Reactions of NH Radicals. V. Photolysis of HN3 in the Presence of C3H8 at 313 nm

Article abstract of DOI:10.1246/bcsj.58.2900

The photolysis of HN3 vapor in the presence of C3H8 was studied at 313 nm and 30 deg C.The main products were N2, H2, CH4, C2H6, C3H6, NH4N3, CH3NH2*HN3, C2H5NH2*HN3, and n- and i-C3H7NH2*HN3.The quantum yields of these products were measured as a function of the pressure of HN3 or C3H8.The following mechanisms for the main reactions were proposed: HN3 + hν(313 nm) -> N2 + NH(a¹Δ); NH(a¹Δ) + HN3 -> 2N2 + 2H, NH2 + N3, and N2 + N2H2* (2); NH(a¹Δ) + C3H8 -> C3H7NH2*(n- and i-propylamine) (3); NH(a¹Δ) + C3H8 -> NH(X³Σ) + C3H8 (4); C3H7NH2* -> CH3 + C2H4NH2 (5); CH4 + C2H4NH (6), C2H4 + CH3NH2 (7), C2H5 + CH2NH2 (8), C2H6 + CH2NH (9), H2 + C3H6NH (10), and NH3 + C3H6 (11); C3H7NH2* + HN3 -> C3H7NH2 + HN3 (12); C3H7NH2* + C3H8 -> C3H7NH2 + C3H8 (13).The rate constant ratios are: k₃/k₂ = 1.28; k₄/k₂ = 0.262; k₆/k₅ = 0.109; k₇/k₅ = 0.050; k₈/k₅ = 1.39; k₉/k₅ = 0.040; k₁₀/k₅ = 1.20; k₁₁/k₅ = 4.72; k₁₂/k₅ = 666 dm³mol^-1; k₁₃/k₅ = 860 dm³mol^-1.The formation ratio of n-C3H7NH2/i-C3H7NH2 was 1.55, regardless of the total pressure.The half-life of 1.78E-10 s for C3H7NH2* was obtained by using the collision theory.The relative and absolute rate constants were compared for the reactions of NH(a¹Δ) with CH4, C2H6, and C3H8; it was found that the relative yield for the insertion of NH(a¹Δ) into a C-H bond increases with a decrease in the C-H bond dissociation energy.