In organic chemistry, a semicarbazone is a derivative of imines formed by a condensation reaction between a ketone or aldehyde and semicarbazide. They are classified as imine derivatives because they are formed from the reaction of an aldehyde or ketone with the terminal -NH₂ group of semicarbazide, which behaves very similarly to primary amines.

Formation

For ketones

H₂NNHC(=O)NH₂ + RC(=O)R → R₂C=NNHC(=O)NH₂

For aldehydes

H₂NNHC(=O)NH₂ + RCHO → RCH=NNHC(=O)NH₂

For example, the semicarbazone of acetone would have the structure (CH₃)₂C=NNHC(=O)NH₂.

Properties and uses

Some semicarbazones, such as nitrofurazone, 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.^[1]

A thiosemicarbazone is an analog of a semicarbazone which contains a sulfur atom in place of the oxygen atom.