Solvent influence on the infrared spectra of β-alkoxyvinyl methyl ketones II. Stretching vibrations and integrated intensities of carbonyl and vinyl bands of (3Z,E)-4-ethoxy-1,1,1-trifluoro-5,5-dimethylhex-3-en-2-one

Infrared spectroscopy studies of beta-alkoxyvinyl trifluoromethyl ketone, with structure C2H5O-C(C(CH3)(3))=CH-COCF3 (1), in twenty three different pure organic solvents were undertaken to investigate the solvent-solute interactions and to correlate solvent properties such as Reichard's parameter and solvatochromic parameters of Kamlet, Abbot, and Taft with carbonyl and vinyl stretching vibrations and their integrated intensities of existing spatial forms. It was shown that conjugation in C=C-C=O system of the (E-s-Z-o-Z) stereoisomer is higher than that in this system of the (Z-s-Z-o-Z) stereoisomer. From derived correlations of the (v) over tilde (C=O) and (v) over tilde (C=C) wavenumbers with solvatochrornic parameters of Kamlet, Abbot, and Taft it is followed that the solvent polarity influences on the (v) over tilde (C=O) and (v) over tilde (C=C) wavenumbers more intense than the solvent HBD acidity, and, at the same time, the influence of these solvent properties is greater for the (E-s-Z-o-Z) stereoisomer. Analysis of derived KAT multiple regressions showed that the increase of the solvent polarity/polarizability (pi*) increased the conjugation in both stereoisomers, whereas the increase of the solvent HBD acidity (alpha) had opposite effect on conjugation in the (Z-s-Z-o-Z) and (E-s-Z-o-Z) stereoisomer. In the former case conjugation was weakened, whereas in the latter it was enhanced. These discrepancies were the consequence of different structure of H-bonded complexes between enone I and HBD solvents. The influence of the solvent HBA basicity (beta) also had peculiarity. The increase of the solvent HBA basicity disturbs the C=C-C=O conjugation in the (Z-s-Z-o-Z) stereoisomer due to carbonyl rotation, whereas in the (E-s-Z-o-Z) stereoisomer such increase enhanced this conjugation and, hence, increased the (v) over tilde (C=O) and (v) over tilde (C=C) coupling. (c) 2008 Published by Elsevier B.V.