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First Kinetic Determination of Partition Coefficients for Organic Compounds between the Three Microenvironments of AOT‐Based Microemulsions
Author(s) -
GarcíaRío Luis,
Méndez María
Publication year - 2007
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200700318
Subject(s) - microemulsion , chemistry , hydrolysis , partition coefficient , reaction rate constant , kinetic energy , molecule , reagent , substrate (aquarium) , sodium , analytical chemistry (journal) , kinetics , octanol , chromatography , organic chemistry , pulmonary surfactant , biochemistry , physics , oceanography , quantum mechanics , geology
Kinetic data for the hydrolysis of N‐picolinoylimidazole ( I ) and 2,4‐dinitrophenylpicolinate ( II ) in AOT [bis(2‐ethylhexyl) sodium sulfosuccinate] microemulsions are used to determine for the first time the two partition constants for each substrate (i.e. K wi and K oi , corresponding to the incorporation of substrate molecules from water microdroplets and the continuous medium, respectively, into the interface). Application of the pseudophase formalism to the partition constants allowed the rate constant in each phase to be determined. The rate of hydrolysis of II increased with decreasing polarity of the medium; as a result, the hydrolysis reaction took place largely at the interface. On the other hand, the rate of hydrolysis of acylimidazole I decreased with decreasing polarity, possibly as a result of changes in the resonance structures of the reagent causing the hydrolysis process to occur preferentially in water microdroplets.