Two-Step Reactions with Total Reversibility

Biphasic kinetics will in principle be observed with (1.123). The associated first-order rate constants k and are related to the rate constants of (1.123) by the relationships (Sec. 1.8.2) 

Only if Kf (= A ,/Ar, ) and A 2(= k2/k i) are known, are all the rate constants calculable. This necessity is removed if one of the steps is pseudo first-order, e. g. A reacts with D in the first step, as we shall now discover. 

The interaction of excess concanavalin A (P) with the chromogenic disaccharide p-nitro-phenyl-2-0-a-Z -mannopyranosyl-a-Z)-mannopyranoside(M) 10(a) displays a spectral-time course shown in Fig. 1.9. It is clearly biphasic and 

The reaction of metal ion M + with the keto, enol tautomeric mixture of acetylacetone (acacH) in acidic aqueous solution has been treated by a similar approach to that outlined above (see Prob. 16). 

Simplifications ease the extraction of accurate values for the rate constants. For example, the keto, enol interconversion may sometimes be ignored, and k 2 Xc, and Xtj k are justifiable assumptions.  

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