Monomer-dimer Reaction Research Articles

Infrared Spectrum of Trifluoroacetic Acid Vapor

The infrared absorption of trifluoroacetic acid vapor in the region between 2 and 24 μ has been studied as a function of temperature. At room temperature both monomer and dimer molecules are present, while at 100°C the vapor is predominantly monomeric. On the basis of the resulting intensity changes it has been possible to conclusively identify the bands due to the two species. A partial assignment of the fundamental modes of vibration has been made using these data and the previously published spectrum of the deuterated acid. The heat of dissociation (ΔH) for the dimer-monomer reaction has been determined from the temperature dependence of the OH stretching bands and found to be 13.7±0.4 kcal/mole.