Reactions of iso-propyl radicals with oxygen, hydrogen and deuterium

i-C3H7 radicals have been produced by the oxidation of i-C3H7CHO at 4400C. From measurements of the relative yields of C3H6 and C3H8 over a wide range of mixture composition, a value for the ratio k4/k1 - 0.003 2 +-0.000 3 has been obtained. From measurements of the increased yield of C3H8 (or C3H7D) in the presence of H2 (or D2), the ratios k1/ksub(2s) = 3060 +- 250, k1/ksub(3s) = 7680 +- 300 at 4400C are obtained. The value for ksub(2s)/ksub(3s) = 2.51 +- 0.20 suggests that Esub(3s) - Esub(2s) = 800 cal mol-1, which indicates a lowering of the zero-point energy in the transition state of about 1 000 cal mol-1 when H2 is replaced by D2. Absolute rate constants and Arrhenius parameters are discussed. (author)