A vibrational spectroscopic study on furan and its hydrated derivatives

In this work, the vibrational spectroscopy of furan and its hydrated products were studied. Infrared and Raman spectra of furan, 2,3-dihydrofuran, 2,5-dihydrofuran and 2,3,4,5-tetrahydrofuran were recorded. Quantum chemical calculations were carried out for these compounds that yielded the optimised geometries, the vibrational force constants and the calculated fundamental frequencies. DFT Becke3P86 functional were used for furan and Becke3LYP for the hydrated derivatives, all with 6-311G(d,p) basis set, in accordance with our former results for pyrrole and pyrrolidine. Raman intensities and depolarisation rations were computed with HF/6-311G(d,p). Normal coordinate analysis was applied, the calculated force field were scaled to the measured fundamental frequencies and potential energy distributions were carried out, too. Using the quantum chemically calculated integrated intensities, depolarisation ratios and scaled fundamental frequencies simulated infrared and Raman spectra were also computed. The changes in the calculated properties of the studied compounds were compared. Similarly, these results were compared with our earlier results with pyrrole and pyrrolidine. (C) 2004 Elsevier B.V. All rights reserved.