For example, consider this hypothetical stepwise reaction:
The lifetime distinguishes true, chemically distinct intermediates from vibrational or conformational states (conformers). Their potential energy with respect to reactants or previous intermediates is defined to have a minimum of depth greater than available thermal energy arising from temperature, with an exact value RT, where R is gas constant and T is temperature.
Many intermediates are short-lived and have a high reactivity, thus having a low concentration in the mixture. When the necessary conditions of the reaction no longer prevail, these intermediates react further and no longer remain in the reaction mixture. Common examples are oxidizing radicals (OOH and OH) found in combustion reactions, which are so reactive that a high temperature is required to constantly produce them to compensate reaction, or the combustion reaction will cease.
There are some operations where multiple reactions are run in the same batch. For example, in an esterification of a diol, a monoester product is formed first, and may be isolated, but the same reactants and conditions promote a second reaction of the monoester to diester. The lifetime of such an "intermediate" is considerably longer than the lifetime of the intermediates of the esterification reaction itself.
Mechanism and Evolution of Multidomain Aminoacyl-tRNA Synthetases Revealed by Their Inhibition by Analogues of a Reaction Intermediate, and by Properties of Truncated Forms
Oct 01, 2013; ABSTRACTMany enzymes which catalyze the conversion of large substrates are made of several structural domains belonging to the...