Manabu Senō

Solid-Solid Phase Transitions of Long-Chain n-Alkyltrimethylammonium Halides

Abstract Transition properties of some compounds of the type, n-C n H2n+1N+(CH3)3X-, with n = 10, 12, 14, 18, 22, and X = Cl, Br, and I, were investigated. All these compounds show a solid-solid phase transition with a large enthalpy change in the range of temperature 350 ∼ 400K. The transition behaviors were investigated by the aid of DSC, TG, X-ray, and optical microscope. The solid-solid phase transition is regarded to be caused by melting of the layer of hydrocarbon chains of the compounds, while the rigid ionic layer retains the regular arrangement. Some relationships between the physical properties and the structure of the compounds are discussed.

Treatment of ion exchange membranes to decrease divalent ion permeability

Abstract In the electrodialysis process for concentrating sea water, the addition of a small amount of the polycationic reagent Nonisold into the sea water feed results in a reduction of divalent cation permeability relative to that of monovalent cations. This is due to the formation of a reagent layer on the surface of the cation-exchange membrane. Divalent cations require greater energy to pass over the potential barrier at the reagent layer than do monovalent cations. The relationship between the height of the potential barrier and the ratio of ionic fluxes or the permselectivity coefficient is deduced on the basis of a kinetic-controlled mechanism of uptake of ions from the solution, and the height of the potential barrier is estimated from the experimental results. The difference between the potential barrier for divalent cations and that for monovalent cations may reach up to about 10 kJ/mol.

Satellites observed in N 1s x-ray photoelectron spectra of N-aryl ylides

Abstract N 1s XPS spectra of N-arylsulfilimines and N-aryliminophosphorane give multi-peak structure, which can be explained as a shake-up phenomenon involving intramolecular charge transfer. The energy separation (2.7 eV) of S,S-dimethyl-N-4-nitrophenylsulfilimine is the largest of all the ylides used in the present investigation, and the value is close to that (3.0 eV) from the ultraviolet measurement.

Properties of water in hexadecyltrimethylammonium bromidechloroform system

Abstract The properties of water in the hexadecyltrimethylammonium bromide (HTAB) chloroform reversed micellar system were investigated. In this system, two types of water are discriminated from measurements of near-infrared spectra and NMR spectra. A sharp band at 1899 nm is assigned to the water dispersed in the bulk organic phase and a broad band around about 1950 nm is assigned to that solubilized in the micellar cores. NMR spectra are split into the contributions of the two types of water. The water in micellar cores has a shorter relaxation time and a lower-field chemical shift than the water in organic phase. Further, the water in the micellar cores is divided into two types: one is strongly interacting with the polar head groups of HTAB and the other is more free but interacting with the water around the head groups of HTAB.

Effects of fluctuation on dissipative structures. II. Appearance of optically active states as dissipative structures

Two chemical systems which fall into chiral states after starting from an optically inactive state are proposed. These optically active states are realized as dissipative structures and consequently disappear when the chemical system comes close to the equilibrium state. These chemical systems involve stereospecific and autocatalytic processes. The stereospecificity is characteristic of enzymatic processes in living systems and the asymmetric syntheses which take place universally in all living systems. The idea proposed here would open a way to an explanation for asymmetric syntheses in living systems.

The concentration polarization effect in ion exchange membrane electrodialysis

Abstract We have studied the concentration polarizations in the ion exchange membrane electrodialyses including their correlative phenomena. The limiting current densities of the ion exchange membranes were measured in the systems formed with various membranes and solutions. It is stressed that the cation-exchange membranes gave lower values of limiting current densities and a lesser effect on the disturbance of the pH value of the solution than the anion exchange membranes in the NaCl solutions. This result was justified by the following experiments: The cation exchange membranes gave the regular and fast pulse currents while the anion exchange membranes gave only unceasingly generated anomalous currents in the NaCl agar-agar solutions and at the current densities which were much higher than the limiting value.

Thermiodynamic and Mesomorphic Properties of Some Phenylthiolbenzoate Derivatives

Abstract A homologous series of 4-n-alkylphenyl 4-n-alkoxythiolbenzoate and 4-nalkoxyphenyl 4-n-alkoxythiolbenzoate were synthesized and their liquid crystal transition temperatures were determined. Among 26 compounds which synthesized, 17 are enantiotropic liquid crystals and 9 are monotropic. The nematic-to-isotropic transition temperatures decrease gradually with an increasing alkyl chain length of homologous series and exhibit and odd-even effect. The thermodynamic parameters of the mesophase teansition were investigated by differential scanning calorimetry. The entropies of the nematic-to isotropic transitions show an odd-even effect, and exhibit the erratic dependence on alkyl chain length of homologous series. The nematic-to-isotropic transition entropies of each homologous series remain nearly constant, being between 1.6 and 2.9 J/mole K.

Kinetic study of ion transport facilitated by crown ethers across water—nitrobenzene interface

Abstract The thermodynamic and kinetic behaviours of alkali metal ion transfer facilitated by some crown ethers (18-crown-6, dibenzo-18-crown-6, dibenzo-24-crown-8) from water to nitrobenzene were studied by means of cyclic voltammetry and impedance measurement. The results indicate that each crown ether forms complexes with the respective alkali metal cations, of which stability constants are dependent on the sort of crown ethers and alkali metal cations. Moreover, the potential dependence of the rate constant of the facilitated ion transfer is sensitive to the stability constant in the nitrobenzene phase.

Conformational studies of basic poly (α-amino acid)s in reversed micelles

The conformation of various basic poly (α-amino acid)s was investigated by CD measurements in aqueous solutions containing bis (2-ethylhexyl)sodium sulfosuccinate (AOT) as well as in the AOT reversed micelles. The addition of AOT into an aqueous solution of poly(L-lysine) induces the conformational transition from coil to ordered structure, followed by aggregation. On the other hand, poly(L-lysine) assumesΒ-structure in the reversed micelles at low wovalue (wo=[H2O]/[AOT]). Similarly to poly(L-lysine), poly(L-ornithine) takes an ordered structure in the aqueous solution containing AOT andΒ-structure in the reversed micelles. In this case, however, these ordered structures are not so stable, compared with that of poly(L-lysine). Poly(L-arginine) undergoes the conformational transition from coil to helix by addition of AOT into the aqueous solution. Further addition of AOT allows transformation intoΒ-structure. Copoly(L-lysyl-L-leucine) with 63% leucine residue was shown to take a stable helical conformation even in pure water. In the reversed micelles, however, this ordered structure is significantly changed probably because the hydrophobic interaction among the leucyl residues is lowered in the reversed micelles.

Kinetic analysis of electron transfer between hexacyanoferrate(III) in water and ferrocene in nitrobenzene by ac impedance measurements

Abstract The rate of electron transfer between hexacyanoferrate(III) in water and ferrocene in nitrobenzene has been investigated by the ac impedance measurements at an equilibrium potential E dc . The impedance data were analysed according to an electrical equivalent circuit. The effective exchange current ( i 0 ) eff and the formal charge transfer coefficient α for the electron transfer reaction were determined. Moreover, the dependence of these kinetic parameters upon the concentrations of Fe(CN) 3- 6 in the aqueous phase and ferrocene in the nitrobenzene phase was also examined. It was observed that the change in the concentration of K 3 Fe(CN) 6 influences the kinetic behaviour of electron transfer reaction to a larger extent than that of ferrocene.