Structure and reactivity of the 2, 4-dinitrophenylhydrazines
Aldehydes and ketones hove been identified for a number of years by virtue of the fact that they form crystalline condensation products with a number of amines. One important example is 2,4-dinitrophenylhydrazine (2,4-D) (1). The crystalline derivatives with their supposedly characteristic melting points provide a means of identification. However, this method of identifying aldehydes and ketones by the melting point of their 2,4-dinitrophenylhydrazones (DNPH's) has been shown to be unreliable in a number of instances, as multiple DNPH's hove been reported differing in melting point, crystal structure, or both ( 1 , 6, 7, 8).