A high performance oxidation method for secondary alcohols by inductive activation of TEMPO in combination with pyridine-bromine complexes

A new TEMPO-mediated catalytic oxidation method in combination with Py·HBr₃ (stoichiometric) is developed for oxidation of secondary alcohols to the corresponding ketones. The performance of this oxidizing system is better compared with that of TEMPO method combined with R₄NBr₃. Poly(4-vinylpyridine)·HBr₃ can be used in place of Py·HBr₃. The electron-withdrawing substituent at the C-4 position of TEMPO increases the reactivity of TEMPO significantly in the oxidation of electron-deficient alcohols such as polyhaloalkylmethanols. Inductive effect of the substituent of TEMPO is discussed through the characterization of the redox potential of N-O radical by cyclic voltammetry.     

Resonant Brillouin scattering by mode converted TA phonons in CdS

Resonant Brillouin scattering in CdS by piezoelectrically inactive TA phonons has been studied at room temperature in the region of photon energies very close to the fundamental absorption edge. The results have shown that the scattering efficiency depends strongly on the damping in the excited electronic states.     

7-Oxo-2-thia-1-azabicyclo[3.2.0]hept-3-ene,a revised structure for penems synthesized via oxidative addition mediated by copper(I)

The structure for the fused β-lactam obtained by treatment of the secolactam $\text{3}$ with base in the presence of Cu(I)-ion is not the penem $\text{1}$(R=CH₃), but the isopenem $\text{4}$ on the basis of X-ray analysis.     

Determination of 134Cs activity with the sum-peak method using a well-type germanium detector

Journal of Radioanalytical and Nuclear Chemistry - The new sum peak method was applied to the samples containing both 137Cs and 134Cs using a well-type HPGe detector. The standard sources...     

Synthesis of 1,2-bis(4-aminocyclohexyl)ethane and its polyamides

The synthetic route to 1,2-bis(4-aminocyclohexyl)ethane from toluene via p-nitrotoluene and p,p′-dinitrodibenzyl was established. The distribution of geometric isomers was estimated by NMR and fractional recrystallization. Polyamides were synthesized from 1,2-bis(4-aminocyclohexyl)ethane and dodecanedioic or sebacic acid. Polymer melting temperatures were varied with isomer compositions. A high content of the trans conformation causes high melting temperatures. Glass transition temperatures of polyamides were in the range of 105–120°C and were less sensitive to isomer compositions.     

Autothermal reforming of biogas over a monolithic catalyst

This study focused on measurement of the autothermal reforming of biogas over a Ni based monolithic catalyst. The effects of the steam/CH₄ (S/C) ratio, O₂/CH₄ (O₂/C) ratio and temperature were investigated. The CH₄ conversions were higher under all examined temperatures than the equilibrium conversion calculated using the blank outlet temperature, because the catalyst layer was heated by the exothermic catalytic partial oxidation reaction. The CH₄ conversion increased with increasing O₂/C ratio. Moreover, the CH₄ conversion was higher than the equilibrium conversion calculated using the blank outlet temperature for O₂/C>0.42 and reached about 100% at O₂/C=0.55. However, the hydrogen concentration decreased for O₂/C>0.45 because hydrogen was combusted to steam in the presence of excess oxygen. On the other hand, the hydrogen and CO₂ concentrations increased and the CO concentration decreased with increasing S/C ratio. As a result, it was found that the highest hydrogen concentrations and CH₄ conversions were attained at the O₂/C ratios of 0.45-0.55 and the S/C ratios of 1.5-2.5. Moreover, the H₂/CO ratio could also be controlled in the range from about 2 to 3.5 to give at least 90% CH₄ conversion, by regulating the O₂/C or S/C ratios.     

The synthesis of new azoniathiahelicenes

Synthesis of new azonia derivatives of thia[6]helicene ( 1 ) and thia[7]helicene ( 2 ) is described. The Knoevenagel condensation of 2‐methylbenzothieno[3,2‐a]quinolizinium salt ( 8 ) with appropriate arylaldehydes yielded 2‐(arylvinyl)benzothieno[3,2‐a]quinolizinium salts ( 9 and 10 ), respectively. Photocyclization of 2‐styrylbenzothieno[3,2‐a]quinolizinium salt ( 8 ) gave 7a‐azonia‐5‐thia[6]helicene ( 1 ) in 63% yield. Similarly, 2‐[2‐(2‐naphthyl)vinyl]benzothieno[3,2‐a]quinolizinium salt ( 10 ) afforded 7a‐azonia‐5‐thia[7]helicene ( 2 ) in 56% yield. The complete and unambiguous assignment of their ¹H‐ and ¹³C‐nmr spectra was performed by utilizing two‐dimensional nmr spectroscopic methods.     

Effect of oxidation dynamics on the film characteristics of Ce:YIG thin films deposited by pulsed-laser deposition

Thin films with different compositions of Ce-substituted yttrium iron garnet (Ce:YIG (Y₂CeFe₅O₁₂)), Ga-doped Ce:YIG (Ce:Ga:YIG (Y₂CeFe_4.25Ga_0.75O₁₂)), and Gd-doped Ce:YIG (Ce:Gd:YIG (Y_1.6CeGd_0.4Fe₅O₁₂)) were deposited on gadolinium gallium garnet (GGG (Gd₃Ga₅O₁₂)) substrates in O₂ or Ar background gas by pulsed-laser deposition (PLD) technique. Crystalline films were obtained at a lower O₂ gas pressure of 20 mTorr or at higher Ar gas pressures of more than 100 mTorr. In addition, the behavior of YO molecules was visualized by two-dimensional laser-induced fluorescence (2D-LIF), in order to investigate the oxidation dynamics in the ablation plume. The oxidation dynamics and the crystallinity had close correlation.     

Quinolizinium hexafluorophosphate

The crystal structure of the title compound, C₉H₈N⁺·PF₆⁻, was measured at 145 K. The cationic part of the compound has crystallographically imposed 2/m symmetry with N/C disorder.