title: A Journey toward Sulfolane Microemulsions Suggested as Inert, Nonaqueous Reaction Media.
abstract: Recently, it turned out that nanostructured reaction media containing highly inert solvents as tetrahydrothiophen-1,1-dioxide (sulfolane) are beneficial for strongly oxidizing or reductive reactions. Because of their ability of solubilizing polar and nonpolar solvents with a large nanostructured interface in particular microemulsions provide such interesting reaction media. Starting from the pseudoternary microemulsion H2O-n-octane-C12E4/C12E5 (polyoxyethylene n-alkyl ether), water was successively replaced by the highly inert tetrahydrothiophen-1,1-dioxide (sulfolane). We found that an increasing sulfolane content drives the system beyond the tricritical point. Replacing the already long chain surfactants C12E4 and C12E5 by a mixture of the even longer chain surfactants C18E6 and C18E8, we were able to prepare nonaqueous sulfolane microemulsions for the first time. We also teach how in a second step the phase behavior of the hydrophilic sulfolane-n-octane-C18E8 system can be tuned at constant temperature (as required by the reaction conditions) by addition of the hydrophobic cosurfactant 1-octanol (C8E0). The change in curvature that occurs by adding 1-octanol is demonstrated measuring the size of reverse micelles by DLS. We found that the radius varies from at least 8 to 16 nm, a suitable sizes for inverse nanoreaction vessels.
authors.affiliation: Department of Chemistry, Physical Chemistry, University of Cologne , Luxemburger Str. 116, D-50939 Cologne, Germany.|Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wielpütz
authors.affiliation: Department of Chemistry, Physical Chemistry, University of Cologne , Luxemburger Str. 116, D-50939 Cologne, Germany.|Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
authors.forename: Helge F M
authors.initials: HF
authors.lastname: Klemmer
authors.affiliation: Department of Chemistry, Physical Chemistry, University of Cologne , Luxemburger Str. 116, D-50939 Cologne, Germany.|Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Strey
authors.affiliation: Department of Chemistry, Physical Chemistry, University of Cologne , Luxemburger Str. 116, D-50939 Cologne, Germany.|Institut für Physikalische Chemie, Universität Stuttgart , Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Sottmann