Self-association and hydrogen bonding of propionaldehyde in binary mixtures with water and methanol investigated by concentration-dependent polarized Raman study and DFT calculations
Article first published online: 28 AUG 2010
Copyright © 2010 John Wiley & Sons, Ltd.
Journal of Raman Spectroscopy
Volume 42, Issue 4, pages 851–858, April 2011
How to Cite
Singh, D. K., Srivastava, S. K., Schlücker, S., Singh, R. K. and Asthana, B. P. (2011), Self-association and hydrogen bonding of propionaldehyde in binary mixtures with water and methanol investigated by concentration-dependent polarized Raman study and DFT calculations. J. Raman Spectrosc., 42: 851–858. doi: 10.1002/jrs.2779
- Issue published online: 19 APR 2011
- Article first published online: 28 AUG 2010
- Manuscript Accepted: 15 JUL 2010
- Manuscript Received: 16 MAR 2010
- hydrogen bonding;
- binary mixture [(CH3CH2CHO + H2O/CH3OH)];
- polarized Raman study;
- DFT calculations
The Raman spectra of neat propionaldehyde [CH3CH2CHO or propanal (Pr)] and its binary mixtures with hydrogen-donor solvents, water (W) and methanol (M), [CH3CH2CHO + H2O] and CH3CH2CHO + CH3OH] 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(CO) 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. Copyright © 2010 John Wiley & Sons, Ltd.