Amphiphilic copolymers of sucrose methacrylate and acrylic monomers: Bio-based materials from renewable resource

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Regioselective sucrose 1'-O-methacrylate obtained by transesterification catalyzed by Proteinase-N was copolymerized with hydrophilic N-isopropylacrylamide and hydrophobic methyl methacrylate in different molar ratios by free radical polymerization. The copolymers were characterized by C-13 nuclear magnetic resonance spectroscopy, gel permeation chromatography, differential scanning calorimetry and thermogravimetry. Solubility and phase behavior of aqueous solutions were also investigated. The glass transition of the copolymers presents a positive deviation from the values of the homopolymers due to the high density of inter and intramolecular hydrogen bonding. Their solubility is strongly dependent on the composition. Copolymers poor in methyl methacrylate are water soluble, while copolymers richer in methyl methacrylate behaves as hydrogel. These hydrogels are not chemically crosslinked and their form can be design prior swelling by the conventional processing methods, such as solvent casting and extrusion for instance. Copolymers of N-isopropylacrylamide are water soluble and their aqueous solutions present a lower critical solution temperature behavior forming thermoreversible hydrogels. (C) 2013 Elsevier Ltd. All rights reserved.941317322Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CNPq [132288/2009-5]FAPESP [2010/02098-0, 2010/17804-7

Homogeneously catalyzed epoxidation of alpha,beta-unsaturated ketones using simple aluminum salts and aqueous H2O2-Is it possible?

Simple aluminum salts activate hydrogen peroxide towards alpha,beta-unsaturated ketones, affording as major products alpha,beta-epoxyketones. The pathway of this reaction involves the interaction between [Al(H2O)(6)](3+) and H2O2, through hydrogen bonds, in the second-coordination sphere. This interaction enhances the proton exchange between non-coordinated water and hydrogen peroxide. as detected by H-1 NMR experiments. By this means, the hydroperoxide anion, formed as reactive intermediate in the proton exchange between H2O and H2O2, can be trapped by alpha,beta-unsaturated ketones. Surprisingly, this pathway is not followed when diethylmaleate is used as substrate. In this case, the radical addition of THF to the C=C bond of diethylmaleate takes place with high selectivity, affording 2-(THF)-derivatives with high yields. (C) 2009 Elsevier B.V. All rights reserved.3074167118Fonds der Chemischen Industri