“Abstraction Kinetics of H-Atom by OH Radical from Pinonaldehyde: Ab Initio and Transition-State Theory Calculations” Manas Ranjan Dash and B. Rajakumar; J. Phys. Chem. A, 2012, 116, 5856-5866.

The kinetics and abstraction rate coefficients of hydroxyl radical (OH) reaction with pinonaldehyde werecomputed using G3(MP2) theory and transition-state theory (TST) between 200 and 400 K. Structures of the reactants, reactioncomplexes (RCs), product complexes (PCs), transition states (TSs), and products were optimized at the MP2(FULL)/6-31G*level of theory. Fifteen transition states were identified for the title reaction and confirmed by intrinsic reaction coordinate (IRC)calculations. The contributions of all the individual hydrogens in the substrate molecule to the total reaction are computed. Thequantum mechanical tunneling effect was computed using Wigner’s and Eckart’s methods (both symmetrical and unsymmetricalmethods). The reaction exhibits a negative temperature dependent rate coefficient,k(T) = (1.97±0.34)×10−13exp[(1587±48)/T]cm3molecule−1s−1,k(T) = (3.02±0.56)×10−13exp[(1534±52/T]cm3molecule−1s−1, andk(T) = (4.71±1.85)×10−14exp[(2042±110)/T]cm3molecule−1s−1with Wigner’s, Eckart’s symmetrical, and Eckart’s unsymmetrical tunnelingcorrections, respectively. Theoretically calculated rate coefficients are found to be in good agreement with the experimentallymeasured ones and other theoretical results. It is shown that hydrogen abstraction from−CHO position is the major channel,whereas H-abstraction from−COCH3is negligible. The atmospheric lifetime of pinonaldehyde is computed to be few hours andfound to be in excellent agreement with the experimentally estimated ones.