Search

The rates of the addition of methoxide ion to the CN bond and the proton/deuteron transfer reactions between methoxide ion and substituted phenylacetonitriles (XC_6H_4CY_1Y_2 CN: X=CH_3O, CH_3, Cl, Y_1=H, D, Y_2=H, D; X=H, Y_1=CH_3, Y_2=H, D) have been determined at high pressures, The rate constant at each pressure is fitted to the previously derived formula which permits the distinction between the structural volume change and the electrostatic volume change. The activation volume varies with the substituent from -(9.5±2.5) to -(13.7±1.8)cm^3/mol for the iminoether formation, and from +(18.2±2.9) to +(7.7±2.7) cm^3/mol for the deuteron transfer. The activation volume of the proton transfer reaction coincides with the value of the deuteron transfer reaction within experimental error. In the iminoether formation, the activation volume is more contributed from the structural term which does not vary so much with the substituent than the electrostatic one. And volume profile for that reaction suggests a product-like transition state. On the other hand, in the deuteron transfer reaction, the electrostatic term which varies considerably with the substituents, contributes to the activation volume much mare than the covalent one. It is also suggested from the fractionation theory that the solvation number does not change remarkably with pressure.

The rates of the nucleophilic attack of methoxide ion to phenylacetonitrile in methanol were studied at high pressure. The attack resulted in two different types of reactions, one being the elimination of α-hydrogens while the other the base-catalyzed methanol addition to C≡N triple bond. Positive (+24cm^3 mol^-1 at 303.2K)and negative(-13.1cm^3 mol^-1 at 313.2K) activation volume changes were observed for the deuterium elimination and the nucleophilic attack of methoxide ion to C≡N triple bond, respectively. An expression which permits the distinction between the electrostatic volume change and the covalent volume change has been derived from a perturbed molecular-orbital theory combined with the Owen-Brinkley formula. Validity of the expression has been tested for various types of high-pressure reactions including those here studied.

The effects of pressure on the reaction of malononitrile have been studied in water, methanol, ethanol, iso-propanol, dioxane, and so on in the temperature range of 323 to 343 K up to 8000 kg cm^-2. The reaction produced a dimer and two trimers only at high pressure. The dimer was identified as 1, 1, 3-tricyano-2-amino-1-propene and the trimers as 2, 4-diamino-3, 5-dicyano-6-cyanomethylpyridine, and ammonium 1, 1, 3, 3-tetracyano-2-cyanomethylpropenide, which are, respectively, the "Trimer 1" and "Trimer 2" reported by Schenck and Finken. The "Trimer 3" was not yielded.1. 3, 5-Tricyanomethyl-s-triazine was not produced in the present reaction either. The polar solvents and the addition of triethylamine increased the reaction rate remarkably. The formation of the dimer is autocatalytic and its mechanism is found to be a Thorpe-type reaction.

The ionic dissociation constans of ionization of triethylamine in methanol were determined from the measurements of electrical conductivities over the range of 1-2000kg cm^-2 at 25℃ and 1-1600kg cm^-2 at 30 and 40℃. The ionization constants were obtained by the Shedlovsky equation which contains the equivalent conductivity of weak electrolyte and the limiting equivalent conductivity of strong electrolyte. The data were treated by the Fuoss-Onsager equation for potassium chloride, triethylammonium chloride, and potassium methoxide to determine the limiting equivalent conductivities after the justification of the Onsager limiting equation at high pressure. The ionic dissociation constant at 25℃ increased from 0.502×10^-6 mol kg^-1 at 1 atm to 5.78×10^-6 mol kg^-1 at 2000kg cm^-2, and decreased with temperature to 0.264×10^-6 mol kg^-1 at 1 atm and 40℃. The pressure dependence of ionization constant was quantitatively explained by the change of dielectric constant with pressure, and the electrostrictive volume change, and the other volume changes (crystal, void volume change et al.) at 1 atm. It was found that both the electrostrictive volume change and the other volume changes play an important role for the pressure effects on the ionization in methanol.

The north-south section of the atmospheric concentration of ^(Kr) over the Pacific is first reported. The most striking feature of the section is a large concentration difference at the geographical position of the intertropical convergence. The ^(Kr) concentration in the air over the North Pacific ranged from 22 to 23pCi m^ and in the South Pacific 16pCi m^. The concentration differences between two hemispheres is about 6pCi m^. Five year records from land stations in Japan indicate that the annual increase is about 1pCi m^y^. It seems that the amount of the southward transport of ^(Kr) from the northern hemisphere is nearly equilibrated with that of radioactive disintegration and/or dissolution of ^(Kr) into the ocean in the southern hemisphere.

Distribution of pCO_2 and δ^C in the air over the ocean and in the surface sea water of the Southern Ocean was determined during the cruise of BIOMASS (November 1983 to February 1984). In the study area, south of Australia, pCO_2 in the air was nearly constant (∿342ppm) throughout the cruise but pCO_2 in the surface sea water varied considerably ranging from 300 to 356ppm. In general, pCO_2 in the surface sea water tended to increase from north to south, and it was relatively higher than that in the air in higher latitudes. The average value in the south of 5°S was -7.97‰ for δ^C and 341.7ppm for pCO_2 of atmospheric CO_2. These results indicate that atmospheric CO_2 over the ocean is not isotopic equilibrium with the surface sea water and kinetic fractionation must be considered for understanding δ^C of atmospheric CO_2.

The rates of the addition of methoxide ion to the CN bond and the proton/deuteron transfer reactions between methoxide ion and substituted phenylacetonitriles (XC_6H_4CY_1Y_2 CN: X=CH_3O, CH_3, Cl, Y_1=H, D, Y_2=H, D; X=H, Y_1=CH_3, Y_2=H, D) have been determined at high pressures, The rate constant at each pressure is fitted to the previously derived formula which permits the distinction between the structural volume change and the electrostatic volume change. The activation volume varies with the substituent from -(9.5±2.5) to -(13.7±1.8)cm^3/mol for the iminoether formation, and from +(18.2±2.9) to +(7.7±2.7) cm^3/mol for the deuteron transfer. The activation volume of the proton transfer reaction coincides with the value of the deuteron transfer reaction within experimental error. In the iminoether formation, the activation volume is more contributed from the structural term which does not vary so much with the substituent than the electrostatic one. And volume profile for that reaction suggests a product-like transition state. On the other hand, in the deuteron transfer reaction, the electrostatic term which varies considerably with the substituents, contributes to the activation volume much mare than the covalent one. It is also suggested from the fractionation theory that the solvation number does not change remarkably with pressure.

The effects of pressure on the reaction of malononitrile have been studied in water, methanol, ethanol, iso-propanol, dioxane, and so on in the temperature range of 323 to 343 K up to 8000 kg cm^-2. The reaction produced a dimer and two trimers only at high pressure. The dimer was identified as 1, 1, 3-tricyano-2-amino-1-propene and the trimers as 2, 4-diamino-3, 5-dicyano-6-cyanomethylpyridine, and ammonium 1, 1, 3, 3-tetracyano-2-cyanomethylpropenide, which are, respectively, the "Trimer 1" and "Trimer 2" reported by Schenck and Finken. The "Trimer 3" was not yielded.1. 3, 5-Tricyanomethyl-s-triazine was not produced in the present reaction either. The polar solvents and the addition of triethylamine increased the reaction rate remarkably. The formation of the dimer is autocatalytic and its mechanism is found to be a Thorpe-type reaction.