Mechanisms of Glycerol Dehydration

Mark R. Nimlos, Stephen J. Blanksby, Xianghong Qian, Michael E. Himmel, David K. Johnson

Research output: Contribution to journalArticlepeer-review

251 Scopus Citations

Abstract

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, Ea = 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 interconvert 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.

Original languageAmerican English
Pages (from-to)6145-6156
Number of pages12
JournalJournal of Physical Chemistry A
Volume110
Issue number18
DOIs
StatePublished - 2006

NREL Publication Number

  • NREL/JA-510-39495

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