The Reaction CH3 + NO -> HCN + H2O. Experimental and Modeling Study

Article abstract of DOI:10.1021/j100118a026

The reaction CH3 + NO -> HCN + H2O was studied behind reflected shocks in a single pulse shock tube by heating mixtures of ethane and nitric oxide and determining the extent of HCN production.The temperature range covered in this investigation was 1100-1330 K at overall densities of approximately 3 x 10^-5 mol/cm³.The postshock mixtures contained in addition to hydrogen cyanide minute quantities of C1 and C2 nitriles and stable products resulting from the decomposition of ethane.These were, in order of decreasing abundance, C2H4, CH4, and C2H2.Profiles of mole percent vs reciprocal temperature of the species HCN, CH4, C2H2, and C2H4 were modeled with a reaction scheme consisting of 18 species and 31 elementary reactions.From these model calculations a rate expression, k₁ = 10^11.8 exp(-15.0 x 10³/RT) cm³mol^-1s^-1, is evaluated for the reaction CH3 + NO -> HCN + H2O where R is expressed in units of cal/(K mol).This reaction is composed of a sequence of reactions, the first one of which is CH3 + NO <-> CH3NO.Since the latter reaches a state of equilibrium at the very early stages of the reaction, it is suggested that k₁ is equal to k_1b x K_1a, where k_1b is the rate constant for the reaction CH3NO (->CH2=NH->O -> CH2=N-OH) -> HCN + H2O and K_1a is the equilibrium constant (K_c) for the reaction CH3 + NO <-> CH3NO.The value for k_1b is k_1b = 10^13.5 exp(-50 x 10³/RT) cm³mol^-1s^-1.