Analytical Investigation of N1 and N2 Isomers of Indazole-3-Carboxylic Acid. Unambiguous Structure Assignment by UV Derivative Spectrophotometry

Abstract Several isomers N1 and N2 substituted indazole-3-carboxylic acids were prepared and their data obtained from current analysis, mp, IR, NMR, TLC were reported. Utilizing these values, it is very difficult to determine to which of the two isomeric structures a product corresponds. On the contrary with the use of UV derivative spectrophotometry it is simple to establish if a product alone, somehow substituted, corresponds to one or to other structure. In fact, the second, third and fourth derivative spectra show evident and characteristic signals able to identify undoubtedly the substituent position of each product of the two series.