Jiro Osugi

Pressure dependence of conductance of the lithium and cesium ions in cooled and supercooled water

Limiting molar conductances (λ0) of the Li+ and Cs+ ions in water have been determined at 0, −5, and −10 °C as a function of pressure up to 2 kbar. In the studied ranges of pressure and temperature, λ0(Li+) increases monotonically with increasing pressure and λ0(Cs+) has a maximum against pressure. The low‐temperature conductances fit well an empirical equation of the critical law form over the pressure range studied; λ0=A(T/TS−1)γ. The parameter TS decreases with a rise in pressure below 1.5 kbar, but above that TS is almost constant. The Hubbard–Onsager (HO) dielectric friction theory has been critically tested against the experimental results obtained under the extreme conditions after λ0 are transformed into the drag coefficient (Δζ) subtracted by that due to Stokes’ law for perfect slip (4πηR). The observed pressure coefficient dΔζ/dP is negative for the small ion Li+ even in cooled or supercooled water as predicted by the HO theory but positive for the large ion Cs+ in contrast to the theoretical pr...

Conductance of alkali metal ions in compressed water at 25 °C

Limiting molar conductances (λ0) of Li+, K+, Cs+, and Cl− ions in water have been determined at 25 °C as a function of pressure up to 2000 kg cm−2 from the measured conductances (Λ) of LiCl, KCl, and CsCl. In the pressure range investigated, λ0(Li+) increases, λ0(Cs+) decreases, and λ0(K+) and λ0(Cl−) have a maximum at 520 and 1230 kg cm−2, respectively. The drag coefficient (Δζ) subtracted by that due to Stokes’ law for perfect slip (4πηR) is obtained for the alkali metal ions and compared with that predicted by the Hubbard and Onsager (HO) dielectric friction theory over the pressure range. The observed decrease in Δζ with pressure for the small ion Li+ can be explained by the HO theory, but the increase for the large ion Cs+ shows a limitation of the continuum theory. The latter trend suggests that Cs+ ions may possibly pass through larger unoccupied cavities in the open structure of water which is less developed at higher pressures. Δζ for the medium‐sized ion K+ is constant, which seems to result fro...

High‐pressure stopped‐flow apparatus up to 3 kbar

A high-pressure stopped-flow apparatus was constructed which could be operative at hydrostatic pressures up to 3 kbar. Some preparative results on anionic sigma-complex formation reactions are presented up to 1.5 kbar between 2,4,6-trinitrobenzene (I) and hydroxide ion and between compound (I) and sulfite ion in water. It was found that this apparatus was sufficient to follow a chemical reaction whose half-life was longer than several milliseconds.

Pressure dependence of conductance of the potassium ion in cooled and supercooled water

Conductance measurements have been carried out on dilute (10−3–10−2 M) aqueous solutions of KCl at low temperatures of −5, −10, −15, and −20 °C at pressure intervals of 250 bar up to 2 kbar. The limiting molar conductance (Λ0) obtained with the aid of the Fuoss–Onsager equation of conductance has a maximum against pressure at each temperature, and the pressure of the maximum conductance increases very slightly with decreasing temperature. The low‐temperature conductances fit well an empirical equation of the critical law form over the pressure range studied; Λ0=A(T/TS−1)γ. The parameter TS decreases with a rise in pressure below 1.5 kbar, but above that TS is almost constant. The pressure dependence of the drag coefficient (Δζ) subtracted by that due to Stokes’ law for perfect slip (4πηR) is obtained for the K+ ion over a wide range of temperature (−10–45 °C) and compared with that predicted by the Hubbard–Onsager (HO) dielectric friction theory. The observed slight decrease in Δζ with pressure at 45 °C c...

Effect of pressure on the conductivities of HCl and KCl in water at 0°C

The electrical conductivities of hydrochloric acid and potassium chloride in water have been measured in the concentration range of 3×10−4–10−3 moles-dm−3 at 0°C up to 3500 bar. The limiting molar conductance (Λ0) for HCl increases with increasing pressure, while Λ0(KCl) has a maximum around 1700 bar. The excess conductance of hydrogen ion [λ0E=Λ0(HCl)−Λ0(KCl)] increases with increasing pressure. Its pressure dependence indicates that the reorientation of water molecules, which is the rate-determining step in the proton jump, becomes faster at higher pressure. This anomaly is attributed to the distortion with pressure of the hydrogen bonds in water.

