Fourier self-deconvolution method is properly used to resolve the overlapped keto and carboxylic IR absorption bands for some bicyclic keto acids, e.g. I and II. The bands are then able to be characterized. With some approximation, the equilibrium constant of the dimerization of bicyclic keto acids in nonpolar solvents at room temperature was calculated from sectral data.

Key words: ANTIMALARIALS, INFRARED SPECTROPHOTOMETRY, BICYCLIC, EQUILIBRIUM CONSTANT, ABSORPTION SPECTRA, ARTEANNUIN, CARBONYL GROUP, KETONE ACID, KETONE P, RESOLVING POWER