Substituted Ethanes. III. Raman and Infrared Spectra, Assignments, Force Constants, and Calculated Thermodynamic Properties for 1,1,1-Trichloroethane

Raman displacements, semiquantitative relative intensities, and quantitative depolarization factors for liquid 1,1,1-trichloroethane, and infrared wave numbers and percentage absorption for both the liquid and gaseous states in the region 400–5000 cm−1 were obtained and compared with previous data. A normal coordinate treatment, using the Wilson FG matrix method, was carried out, and a reasonable set of force constants was determined. Assignments were made for all observed bands of the infrared and Raman spectra. The heat content, free energy, entropy, and heat capacity at constant pressure were calculated for 9 temperatures in the range 298.16° to 1000°K. A comparison of calculated and observed entropy values indicated that the potential barrier hindering the internal rotation is about 2840 cal/mole, which leads to a value of 205±20 cm−1 for the torsional frequency and to 0.786×10−12 erg/radian for the torsional force constant.