Highly efficient D/H scrambling and highly selective chlorination in γ-irradiated D- and H-octane mixture in freon 113: Trace back of transient processes by the observation of D/H scrambling with high resolution nuclear magnetic resonance

Abstract

A high resolution nuclear magnetic resonance (NMR) study on the γ-irradiated isotopic mixture of protiated and deuteriated octanes in freon 113 revealed that the protons and the deuterons are scrambled very efficiently (G>2000) at all the positions. While the solvent freon was substituted selectively with a proton and chlorination of protiated octane occurred selectively at the secondary position. These observations, coexistence of the random D/H scrambling and the selective substitution reactions, are the evidence that: (1) in the ‘‘hot’’ period rapid intermolecular radical migration occurs among the solute alkanes, the solvent freons, and the product chloroalkanes, (2) on the other hand, in the following ‘‘thermalized’’ period, chemical bonds within which radical site migration occurs are limited to those with smaller bonding energies, i.e., the secondary position of (protiated) alkane, the C–Cl bonds of freon, and the C–Cl bond of chloroalkanes.