Mechanisms of glycerol dehydration

J Phys Chem A. 2006 May 11;110(18):6145-56. doi: 10.1021/jp060597q.


Dehydration of neutral and protonated glycerol was investigated using quantum mechanical calculations (CBS-QB3). Calculations on neutral glycerol show that there is a high barrier for simple 1,2-dehydration, E(a)=70.9 kcal mol(-1), which is lowered to 65.2 kcal mol(-1) for pericyclic 1,3-dehydration. In contrast, the barriers for dehydration of protonated glycerol are much lower. Dehydration mechanisms involving hydride transfer, pinacol rearrangement, or substitution reactions have barriers between 20 and 25 kcal mol(-1). Loss of water from glycerol via substitution results in either oxirane or oxetane intermediates, which can inter-convert over a low barrier. Subsequent decomposition of these intermediates proceeds via either a second dehydration step or loss of formaldehyde. The computed mechanisms for decomposition of protonated glycerol are supported by the gas-phase fragmentation of protonated glycerol observed using a triple--quadrupole mass spectrometer.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Desiccation
  • Glycerol / chemistry*
  • Mass Spectrometry
  • Models, Molecular*
  • Molecular Structure
  • Quantum Theory*
  • Stereoisomerism
  • Thermodynamics
  • Water / chemistry*


  • Water
  • Glycerol