Isotopic exchange reactions, exponential

In summary, because the forward reaction rate constant is similar to the back reaction rate constant, the concentration evolution of a second-order isotopic exchange reaction often reduces to that of a first-order reaction (exponential evolution) but the rate "constants" and mean reaction time for the reduced reaction depend on total concentrations. 

A AZPE = AZPEii — AZPEd AZPEt) corresponds to the terms for the reactions of monodeuteriated aldehydes. Terms defined by IE = MMl x EXC x EXP (IE is the Isotopic exchange equilibrium, MMl is the mass moment of inertia term representing the rotational and translational partition function ratios, EXC is the vibrational excitation term and EXP is the exponential zero point energy). 

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