Vapor-Phase Vibrational Spectrum of Glycolic Acid, CH2OHCOOH, in the Region 2000−8500 cm-1

This work presents an analysis of the previously unobserved vapor-phase spectrum of glycolic acid in the IR/near-IR region (2000−8500 cm -1 ). The focus is on distinguishing between the O−H stretches of both the acid and alcohol functional groups by using intermediate resolution FTIR spectroscopy. Vibrational transitions due to combination bands and overtones were assigned and relative intensities were obtained. The contribution of a rotational isomer to the vibrational spectrum of CH 2 OHCOOH at 353 K is discussed. Theoretical calculations of harmonic frequencies and anharmonicities are reported on the two lowest energy conformers of glycolic acid and provide supporting evidence for the proposed assignments.