Catalytic oxidation of olefins and alcohols with hydrogen peroxide in a two-phase system giving mono- and dicarboxylic acids

The present study considered the influence of various factors on the catalytic activity of systems based on a combination of tetrakis(oxodiperoxotungsto)phosphate(3−) with quaternary ammonium cations, for example, with methyltri-n-octylammonium [Me(n-C₈H₁₇)₃N]⁺. The catalysts were tested in oxidation of cycloolefins (cyclohexene and cyclooctene), alcohols (octan-1-ol and phenylmethanol), and unsaturated fatty acids (cis-9-octadecenoic and 12-hydroxy-9Z-octadecenoic acids) with a 30% hydrogen peroxide solution. These reactions proceed under mild conditions (atmospheric pressure, 80–90 °C) to give carboxylic acids. The catalytic systems were characterized by vibrational (IR and Raman) spectroscopy. The state of the systems formed from various precursors, viz., polyoxometallates and phase-transfer catalysts, was studied. It was demonstrated for the first time that the structure formation of peroxo complexes depends on the nature of the halide anion of the quaternary ammonium salt used. The melting points of individual catalytic complexes were determined. The optimal conditions for oxidation were found. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1794–1801, August, 2005.     

Thermal decomposition of alkali metal perchlorates

The effect of past mechanical history on the subsequent thermal decomposition kinetics of sodium, potassium, rubidium and caesium perchlorates, has been investigated. At low temperatures the decomposition of all these salts is significantly sensitized by pre-compression. At high temperatures, however, prior compression results in a lowered decomposition rate in the case of potassium, rubidium and caesium perchlorates and in an increase in the thermal reactivity of sodium perchlorate. The high temperature behaviour is shown to be an indirect consequence of the low temperature behaviour. The difference in behaviour between sodium perchlorate and the other alkali metal perchlorates is explained on the basis of the stability of the respective chlorates, formed during the low temperature decomposition. This is substantiated by experiments which show that the addition of sodium chlorate to sodium perchlorate brings about a sensitization while potassium perchlorate admixed with potassium chlorate results in a desensitization at high temperatures.     

Anomalous1H NMR spectra of 3,4-dihydroisoquinolines and related compounds

Solutions of 3,4-dihydro-6,7-methylenedioxyisoquinoline (1) and analogues2–5 and9 as well as isoquinolines7 and8 in certain samples of CDCl₃, CCl₄, DMSO-d₆ or acetone-d₆ gave rise to anomalous¹Hnmr spectra with extreme line broadening, signals due to protons at C-l and C-3 most often not being seen. The spectra of1 and3 were most striking in this respect.¹Hnmr spectra of the quaternary salt10 and the model schiff base11 were normal. Several hypotheses for the observed line broadening have been considered and rejected, a slow equilibrium1 ⇆13 being one of them. NaBH₄ reduction of1 and2 followed by mass spectrometric analysis of the crude tetrahydroisoquinolines16 and17 ruled out a slow equilibrium1 ⇆14 and2 ⇆15 as contributory cause for line broadening. The crude reduction products unexpectedly contained N-ethyl species22 and25. Their formation is rationalised     

New synthesis of cis-3,4-diaryl-1-tosylpyrrolidines

Unsymmetrically substituted cis-3,4-diarylpyrrolidines are synthesized in nearly 25% overall yields starting from 4-aryl-1,2,5,6-tetrahydropyridines by iterative reactions using the combination of m-chloroperoxybenzoic acid (MCPBA) and boron trifluoride etherate (BF₃·OEt₂) followed by Grignard addition, elimination and hydrogenation sequence.     

由付里叶分析到小波分析的进展

本文通过对付里叶分析和小波分析的详细比较 ,展示小波分析的特点和优越性 ,有助于深化对小波分析的认识和理解     

DTA studies on the thermal oxidation and crosslinking reactions of carboxyl-terminated polybutadiene

Studies on the thermal oxidation of carboxyl-terminated polybutadiene in the presence of antioxidants have been carried out by dynamic DTA. Bis-thioacetylacetonato nickel(II) compounds are found to be effective in inhibiting the air oxidation reaction in the polymer. The crosslinking reaction of the polymer through the double bonds present in the polymer molecule is desensitized by the antioxidants and the effect is more with N-phenyl-1-naphthylamine. An exothermic peak formed at 270°C in the presence of tris(2-methylaziridinyl-1) phosphine oxide has been identified as the curing reaction. The infrared spectra of CTPB in the presence of MAPO at various temperatures confirm the various stages of reaction.     

Peak effect in surface resistance at microwave frequencies in Dy-123 thin films

A pronounced peak in the microwave (at frequency 9.55 GHz) surface resistance, R _s vs. T plot (where T is the temperature) has been observed in epitaxial DyBa₂Cu₃O_7−y superconducting thin films in magnetic fields (parallel to c-axis) in the range 2 to 8 kOe, and temperatures close to the superconducting transition temperature T _c(H). Our data suggest that the nature of peaks observed in the two films is different, thereby indicating different defect structures in the films.     

Thermal Decomposition of hydrazinium monoperchlorate in the solid state

Hydrazinium monoperchlorate (HP-1) has been shown to decompose thermally in the solid state according to the chemical equation:

The activation energy for the evolution of HCl as determined mass spectrometrically is 8.05 kcal mol^?1 in the temperature range of 80 to 120°C. The rate of decomposition is seen to be altered by doping HP-1 with small concentrations of SO^2?₄, Ca²⁺ and Al³⁺.     

On properties of sets related to f-projections

Given a continuous sub-linear function f on a Hausdorff locally convex space X and a closed subset K of X, we define here the associated f-projection P_f supported on K. The relationships between various continuity and other properties of P_f with the structure of the underlying set K are discussed here.