What is the product of a specific semicarbazide reaction?

1 Answer
Feb 13, 2017

Semicarbazides are typically reacted with aldehydes and ketones to give semicarbazide derivatives...............

Explanation:

And for an aldehyde, #"R'C(=O)H"#:

#"R'C(=O)H" + "H"_2"NN(H)C(=O)NH"_2rarr#
#"R'C=NNH"-"C(=O)NH"_2+"H"_2"O"#

The semicarbazide derivative is typically crystalline, and fairly high-melting, and the melting points of semicarbazide derivatives of ketones and of aldehydes have been extensively tabulated. Measurement of the melting points of the semicarbazide derivatives can thus identify a unknown aldehyde or ketone; if the melting point of another derivative is measured, the identification becomes unequivocal. This is usually the quickest way to identify an unknown organic compound, despite today's vast array of sophisticated spectroscopic techniques.