Effects of

Area of Science:

• Physical Chemistry
• Chemical Kinetics
• Supramolecular Chemistry

Background:

• Surfactant micelles influence chemical reaction rates.
• Understanding these effects is crucial for reaction mechanism elucidation.

Purpose of the Study:

• To investigate the impact of cetyltrimethylammonium bromide (CTABr) micelles on the kinetics of nucleophilic reactions.
• To quantify the binding of ionized phenyl salicylate (PS(-)) to CTABr micelles.

Main Methods:

• Studied second-order rate constants (k(n)(obs)) for reactions between amines (piperidine, n-butylamine) and PS(-).
• Analyzed data using a pseudophase micellar model at constant temperature (35°C) and varying CTABr concentrations.
• Investigated the effect of sodium bromide (NaBr) concentration on micellar binding constants.

Main Results:

• Observed a nonlinear decrease in k(n)(obs) with increasing CTABr concentration ([D(n)]).
• The pseudophase model successfully described the kinetic data, yielding micellar binding constants (K(S)) for PS(-).
• Found that NaBr concentration affects K(S) according to an empirical relationship.

Conclusions:

• CTABr micelles significantly alter the reaction kinetics of amines with PS(-).
• The pseudophase model provides a valid framework for understanding these micellar effects.
• The study quantifies the interaction between PS(-) and CTABr micelles, influenced by ionic strength.