Conductometric studies of ion binding to poly(oxyethylene) in methanol

Abstract

Ion Binding to Poly(oxyethylene) in Methanol latter for the p-nitroperbenzoic acid results could be appreciable. Effect of Brownian Motion of the LigandWhen the target area is smaller than the mean free path of the ligand, the diffusion-controlled rate constant cannot be deduced from a simple diffusion equation.36 However, the mean free path, L, calculated from the following equation36 is only 0.07 Á for p-nitroperbenzoic acid, where M is molecular weight and R is gas constant: L D( §iY Therefore, the effect of Brownian motion is almost negligible for the horseradish peroxidase-ligand system. Publication costs assisted by Tohoku UniversityThe binding of alkali metal cation with poly(oxyethylene) was studied by means of conductometry in methanol. Apparent binding constants, KA, were determined by assuming the existence of discrete binding sites distributed every a monomer units along the polymer chain. KA increased in the order Li < Na < K < Cs < Rb. For large anions, such as thiocyanate or perchlorate, the formation of an ion pair complex was indicated. KA and a increased rapidly with decreasing salt concentration. This result was interpreted by the increased electrostatic repulsion between bound ions. The linear relationship between a1/2 and Cs"1/2 conforms to the Gaussian distribution of the segment between charges as well as to the partial retention of crystalline conformation of the poly-(oxyethylene)-ion complex.Publication costs assisted by the National Science Foundation and the Petroleum Research Fund Two recent theories for ionic mobility, the Hubbard-Onsager theory which is based on a continuum model and the Wolynes theory which is based on a stochastic model, are critically tested by comparison with conductance data. Both theories predict finite mobilities as the ionic size decreases and thus can successfully account for many of the observed features of conductance data. The models upon which the theories are based are described in detail and the current state of ionic mobility theory is discussed.

Effect of polyethylene glycol 400 on the allylation of phenoxide in a homogeneous phase

“…This value of a indicates that four monomer units of OCH2CH2 will bind with one sodium cation. The special case of this result (C, -a) is exactly the same as that reported by Ono et al (1979), from which the results were obtained for the nonreacting system. In Figure 7, the results were obtained from the allylation of sodium phenoxide at different temperatures for different temperatures, the KA value, thus, can be obtained from Figure 7 with eq 15.…”

“…That is, the function of PEG-400 is to promote the dissociation of sodium phenoxide. As indicated by Ono et al (1979), the formation of an ion pair from PEGNa' with an anion can be neglected. Both P E G N a + and PhOare exhibited in free ion form.…”

“…Both P E G N a + and PhOare exhibited in free ion form. As shown in eq 10, the equilibrium relationship is built up based on the discrete site binding model (Ono et al, 1979). The basic assumptions of the discrete site binding model are as follows.…”

“…Then, PEG-400 will associate with the sodium cation to form a complex by loosening the interaction between the phenoxide anion and the sodium cation. The discrete site-binding model (Ono et al, 1979) and the dissociation of sodium phenoxide are used to build up the reaction model. The proposed reaction mechanism is verified by the experimental data.…”

“…The reaction is carried out by reacting allyl chloride with sodium phenoxide and with PEG-400 in an EtOH solvent. The dissociation constant of sodium phenoxide in the reacting system was determined by the conductometric method (Poonia et al, 1979;Ono et al, 1979). The apparent binding constants at different temperatures were obtained.…”