To date there are but two methods for distinguishing between these compounds. The first involves the reduction of the hydrazone with sodium amalgam to give aniline and the corresponding aliphatic amine. The yields are low and many cases tried have given negative results. The pyrazolines do not suffer this change. The second method is based on the fact that many of these hydrazones are rearranged by boiling acetic acid to the isomeric pyrazolines. If, in this way, the compound in question is converted into a new product, the latter is probably, but not certainly, a pyrazoline. If the latter can be oxidized to benzoic and a pyrazole acid, the pyrazoline is more clearly indicated.
Proceedings of the Iowa Academy of Science
©1935 Iowa Academy of Science, Inc.
Peterson, Walter J. and Raiford, L. Chas.
"Identification of Hydrazones and Isomeric Pyrazolines Obtained from α, ß-Unsaturated Ketones,"
Proceedings of the Iowa Academy of Science, 42(1), 123-124.
Available at: https://scholarworks.uni.edu/pias/vol42/iss1/49