Microwave Spectrum and Barrier to Internal Rotation of Acetic Acid

“The microwave spectra of CH₃COOH and CD₃COOH have been measured leading to a threefold barrier of 483 \± 25 cal./mol. To treat this relatively low barrier case in the usual high barrier representation, it was necessary to include perturbation terms up to fourth order. A structure of acetic acid was determined assuming the carboxyl group is the same as that in formic acid.”