Photocatalytic efficiency of nanocrystalline zeolite TS-1 for the degradation of methyl orange

The photocatalytic properties of nanocrystalline TS-1 were confirmed via the degradation of an aqueous solution of the model compound methyl orange (MO). The light intensity and quantum yield were measured by ferrioxalate actinometry and the values are 1.7 × 10⁻⁵ einstein l⁻¹ s⁻¹ and 0.71, respectively. The experimental parameters such as catalyst loading, pH and initial concentration of MO were optimized at 1.5 g/L, 10 and 300 μM, in order. The results showed that the dye molecules are completely degraded to CO₂, H₂O and simple inorganic ions.     

Sequential one-pot InBr(3)-catalyzed 1,4- then 1,2-nucleophilic addition to enones

Low sensitivity toward traces of moisture and high tolerance of different functional groups make indium tribromide suitable for carrying out multistep synthetic sequences. In particular, we have realized a 1,4-conjugated addition of indoles/thiols to alpha,beta-unsaturated ketones mediated by a catalytic amount (10 mol %) of InBr(3) obtaining the desired beta-substituted ketones in good yields. The Lewis acidity of indium salts was not affected by coordinating and acid nucleophiles; therefore, the subsequent catalytic 1,2-addition of Me(3)SiCN to carbonyl compounds can be performed in one pot. With the optimized atom-efficient protocol, several polyfunctionalized alpha-silyloxy cyanohydrins were synthesized in good to excellent yields (up to 97%) and a notable level of simple 1,3-diastereoselection (up to 84:16) was recorded in the case of 2-cyclohexen-1-one 2c.     

Multiphase heterogeneous catalytic enantioselective hydrogenation of acetophenone over cinchona-modified Pt/C

The multiphase heterogeneous enantioselective hydrogenation of acetophenone in the presence of cinchona-modified Pt/C was investigated. The system demonstrated the feasibility of this reaction on non-activated ketones. The reaction proceeded selectively, at room temperature and atmospheric pressure, towards the formation of 1-phenylethanol, with up to 20% ee (enantiomeric excess) of either enantiomer depending on the modifier used. A mode of action of the modifier is proposed to account for the mechanism. A comparison with other systems indicates that the investigated system likely acts by a different mechanism, and that it is quite specific for acetophenone.     

The stokes-kirchhoff relation in chemically reacting fluids

A generalized Kirchhoff-Stokes equation for the sound attenuation coefficient is derived from irreversible thermodynamics. The discrepancy between the experimental value of the absorption coefficient and the value calculated from the generalized equation is analyzed. In particular, the so-called effective bulk viscosity and the transport coefficient which links a chemical reaction to the viscous processes are emphasized. An experimental example illustrating the general situation is also given.     

Retrosynthetic reactions in mass spectrometry. Deacylation of ortho phthalamic acids under electron impact

Ortho Phthalamic acids under electron impact show a retrosynthetic reaction leading to both phthalic anhydride and amine complementary ions, the corresponding neutrals of which are the usual synthetic precursors of the original compounds. The single case of a primary amine derivative is examined, which shows the formation of [M? H₂O]^+˙ ions having the structure of the related N-substituted imide, by a process which parallels a well known thermal reaction. It also gives the species [C₈H₆NO₂]⁺ (of the same nominal mass as phthalic anhydride), the structure of which is still under study. Ionic structures are supported by collision induced mass analyzed ion kinetic energy spectra.     

Ion chemistry of α-diazoketones. 1. A collissional activation study of 1-diazo-3-phenoxypropan-2-one upon elecgtron impact

The gaseous ionic products of 1-diazo-3-phenoxypropan-2-one upon electron impact show that cyclization reactions, which have counterparts in condensed-phase chemistry, occur in competition with a mass spectral Wolff type rearrangement.     

β-Cyclodextrin and 5-Methoxytryptammonium Ion Host-Guest Association in vacuo: Simulation of Non-Covalent Inclusion by Molecular Dynamics

The structure of gaseous charged host-guest adducts ofcyclodextrins (CDs) generated by mass spectrometry (MS) still requires to be addressed correctly,as these adducts could be true inclusion complexes or non-specific proton bound heterodimers(PBHs). The present theoretical study of inclusion complex vs. PBH of 5-methoxytryptammonium ion(5-MTA⁺) with -CD in vacuo by energy minimisation and moleculardynamics proved that the most stable forms of -CD/5-MTA⁺ non-covalent associationare inclusion complexes. PBHs evolved to genuine inclusion complexes with two differenthost-guest arrangements during MD runs.     

Relationship between radial diffusion of copper ions released from a metal disk and cytotoxic effects. Comparison with results obtained using extracts

The extended use of metallic biomaterials yields to increasing sources of metal ions within the human body and may result in inflammation of the surrounding tissues, cell damage, and cancer. The aim of this study was to investigate the relationship between the radial diffusion of metal ions released from a metal disk by the corrosion process and the toxic effect on a cell line that grew around it. Results obtained with the metal disks (direct contact) were compared with assays made with extracts obtained from the dissolution of a metallic sample ex situ and then added to the cell culture to elucidate the cause of apparent inconsistencies in previous reports. The change of copper concentration due to corrosion and transient diffusion of copper ions from the copper disks into the cell line was evaluated according to Fick's 2nd law. Surviving cells distribution was interpreted considering the radial and time-dependence of copper concentration. We concluded that the toxic effect on those cells close to metallic biomaterials may be underestimated when only the extract methodology is employed for cytotoxic tests or when during the experiments with disks the presence of concentration gradients and the non-homogeneous distribution of dead cells are disregarded.