Premium
Raman spectral study of ‘neat’ formic acid and aqueous and organic solutions of formic acid
Author(s) -
Bartholomew R. J.,
Irish D. E.
Publication year - 1999
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/(sici)1097-4555(199904)30:4<325::aid-jrs371>3.0.co;2-5
Subject(s) - formic acid , chemistry , aqueous solution , acetonitrile , monomer , hydrogen bond , solvent , raman spectroscopy , acetic acid , carboxylic acid , dichloromethane , photochemistry , molecule , inorganic chemistry , polymer , organic chemistry , physics , optics
The Raman spectra of ‘neat’ formic acid and formic acid in several solvents (water, acetonitrile, 1,4‐dioxane and dichloromethane) were measured. In aqueous solution a very clear non‐coincidence effect (NCE) indicative of resonance energy transfer was observed. The size of the NCE ( ca 64 cm −1 ) indicates that strong intermolecular forces exist between the formic acid molecules, no doubt augmented by hydrogen bonding. In acetonitrile and 1,4‐dioxane, two bands (at 1735 and 1765 cm −1 ) develop with dilution. The 1735 cm −1 band was assigned to ‘free’ formic acid monomer and the band at 1765 cm −1 to formic acid ‘complexed’ to the solvent. Liquid formic acid is unlike acetic acid in that it does not arrange itself into discrete, long‐lived dimers or polymers. It is viewed as a collection of monomeric units which interact through hydrogen bonding, thereby imposing local, short‐term order in the liquid. This allows the resonance energy transfer to occur and results in a large non‐coincidence effect. Copyright © 1999 John Wiley & Sons, Ltd.