Oxidation of cyclohexene into adipic acid in aqueous dispersions of mesoporous oxides with built-in catalytical sites

Reactant incompatibility is a common problem in organic chemistry. This study investigates the use of concentrated aqueous dispersions of mesoporous oxides to overcome incompatibility. Oxidation of cyclohexene into adipic acid using aqueous hydrogen peroxide as oxidant has been performed in a range of ordered and disordered mesoporous materials. The different mesoporous oxides have been characterised with diffraction techniques (XRD and SAXS), electron microscopy (TEM and SEM) and nitrogen adsorption isotherms (BET and BJH methods). The catalyst used in the reaction was either soluble sodium tungstate added to a reaction system based on mesoporous silica, alumina or a silica/alumina mixture; or a catalytic oxide, tungsten oxide or titania, present in the framework of the mesoporous material. Tungsten oxide, either used as the sole oxide material or as a mixed oxide with silica turned out to be very efficient and gave almost quantitative yield of adipic acid. A major advantage with having the catalyst chemically incorporated in the walls of the porous material is that it can be easily reused. The results from recycling experiments show that the catalytic activity is retained

Small-angle X-ray diffraction study of the thermotropic and lyotropic phases of five alkyl cyclic and acyclic disaccharides: Influence of the linkage between the hydrophilic and hydrophobic moieties

We present a comparative study of the thermotropic and lyotropic phases of 5 surfactants with an aliphatic chain of 12 carbon atoms and a cyclic or acyclic sugar head with different linkages between the two moieties. These linkages can concern different chemical groups or different orientations between the head and the chain. The compounds included the $\alpha$- and $\beta$-N dodecyl-D-maltosides, N-dodecylamino-1-deoxylactitol, N-dodecyl lactobionamide and N-acetyl N-dodecyl lactosylamine. The influence of the polar head (with closed- and opened-type sugars) and the linkage with the hydrocarbon chain on the phases obtained by the heating of the anhydrous compounds and after addition of water was studied by X-ray diffraction and optical microscopy. In the anhydrous state, the surfactants were either crystalline or amorphous. On heating, they went through a liquid crystal smectic phase which, in some cases, was preceded by solid-to-solid transitions. On addition of water, the sequence of phases from the micellar phase to the lamellar phase was accounted for in terms of the geometric model of Sadoc and Charvolin. However, with certain surfactants this sequence was not complete, and the domains of existence of phases were altered