FTIR study of the solvent influence on the carbonyl absorption peak of ethyl acetate

Abstract

6217dependent on the geometrical profile of the detector. The speeds of sound in (CH,),Si, (CH3),Ge, and (CH,),Sn were determined. The C-H cross sections (Au = 7) were obtained for the three molecules. Accurate determination of the peak positions was enhanced by computer deconvolution of the overtone spectra (Au = 6.7) of the (CH3),M molecules (M = Si, Ge, Sn). Additional bands were assigned to various local mode and normal mode combination bands. The deconvolution also allows for the determination of the overtone bandwidths. The narrow bandwidths observed for the metal-centered compounds may reflect basic changes in molecular properties such as bond lengths and electron density distributions caused by the larger central atom. These changes may affect energy transfer processes by creating a different environment for the excited C-H group. It is possible that the large metal atom limits coupling between different methyl groups in the molecules. Possible energy level resonances in the compounds do not seem to have a strong effect on energy transfer.

Molecular Vibrations of Solvated Uracil. Ab Initio Reaction Field Calculations and Experiment

“…50 The largest frequency shiftsstoward lower energiessare expected for the O4-H stretching vibrations in the cation, ∆ν ) 91 cm -1 . The predicted CdO stretching shift in neutral uracil and the anions in bulk water ( ) 78.54), ∆ν(average) ) 43 cm -1 , compares well with the 14-38 cm -1 red shifts observed 50,103 for the CdO stretching vibration in smaller carbonyl compounds in acetonitrile ( ) 35.9) and dimethyl sulfoxide ( ) 46.68), in comparison to vapor phase ( ) 1.0). By constrast, the in-plane bending modes, spanning the intermediate region ∼1050 cm -1 to ∼1550 cm -1 (950 cm -1 to 1350 cm -1 in the dianion) are not expected to exhibit significant frequency shifts in a high dielectric medium; this is probably true for the C5H and C6H vibrations.…”

Measurement of enthalpies of association between CO2 and polymers via in situ ATR-FTIR spectroscopy

“…Several authors [5,15,16] have quantified specific interactions between a solvent and an electron donating functional group (e.g. C O, P O, or S O) in a solute via the shift in the stretching frequency of the electron donating functional group.…”

“…However, quantum calculations [25] suggest that the carbonyl peak of small molecules should shift to a lower wavenumber when Lewis acid-base complexes are formed. This apparent discrepancy can be explained by invoking the Kirkwood-Bauer-Magat (KBM) equation as follows [4,16,26]:…”

Influence of the Dielectric Medium on the Carbonyl Infrared Absorption Peak of Acetylferrocene

“…The electronic and vibrational properties of a substance are affected by several microscopic and macroscopic properties of the medium. Consequently, there is considerable interest in the study of solvent-induced perturbations on characteristic infrared absorption peaks and linear and nonlinear optical properties of organic compounds [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. In effect, a number of semiempirical solvatochromic parameters representing “solvent polarity” have been applied to the quantification of medium effects on these properties [ 13 , 27 , 28 ].…”

“…In effect, a number of semiempirical solvatochromic parameters representing “solvent polarity” have been applied to the quantification of medium effects on these properties [ 13 , 27 , 28 ]. It is known that vibrational frequencies for a molecule dissolved in a liquid depend principally on the dielectric nature of medium (solvent polarity-dipolarity) when specific local interactions are absent [ 1 , 3 , 4 , 23 , 27 ]. It was shown for solute molecules having large permanent dipole moments, that the solvent effect can be explained well by the Onsager reaction field model [ 16 , 24 ].…”