Reaction of alkaline sodium picrate with creatinine: I. Kinetics and mechanism of formation of the mono-creatinine picric acid complex.
Spectrophotometric, kinetic, and nuclear magnetic resonance studies indicate that alkaline sodium picrate and creatinine react to form a 1/1 aduct between picric and creatinine, with a stability constant of log K= 4.26. Kinetic studies indicate that the forward reaction is first order with respect to picric acid, hydroxide, and creatinine concentration. The reverse reaction, the dissociation of the 1/1 complex, shows a complex dependence on hydroxide concentration. The expression for the observed pseudo-first-order rate constant in the presence of excess picric acid is: Kobsd = K1K0[P][OH] +[K2[OH]x. A value of K1K0 = 5.0 (mol/liter)-2s-1 is obtained. For accurate analytical results with this reaction, hydroxide concentration must be maintained at a constant value for both samples and standards.
D055598:Chemical Phenomena; D002621:Chemistry; D003404:Creatinine / Q000032:analysis*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008722:Methods; D010851:Picrates; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet
D007202:Indicators and Reagents; D010851:Picrates; D003404:Creatinine