Direct Henry reactions with modified calcium oxide as solid catalyst

Commercial CaO was modified simply with benzyl bromide. The modified CaO had good water resistance, and characterization by FTIR and TG revealed the modifier was chemically bonded to the CaO surface. Commercial CaO and CaO modified with benzyl bromide were investigated as catalysts for the Henry reaction between benzaldehyde and nitromethane. It was found that the catalytic activity of the modified CaO was greatly improved, with high conversion of benzaldehyde to the (E)-phenyl nitroolefin and 1-phenyl-2-nitroethanol, and with different selectivity from commercial CaO. The effect of modification and reaction conditions on yield, selectivity, and mechanism were studied thoroughly.     

Dynamics of shock induced ignition in Fickett’s model: Influence of χ

Using Fickett’s model for reactive compressible flows, i.e., the reactive form of Burgers’ equation, we address the problem of shock induced ignition by a piston in a reactive medium characterized by a 2 step induction-reaction kinetics. Owing to the model’s simplicity, the ignition and acceleration mechanism is explained using the two families of characteristics admitted by the model. The energy release along the particle paths provides the amplification of forward-traveling pressure waves. These waves pre-compress the medium in the induction layer ahead of the reaction zone, therefore changing the induction delays of successive particles. The variation of the induction delay provides the modulation of the amplification of the forward traveling pressure waves by controlling the residence time of the pressure waves in the reaction zone. A closed form analytical solution is obtained by the method of characteristics and high activation energy asymptotics. The acceleration of the reaction zone was found to be proportional to the product of the activation energy, the ratio of the induction to reaction time and the heat release. This finding provides a theoretical justification for the previous use of this non-dimensional number to characterize the ignition regimes observed experimentally in detonations and shock induced ignition phenomena. Numerical simulations are presented and analyzed. Both subsonic and supersonic internal flame propagation are observed, consistent with experiment and previous reactive Euler models.     

New reactivities of deltaline analogs: an efficient O-demethylation at C-1 and an unusual extrusion of the C-14 atom

O-Demethylation at C-1 in the C₁₉-diterpenoid alkaloids is very challenging. In this paper, it was firstly observed that 10-OH group in deltaline (1) is a determining factor for the O-demethylation reaction. After removal of this hydroxyl group, 1-O-methyl group in the corresponding deltaline analogs can be readily removed by treatment with HBr–HOAc. Meanwhile, the C-14 atom in bromides 18 or 20 can be extruded under basic condition probably via a sequence, including Grob fragmentation, aerobic oxidation, deformylation, and S_N2 nucleophilic substitution, to give enone 21 (70%) and oxetane 22 (14%). The structure of compound 22 was confirmed by X-ray crystallographic analysis of its derivative 21.     

Solutions of the Schr?dinger equation in the tridiagonal representation with the noncentral electric dipole plus a novel angle-dependent component

A noncentral ring-shaped potential is proposed in which the noncentral electric dipole and a novel angle-dependent component are included, the radial part is selected as the Coulomb potential or the harmonic oscillator potential. The exact solution of the Schr?dinger equation with this potential is investigated by working in a complete square integrable basis that supports a tridiagonal matrix representation of the wave operator. The resulting three-term recursion relation for the expansion coefficients of the wavefunctions (both angular and radial) are presented. The angular/radial wavefunction is written in terms of the Jacobi/Laguerre polynomials. The discrete spectrum of the bound states is obtained by diagonalization of the radial recursion relation.     

Organophosphine/phosphite‐stabilized silver(I) complexes bearing N‐acetylbenzamide ligand: synthesis,characterization and potential application in metal organic chemical vapor deposition

New N‐silver(I) acetylbenzamide complexes of type L_n?AgNC₉H₈O₂ (L = PPh₃; n = 1, 2a; n = 2, 2b; n = 3, 2c; L = P(OEt)₃; n = 1, 2d; n = 2, 2e; n = 3, 2f) were prepared. These complexes were obtained in high yields and characterized by elemental analysis, ¹H NMR, ¹³C{H} NMR, ³¹P{H} NMR and IR spectroscopy, respectively. The molecular structure of 2b has been determined by X‐ray single‐crystal analysis in which the silver atom is in a distorted tetrahedral geometry and crystallizes as cis–trans. New N‐silver(I) acetylbenzamide complexes have a four‐membered ring, which could influence their chemical and physical properties and modulate volatility. Metal organic chemical vapor deposition experiments were carried out successfully at 400°C and 450°C using 2e as precursor for the deposition of silver films, respectively. The high‐purity silver film obtained at 400°C is dense and homogeneous. Copyright © 2012 John Wiley & Sons, Ltd.     

Growth of apatite on chitosan-multiwall carbon nanotube composite membranes

Bioactive membranes for guided tissue regeneration would be of value for periodontal therapy. Chitosan-multiwall carbon nanotube (CS-MWNT) composites were treated to deposit nanoscopic apatite for MWNT proportions of 0-4 mass%. Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction were used for characterization. Apatite was formed on the CS-MWNT composites at low MWNT concentrations, but the dispersion of the MWNT affects the crystallite size and the Ca/P molar ratio of the composite. The smallest crystallite size was 9 nm at 1 mass% MWNT.