Microwave spectrum and structure of furfural

Electronic excitation of furfural as probed by high-resolution vacuum ultraviolet spectroscopy, electron energy loss spectroscopy, and ab initio calculations

“…The third calculation considered the geometry optimization and zero point energy at the HF/MP2/aug-cc-pVDZ level, with the total energy being calculated at the CCSD(T)/augcc-pVDZ level to obtain 0.0236 eV (using the scale frequency factor equal to 0.959, we obtained 0.0265 eV). The values obtained for this energy difference agree with previous calculations 51 and are in reasonable accord with the experimental values 21,28 and experimentally observed conformer populations. 29 The optimized geometries of both the trans and cis conformers obtained at the B3LYP/augcc-pVDZ level were therefore deemed suitable to use for further computations.…”

“…28 This value is in reasonable agreement with that of 250 ± 40 cm −1 (0.031 ± 0.005 eV) as reported by Zwarich and Rabinowitz, 21 and with the relative population weight between trans to cis of ∼3:1 determined by Miller et al 29 using the torsional frequencies in the far infrared spectrum. Vibrational analysis of the two conformers of furfural has been carried out on the basis of their IR and Raman spectra by Rogojerov et al, 30 whereas Gandini and coworkers 20,31 have reported on the photochemistry of furfural in the (π * ← n) and the lowest (π * ← π) absorption bands.…”

Microwave spectroscopy of furfural in vibrationally excited states

“…The results of analysis of excited vibrational states of furfural together with the results reported in [1] represent a complete investigation of the microwave spectrum of low-lying vibrational states of furfural. In total, accurate values of rotational and centrifugal distortion constants were obtained for the ground states of both conformations and for 14 excited vibrational states.…”

“…The present analysis has been carried out on the basis of the microwave spectrum records of furfural in the frequency range 49-149 GHz obtained previously [1] using an automated, synthesizer-based, millimeter-wave spectrometer at the Institute of Radio Astronomy of the National Academy of Science of Ukraine at Kharkov. The measurement uncertainty for an isolated line varies in the range 10-20 kHz depending on the energy of the states and signal-to-noise ratio.…”

“…It is commonly used as a solvent. In our recent paper [1] the results of microwave spectrum investigation of furfural were reported. In this paper we assigned and analyzed the states that give the most intense lines in the spectrum: the ground and first excited torsional states of trans conformer and the ground state of cis conformer which is about 286 cm À1 less stable (see Fig.…”