			15min:

MICROWAVE INVESTIGATION OF THE GROUND AND FIRST EXCITED TORSIONAL STATES OF ACETIC ACID MONOHYDRATE..

GALEN SEDO, JAMIE DORAN, SHENGHAI WU, KENNETH R. LEOPOLD, University of Minnesota, Department of Chemistry, 207 Pleasant St SE, Minneapolis MN 55455.

Rotational spectra of CH₃COOH-H₂O and ¹³CH₃COOH-H₂O have been observed by Fourier transform microwave spectroscopy. A total of 14 A state and 13 E state transitions have been analyzed. The resulting rotational constants are consistent with a structure similar to that of acetic acid dimer, where the water moiety forms a primary hydrogen bond with the carboxylic acid proton and a secondary hydrogen bond with the carbonyl oxygen. The barrier to internal rotation of the methyl group was determined to be 138.45(3) cm^-1, which represents a decrease of 18.7% when compared with that of the acetic acid monomer.