Thermodynamic Study of Dilute Aqueous-solutions of Organic-compounds .5. Open-chain Saturated Bifunctional Compounds

Values have been determined at 25°C of the changes in the free energy, enthalpy and entropy corresponding to the process of transfer from the ideal gas state to dilute aqueous solution for ethylene-diamine, 2-methoxyethylamine, 3-methoxypropylamine, 1,2-dimethoxymethane and four 2-alkoxy-ethanols (methoxy to n-butoxy). These data have been used to calculate the variations in the thermodynamic functions of hydration for the hypothetical process of introducing a Y group (Y = O, NH) into a monofunctional RX compound (X = O, NH, NH2, OH), either by breaking a C—C or a C—H bond. Evidence of strong interactions between hydrophilic centres in bifunctional compounds emerges. The strength and nature (entropic or enthalpic) of these interactions depend on both the type of functional groups and their relative distance

Excess Gibbs energy. Perhydroazepine-cyclohexane system

A data table and a correlation equation are presented for the excess free energy of the perhydroazepine-cyclohexane system at 298.15 K

Excess enthalpy. Pyrrolidine-cyclohexane system

A data table and a correlation equation are presented for the excess enthalpies of the pyrrolidine-cyclohexane system, single-phase, both components liq. at 298.15 K

Thermodynamic and Kinetic Aspects of the Binding Reaction of Molecular Oxygen on Co(II) Complexes in Aqueous Solution

A short survey is given of the main characteristics of the reaction of uptake of molecular oxygen by biological dioxygen carriers. Co(II) complexes able to bind dioxygen are then examined in order to determine whether the type and features of the peroxocomplexes formed are related to the nature of the ligand and the solvent. The thermodynamic and kinetic data relative to the formation in aqueous solution of peroxocompounds starting from Co(II) complexes with ligands belonging to three families (open-chain, macrocyclic and macropolytopic) of saturated polyamines are also examined in greater detail

Liquid-vapor equilibrium. N-methylpiperidine-cyclohexane system

A data table and correlation equations are presented for the binary N-methylpiperidine-cyclohexane system, single-phase liq. in equil. with vapor, pure components liq. in equil. with vapor at 298.15 K

Free-energy and Enthalpy Changes For the Process of Transfer From Gas and From Dilute Aqueous-solutions of Some Alkanes and Monofunctional Saturated Organic-compounds

Standard free energies, DELTA-solvG-degrees-(oct), and enthalpies, DELTA-solvH-degrees-(oct), of solvation in octan-1-ol of some alkanes (heptane, octane), ketones (propan-2-one, butan-2-one, hexan-2-one, heptan-4-one), ethers (dipropyl ether, dibutyl ether, tetrahydropyran), alkanols (butan-1-ol, butan-2-ol, 2-methylpropan-2-ol) and amines (pyrrolidine, N-methylpyrrolidine, and piperidine) with open-chain and cyclic structure have been determined at 298.15 K. The DELTA-solvG-degrees-(oct) values were obtained from measurements of partial vapor pressures of dilute solutions and the DELTA-solvH-degrees-(oct) values, by adding the heats of solution, determined by calorimetry, to known values of enthalpy of vaporization. These data are compared with the standard free energies and enthalpies of solvation in water, and the standard thermodynamic functions for the ideal transfer process of the solutes from pure water to pure octan-1-ol, DELTA-trX-degrees-(w-oct) (X = G, H) are calculated. For the examined solutes, hydrocarbons and monofunctional saturated organic compounds, the thermodynamic functions of solvation in octanol and in water are closely correlated to the position of the functional group in the molecular skeleton. The values of the enthalpy of transfer from water to octan-1-ol are also related more to the topologic characteristics of the solute molecules than to their size or to the nature of their functional group. In contrast, the size of the molecules, as well as the presence of a functional group, are important with regard to DELTA-trG-degrees-(w-oct). An increase of 1 cm3 mol-1 in the intrinsic volumes corresponds to an increase in the value of the partition coefficients of ca. 15%. The substitution of a part of the hydrocarbon surface with a polar surface produces a very large increase in the values of the partition coefficients. The values of the enthalpy of transfer from water to octan-1-ol are always positive, in contrast to the standard free energies of transfer. The entropic term operates by always favouring the transfer towards the alcoholic phase. The potential ability of anhydrous octanol to extract organic solutes of various molecular structure from water-saturated octanol and from hexadecane is also evaluated and discussed

Thermodynamic Study of Organic-compounds In Octan-1-ol .3. Enthalpy Effects Connected With the Partitioning of Some Bifunctional Compounds Between Water and Octan-1-ol

The values of the enthalpy changes for the transfer of some open-chain and cyclic bifunctional organic compounds (diethers, diamines, aminoethers) from gas state to dilute solution in octan-1-ol have been obtained by the enthalpies of vaporisation of the pure solutes and the limiting enthalpies of solution in octanol. These data have been combined with the known values of the enthalpy of solvation in water, and the values of enthalpy of the transfer process from pure water to pure octan-1-ol have also been calculated. From an analysis of these data, it emerges that: the enthalpies of solvation in water and in octan-1-ol are linearly related and distinctive values were obtained for the slopes of the two straight lines which connect bifunctional open-chain and cyclic compounds; the enthalpies of transfer from water to octanol are always endothermic and linearly related to the intrinsic volumes of the solutes, irrespective of whether they have an open-chain or a cyclic structure. The enthalpy changes for the transfer from gas to aqueous or alcoholic solution, or for the transfer from water to octan-1-ol, have been related to the molecular structure of the solutes

Thermodynamic Study of Organic-compounds In Octan-1-ol - Processes of Transfer From Gas and From Dilute Aqueous-solution

Free energies and enthalpies of solvation of water and some hydrocarbons (hexane, cyclohexane), ethers (diethyl ether, tetrahydrofuran) and ketones (propanone, pentan-3-one, cyclopentanone) in octan-1-ol have been determined at 298.15 K from vapour-pressure measurements of dilute solutions and from limiting heats of solution. These solvation functions in octanol have been used together with the corresponding hydration functions in order to obtain water–octan-1-ol partition coefficients and their dependence on temperature. A comparison is made with the practical partition coefficients relative to mutually saturated solvents