A theoretical analysis of the reaction between hydrogen atoms and isocyanic acid

Using BAC‐MP4 potential‐surface parameters, supplemented by an MP2 normal‐mode analysis at one transition state, and statistical theoretical methods, we have computed thermal rate coefficients for the reactions, equation image and equation image Over the entire temperature range considered, 300 K < T < 3300 K, reaction (2) is the dominant product channel. The theoretical predictions are in excellent agreement with the experimental results available for k2 and k−1, the rate coefficient for the reverse of reaction (1). Modified Arrhenius expressions are given for k1, k−1, and k2. In addition, we identify and discuss a weakness in utilizing a Hartree‐Fock normal‐mode analysis in the prediction of k2. The present result for k2 is much smaller than that used in the initial modeling of the RAPRENOx process. The implications of this are discussed.