Thiosemicarbazone

In organic chemistry, a semicarbazone is a derivative of an aldehyde or ketone formed by the addition-elimination (condensation) reaction between a ketone (or aldehyde) and a semicarbazide.

For ketones: H2NNHC(=O)NH2 + RC(=O)R (ketone) --> R2C=NNHC(=O)NH2.

For aldehydes: H2NNHC(=O)NH2 + RCHO (aldehyde) --> RCH=NNHC(=O)NH2.

For example, the semicarbazone of acetone would have the structure (CH3)2C=NNHC(=O)NH2. A 'thiosemicarbazone' contains a sulfur thio atom (sulfur) in lieu of the carbonyl oxygen.

Both semicarbazones and thiosemicarbazones are known to have anti-viral and anti-cancer activity, usually mediated through binding to copper or iron in cells. Many semicarbazones are crystalline solids, useful for the identification of the parent aldehydes/ketones by melting point analysis.