Center for Green Chemistry
Center for Green Chemistry
Wallis P.J.,Center for Green Chemistry |
Wallis P.J.,Monash University |
Gates W.P.,Monash University |
Patti A.F.,Center for Green Chemistry |
Patti A.F.,Monash University
Langmuir | Year: 2010
Fe(III) montmorillonite clay that was partially exchanged with hexadecyltrimethylammonium (HDTMA +) cations achieved increased catalytic activity for the oxidative coupling of hydrophobic organic substrates. A series of mixedcation organoclays were produced, where the organic cation content ranged from 6 to 50% relative to the cationexchange capacity (CEC) of the clay, and were tested for catalytic activity using different Fe(III)-mediated oxidative coupling reactions. Enhanced catalytic activity by Fe 3+/HDTMA + montmorillonite for coupling hydrophobic substrates was observed, with maximum catalytic activity in the oxidative coupling of 2-naphthol observed at 6% HDTMA + coverage. However, maximum catalytic activity with a more hydrophobic substrate, anthrone, was achieved with 50% HDTMA + coverage, indicating that matching levels of organic modification to substrate hydrophobicity improves catalytic activity. The organization of the organic cations at the clay surfaces proved to be heterogeneous, as determined by scanning transmission X-ray microscopy (STXM) and powder X-ray diffraction. Results from molecular dynamics simulations supported the heterogeneous nature of the catalysts but also pointed toward large regions within the interlayers that may be filled with nonreactive hydrated Fe oxides resulting from the organic cation treatment. The exchangeable Fe content of the organic treated clays, as determined by AAS and ICP measurements, was observed to be higher than expected relative to that of Fe-saturated clay, substantiating this hypothesis. These findings have implications for the development of substrate-specific clay catalysts, where the composition and configuration of exchangeable cations can be matched to a particular substrate or reaction. © 2010 American Chemical Society.
Foley P.M.,Center for Green Chemistry |
Phimphachanh A.,Lycee Pierre Gilles de Gennes Ecole Nationale de Chimie |
Beach E.S.,Center for Green Chemistry |
Zimmerman J.B.,Center for Green Chemistry |
Anastas P.T.,Center for Green Chemistry
Green Chemistry | Year: 2011
Carbohydrate-based surfactants have long been of interest due to their desirable performance properties and their potential to be derived from renewable feedstocks. Although most carbohydrate based surfactants utilize an O-glycosidic linkage, recent advances in carbohydrate C-C bond formation allows for the facile synthesis of new classes of carbohydrate-based surfactants on a C-glycosidic linkage. Herein is described an approach that can generate a wide variety of C-glycoside surfactants in moderate to very good yield by treating the nonulose C-glycoside intermediate first described by Lubineau et al. with pyrrolidine in the presence of an alkyl aldehyde. Depending on the stoichiometry and reaction conditions, this chemistry will result in either a linear enone C-glycoside, or a cyclohexenone C-glycoside, both of which demonstrate interesting surfactant properties. Further, the linear enone series can be photochemically modified or reacted with other alkyl aldehydes to generate additional analogs. © 2011 The Royal Society of Chemistry.
Zeng A.X.,Center for Green Chemistry |
Chin S.-T.,Center for Green Chemistry |
Marriott P.J.,Center for Green Chemistry
Journal of Separation Science | Year: 2013
Fatty acid methyl ester (FAME) profiling in complex fish oil and milk fat samples was studied using integrated comprehensive 2D GC (GC × GC) and multidimensional GC (MDGC). Using GC × GC, FAME compounds - cis- and trans-isomers, and essential fatty acid isomers - ranging from C18 to C22 in fish oil and C18 in milk fat were clearly displayed in contour plot format according to structural properties and patterns, further identified based on authentic standards. Incompletely resolved regions were subjected to MDGC, with Cn (n = 18, 20) zones transferred to a 2D column. Elution behavior of C18 FAME on various 2D column phases (ionic liquids IL111, IL100, IL76, and modified PEG) was evaluated. Individual isolated Cn zones demonstrated about four-fold increased peak capacities. The IL100 provided superior separation, good peak shape, and utilization of elution space. For milk fat-derived FAME, the 2D chromatogram revealed at least three peaks corresponding to C18:1, more than six peaks for cis/trans-C18:2 isomers, and two peaks for C18:3. More than 17 peaks were obtained for the C20 region of fish oil-derived FAMEs using MDGC, compared with ten peaks using GC × GC. The MDGC strategy is useful for improved FAME isomer separation and confirmation. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.