Kinetics and mechanism of interaction of dipeptide (glycyl–glycine) with ninhydrin in aqueous micellar media

Abstract

The rates of reaction between ninhydrin and dipeptide glycyl-glycine (Gly-Gly) have been determined by studying the reaction spectrophotometrically at 70 • C and pH 5.0 in aqueous and in aqueous cationic micelles of cetyltrimethylammonium bromide (CTAB). The reaction follows first-and fractional-order kinetics, respectively, in [Gly-Gly] and [ninhydrin]. The observed rate constant is affected by [CTAB] changes and the maximum rate enhancement is ca. three-fold. As the k ψ − [CTAB] profile shape is characteristic of bimolecular reactions catalyzed by micelles, the catalysis is explained in terms of the pseudo-phase model of the micelles (proposed by Menger and Portnoy and developed by Bunton and Romsted). The presence of inorganic salts (NaCl, NaBr, Na 2 SO 4 ) does not reveal any regular effect but the data with organic salts (NaBenz, NaSal) show an increase in the rate followed by a decrease. The kinetic data have been used to calculate the micellar binding constants K S for Gly-Gly and K N for ninhydrin and the respective values are 317 and 69 mol −1 dm 3 .

Kinetic and Mechanistic Studies on [Zn(II)-Gly-Phe]+–Ninhydrin Reaction in Aqueous and Cationic CTAB Surfactant Micelles

“…[2,3] For this reason, the mechanism of this reaction has been a subject of extensive investigations, [1] but kinetic studies are sparse. [4][5][6] Although breakthroughs have been made in the understanding of reactions of ninhydrin with amino functionality, there are still questions that await answers.…”

Reactions of Aldehydes and Ketones and their Derivatives

“…The kinetics and mechanism of the reaction of glycylglycine 21 and of valine 22 with ninhydrin (8) have been studied in aqueous micellar media.…”

“…A QUINAP auxiliary (21), bound to copper(I), gives excellent enantioselectivity in the addition of terminal alkynes to isolated isoquinoline iminium cations. 55 ee DFT calculations have been used to follow the formation of iminium ions from secondary amines and acrolein.…”

Kinetic Study of the Formation of Ruhemann's Purple in Micellar and Microemulsion Phases

“…The ninhydrin reaction" forms a product known as "Ruhemann's purple" which is the anionic dye diketohydrindylidenedilceto-hydrindamine (DYDA). In this regard recent studies had shown success toward in creased sensitivity of ninhydrin-amino acid reaction by in volving cationic surfactant micelles, solvents, complexion with metal cations and dipeptide [10][11][12][13][14]. To improve the methods sensitivity, how ever, modifications are continuously being made [8,9].…”