Radical kinetics in sub- and supercritical carbon dioxide: thermodynamic rate tuning

We report rate constants for muonium addition to 1,1-difluoroethylene (vinylidene fluoride) in CO2 at 290–530 K, 40–360 bar, and 0.05–0.90 g cm−3. Rate constants are mapped against their thermodynamic conditions, demonstrating the kinetic tuning ability of the solvent. The reaction exhibits critical slowing near conditions of maximum solvent isothermal compressibility, where activation volumes of unprecedentedly large magnitudes on the order of ±106 cm3 mol−1 are observed. Such values are suggestive of pressure being a significant parameter for tuning fluorolkene reactivity.