Kinetics and thermodynamics of unimolecular dissociation of n-C₃H₇I

The present work expands previous studies on the kinetics of the n-C3H7I unimolecular decomposition and the thermodynamic properties of n-C3H7I and i-C3H7I molecules, by providing combined experimental and theoretical data on the rate constant for reaction of n-C3H7I + Ar (sic) n-C3H7 + I + Ar, as well as thermodynamic data for iodopropane isomers, calculated based on the density functional theory. The n-C3H7I dissociation rate constant has been precisely determined in shock-tube experiments by applying atomic resonance absorption spectrometry (ARAS) at the resonance transition wavelength of atomic iodine (183.0 nm) in a temperature range from 830 to 1230 K at a pressure of 3-4 bar. The resulting expression is presented in the Arrhenius form: k(1st) = 1.17 x 10(13)exp(-191.4 kJ mol(-1)/RT) (s(-1)). Theoretical RRKM/ME calculation of the temperature- and pressure-dependent rate constant and channel branching ratio have been based on quantum chemical calculations and were performed over a wide range of thermodynamic conditions (T = 300-2000 K, p = 10(-4) to 10(2) bar). Additionally, the thermochemistry of the reactions of n-C3H7I dissociation and isomerization has been calculated on B3LYP/cc-pVTZ-PP level of theory. Thermodynamic data, which are provided in NASA polynomial format, are in a better agreement with the available experimental data and previous theoretical estimates.