The kinetics of mutarotation in L-fucose as monitored by dielectric and infrared spectroscopy

J Chem Phys. 2014 Jun 7;140(21):215101. doi: 10.1063/1.4880718.

Abstract

Fourier Transform Infrared Spectroscopy and Broadband Dielectric Spectroscopy are combined to trace kinetics of mutarotation in L-fucose. After quenching molten samples down to temperatures between T = 313 K and 328 K, the concentrations of two anomeric species change according to a simple exponential time dependence, as seen by an increase in absorbance of specific IR-vibrations. In contrast, the dielectric spectra reveal a slowing down of the structural (α-) relaxation process according to a stretched exponential time dependence (stretching exponent of 1.5 ± 0.2). The rates of change in the IR absorption for α- and β-fucopyranose are (at T = 313 K) nearly one decade faster than that of the intermolecular interactions as measured by the shift of the α-relaxation. This reflects the fact that the α-relaxation monitors the equilibration at a mesoscopic length scale, resulting from fluctuations in the anomeric composition.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Fucose / chemistry*
  • Kinetics
  • Spectroscopy, Fourier Transform Infrared*
  • Temperature

Substances

  • Fucose