The mechanisms and dynamics studies of the multichannel reactions of CH(2)FCF(2)OCHF(2) + OH (R1) and CH(2)FOCH(2)F + OH (R2) have been carried out theoretically. Three hydrogen abstraction channels and two displacement processes are found for reaction R1, whereas there are two hydrogen abstraction channels and one displacement process for reaction R2. The minimum energy paths are optimized at the B3LYP/6-311G(d,p) level, and the energy profiles are further refined by interpolated single-point energies (ISPE) method at the BMC-QCISD level of theory. By means of canonical variational transition state theory with small-curvature tunneling correction, the rate constants of reactions R1 and R2 are obtained over the temperature range of 220-2000 K. The rate constants are in good agreement with the experimental data for reaction R1 and estimated data for reaction R2. The Arrhenius expression k(1) = 1.62 x 10(-20) T(2.75) exp(-1011/T) for reaction R1 and k(2) = 3.40 x 10(-21) T(3.04) exp(-384/T) for reaction R2 over 220-2000 K are obtained. Furthermore, to further reveal the thermodynamics properties, the enthalpies of formation of reactants CH(2)FCF(2)OCHF(2), CH(2)FOCH(2)F, and the product radicals CHFCF(2)OCHF(2), CH(2)FCF(2)OCF(2), and CHFOCH(2)F are calculated by using isodesmic reactions.

The mechanisms and kinetics studies of the OH radical with alkyl hydroperoxides CH(3)OOH and CH(3)CH(2)OOH reactions have been carried out theoretically. The geometries and frequencies of all the stationary points are calculated at the UBHandHLYP/6-311G(d,p) level, and the energy profiles are further refined by interpolated single-point energies method at the MC-QCISD level of theory. For two reactions, five H-abstraction channels are found and five products (CH(3)OO, CH(2)OOH, CH(3)CH(2)OO, CH(2)CH(2)OOH, and CH(3)CHOOH) are produced during the above processes. The rate constants for the CH(3)OOH/CH(3)CH(2)OOH + OH reactions are corrected by canonical variational transition state theory within 250-1500 K, and the small-curvature tunneling is included. The total rate constants are evaluated from the sum of the individual rate constants and the branching ratios are in good agreement with the experimental data. The Arrhenius expressions for the reactions are obtained.

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The reaction mechanism of the multi-channel reaction of CF 3 OCHF 2 þ O( 1 D) has been investigated theoretically. Three possible initial association ways are found, i.e. O( 1 D) insertion into the C-H bond to form energy-rich intermediates a(a 1 -a 4 ) CF 3 OCF 2 OH, O( 1 D) insertion into the C-O bond to form energy-rich intermediate b CF 3 OOCHF 2 , O( 1 D) addition to the F atom to generate intermediates c CHF 2 OCF 3 O and c 1 CF 3 OCFHOF. The geometries are optimized at the B3LYP/6-311G(d, p) level, and the energy profiles are further refined by MC-QCISD level of theory. The mechanism can generally be described as association, isomerization, and dissociation. There are five energetically accessible reaction pathways. Eight products are located on potential energy surfaces (PESs). It is predicted that the main products are P2 (F 2 CO þ CF 3 OH), P3 (2F 2 CO þ HF), and P4 (CF 3 OCFO þ HF), while P1 (CF 2 O(O)CF 3 þ H) and P5 (CF 3 O þ CF 2 HO) are minor products. Furthermore, to further reveal the thermodynamic properties, the enthalpies of formation of CF 3 OCHF 2 are evaluated via isodesmic reactions at the MC-QCISD//B3LYP/6-311G(d, p) level and the reaction enthalpies of the major reaction channels are calculated at the same level.