Hydroquinone oxidation catalyzed by pyridine–Cu(II) complexes attached to polyorganosiloxane. II. Elucidation of factors related to catalytic activity

The oxidation of hydroquinone catalyzed by pyridine-Cu(II) complexes attached to polyorganosiloxane was investigated in the mixed solvent of methanol/water (vol. ratio 2/1). The catalytic oxidation followed Michaelis-Menten-like kinetics. The large k₂ term related to a turnover number indicated that the present polymeric catalysts have a remarkable effect on the activation process. The methylene number between the side-chain acid amido and pyridyl groups of the polymeric ligand was shown to be closely related to the appearance of hydrophobic effects in both the substrate-binding and the activation processes as deduced from the Michaelis constant and the thermodynamic and activation parameters. The binding parameters for 4-methoxyphenol with pyridyl-functionalized polyorganosiloxanes supported that the flexible backbone is also effective in the oxidation of hydroquinone. The Cu(II) complexes with pyridyl-functionalized polyorganosiloxane would have the structures distorted from square planar formation, which would promote the reduction of Cu(II) to Cu(I), as concluded from ESR spectroscopy and electrochemical measurement. © 1994 John Wiley & Sons, Inc.     

Thermal and photochemical reactions of a stable thiobenzaldehyde, 2,4,6-tri-t-butylthiobenzaldehyde

Thermal and photochemical reactions of the title compound gave benzothiolane $\text{2}$ in high yield; the reaction with free radicals also afforded $\text{2}$ along with some other products.     

Proton decay

The lifetimes and branching ratios of the proton and bound neutron are calculated in the SO(10) grand unified theory by taking into account the form factor effect (by making use of SU(6) symmetric wave functions for the nucleons and mesons) and the generation mixing, based on the assumption that the ΔB = ? 1 decay interaction is generated by the exchange of superheavy leptoquark gauge bosons, D (X and Y) and E (X' and Y'). In our approach there is a free parameter M_D/M_E, which should be determined by experiment. The branching ratio of the inclusive decay of an I = 0 nucleus into neutrinos and anything is found to be most dependent on the ratio M_D/M_E. The nucleon lifetime is τ_N = [M_D (GeV)/5 × 10¹⁴]⁴ × (0.0015,2.5,4.6) × (1_?0.4⁺²) × 10³⁰ year, for M_D/M_E = (10,1,0.1). Only the cases in which M_DapM_E are found to be possible for Λ_ms[? 0.26 GeV and τ_N ? 5 × 10³⁰ year if there is not a fourth generation of light fermions, technicolored particles nor supersymmetric particles.     

High frequency titrations involving chelation with ethylenediaminetetraacetic acid: Complexation of thorium nitrate

High frequency titrations have confirmed the reacting ratio of thorium to ethylenediaminetctraacetic acid to be l to 1. It has also been shown that thorium can be determined by oscillometric titration using either the hydrogen release method or the direct titration technique. The method is especially interesting for the determination of small amounts of thorium in dilute solution.     

Sedimentation transport method for determination of molecular weight distributions

The sedimentation of the system polystyrene-cyclohexane at the Flory temperature has been studied with emphasis on the effects of pressure as well as concentration. The relation between the molecular weight M and the limiting sedimentation coefficient s₀⁰, is found to be s₀⁰ = 1.50 × 10^?15 M^1/2 (sec.) The concentration dependence parameter k_s has the form, k_s = k′M^1/2 = k″s₀⁰ with k′ = 4.5–5.5 × 10^?4. However, a rather unexpected dependence of k_s on the rotor speed is also found. A procedure is proposed for deducing solute molecular weight distributions from boundary spreading data in sedimentation transport experiments, a so-called “single concentration” method, requiring only one sedimentation run. Application to several polystyrenes (in cyclohexane at 35°C) with narrow, broad, and very broad distributions demonstrates the feasibility of the procedure. Comparisons are made with data from elution chromatography and gel permeation chromatography. The GPC method predicts somewhat broader distributions than those obtained by the other two methods.     

A resistance minimum and the electronic structures of some one-dimensional Pt-complexes at high pressures

The effect of pressure has been measured up to 650 kbar on the electrical resistance in six one-dimensional Pt-complexes, including two mixed valence ones. SrPt(CN)₄·2H₂O, MgPt(CN)₄·7H₂O and BaPt(CN)₄·4H₂O do not show a resistance minimum, contrary to other d⁸-metal complexes, suggesting a considerable contribution of π¹ orbitals of CN^- ligands to the conduction.     

Remarks on the theory of diffusion in electrolyte solutions

The assumptions usually made that the ionic atmosphere has spherical symmetry in the diffusion of binary electrolytes and that the electrophoretic effect is negligible in the tracer diffusion of ions are pointed out to be incorrect when terms up to order κ² ln κ (κ is the Debye-Hückel parameter) are considered.