Abstract
Kinetics of the interaction of histidine and histidine methyl ester with ninhydrin under varying concentrations of reactants, anionic (sodium dodecyl sulphate, SDS), cationic (cetyltrimethylammonium bromide, CTAB) and non‐ionic (Triton X‐100, TX‐100) micelles have been carried out. Rate of the reaction was found to be independent of the initial concentration of histidine (and histidine methyl ester) but was dependent on [Ninhydrin]. The SDS micelles had no effect on the rate of the reaction. In the presence of the CTAB micelles a small enhancement in the rate was observed. The rate − [CTAB] profile showed that the increase in [CTAB] increased the rate up to a maximum value and a further increase had a decreasing effect on the rate. The rate was enhanced by TX‐100 also but, unlike CTAB micelles, TX‐100 possessed a curve without peak for the rate − [TX‐100] profile. The following rate equation was obeyed by the reaction in CTAB and TX‐100 micelles:
$$k_{\Psi }={k_{w}\ {\rm [N]}_{T}+(k_{m}\ {\rm K_{S}}-k_{w}{\rm )\ [D}_{n}]\ {\rm M_{N}\ \!\!\!^{S}}\over 1+{\rm K_{S}\ [D}_{n}]}$$
Values of kw, km, and KS were evaluated and are reported herein. ©1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 103–111, 1999