Toshiro Iijima

Ionic partition equilibria of a simple organic electrolyte in chemically modified charged cellulosic membranes

Abstract An investigation of ionic partition equilibria of sodium benzene sulfonate in cellulosic membranes containing added carboxymethyl, sulphoethyl or phosphoric groups is reported. The results in the electrolyte concentration range of 1 x 10-3 to 4 x 10-1 mol-dm-3 could not be interpreted satisfactorily in terms of the simple (equipotential volume) Donnan equilibrium theory, even on the assumption of counterion binding by the fixed charged groups. Application of the treatment of Glueckauf or of the equipotential surface pore model suggests that the observed behaviour can be explained in terms of membrane nonhomogeneity (resulting in nonuniform charge distribution), which appears to be considerably more pronounced than in the case of the cellulose membranes studied by Tsimboukis and Petropoulos. Attention is also drawn to certain important points concerning the experimental applicability of the Glueckauf power law and the method of testing the validity of the equipotential volume Donnan law.

Ester hydrolysis by poly(allylamine)s having hydrophobic groups : Catalytic activity and substrate specificity

Abstract The hydrolysis of phenyl esters having anionic, hydrophobic, and stereoisomeric groups by poly(allylamine)s (I) with various hydrophobic groups was investigated. The derivatives of I with dodecyl and benzyl groups (IIc and III) form a hydrophobic microdomain near the catalytic site. For I, the hydrolysis rate of 4-acetoxy-3-nitro-benzoic acid is extremely high, indicating a significant contribution of the electrostatic effect. IIc (degree of substitution, DS ≧ 0.12) and III (DS ≧ 0.48) have a considerable large catalytic activity for the more hydrophobic substrates than p-nitrophenyl acetate. The reaction mechanism was found to be of the Michaelis-Menten type. According to kinetic and thermodynamic analysis, it was found that the lower polarity (E T ≈ 55) and compact structure lead to effective hydrophobic interaction and high substrate binding, resulting in enhancement of the catalytic activity. In the case of III (DS = 0.75), it was suggested that the substrate should be bound and fixed in the ...