High-Pressure 19F NMR Measurements of a Series of Fluorinated Benzenes in Supercritical Carbon Dioxide

The high-pressure and high-resolution NMR cell method has been developed for precise measurements of supercritical carbon dioxide solutions. ¹⁹F NMR chemical shifts of a series of fluorinated benzenes, C₆H _n F _m (n = 6 ? m and m = 1 ～ 6) in CO₂ at dilute concentrations were measured over a wide pressure range up to 35 MPa at 314.3 K. The density dependence of the corrected chemical shift, where the bulk magnetic susceptibility contribution was subtracted, was well represented by a cubic function of CO₂ density for any fluorinated benzene. The linear coefficients, arising from pairwise intermolecular interactions, were found to be dependent on the numbers and positions of fluorine atoms in the fluorinated benzenes. The solute–solvent interaction between fluorine and CO₂ was discussed.     

Generation of bis(pentafluorophenyl)borane-dimethyl sulfide complex as a solution of hexane and its application to hydroboration of alk-1-yne with pinacolborane

A solution of bis(pentafluorophenyl)borane-dimethyl sulfide complex in hexane was generated by redistribution between tris(pentafluorophenyl)borane and borane-dimethyl sulfide complex. In the resulting solution a stoichiometric hydroboration of alk-1-yne with pinacolborane proceeded well at room temperature to afford (E)-alk-1-enylboronic acid pinacol ester in high yield. Bis(pentafluorophenyl)borane-dimethyl sulfide complex served as a mediator for the hydroboration.     

Intermolecular hydrophosphination of alkynes and related carbon[bond]carbon multiple bonds catalyzed by organoytterbiums

Intermolecular hydrophosphination of alkynes with diphenylphosphine is catalyzed by a Yb[bond]imine complex, [Yb(eta(2)-Ph(2)CNPh)(hmpa)(3)], to give alkenylphosphines and phosphine oxides after oxidative workup in good yields under mild conditions. This reaction is also applicable to various carbon[bond]carbon multiple bonds such as conjugated diynes and dienes, allenes, and styrene derivatives. Regio- and stereoselectivity and the scope and limitation of the present reaction clearly differ from those of the corresponding radical reaction. Instead, the reaction takes place through insertion of alkynes to a Yb[bond]PPh(2) species, followed by protonation. In fact, the Yb[bond]phosphido complex, [Yb(PPh(2))(2)(hmpa)(3)], is obtained from the imine complex and phosphine, which exhibits similar catalyst activity for the hydrophosphination. The empirical rate law is nu = k[catalyst](2) [alkyne](1)[phosphine](0) at least under the standard conditions.     

Microscopic inhomogeneities in weakly-charged temperature sensitive polymer gels and solutions

A comparison of small-angle neutron scattering (SANS) intensity functions, I(q), was made between gels and solutions of poly(N-isopropyl acrylamide-co-acrylic acid) (NIPA/AAc), where q is the magnitude of the scattering vector. I(q)'s were strongly dependent on polymer concentration as well as temperature. At low temperatures, I(q)'s for both gels and solutions were similar to each other and were monotonous decreasing functions. However, at high temperatures above θ, the so-called theta temperature of poly-NIPA in aqueous solution, both had a distinct peak and a significant difference appeared in I(q) due to the presence or absence of crosslinks. Origins of the peak and the differences in I(q) are discussed.     

The Complexing Abilities of Diethyleneoxy-and Xylene-bridged Cryptophanes with Alkanes

Abstract

The Syn isomers (3b and 4b) of xylene-bridged cryptophane showed selective complexing abilities for 2,2-dimethylbutane, 3-methylpentane, 3,3-di-methylpentane and 3-ethylpentane among the investigated alkanes, although the Anti isomers (3a,4a,5a) did not complex with these alkanes. However, both the Anti-and Syn-isomers (2a and 2b) of the diethyleneoxy-bridged cryptophane showed selective complexing abilities for 2,2-dimethylbutane, 3,3-dimethylpentane, 2,2,3-trimethylbutane and 2,2,3,3-terramethybutane among the investigated alkanes.     

Interaction study of acetylcholinestrase inhibitors on pharmacokinetics of memantine in rat plasma by HPLC‐fluorescence method

The present study aims to investigate the possibility of interaction of donepezil (DP) and galantamine (GAL) as acetylcholinestrase inhibitors, on memantine (MT) hydrochloride in rat plasma by HPLC‐fluorescence detection. The separation of MT was achieved within 12 min without interference of DP and GAL on the chromatogram. MT levels in rat plasma with a single administration of MT (2.5 mg/kg, i.p.) and those with a co‐administration of DP (5.0 mg/kg, i.p.) and GAL (3 mg/kg, i.p.) were monitored. MT concentrations determined in rat plasma ranged from 10.0 to 245.6 ng/mL. Significant difference was observed in the behavior of MT with a co‐administration of DP, while no significant difference was observed with a co‐administration of GAL. Copyright © 2013 John Wiley & Sons, Ltd.     

Numerical verifications of solutions for elliptic equations in nonconvex polygonal domains

Summary In this paper, methods for numerical verifications of solutions for elliptic equations in nonconvex polygonal domains are studied. In order to verify solutions using computer, it is necessary to determine some constants which appear in a priori error estimations. We propose some methods for determination of these constants. In numerical examples, calculating these constants for anL-shaped domain, we verify the solution of a nonlinear elliptic equation.     

Novel frequency dependence of dielectric biaxiality of surface stabilized ferroelectric liquid crystals

The frequency dependence of the dielectric biaxiality of surface stabilized ferroelectric liquid crystals (SSFLCs) was studied. The principal values of the dielectric tensor ε₁, ε₂ and ε₃ were measured by the MOM (molecular orientational model) method. Three dielectric permittivities were measured for each of two samples. These were the permittivity of the homeotropic cell and the permittivity of the planar homogeneous cell with and without the DC bias. Then the dielectric tensor components were calculated based on the molecular orientational models. We present the theory and experimental procedure of the MOM method. Measurements have been performed on Merck FLC compound SCE-8. The following novel dielectric behaviour was observed, as the DC bias voltage was increased the dielectric permittivity of the planar homogeneous cell decreased at the low frequencies (∼ 1 kHz) while increased at the high frequencies (10kHz ∼). The sign of the dielectric biaxiality ∂εε (= ε₂ - ε₁) inverted around 1 kHz, being negative at low frequencies and positive at high frequencies. The roles of the biaxiality on the dielectric behaviour of SSFLC cells are discussed.