Abstract
Bulk phase chemistry is hardly ever a reasonable approximation to interpret chemical reactivity in compartmentalized systems, because multiphasic systems may alter the course of chemical reactions by modifying the local concentrations and orientations of reactants and by modifying their physical properties (acid-base equilibria, redox potentials, etc.), making them—or inducing them—to react in a selective manner. Exploiting multiphasic systems as beneficial reaction media requires an understanding of their effects on chemical reactivity. Chemical reactions in multiphasic systems follow the same laws as in bulk solution, and the measured or observed rate constant of bimolecular reactions can be expressed, under dynamic equilibrium conditions, in terms of the product of the rate constant and of the concentrations of reactants. In emulsions, reactants distribute between the oil, water, and interfacial regions according to their polarity. However, determining the distributions of reactive components in intact emulsions is arduous because it is physically impossible to separate the interfacial region from the oil and aqueous ones without disrupting the existing equilibria and, therefore, need to be determined in the intact emulsions. The challenge is, thus, to develop models to correctly interpret chemical reactivity. Here, we will review the application of the pseudophase kinetic model to emulsions, which allows us to model chemical reactivity under a variety of experimental conditions and, by carrying out an appropriate kinetic analysis, will provide important kineticparameters.
Highlights
The three-dimensional interfaces between two immiscible liquids found in emulsions and other colloidal systems have been widely used as models of membrane function to mimic their behavior, as models of lipid-based foods and to model importantchemical reactions such as the oxidation of lipids [1,2,3,4]
Topseudo-phase interpret chemical reactivity in emulsions, kinetic we model on theits formalof the was devised
Significant differences are expected from those reactions taking place to a reactive interface
Summary
The three-dimensional interfaces between two immiscible liquids (oil and water) found in emulsions and other colloidal systems have been widely used as models of membrane function to mimic their behavior, as models of lipid-based foods and to model important (bio)chemical reactions such as the oxidation of lipids [1,2,3,4]. Lipid oxidation reactions and those between antioxidants and lipid radicals are largely affected by the presence of interfacial regions, because they are highly anisotropic regions composed of a mélange of oil, water, and surfactants [2,14,15,16]. For the sake of simof reactants and other components, if any, do not affect molecular transport.to Prior to plicity, the review will focus exclusively on fluid emulsions where restrictions the free considering modeling the chemical reactivity, we will briefly discuss some properties of movement of reactants and other components, if any, do not affect molecular transport. Prior to considering modeling the chemical reactivity, we will briefly discuss some properties of emulsions and their dynamic aspects
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