title: Evaluation of the hydrophilic property of sodium ion-pair complexes with 3m-crown-m ethers (m = 5, 6) and their benzo-derivatives by solvent extraction.
abstract: The ion-pair formation constants {K(j)(0): j = MA (metal salt), MLA} of NaO(2)CCF(3) (Na(+)tfa(-)) and its ion-pair complexes (MLA) in water (w) were determined potentiometrically at 25 degrees C and an ionic strength (I) of zero. 15-Crown-5 (15C5), 18-crown-6 ethers (18C6), and their mono-benzo derivatives were used as crown ethers (L). The extraction of Natfa by these four L from w into 1,2-dichloroethane was done at 25 degrees C, and then the extraction constants (K(ex)) for NaLtfa were calculated by using the K(j) values, which were estimated from the corresponding K(j)(0) ones at I of the w-phases, and other equilibrium constants. Also, the distribution constants (K(D,MLA)) of NaLtfa between the two phases were obtained from a thermodynamic cycle expressing K(ex). An interaction of w-molecules with NaLA was considered using a relation of log K(D,MLA) with log K(D,L), derived from the Scatchard-Hildebrand equation, where K(D,L) denotes the distribution constant of L between the two phases. The interaction increased in the order of NaL (picrate) < free L </= NaLMO(4) (M = Mn, Re) < NaLtfa for L = 15C5 and 18C6.
authors.affiliation: Graduate School of Science, Chiba University, Japan. iakudo@faculty.chiba-u.jp
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kudo
authors.forename: Ryo
authors.initials: R
authors.lastname: Fujihara
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Ohtake
authors.forename: Shoichi
authors.initials: S
authors.lastname: Katsuta
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Takeda