VIBRATIONAL ASSIGNMENT AND ANALYSIS FOR 2,3-DIHYDROFURAN AND 2,5-DIHYDROFURAN

The vibrational spectra of 2,3-dihydrofuran and 2,5-dihydrofuran have been recorded using IR and Raman spectroscopy for the gas, liquid and solid states. A vibrational assignment consisting of a nearly complete set of vapor phase wavenumbers is proposed for both molecules based o n the observed spectra and normal coordinate analyses. The normal coor dinate analyses have been made by scaling the AMI force field for each molecule with scale factors transferred from an analysis of the cyclo pentene fundamental vibrations. The predicted a priori vibrational fre quencies justify one reassignment of the fundamentals for 2,5-dihydrof uran from that previously reported. The vibrational assignment for 2,3 -dihydrofuran is reported for the first time. Thermodynamic functions are computed for each molecule using the experimentally determined vib rational frequencies.