Self‐association and hydrogen bonding of propionaldehyde in binary mixtures with water and methanol investigated by concentration‐dependent polarized Raman study and DFT calculations

Abstract

The Raman spectra of neat propionaldehyde [CH 3 CH 2 CHO or propanal (Pr)] and its binary mixtures with hydrogen-donor solvents, water (W) and methanol (M), [CH 3 CH 2 CHO + H 2 O]and CH 3 CH 2 CHO + CH 3 OH] with different mole fractions of the reference system, Pr varying from 0.1 to 0.9 at a regular interval of 0.1, were recorded in the ν(C O) stretching region, 1600-1800 cm −1 . The isotropic parts of the Raman spectra were analyzed for both the cases. The wavenumber positions and line widths of the component bands were determined by a rigorous line-shape analysis, and the peaks corresponding to self-associated and hydrogen-bonded species were identified. Raman peak at ∼1721 cm −1 in neat Pr, which has been attributed to the self-associated species, downshifts slightly (∼1 cm −1 ) in going from mole fraction 0.9 to 0.6 in (Pr + W) binary mixture, but on further dilution it shows a sudden downshift of ∼7 cm −1 . This has been attributed to the low solubility of Pr in W (∼30%), which does not permit a hydrogen-bonded network to form at higher concentrations of Pr. A significant decrease in the intensity of this peak in the Raman spectra of Pr in a nonpolar solvent, n-heptane, at high dilution (C = 0.05) further confirms that this peak corresponds to the self-associated species. In case of the (Pr + M) binary mixture, however, the spectral changes with concentration show a rather regular trend and no special features were observed.

Monitoring potential molecular interactions of adenine with other amino acids using Raman spectroscopy and DFT modeling

“…In our earlier studies, [25][26][27][28][29][30] the combined Raman and DFT approach successfully has been applied to a large number of hydrogen-bonded systems, probing the intermolecular interactions and studying their influence on the spectral features. Raman spectra of Ade and its different complexes Ade-(Gly/Lys/Arg) at different molar ratios were recorded in the spectral region 1550-550 cm À1 .…”

Raman scattering and DFT calculations used for analyzing the structural features of DMSO in water and methanol

“…17 There are a few quite early experimental studies, [18][19][20] which have dealt with structure determination of DMSO. Raman study of solutions of DMSO in carbon tetrachloride CCl 4 and water has been also reported, 21 for both parallel and perpendicular polarizations in the SLO stretching region. A few studies on the structure of the DMSO using different experimental techniques and in different environments were also carried out in the 909s.…”

Unexpected Composition Dependence of the First Sharp Diffraction Peak in an Alcohol–Aldehyde Liquid Mixture:n‐Pentanol and Pentanal

“…As far as mixtures are concerned, experimental and simulation studies on aqueous liquid mixtures of organic molecules are frequent (see, e.g., Franks). On the other hand, investigations of alcohol/aldehyde mixtures are scarce: only a combined Raman spectroscopic and density functional theoretical (DFT) study of propionaldehyde/methanol, and a microwave dielectric relaxation investigation of n ‐propanol/propanal mixtures could be found.…”