ChemInform Abstract: HYDROGEN ISOTOPE EFFECT AND MECHANISM IN THE SELECTIVE ALIPHATIC HYDROGEN EXCHANGE IN 4-ISOPROPYLANISOLE

The D/H ratio of hydrogen gas in equilibrium with aqueous alkaline earth (Mg, Ca, Sr or Ba) chloride solutions measured at 25◦C using a hydrophobic platinum catalyst, was found to be higher than the D/H ratio equilibrated with the applied pure water. The hydrogen isotope effect between such solutions and pure water changes with the molality of the solutions. The order of the D/H ratios in alkaline earth chlorides is found to be BaCl2 > SrCl2 ≥ CaCl2 ≥ MgCl2. The hydrogen isotope effect in the aqueous chloride solutions of Mg, Ca, Sr or Ba ions is significantly larger than that in the aqueous chloride solutions of Li, Na, K or Cs ions. For MgCl2 and CaCl2 solutions, the hydrogen isotope effect is opposite to the oxygen isotope effect. The results are compared with the free energy change of transfer from H2O to D2O, and are discussed for the vapour pressure ratio of H2O and D2O of CaCl2 solutions.

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Hydrogen Isotope Fractionation in Aqueous Alkali Halide Solutions

Zeitschrift für Naturforschung A ◽

10.1515/zna-1997-1109 ◽

1997 ◽

Vol 52 (11) ◽

pp. 811-820 ◽

Cited By ~ 9

Author(s):

Masahisa Kakiuchi

Keyword(s):

Oxygen Isotope ◽

Isotope Effect ◽

Alkali Halide ◽

Hydrogen Isotope ◽

Isotope Fractionation ◽

Free Water ◽

Aqueous Alkali ◽

Water Molecules ◽

Oxygen Isotope Fractionation ◽

Hydrogen Isotope Effect

Abstract The D/H ratios of hydrogen gas in equilibrium with aqueous alkali halide solutions were deter-mined at 25 °C, using a hydrophobic platinum catalyst. The hydrogen isotope effect between the solution and pure water changes linearly with the molality of the solution at low concentrations, but deviates from this linearity at higher concentration for all alkali halide solutions. The magnitude of the hydrogen isotope effect is in the order; Kl > Nal > KBr > CsCl ≧ NaBr > KCl > NaCl > LiCl, at concentrations up to a molality of 4 m. The sign and trend of the hydrogen isotope effect is different from that of oxygen. In aqueous alkali halide solutions, the hydrogen isotope effect is influenced by both the cation and the anion species, while the oxygen isotope effect is mainly caused by the cation species. This suggests that the mechanism of hydrogen isotope fractionation between the water molecules in the hydration spheres and the free water molecules differs from the mechanism of the oxygen isotope fractionation. The hydrogen and oxygen isotope effects for alkali halides, except LiCl and NaCl, may be influenced by changes in energy of the hydrogen bonding in free water molecules.

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Theoretical Study on Thermodynamic Hydrogen Isotope Effect of VQ2 (Q=H, D and T)

Rare Metal Materials and Engineering ◽

10.1016/s1875-5372(10)60080-x ◽

2010 ◽

Vol 39 (2) ◽

pp. 204-208

Author(s):

Lei Qianghua ◽

Chen Chang'an ◽

Huang Li ◽

Zhang Yongbin

Keyword(s):

Isotope Effect ◽

Hydrogen Isotope ◽

Theoretical Study ◽

Hydrogen Isotope Effect

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HYDROGEN ISOTOPE EFFECT IN THE AMINATION OF CHLOROBENZENE BY SODAMIDE

Canadian Journal of Chemistry ◽

10.1139/v61-022 ◽

1961 ◽

Vol 39 (1) ◽

pp. 180-191 ◽

Cited By ~ 9

Author(s):

G. E. Dunn ◽

Peter J. Krueger ◽

Walter Rodewald

Keyword(s):

Isotope Effect ◽

Hydrogen Isotope ◽

Liquid Ammonia ◽

Strong Support ◽

Starting Material ◽

Slow Step ◽

Hydrogen Isotope Effect

Mixtures of chlorobenzene and chlorobenzene-2-2H have been subjected to partial amination by sodamide in liquid ammonia and both the unreacted starting material and the product aniline have been analyzed for deuterium. Deuterium in the aniline is distributed approximately equally between the ortho and meta positions. The results give strong support to the mechanism proposed by Roberts and co-workers in which the slow step is the formation of an intermediate, such as benzyne, which is symmetrical with respect to carbon atoms 1 and 2.

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