Gas-phase hydration reactions of protonated alcohols. Energetics and bulk hydration of cluster ions

Journal Article · Wed Sep 17 00:00:00 EDT 1986 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00279a004· OSTI ID:5367739

Hiraoka, K; Takimoto, H; Morise, K

The gas-phase equilibria for hydration reactions of protonated methyl alcohol, ethyl alcohol, n-propyl alcohol, and isopropyl alcohol, ROH/sub 2//sup +/(H/sub 2/O)/sub n-1/ + H/sub 2/O = ROH/sub 2//sup +/(H/sub 2/O)/sub n/, were measured with a pulsed electron beam mass spectrometer. Van't Hoff plots of the equilibrium constants lead to ..delta..H/sup 0//sub n-1/,n/ and ..delta..S/sup 0//sub n-1,n/ up to n = 6. While the proton affinities increase in the order methyl alcohol < ethyl alcohol < n-propyl alcohol < isopropyl alcohol, the stabilities of clusters ROH/sub 2//sup +/(H/sub 2/O)/sub n/ toward dissociation increase in the reverse order, i.e., isopropyl alcohol < n-propyl alcohol < ethyl alcohol < methyl alcohol. The deprotonation from the base alcohol in the cluster ROH/sub 2//sup +/ (H/sub 2/O)/sub n/ was not observed up to n = 6 or 7. The acid-catalyzed dehydration of alcohols was not observed either. The stepwise sums of free energy changes ..delta..G/sup 0//sub n-1,n/ for gas-phase hydration reactions of protonated alcohols and other ions are compared with the free energies of hydration. The anomalous order of basicities for H/sub 2/O and aliphatic alcohols is suggested in the gas phase and in aqueous solution. The sums of ..delta..G/sup 0//sub n-1,n/ for halide ions converge more gradually to the ultimate free energies of hydration than those for other positive ions.

• Research Organization: Yamanashi Univ., Kofu, Japan
• OSTI ID: 5367739
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 108:19; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

090210* -- Alcohol Fuels-- Properties-- (1976-1989)
10 SYNTHETIC FUELS
ALCOHOLS
BARYONS
DATA
ELEMENTARY PARTICLES
EQUILIBRIUM
ETHANOL
EXPERIMENTAL DATA
FERMIONS
FLUIDS
GASES
HADRONS
HYDRATION
HYDROXY COMPOUNDS
INFORMATION
MASS SPECTROSCOPY
METHANOL
NUCLEONS
NUMERICAL DATA
ORGANIC COMPOUNDS
PH VALUE
PHYSICAL PROPERTIES
PROPANOLS
PROTONS
SOLVATION
SPECTROSCOPY
THERMODYNAMIC PROPERTIES
THERMODYNAMICS