Identify an unknown carbonyl compound
Objective
To classify a carbonyl compound by a simple test and to identify it by the precipitation of a derivative.
Principle
In this experiment, the unknown compound is either an aldehyde or a ketone from Table 90. In the first part, on undergoing Tollen's & Fehling's tests, ketone will have no reaction. In the second part, by preparing a derivative of the compound with 2,4-dinitrophenylhydrazine, the sharp melting point can be used to identify the unknown carbonyl compound.
Carbonyl compound can form a precipitate with 2,4-dinitrophenylhydrazine with high melting point: