Reactions of ground state chlorine atoms with fluorinated methanes and ethanes

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Abstract
The reactions of photochemically generated Cl(2PJ) atoms with a number of fluorohydrocarbons have been investigated in the temperature range 8–95 °C by the competitive photochlorination technique using CH4 as a primary standard. Relative and absolute rate parameters are reported for CH3F, CH2F2, CH3CH2F, CH2FCH2F, CH3CHF2, CH3CF3, CH2FCHF2, CHF2CHF2, and several auxiliary reactions including CH3Cl, C2H6, and C3H8. The internal competition for hydrogen abstraction in asymmetric fluorethanes is examined in detail. The reactivity trends are discussed and it is found that the activation energies in the fluoromethane series correlate with the known C–H bond dissociation energies. The hydrogen reactivity in the fluoroethane series for which a sufficient data base of DH°(C–H) values is not available is best rationalized in terms of inductive effects and resonance interactions.