The properties and synthesis of 2-phenyl-4/,5,6,7-tetrahydroindazol-
3-one-5,5-dicarboxylic acid (IID, 2-phenyl-4,5,6,7- tetrahydroindazol-
3-one-5-carboxylic aaid (V) and their ethyl esters II
and IV were described. Indazolone dicarboxylic acid III showed the exceptional properties that indicated chelatizing tendencies of this compound. It formed a monohydrate which built in the molecule of crystal water steadily. The content of water was determined by proton magnetic resonance. Potentiometric titrations gave the number of the acidic groups of acids and corresponding esters, as well as the existence of enol form of these compounds. The ultraviolet and infra red absorption spectra were recoDded
