Evaluation of proton activity in microemulsions by a kinetic probe.
The decomposition reaction of the purple dye murexide in acidic media is used as a probe indicator for protons in nonionic microemulsions. The reaction kinetics primarily rely on the proton concentration and permit assessment of the proton activity in the nonionic microemulsions of water/cyclohexane/Igepal and water/heptane/Igepal. The experiments performed in the two microemulsions covered a wide range of water-to-oil mass fraction for the two systems. The kinetic runs were monitored under pseudo-first order conditions by the stopped-flow technique. The equilibrium constants for the formation of purpuric acid and the kinetic constants for the ensuing decomposition reaction fulfill a trend consistent with the micro compartmentalized nature of the multicomponent medium, and support the use of murexide as an indicator of the proton activity in microemulsions.
Peñacoba
Indalecio A
IA
Universidad de Burgos, Departamento de Química, 09001 Burgos, Spain.
García
Begoña
B
Navarro
Ana M
AM
Hoyuelos
F Javier
FJ
Leal
José M
JM
D004396:Coloring Agents / Q000737:chemistry*; D003510:Cyclohexanes / Q000737:chemistry; D004655:Emulsions / Q000737:chemistry; D006536:Heptanes / Q000737:chemistry; D007700:Kinetics; D009114:Murexide / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D011522:Protons; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry; D014867:Water / Q000737:chemistry
D004396:Coloring Agents; D003510:Cyclohexanes; D004655:Emulsions; D006536:Heptanes; D011522:Protons; D013501:Surface-Active Agents; D014867:Water; D011092:Polyethylene Glycols; C506365:Cyclohexane; D009114:Murexide