ABSTRACT
The measurement of short-lived radicals is facilitated by the use of rapid-mixing flow techniques. Since electron paramagnetic resonance can detect paramagnetic species selectively with a high sensitivity, it is a preferred method for investigations of kinetics of reactions with radicals as intermediates or products and has been applied to many radical reactions in liquid-phase materials. A similar experiment succeeded in the measurement of the end radical of chain reactions in radical polymerization in polymer chemistry. Biologists have used rapid-mixing techniques, as well as temperature jump and laser-flash techniques, to study the reaction kinetics of paramagnetic intermediates from biologically active materials. The rapid-mixing techniques include continuous-flow and stopped-flow methods. The time course of the reaction can be sampled at various positions down the reaction tube by varying the distance between the mixing chamber and the center of the cavity and/or by varying the flow rate.
