ISSN:
1572-8927
Keywords:
Alcohols
;
liquid
;
structure
;
hydrogen bond
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract We have measured the Raman spectra of liquid methanol at temperatures between 50° and −77°C. The weak O−H stretching bands appear, under amplification, more and more asymmetric as the temperature is lowered. They can be decomposed into three Gaussian components centered at about 3220, 3310, and 3400 cm−1. The former, predominant at low temperature, corresponds to single, linear hydrogen bonds (LHB) between two molecules. The other two are assigned to branched hydrogen bonds, respectively bifurcated (BHB), between three molecules, and trifurcated (THB), between four molecules. We conclude that the molecular structure of liquid alcohols is not chain-like, as presumed so far, but a three-dimensional network featuring a mixture of single (LBH), and multiple hydrogen bonds (BHB, and THB). They are mainly electrostatic in nature, their relative proportions and geometry governed by the packing conditions for minimum energy. They form distinct trimers and tetramers in dilute solutions of alcohols in inert solvents and frozen matrices, and the latter even in the vapor.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00647798
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