Deuterium kinetic isotope effects in the gas-phase S N2 reactions of solvated fluoride ions with methyl halides

Date

2004-11-11

Author

Kato, Shuji
Hacaloğlu, Jale
Davico, Gustavo E.
DePuy, Charles H.
Bierbaum, Veronica M.

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

183
views

0
downloads

Rate constants and deuterium kinetic isotope effects (KIEs) are measured for gas-phase nucleophilic substitution (S(N)2) reactions of solvated fluoride ions of F-(methanol) + CH3X (X = Br, I), F-(isopropyl alcohol) + CH3I, and F-(hydrogen fluoride) + CH3I at 300 K. The isotope effects are determined as the rate constant ratio k(H)/k(D) for specifically deuterated reactants, that is, methanol (CH3OH, CD3OH, CH3OD, and CD3OD), isopropyl alcohol (i-C3H7OH and i-C3H7OD), hydrogen fluoride (HF and DF), and methyl halides (CH3X and CD3X). The data reveal identical trends to those previously observed for F-(water) + CH3X (O'Hair, R. A. J.; Davico, G. E.; Hacaloglu, J.; Dang, T. T.; DePuy, C. H.; Bierbaum, V. M. J. Am. Chern. Soc. 1994, 116, 3609). The S(N)2 reactivities decrease as reaction exothermicity decreases (CH3I > CH3Br > CH3Cl) and as the nucleophile is solvated. Moderate inverse kinetic isotope effects (k(H)/k(D) < 1) are observed for the deuteration of the rnethyl halide, whereas substantial inverse KIEs are measured for the deuteration of the hydroxyl group of the solvent (or the deUteration of hydrogen fluoride). Moderate inverse KIEs are also measured for the deuteration of the methyl group in methanol. The observed trends and magnitudes of the isotope effects are rationalized qualitatively in terms of the S(N)2 transition-state structure and bonding interactions analogous to those in the F-(H2O) + CH3X system.

Subject Keywords

AB-INITIO, CH3CL, CH3BR, Energy

URI

https://hdl.handle.net/11511/30289

Journal

Journal of Physical Chemistry A

DOI

https://doi.org/10.1021/jp040362j

Collections

Graduate School of Natural and Applied Sciences, Article

Suggestions

OpenMETU
Core

Covalent Dimers of 1,3-Diphenylisobenzofuran for Singlet Fission: Synthesis and Electrochemistry Akdağ, Akın; Beran, Pavel; Rulisek, Lubomir; Dron, Paul I.; Ludvik, Jiri; Michl, Josef (2015-01-01) The synthesis of covalent dimers in which two 1,3-diphenylisobenzofuran units are connected through one phenyl substituent on each is reported. In three of the dimers, the subunits are linked directly, and in three others, they are linked via an alkane chain. A seventh new compound in which two 1,3-diphenylisobenzofuran units share a phenyl substituent is also described. These materials are needed for investigations of the singlet fission process, which promises to increase the efficiency of solar cells. Th...
Electrochemical Behavior of Hydrazine Borane in Methanol Solution Ozhava, Derya; Önal, Ahmet Muhtar; Özkar, Saim (The Electrochemical Society, 2014-01-01) Electrochemical behavior of hydrazine borane (HB) was investigated on gold electrode in 0.5 M LiClO4 solution in methanol using cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and chronoamperometry. Two irreversible peaks at 164 and 530 mV are attributed to direct electro-oxidation of HB on gold electrode in methanol. Both EIS results and CV data at different scan rates indicate a diffusion controlled electron transfer reaction. Furthermore, the Tafel slope (b = 0.191 V) and charge transfer...
Poly(4-styrenesulfonic acid-co-maleic acid) stabilized nickel(0) nanoparticles: Highly active and cost effective catalyst in hydrogen generation from the hydrolysis of hydrazine borane Sencanli, Selin; Karahan, Senem; Özkar, Saim (Elsevier BV, 2013-11-13) When hydrazine borane is added to the solution of nickel(II) chloride and poly(4-styrenesulfonic acid-co-maleic acid), PSSMA, both reduction of nickel(II) ions to nickel(0) nanoparticles and hydrogen release from the hydrolysis of hydrazine borane occur concomitantly at room temperature. Using the hydrogen evolution from the hydrolysis of hydrazine borane as reporter reaction provides valuable insights to the formation kinetics of nickel(0) nanoparticles. Nickel(0) nanoparticles are in situ formed from the ...
Partial oxidation of methane on the SiO2 surface - A quantum chemical study Ozturk, S; Onal, I; Senkan, S (2000-02-01) Reaction pathways for methane partial oxidation (MPO) on silica were theoretically investigated using the semiempirical MOPAC-PM3 molecular orbital method. The surface of SiO2 was modeled by a helical Si6O18H12 molecular cluster that also exhibits a strained siloxane bridge defect. First, a bond energy analysis was performed on the silica cluster with isolated 3- and 4-coordinated Si surface atoms. Calculated bond dissociation energies for Si-H, SiO-H, and SI-OH were comparable to H-CH3, H-OH, and O-O. In t...
High school students conceptions about energy in chemical reactions Yalçınkaya, Eylem; Taştan Kırık, Özgecan; Boz, Yezdan (2009-01-01) The aim of this study is to investigate students’ understanding of the energy concept in chemical reactions including heat and temperature, endothermic-exothermic reactions, combustion reactions, bond energy, enthalpy, stability in chemical reactions and calorimeter. The sample consisted of 222, 10th grade students. Both qualitative and quantitative methodology was used for this investigation. A twenty-item multiple choice test was developed about the topic to measure the students’ understandings. This conc...

Citation Formats

S. Kato, J. Hacaloğlu, G. E. Davico, C. H. DePuy, and V. M. Bierbaum, “Deuterium kinetic isotope effects in the gas-phase S N2 reactions of solvated fluoride ions with methyl halides,” Journal of Physical Chemistry A, pp. 9887–9891, 2004, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/30289.