Theoretical kinetics for the decomposition of iso-butanol and related $\mathrm{(CH3)(2)\dot{C}H}$ plus $\mathrm{\dot{C}H_2OH}$ reactions

The potential energy surface for the thermal decomposition of iso-butanol has been investigated using high level ab initio electronic structure methods. Temperature and pressure dependent rate coefficients for the three channels with the lower energy barriers, forming (CH3)(2)(C)over dotH + (C) over dotH(2)OH (k(1)), CH3(C)over dotHCH(2)OH + (C) over dotH(3) (k(2)) and (CH3)(2)C=CH2 + H2O (k(3)) were computed with the master equation method employing ab initio transition state theory estimates for the microcanonical rate coefficients. The two radical forming channels were treated with variable-reaction-coordinate transition state theory employing directly sampled CASPT2(2e, 2o) cc-pVDZ orientation dependent interaction energies coupled with one-dimensional basis set and relaxation corrections. The other channel was treated with conventional TST including Eckart tunneling and one-dimensional hindered rotor corrections. For temperatures higher than 1000 K and pressures of 1 Torr or greater, the direct C-C bond fission forming (CH3)(2)(C) over dotH + CH2OH is dominant, while the formations of CH3(C)HCH2OH vertical bar (C) over dot H-3 and (CH3)(2)C = CH2 + H-2 together contribute less than 20%. The bi-molecular recombination of (CH3)(2) (C) over dotH + (C) over dotH(2)OH has also been investigated, with the formation of iso-butanol found to be dominant at high pressure and the production of CH3(C) over dotHCH(2)OH + (C) over dot H-3 favored at low pressure. (C) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.The potential energy surface for the thermal decomposition of iso-butanol has been investigated using high level ab initio electronic structure methods. Temperature and pressure dependent rate coefficients for the three channels with the lower energy barriers, forming (CH3)(2)(C)over dotH + (C) over dotH(2)OH (k(1)), CH3(C)over dotHCH(2)OH + (C) over dotH(3) (k(2)) and (CH3)(2)C=CH2 + H2O (k(3)) were computed with the master equation method employing ab initio transition state theory estimates for the microcanonical rate coefficients. The two radical forming channels were treated with variable-reaction-coordinate transition state theory employing directly sampled CASPT2(2e, 2o) cc-pVDZ orientation dependent interaction energies coupled with one-dimensional basis set and relaxation corrections. The other channel was treated with conventional TST including Eckart tunneling and one-dimensional hindered rotor corrections. For temperatures higher than 1000 K and pressures of 1 Torr or greater, the direct C-C bond fission forming (CH3)(2)(C) over dotH + CH2OH is dominant, while the formations of CH3(C)HCH2OH vertical bar (C) over dot H-3 and (CH3)(2)C = CH2 + H-2 together contribute less than 20%. The bi-molecular recombination of (CH3)(2) (C) over dotH + (C) over dotH(2)OH has also been investigated, with the formation of iso-butanol found to be dominant at high pressure and the production of CH3(C) over dotHCH(2)OH + (C) over dot H-3 favored at low pressure. (C) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.