Methods for Measuring Rate Constants of Radical Reactions
Atoms and free radicals are extremely active and enter into reaction very quickly with molecules and with each other (stable free radicals represent an exception). Therefore, the concentration of radicals in a system, when they are being formed continuously and reacting, is very small. Direct measurement of radical concentration, for instance by the EPR method, is possible only with specially selected systems and conditions. In the majority of cases, the concentrations of free radicals cannot be measured. This has led to a widespread use of methods that measure the relative rate constants of radical reactions. These methods are based on the ability of radicals to react in parallel, in two or in several directions; i.e., all these methods are, as a matter of fact, different variants of the method of competing reactions. The errors in measuring relative rate constants usually amount to 2 to 5%.
KeywordsElectron Paramagnetic Resonance Radical Reaction Emulsion Polymerization Iodine Atom Stable Free Radical
Unable to display preview. Download preview PDF.