## Abstract

Kinetics and mechanisms for the reactions of HNO with CH_{3} and C_{6}H_{5} have been investigated by ab initio molecular orbital (MO) and transition-state theory (TST) and/or Rice-Ramsperger-Kassel-Marcus/ Master Equation (RRKM/ME) calculations, The G2M(RCC, MP2)//B3LYP/6-31G(d) method was employed to evaluate the energetics for construction of their potential energy surfaces and prediction of reaction rate constants. The reactions R + HNO (R = CH_{3} and C_{6}H_{5}) were found to proceed by two key product channels giving ( 1 ) RH + NO and (2) RNO + H, primarily by direct abstraction and indirect association/decomposition mechanisms, respectively. As both reactions initially occur barrierlessly, their rate constants were evaluated with a canonical variational approach in our TST and RRKM/ME calculations. For practical applications, the rate constants evaluated for the atmospheric-pressure condition are represented by modified Arrhenius equations in units of cm^{3} mol^{-1} s^{-1} for the temperature range 298-2500 K: script k sign _{1A} = 1.47× 10 ^{11}T^{0.76}exp[-175/T], script k sign_{2A} = 8.06 × 10^{3}T^{2.40}exp[-3100/T], script k sign_{1B} = 3.78 × 10^{5}T^{2.28}exp[230/T], and script k sign _{2B} = 3.79 × 10^{9}T^{1.19}exp[-4800/T], where A and B represent CH_{3} and C_{6}H_{5} reactions, respectively. Based on the predicted rate constant at 1 atm pressure for R + HNO → RNO + H, we estimated their reverse rate constants for R + HNO production from H + RNO in units of cm^{3} mol^{-1} s ^{-1} script k sign_{-2A′} = 7.01 × 10 ^{10}T^{0.84}exp[120/T and script k sign_{2B′} = 2.22×10^{19}T-^{1.01}exp[-9700/T].The heats of formation at 0 K for CH_{3}NO, CH_{3}N(H)O, CH_{3}NOH, C _{6}H_{5}N(H)O, and C_{6}H_{5}NOH have been estimated to be 18.6, 18.1, 22.5, 47.2, and 50.7 kcal mol^{-1} with an estimated ≠1 kcal mol^{-1} error.

Original language | English |
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Pages (from-to) | 261-274 |

Number of pages | 14 |

Journal | International Journal of Chemical Kinetics |

Volume | 37 |

Issue number | 5 |

DOIs | |

State | Published - 16 Mar 2005 |