Sulfinate Esters from Methoxymethyl Sulfides

Several benzene (or phenylmethane) sulfinate esters were synthesized in 53–98% yields from the corresponding methoxymethyl (MOM) sulfides employing NBS as oxidant.     

Electron-stimulated desorption from ionic crystal surfaces

Inelastic interactions of electrons with surfaces of ionic crystals result in emission of various particles such as ions, atoms and molecules. We will review such electron-stimulated desorption processes for the particular class of ionic crystals, namely for alkali halides. In this case, a dominant fraction of the emission is in the form of halogen and alkali atoms characterized by a thermal (Maxwellian) spectrum of translational energies. For several alkali halides (potassium and rubidium chlorides, bromides, and iodides), however, a significant part of the halogen atoms is ejected with nonthermal energies, i.e. energies of the order of 0.1 eV. The results of recent systematic studies of angular-resolved kinetic energy distributions of the emitted particles will be reported and current views on the electronic mechanisms of desorption will be described. In particular, it will be shown that the ESD mechanism can be understood in terms of the model involving a surface localisation of the so called “hot-holes” created by electron bombardment of alkali halides. A role of hot holes in ESD processes will further be discussed in relation to very recent experimental results obtained for the KBr crystals doped with In impurities which act as efficient hole traps.     

Efficient One‐Pot Synthesis of a Densely Functionalized Tetrahydropyridine in the Presence of [1,1′‐Binaphthalene]‐2,2′‐diol/Indium(III) Chloride (binol/InCl3) or Simple Brønsted Acids as Catalysts

The highly functionalized tetrahydropyridine 4 was obtained in an indium(III) chloride catalyzed multi‐component reaction from benzaldehyde, 4‐methoxyaniline, and ethyl acetoacetate (=ethyl 3‐oxobutanoate) in the presence of [1,1′‐binaphthalene]‐2,2′‐diol (binol). It was found that binol played a beneficial role in this reaction, allowing a substantial decrease of the amount of indium salt. Also, simple organic Brønsted acids may serve as effective organocatalysts in this process.     

Phase transition induced improvement in H2 desorption kinetics: the case of the high-temperature form of Y(BH4)3

The high-temperature (HT) phase of Y(BH(4))(3) has been prepared by heating of the as mechanochemically synthesised low-temperature (LT) phase of Y(BH(4))(3) to 194-216 °C and subsequent rapid cooling to ambient temperature. Although the differences in the crystal structure and vibrational spectra for these closely-related polymorphs are rather small, yet the NMR MAS (1)H and CP MAS (89)Y spectra reveal clear differences in the chemical shifts for both nuclei. The thermal decomposition process of both forms differs noticeably below 260 °C, decomposition being faster and more facile for the HT phase. The activation energy for thermal decomposition, calculated according to the Kissinger equation, is nearly three times lower for the HT than for the LT polymorph for the first step of the thermal decomposition signalling giant improvement of kinetics of H(2) desorption.     

Reaction of Trimethylbenzene over Alumina-Pillared Montmorillonite

The reaction of trimethylbenzene (TMB) over alumina-pillared montmorillonite (Al-PM) had been investigated in a fixed-bed flow reactor at 300 °C and atmospheric pressure. Al-PM calcined in the range 300-500 °C exhibited decreased layer distance, surface area and acid amount. The strong acid sites of Al-PM calcined at 500 °C were greatly diminished according to measurements of ammonia temperature-programmed desorption. Under our conditions the reaction proceeded mainly via isomerization and disproportionation with little dealkylation. The conversion of reactant decreased in the order 1,2,3-TMB ≥ 1,2,4-TMB > 1,3,5-TMB and the selectivity of isomerization in the order 1,2,3-TMB > 1,3,5-TMB > 1,2,4-TMB, corresponding to the order of diminishing thermal instability. Both the catalytic activity and the selectivity ratio of disproportionation to isomerization decreased with increased calcined temperature and time-on-stream. o-Xylene content in the total xylene produced from 1,2,4-TMB or 1,2,3-TMB greatly exceeded the composition at thermodynamic equilibrium. These results arc consistent with the decrease of both the strong acid sites and the pore size of Al-PM which exhibits the restricted transition state selectivity.     

FT‐IR and Isotherm Study on Anion Adsorption onto Novel Chelating Fibers

A new chelating fiber, poly(acrylo‐amidino diethylenediamine), was synthesized based on polyacrylonitrile fibers in diethylenetriamine with the aid of AlCl₃. Complex formation with CrO₄^2– was strongly pH‐dependent, as complexes formed only in the presence of NH₃⁺ and NH₂⁺. In the medium pH region, both ionic and hydrogen bonds were formed between poly(acrylo‐amidino diethylenediamine) and the chromate ion, as was confirmed by means of FT‐IR spectroscopy.