Synthesis of AgWCNx Nanocomposites for the One-Step Conversion of Cyclohexene to Adipic Acid and Its Mechanistic Studies.

A novel catalyst composed of silver nanoparticles grafted on WCNx has been prepared by using a facile pH-adjusted method. The material reported in this study presents a non-mineral acid route for the synthesis of the industrially significant monomer adipic acid through the selective oxidation of cyclohexene. Ag has been stabilized in the hydrophobic matrix during the formation of the mesoporous silica material by using aniline as stabilizing agent. A cyclohexene conversion of 92.2 % with 96.2 % selectivity for adipic acid was observed with the AgWCNx -2 catalyst, therefore, the AgWCNx catalyst was found to be efficient for the direct conversion to adipic acid with respect to their monometallic counterparts. The energy profile diagrams for each reaction path by using the AgWCNx catalyst were studied along with their monometallic counterparts by using the Gaussian 09 package. The reported material can avoid the use of harmful phase-transfer catalysts (PTC) and/or chlorinated additives, which are two among other benefits of the reported work.

Ionic-Liquid-Functionalized Copper Oxide Nanorods for Photocatalytic Splitting of Water.

Thin films of imidazolium (Im) ionic liquids with bis(salicylato)borate (BScB) and hexafluorophosphate (PF6 - ) anions were grafted onto copper oxide (CuO) nanorods. Chemical and structural features of ionic-liquid-functionalized CuO (CuO-IL) nanorods were examined by X-ray photoelectron spectroscopy, FTIR spectroscopy, XRD, and high-resolution TEM analyses. The CuO-IL nanorods were demonstrated to be efficient photocatalysts for the splitting of water under visible-light irradiation without using any sacrificial agent. The pristine CuO nanorods could not split water, whereas CuO-IL nanorods exhibited excellent photocatalytic activities and produced 1827 and 1082 µmol of hydrogen in 2 h with 20 mg of CuO-ImBScB and CuO-ImPF6 as photocatalysts, respectively. The photocatalytic activity of the CuO-IL nanorods was attributed to the synergistic effect of ionic-liquid thin films and CuO nanorods. The trapping of photoinduced charge carriers by ionic liquids inhibits the recombination process, and consequently, the CuO nanorods facilitate the water-splitting reaction. The CuO-IL photocatalysts were efficiently recycled without loss of catalytic activity, which revealed the stability of the ionic-liquid thin films grafted on the CuO nanorods.

Dual catalysis with magnetic chitosan: direct synthesis of cyclic carbonates from olefins with carbon dioxide using isobutyraldehyde as the sacrificial reductant.

Chitosan coated magnetic nanoparticles were synthesized and used as a support for the immobilization of the cobalt(II) acetylacetonate complex [Co(acac)2] and quaternary triphenylphosphonium bromide [P(+)Ph3Br(-)] targeting -NH2 and -OH moieties located on the surface of chitosan. The synthesized material was used as a catalyst for one pot direct synthesis of cyclic carbonates from olefins via an oxidative carboxylation approach with carbon dioxide using isobutyraldehyde as the sacrificial reductant and molecular oxygen as the oxidant. After the reaction, the catalyst was recovered by applying an external magnet and reused for several runs without significant loss in catalytic activity and no leaching was observed during this course.