16978-68-0Relevant articles and documents
Gas-Phase Hydrogen-Deuterium Exchange Reactions of Anions: Kinetics and Detailed Mechanism
Grabowski, Joseph J.,DePuy, Charles H.,Doren, Jane M.Van,Bierbaum, Veronica, M.
, p. 7384 - 7389 (2007/10/02)
Rate coefficients and branching ratios for anionic hydrogen-deuterium exchange reactions between isotopically labeled hydroxide, amide, hydrogen sulfide, and methoxide ions and their corresponding neutral compounds have been measured in the gas phase by using the selected ion flow tube (SIFT) technique.The kinetic data for the methoxide-methanol systems lead to a determination of the relative base strength of CD3O(1-) and CH3O(1-).The reaction efficiencies and branching ratios of hydroxide-water, amide-ammonia, and amide-water systems are discussed in terms of the mechanism by which exchange occours; the multiply labeled systems reveal that more proton transfer occur than one might expect upon initial inspection of the data.The product distributions are discussed in terms of relative ion-molecule complex lifetimes and dissociation of the complex is competition with scrambling.Efficient H/D exchange was also observed to occur between compounds containing second-row elements and the implications of this are discussed.
Thermoneutral Isotope Exchange Reactions of Cations in the Gas Phase
Ausloos, P.,Lias, S. G.
, p. 3641 - 3647 (2007/10/02)
Rate constants have been measured for reactions of the type AD2+ + MH --> MD + ADH+, where AD2+ is CD3CND+, CD3CDOD+, (CD3COCD3)D+, or (C2D5)2OD+ and the MH molecules are alcohols, acids, mercaptanes, H2S, AsH3, PH3, or aromatic molecules.Rate constants are also presented for the reactions ArHD+ + D2O --> ArDD+ + HDO, where ArHD+ is a deuteronated aromatic molecule and ArDD+ is the same species with a D atom incorporated on the ring.In all but two cases, the competing deuteron transfer is sufficiently endothermic that it cannot be observed under the conditions of the ICR experiments at 320 - 420 K.The efficiencies of the isotope exchange reactions are interpreted in terms of estimated potential surface cross sections for the reactions AD2+ + MH --> 2+*MH> --> +> --> +*MD> --> ADH+ + MD.When the formation of the +> complex is estimated to be thermoneutral or slightly endothermic, the isotope exchange process is inefficient (probability of a reactive collision 2+*MH> --> +> is exothermic.For most of the systems, trends in reaction efficiency appear to be related to factors such as dipole moments of reactant species (or for aromatic compounds, the electron-donating or -withdrawing properties of ring substituents) which influence the relative orientation of the two reactant species in the complex.
