麻豆影音

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Extension of Structure鈥揜eactivity Correlations for the Hydrogen Abstraction Reaction to the Methyl Radical and Comparison to the Chlorine Atom, Bromine Atom, and Hydroxyl Radical

Publication Type
Journal
Journal Name
The Journal of Physical Chemistry A
Publication Date
Volume
120
Issue
26

Recently, we presented structure鈥搑eactivity correlations for the gas-phase rate constants for hydrogen abstraction from sp3-hybridized carbon by three electrophilic radicals (X鈥� + HCR3 鈫� XH + 鈥R3; X = Cl鈥�, HO鈥�, and Br鈥�); the reaction enthalpy effect was represented by the independent variable 螖rH and the 鈥減olar effect鈥� by the independent variables F and R, the Hammett鈥揟aft constants for field/inductive and resonance effects. Here we present a parallel treatment for the less electronegative CH3鈥�. In spite of a limited and scattered database, the resulting least-squares fit [log鈥痥437(CH3鈥�) = 鈭�0.0251(螖rH) + 0.96(危F) 鈥� 0.56(危R) 鈥� 19.15] was modestly successful and useful for initial predictions. As expected, the polar effect appears to be minor and its directionality, i.e., the 鈥減hilicity鈥� of CH3鈥�, may depend on the nature of the substituents.