Insertion Reaction of NH (¹Δ) Radicals into the C-H Bonds of 2-Methylbutane

Abstract

In order to determine the relative reaction rates of inserting NH (¹Δ) radicals into the different C-H bonds of 2-methylbutane, hydrogen azide has been photolyzed in 2-methylbutane solution at 5 and -72°C. The relative yields of the amines produced by the insertion of NH(¹Δ) radicals into the primary, secondary and tertiary C-H bonds were found to be 1.0: O.26: O.19 at 5°C and 1.0: 0.40: 0.33 at -72°C, respectively. Therefore, the relative reaction rates per bond are 1.0: 1.2: 1.7 at 5°C and 1.0: 1.8: 3.0 at -72°C, respectively, for the primary, secondary and tertiary C-H bonds.
Three conclusions were obtained from these experiments: 1) The fraction of the hydrogen atom-abstraction reaction of NH(¹Δ) radicals is negligibly small compared with the insertion reaction.2) The insertion reaction of NH(¹Δ) radicals seems to have an activation energy.3) Hydrogen azide forms a "cluster" in the alkane solution.