Role of ion-neutral complexes during acid-catalyzed dehydration of ethanol in the gas phase
- Ecole Polytechnique, Palaiseau (France)
Acid-catalyzed dehydration of ethanol in the gas phase has been studied both theoretically and experimentally. Molecular orbital calculations have been done at the MP3/6-31G*//6-31G* level with correction of the zero-point vibrational energy. Protonated ethanol, 1 is predicted to isomerize easily into the C{sub 2}H{sub 4} {hor ellipsis} H {hor ellipsis} OH{sub 2}{sup +} complex, 2 (activation energy 120 kJ/mol). This result is in agreement with the observation of a near statistical hydrogen exchange preceding the dehydration reaction 1 {yields} C{sub 2}H{sub 4} + H{sub 3}O{sup +}. In the case of the water-solvated ion C{sub 2}H{sub 5}OH{sub 2} {hor ellipsis} OH{sub 2}{sup +}, 5, isomerization into a proton-bound complex C{sub 2}H{sub 4} {hor ellipsis} H{sub 5}O{sub 2}{sup +}, 6, needs a larger amount of energy (ca. 180 kJ/mol). Again the calculations agree with experiments: the important activation energy for the process 5 {yields} 6 prevents hydrogen exchanges and ethene elimination. Extension of these calculations to higher systems is discussed.
- OSTI ID:
- 5964914
- Journal Information:
- Journal of the American Chemical Society; (United States), Vol. 112:25; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
Similar Records
Ammine ligand exchange in tetraamminegold(III) in aqueous solution. Composition of transition states and relative reactivity of tetraamminegold(III) and its conjugated base, amidotriamminegold(III)
Hydronium ions in zeolites. 1. Structures of partially and fully dehydrated Na, H{sub 3}O-X by X-ray and neutron diffraction
Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ETHANOL
DEHYDRATION
BOND ANGLE
BOND LENGTHS
CHEMICAL REACTION KINETICS
EIGENVALUES
FORMATION HEAT
HARTREE-FOCK METHOD
HIGH VACUUM
HOMOGENEOUS CATALYSIS
ION PAIRS
POTENTIAL ENERGY
REACTION INTERMEDIATES
ALCOHOLS
CATALYSIS
DIMENSIONS
ENERGY
ENTHALPY
HYDROXY COMPOUNDS
KINETICS
LENGTH
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
REACTION HEAT
REACTION KINETICS
THERMODYNAMIC PROPERTIES
100200* - Synthetic Fuels- Production- (1990-)
400201 - Chemical & Physicochemical Properties