of 5.8 gm (0.1 mole) of acetone in 30 ml of glacial acetic acid is added dropwise a concentrated aqueous solution containing 15 gm of sodium nitrite. Stirring at 0°C is continued for 45 min, then 100 ml of water is added and the crude product is extracted with ether. The ether extracts are combined, washed repeatedly with 10 ml portions of water, and dried with sodium sulfate. The ether is evaporated off under reduced pressure and the residue is dried on a porous plate. After recrys-tallization from benzene, 6 gm (69%) of the product is isolated, m.p. 65°C.