In chemistry, a radical clock is a chemical compound that assists in the indirect methodology to determine the kinetics of a free-radical reaction.
[2][3] An alternative, perhaps more direct approach involves generation and isolation of the intermediates by flash photolysis and pulse radiolysis, but such methods are time-consuming and require expensive equipment.
[3] Through the usage of EPR spectroscopy, the absolute rate constants for unimolecular reactions can be measured with a variety of temperatures.
[3][4] The Arrhenius equation can then be applied to calculate the rate constant for a specific temperature at which the radical clock reactions are conducted.
[1][failed verification] By selecting among the general classes of radical clocks and the specific substituents on them, one can be chosen with a rate-constant suitable for studying reactions having a wide range of rates.