Effect of molecular packing on radiolytic processes of n-alkanes

Abstract

Both ionic and radical processes in the radiolysis of n-alkanes may be affected by the packing arrangements of the respective reagents. On the ionic side, proton transfer from alkane radical cations to alkane molecules is greatly affected by the accessibility of secondary C–H bonds in alkane molecules to planar C–H bonds in alkane radical cations from which proton donation takes place. As a result, the proton transfer from ground-state radical cations is not an efficient process in neat n-alkane crystals but occurs readily in the presence of longer-chain n-alkane solutes. With respect to radical reactions, the effect of molecular packing on alkyl radical production (resulting from the preferential migration of hydrogen atoms in the intermolecular boundary region) and on radical transformation and recombination (resulting from intermolecular radical-site transfer) is being discussed. The effect of crystalline structure on radical transformation by intermolecular radical-site transfer is utilized to determine the physical state of n-alkane aggregates in CCl 3F.