FREE-RADICAL CHLORINATION OF ALKANES IN SUPERCRITICAL CARBON-DIOXIDE - THE CHLORINE ATOM CAGE EFFECT AS A PROBE FOR ENHANCED CAGE EFFECTS IN SUPERCRITICAL-FLUID SOLVENTS

The chlorine atom cage effect was used as a highly sensitive probe for studying the effect of viscosity and the possible role of solvent clu sters on cage lifetimes and reactivity for reactions carried out in su percritical fluid solvents. These experiments were conducted in superc ritical carbon dioxide (SC-CO2, 40 degrees C, at various pressures) wi th parallel experiments in conventional solvents and in the gas phase. The results of these experiments provide no indication of an enhanced cage effect near the critical point in SC-CO2 solvent. The magnitude of the cage effect observed in SC-CO2 at all pressures examined is wel l within what is anticipated on the basis of extrapolations from conve ntional solvents.