Infrared Spectra of Troponoid Compounds. V. Absorption Bands in the Region of 1700∼1530 cm−1 of Tropone, 2-Chlorotropone and Tropolone

Infrared absorption spectra of tropone, 2-chlorotropone, and tropolone in the region of 1700∼1500 cm−1 were measured in various states and in various solvents, and the variation of two strong Bands I and II in the region of 1700∼1530 cm−1 was investigated. The data are shown in tables and figures. These two bands are explained as the participation of both of the C=O and C=C stretching vibrations in a tropone skeleton. The variation of the spectrum of tropolone with the measuring condition is much smaller than that of tropone. This is because the carbonyl group in tropolone is fixed by the intramolecular hydrogen bond.