Semicarbazone

It is a condensation product of carbonyl compounds and semicarbazide. It is represented by the general formula RR'C= _NNHCONH2 . If semicarbazide hydrochloride ( _NH2CONHNH2 ·HCl) and sodium acetate are added to an aqueous or ethanolic solution _of an aldehyde or ketone, shaken well, heated once, and allowed to cool, semicarbazone crystals will precipitate. It is generally a colorless solid. It is poorly soluble in water. It has good crystallinity. For example, acetaldehyde semicarbazone _CH3CH = _NNHCONH2 has a melting point of 162°C. Acetone semicarbazone ( _CH3 ) _2C = _NNHCONH2 has a melting point of 187°C. When treated with a strong acid, it is easily hydrolyzed to produce carbonyl compounds.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

カルボニル化合物とセミカルバジドとの縮合生成物．一般式RR′C=NNHCONH₂で表される．アルデヒド，ケトンの水溶液またはエタノール溶液にセミカルバジド塩酸塩NH₂CONHNH₂･HClおよび酢酸ナトリウムを加えてよく振り，一度加熱してから放冷すると，セミカルバゾンの結晶が析出する．一般に，無色の固体．水に難溶．結晶性がよい．たとえば，アセトアルデヒドセミカルバゾンCH₃CH=NNHCONH₂は，融点162 ℃．アセトンセミカルバゾン(CH₃)₂C=NNHCONH₂は，融点187 ℃．強酸を作用させると容易に加水分解されてカルボニル化合物を生じる．

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