Titanium dioxide functionalized silicon carbide phases as heterogeneous epoxidation catalysts.

We report silicon carbide (SiC) based epoxidation catalysts constituted of a silicon carbide core and a silica/titania (SiO/TiO) shell. The catalysts were obtained surface modification of SiC microparticles and were used as heterogeneous catalysts for the epoxidation of cyclohexene using -butyl hydroperoxide or cumyl hydroperoxide as the oxidant. Conversions up to 83% and selectivities of more than 90% were obtained.

Evaluation of the Hydrophilic/Hydrophobic Balance of 13X Zeolite by Adsorption of Water, Methanol, and Cyclohexane as Pure Vapors or as Mixtures.

Adsorption isotherms of pure vapors and vapor mixtures of water, methanol, and cyclohexane were studied using a synthesized 13X zeolite (FAU topology), by means of a DVS gravimetric vapor analyzer. These results were validated by GCMC calculations. The surface chemistry of the adsorbent was characterized by the thermodesorption of ammonia, and its textural properties were studied using nitrogen physisorption.

Influence of the Mesoporosity of Hierarchical ZSM-5 in Toluene Alkylation by Methanol.

Among the different strategies to design highly shape-selective ZSM-5 to obtain para-xylene through toluene alkylation with methanol, the introduction of mesopores to increase reactant and product diffusion has been proposed but barely studied. In this study, we prepared mesoporous ZSM-5 catalysts, named ZSM5-MT(x), from commercial ZSM-5 (Si/Al = 15), using a two-step micelle-templating procedure with octadecyltrimethylammonium bromide as a surfactant in basic medium (x = NaOH/Si). These materials were used as catalysts for the alkylation of toluene by methanol at a low contact time to avoid thermodynamic equilibrium of the xylene isomers.

Synthesis and Phase Behavior of a Platform of CO-Soluble Functional Gradient Copolymers Bearing Metal-Complexing Units.

The synthesis and characterization of a platform of novel functional fluorinated gradient copolymers soluble in liquid and supercritical CO is reported. These functional copolymers are bearing different types of complexing units (pyridine, triphenylphosphine, acetylacetate, thioacetate, and thiol) which are well-known ligands for various metals. They have been prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization in order to obtain well-defined gradient copolymers.

Hydrolytic vs. Nonhydrolytic Sol-Gel in Preparation of Mixed Oxide Silica-Alumina Catalysts for Esterification.

The development of green and sustainable materials for use as heterogeneous catalysts is a growing area of research in chemistry. In this paper, mesoporous SiO-AlO mixed oxide catalysts with different Si/Al ratios were prepared via hydrolytic (HSG) and nonhydrolytic sol-gel (NHSG) processes. The HSG route was explored in acidic and basic media, while NHSG was investigated in the presence of diisopropylether as an oxygen donor.

Insight into the Alcohol-Free Ring-Opening Polymerization of TMC Catalyzed by TBD.

We report herein a study on the alcohol-free, ring-opening polymerization of trimethylene carbonate (TMC) in THF, catalyzed by 1,5,7-triazabicyclo [4.4.0] ec-5-ene (TBD) with ratios n/n ranging between 1/20 and 1/400.

Water Extraction of Tannins from Aleppo Pine Bark and Sumac Root for the Production of Green Wood Adhesives.

The extraction of condensed tannins from Aleppo pine bark and sumac roots () was examined in near industrial conditions, using a water medium in the presence of 2% NaHCO and 0.5% NaHSO at two different temperatures (70 °C and at 100 °C). The tannins extracts were recovered in high yields (~25% of Aleppo pine and ~30% for sumac) with high phenolic contents (>75%).

May Trifluoromethylation and Polymerization of Styrene Occur from a Perfluorinated Persistent Radical (PPFR)?

The radical polymerization of styrene (St) initiated by a trifluoromethyl radical generated from a perfluorinated highly branched persistent radical (PPFR) is presented with an isolated yield above 70 %. The release of CF radical occurred from a temperature above 85 °C. Deeper H and F NMR spectroscopies of the resulting fluorinated polystyrenes (CF -PSts) evidenced the presence of both CF end-group of the PSt chain and the trifluoromethylation of the phenyl ring (in meta-position mainly).

UV-Initiated Ring Opening Polymerization of l-Lactide Using a Photobase Generator.

Photoinitiated ring-opening polymerization of l-lactide (L-LA) using a photobase generator (PBG) able to release 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) is reported.

Well-defined multiblock poly(vinylidene fluoride) and block copolymers thereof: a missing piece of the architecture puzzle.

Unprecedented synthesis of multiblock poly(vinylidene fluoride) (PVDF, up to 16 300 g mol) with narrow-dispersity blocks (Đ = 1.26) mediated by a fluorinated cyclic xanthate via reversible addition-fragmentation chain transfer (RAFT) polymerization is reported. The as-synthesized multiblock PVDF was employed as a macroRAFT agent to prepare valuable multiblock copolymers with potential applications in emerging areas.

Organosolv Lignin-Based Wood Adhesive. Influence of the Lignin Extraction Conditions on the Adhesive Performance.

Ethanol organosolv alfa grass lignins were extracted in the presence of sulfuric acid or Lewis acids (Sc(OTf)₃, FeCl₃) as catalysts and subjected to a comprehensive structural characterization by solid state C NMR, GPC, MALDI-TOF, and ASAP-MS/MS. The impact of the severity of the treatment and of the nature of the acid catalyst on the recovered lignin structure was investigated. The lignins isolated at high severity were highly recondensed and partly composed of regular structures composed of furan-like rings.

Styryllactones and acetogenins from the fruits of Goniothalamus macrocalyx.

Two new styryllactones, macrocalactone (1) and 3-deoxycardiobutanolide (2), were isolated from the fruits of Goniothalamus macrocalyx Ban (Annonaceae), together with seven known compounds including four acetogenins, annonacin (3), solamin (4), isoannonacin (5), trans-murisolinone (6), and three other compounds, 7-acetylaltholactone (7), beta-caryophyllene-8R,9R-oxide (8) and 2-(2'-hydroxytetracosanoylamino)-octadecane-1,3,4-triol (9). Their structures were determined by spectroscopic and MS analysis. The absolute configuration of 1 was determined by X-ray crystallographic analysis.