Finding the possible mechanisms for a given type of overall reaction

Abstract

A systematic way to derive all thea priori possible mechanisms classified according to the numbers, ϱ, of elementary or molecular reaction steps was presented recently. The method is now applied to overall reactions of the type A +B ⇒ C+D. The “laminar” (elementary steps' stoichiometric coefficients unity) mechanisms that turn out possible are derived and listed for the important ϱ = 2 case. The ϱ = 3 three step mechanisms were reported in another paper. Many examples from actual chemical, biochemical mechanisms, such as SE1, SN1, SE2, SN2, activated complex theory of abstraction reactions, free radical chain propagation and biochemical electron transport chains are given. By far most mechanisms usually encountered are of the laminar type, although the method also gives the “turbulent” ones, i.e. with some stoichiometric coefficients in elementary steps larger than one or some species occurring in many of the steps.