The role of franck-condon factors in intersystem crossing from the S1 state of anthracene

Abstract The Franck-Condon factor between S 1 and T 2 for anthracene is estimated as a function of the electronic energy gap. It is shown that the intersystem crossing rate for S 1 → T 2 depends on changes in the S 1 → T 2 gap. Some phenomena associated with this transition are interpreted and predicted from the calculations.

Mannich Reaction Under High Pressee. Dimethylaminomethylation of Ketones with bis(Diyethylamino)methane under Mild Conditions

Abstract Dimethylaminomethylation of ketones with bis(dimethyl-amino)methane takes place cleanly in methanol at room temperature in the kiro bar region.

High-pressure kinetics of electron donor–acceptor complex formation and cycloaddition between tetracyanoethylene and enol ethers

The kinetics of the high-pressure cycloaddition reaction between tetracyanoethylene and enol ethers (n-butyl vinyl ether and ethyl 2-methylpropenyl ether) in chloroform have been studied, by following spectrophotometrically the disappearance of the electron donor–acceptor complex (e.d.a. complex) at 25 °C and up to 1 500 bar. It is concluded that the e.d.a. complex is on the pathway to the zwitterionic intermediate and the final cycloaddition product. The reaction volume ΔV1 of e.d.a. complex formation is –11.0 ± 1.4 and –5.8 ± 1.0 cm3 mol–1 for n-butyl vinyl ether and ethyl 2-methylpropenyl ether, respectively. The volume of activation ΔV2‡ of cycloaddition step from e.d.a. complex to the adduct is –30.8 ± 1.5 and –41.8 ± 1.5 cm3 mol–1 for n-butyl vinyl ether and ethyl 2-methylpropenyl ether, respectively. The variation of ΔV1 and ΔV2‡ is discussed from the viewpoint of the ionization potential and the electron density at the β-carbon atom of the enol ether.

High-pressure kinetics of the reactions of p-benzoquinone with aliphatic amines in aprotic solvents

The rates of substitution reaction between p-benzoquinone and dibutylamine and of the electron-transfer reaction between chloranil and tripropylamine were examined spectrophotometrically, under pressure, in dichloromethane, 1,2-dichloroethane, chloroform, and acetonitrile. For the substitution to produce 2-dibutylamino-p-benzoquinone the reaction rate obeyed a third-order kinetic equation: first order with respect to p-benzoquinone and second order with respect to dibutylamine. The activation volume was as large as ca.–60 cm3 mol–1 in the solvents used, and a negative activation energy of –31 kJ mol–1 was observed in acetonitrile. A reaction scheme has been proposed where an electron-transfer reaction to form the p-benzoquinone anion radical occurs prior to the rate-determining step, which is the second attack by the amine. By taking into account the result that the electron transfer from chloranil to tripropylamine accompanied the activation volume of ca.–30 to –45 cm3 mol–1, the reaction volume of this process was estimated to be ca.–45 cm3 mol–1. Thus, in the p-benzoquinone–dibutylamine system we may reasonably assign the activation volume of –10 to –15 cm3 mol–1 to the second bimolecular attack by the amine.

Solvent, pressure, and deuterium isotope effects on proton tunnelling. The reaction between 2,4,6-trinitrotoluene and 1,8-diazabicyclo[5.4.0]undec-7-ene in aprotic solvents

Proton tunnelling has been examined for the reaction between 2,4,6-trinitrotoluene and 1,8-diazabicyclo-[5.4.0]undec-7-ene in several aprotic solvents (acetonitrile, benzonitrile, 1,2-dichloroethane, and dichloromethane) in view of the solvent and pressure effects on the rate ratio kH/kD. The reaction rates have been measured in the range 1–1 000 bar, at 25 °C by a high-pressure stopped-flow method. The reaction rate ratios kH/kD in all these solvents are greater than the semiclassical limit of the primary kinetic isotope effect and show a significant tunnelling contribution. Further, with increasing pressure from 1 to 1 000 bar, the ratio kH/kD at 25 °C diminishes from 19.1 to 16.9 in acetonitrile, from 15.9 to 15.0 in benzonitrile, and from 29.9 to 22.5 in 1,2-dichloroethane, respectively. However, the increases of the effective mass of the transferred particle with pressure are calculated to be about the same in all these solvents.