15) (a) a's for processes a. b, and c are defined by the following relation: a = [-K+ (K+ 4 Kct/2]/2c°, where Kand c°are the dissociation constant and the initial concentration of B, BH+, or BH22+, respectively, in processes a, b, or c. (b) The value of a for process d is calculated from: a = 2(K'1//C2)1,2/[1 + 2(K1/K2)V2j, where K, and K2 are the dissociation constants for proton ionization processes b and c. In deriving a, processes b and c for the products of disproportionation have been assumed to be negligible. This is a valid assumption for the solutions of the monohydrochlorides of the diamines here examined, because the difference between cB and Cbh22+ does not exceed 1 ppm. The pK for process d is related to p/ , and pK2 by pK= 2( -pK2).
Publication costs assisted by Consiglio Nazionale delle Ricerche, Rome Apparent molar volumes, , at various concentrations in water at 25 °C of some cyclic bifunctional amines [morpholine, 4-methylmorpholine, piperazine, 1-methylpiperazine, 1,4-dimethylpiperazine, 1,4-diazabicyclo-[2.2.2]octane (triethylenediamine)] and their mono-and dihydrochlorides have been determined. The volume changes AV^a nd AV2°, involved in the first and second proton ionizations from the protonated amines, have been calculated from the limiting partial molar volumes V2°. Furthermore, the volumes of ionization for the bifunctional cyclic amines have been compared with those for the monofunctional amines and the relationship between entropies and volumes of ionization has been examined.
Basic ionization constants (Kb) of 2-methoxyethylamine, 3-methoxypropylamine, and bis-2-methoxyethylamine in water have been measured as a function of temperature between 5 and 45 °C, thus enabling values of ΔGb0, ΔHb0, ΔSb0, and ΔCpb0 to be calculated. The results conform with the ability of the ether function to destroy hydrophobicity in water.
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