Aminoacetone semicarbazone hydrochloride

AMINOACETONE SEMICARBAZONE HYDROCHLORIDE (Amino-2-propanone, setnicarbazone hydrochloride)... 

Aminoacetone is a versatile starting material for many syntheses, particularly for the preparation of heterocycles. The present procedure describes a convenient method for its preparation in a form suitable for storage. The aminoacetone can be generated from aminoacetone semicarbazone hydrochloride in situ as needed. 

C. Aminoacetone semicarbazone hydrochloride. The product from step B is dissolved in 250 ml. of absolute alcohol in a 1-1. Erlenmeyer flask, and to this solution is added a solution of 48 g. of semicarbazide hydrochloride (Note 1) in 100 ml. of water. The mixture is allowed to stand at room temperature for 2 hours, the crystalline precipitate is collected by suction filtration, and the off-white product is washed on the filter with absolute alcohol. The crystals, after air-drying, amount to 54-58 g. (72-78%) and melt at 208-210°. The product is essentially pure and can be used for most purposes without further purification (Note 6). 

Aq. semicarbazide hydrochloride added to a soln. of aminoacetone hydrochloride in alcohol, and allowed to stand 2 hrs. at room temp. aminoacetone semicarbazone hydrochloride. Y 72-78%. J. D. Hepworth, Org. Synth. 45, 1... 

Senucarbazide hydrochloride, conversion to semicarbazone, 46, 2 reaction with aminoacetone hydrochloride, 46, 2... 

Aminoacetone hydrochloride is very hygroscopic and is best stored as the semicarbazone. If the compound itself is desired, however, the dark red oil is dried under reduced pressure over phosphorus pentoxide. The resulting crystalline aminoacetone hydrochloride can be purified by dissolving it in absolute ethanol and precipitating it by the addition of dry ether. 

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