NH2NHCONH2

NH2NHCONH2, also known as semicarbazide, is an organic compound with the chemical formula CH5N3O. It is the amide of carbazic acid. Semicarbazide is typically a white crystalline solid that is soluble in water. It exists in two tautomeric forms, one with the carbonyl group and the other with a hydroxyl group.

The primary use of semicarbazide is as a reagent in organic chemistry. It is particularly useful for the characterization and derivatization of aldehydes and ketones. When reacted with aldehydes or ketones, semicarbazide forms semicarbazones, which are often crystalline solids with sharp melting points, allowing for the identification and purification of the carbonyl compound. This reaction is a classic example of nucleophilic addition to a carbonyl group followed by dehydration.

Semicarbazide has also found applications in analytical chemistry for the determination of certain substances. Historically, it has been investigated for potential pharmaceutical properties, though its widespread use in medicine is limited due to toxicity concerns. It can be synthesized through the reaction of urea with hydrazine or by the reaction of ethyl carbazate with ammonia. Care should be taken when handling semicarbazide as it can be an irritant and potentially toxic.