Thermodynamics and Kinetics in Micellar Media. Reaction of the Hydroxide Ion with 1,3,5-Trinitrobenzene in Aqueous Solutions of a Neutral Nonionic Surfactant. Effect of the Concentration of Background Electrolyte

• Published in: The journal of physical chemistry. B Vol. 107; no. 33; pp. 8454 - 8461
• Main Authors: Le Gall, M, Lelièvre, J, Loppinet-Serani, A, Letellier, P
• Format: Journal Article
• Language: English
• Published: American Chemical Society 21.08.2003
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp0223915

The use of a neutral surfactant (Brij 35) allows us to investigate its influence upon the kinetics of the reaction between a neutral substrate and a charged reactant. The thermodynamic description of a micellar system can be obtained by introducing a variable of area in the expression of the internal energy. Thus, the content of micellar solutions is separated into two components:  a volume content associated with dimension 3, and an area content associated with dimension 2. The volume is an extensive parameter and a homogeneous function of degree unity of its content, but the area is not necessarily an extensive function and does not vary linearly with content. In this way, we can describe the evolution of the behavior of micellar solutions when the concentration of surfactant increases. We introduce the notion of “micellar catalysis” in terms of an increase of the exchange rate at equilibrium, m v 0, for the studied reaction. The formal separation of the content of the solution into two components with different dimensions leads us to suppose a difference in reactivity. The exchange rate associated with the content of dimension 2 equals 40 times the one associated with the content of dimension 3.