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Hydronium Ion (hydronium + ion)

Distribution by Scientific Domains

Chemistry	83%

Selected Abstracts

One-Step Synthesis of Lumazine and Xanthine: First Co-Crystal of Lumazine and Perchloric Acid with a Unique Monohydrated Hydronium Ion (H5O2+) Mediated Supramolecular Assembly of the Lumazine Dimer.

CHEMINFORM, Issue 50 2007
Shyamaprosad Goswami
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

Kinetics and mechanism for oxime formation from benzoylformic acid: Electrostatic interactions in the dehydration of carbinolamines

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 9 2008
A. Malpica
The evidence establishes that oxime formation from benzoylformic acid in the pH range from 0.25 to 5.5 occurs with acid-catalyzed dehydration of carbinolamines derived from the acid and its anion. The pH-rate profile shows in order of decreasing pH in two regions: (1) In the pH range from 5.5 to ,2.2 the second-order rate constants are linearly dependent on the concentration of hydronium ion and (2) from pH ,2.2 to 0.25 the rate constants deviate slightly from the line of slope = ,1. This slight deviation is a consequence of the very similar values of limiting rate constants of the two forms of the substrate. Electrostatic interactions between charged carbinolamines and hydronium ions are analyzed. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 554,558, 2008 [source]

Ab initio QM/MM dynamics of H3O+ in water

JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 14 2006
Pathumwadee Intharathep
Abstract A molecular dynamics (MD) simulation based on a combined ab initio quantum mechanics/molecular mechanics (QM/MM) method has been performed to investigate the solvation structure and dynamics of H3O+ in water. The QM region is a sphere around the central H3O+ ion, and contains about 6,8 water molecules. It is treated at the Hartree-Fock (HF) level, while the rest of the system is described by means of classical pair potentials. The Eigen complex (H9O) is found to be the most prevalent species in the aqueous solution, partly due to the selection scheme of the center of the QM region. The QM/MM results show that the Eigen complex frequently converts back and forth into the Zundel (H5O) structure. Besides the three nearest-neighbor water molecules directly hydrogen-bonded to H3O+, other neighbor waters, such as a fourth water molecule which interacts preferentially with the oxygen atom of the hydronium ion, are found occasionally near the ion. Analyses of the water exchange processes and the mean residence times of water molecules in the ion's hydration shell indicate that such next-nearest neighbor water molecules participate in the rearrangement of the hydrogen bond network during fluctuative formation of the Zundel ion and, thus, contribute to the Grotthuss transport of the proton. © 2006 Wiley Periodicals, Inc. J Comput Chem, 2006 [source]

Acid,Base Chemistry at the Ice Surface: Reverse Correlation Between Intrinsic Basicity and Proton-Transfer Efficiency to Ammonia and Methyl Amines

CHEMPHYSCHEM, Issue 17 2007
Seong-Chan Park Dr.
Abstract Proton transfer from the hydronium ion to NH3, CH3NH2, and (CH3)2NH is examined at the surface of ice films at 60 K. The reactants and products are quantitatively monitored by the techniques of Cs+ reactive-ion scattering and low-energy sputtering. The proton-transfer reactions at the ice surface proceed only to a limited extent. The proton-transfer efficiency exhibits the order NH3>(CH3)NH2=(CH3)2NH, which opposes the basicity order of the amines in the gas phase or aqueous solution. Thermochemical analysis suggests that the energetics of the proton-transfer reaction is greatly altered at the ice surface from that in liquid water due to limited hydration. Water molecules constrained at the ice surface amplify the methyl substitution effect on the hydration efficiency of the amines and reverse the order of their proton-accepting abilities. [source]

Stresses in ion-exchange layers of soda-lime-silicate glass

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 6 2005
T. FETT
ABSTRACT This paper presents a new method to determine both the magnitude and the sign of the surface stresses that develop as a consequence of sodium/hydrogen ion exchange in soda-lime-silicate glass immersed in water. At 90 °C, very thin layers that develop at the surfaces of polished glass specimens are found to have extremely high compressive stresses, ,2.4 GPa. The negative sign of the stress is consistent with earlier findings that the ion-exchange process involves hydronium ions (H3O+) and not bare protons (H+). [source]