KINETIC-STUDIES OF THE REACTIONS OF H2CN AND D2CN RADICALS WITH N AND H

Absolute rate constants for the reactions of H2CN and D2CN with N atoms have been measured by using the discharge flow-mass spectrometry technique between 200 and 363 K. No isotope effect was observed. The results are as follows (10-11 cm3 s-1): k1(200 K) = 3.9 ± 2.2, k1(298 K) = 4.4 ± 1.4, k1(363 K) = 6.7 ± 2.0. Quoted uncertainties reflect statistical errors at the 95% confidence level. The reactions of D2CN with H and with D atoms were also studied. Analysis of the data from these experiments was difficult, but a lower limit for the rate constant for this reaction of 7 × 10-11 cm3 s-1 was obtained at 298 K, no isotope effect being observed. Ignoring isotopic variations, the products are represented by NH + HCN and H2 + HCN for reactions with N and H, respectively. This study represents the first determination of the rate constants for these reactions. The significance of these processes in models of the atmospheres of Titan and Jupiter and in the chemistry of circumstellar and interstellar clouds is discussed; their role in laboratory experiments on active nitrogen/hydrocarbon reactions is also considered. © 1990 American Chemical Society.