Acid In Two-phase System Research Articles

Kinetics of thermochemical reaction of TBP solutions in HCBD with nitric acid in two-phase systems

Kinetics of thermochemical reaction of TBP solutions in HCBD with nitric acid in two-phase systems

Studies on the Physical Chemistry of (2,4-Dichlorophenoxy)acetic Acid in Two-phase Systems: Organic Solvent-Water

The dissociation constants (p s K a ) of 2,4-D acid were determined in methanol-water mixtures of 10.9 to 38.9 wt.% methanol content. The Yasuda-Shedlovsky procedure was used to obtain the pK a value in zero-% methanol. The distribution of 2,4-D acid in twelve two-phase organic solvent + water systems and its dimerization in the organic phase were investigated. Values of the distribution coefficient (D HR), distribution constant (K D ), and dimerization constant (K dim) of 2,4-D were obtained. The influence of the structure and polarity of the investigated organic solvents, as well as that of pH of the aqueous phase, on the physical chemistry of 2,4-D in the two-phase systems are described.

Distribution of phenoxyacetic acid in two-phase organic solvent-water systems

The distribution of phenoxyacetic acid in two-phase organic solvent-water systems and its dimerization in the organic phase were studied. Organic solvents were normal aliphatic alcohols (C5–C10), benzene, and its derivatives. The distribution (K dis) and dimerization (K dim) constants of this acid were determined. The correlations of these quantities with physicochemical parameters of the organic solvents were revealed. The influence of the organic solvent polarity, pH of the aqueous phase, and acid concentration on the physicochemical behavior of the acid in the two-phase systems was analyzed.

Studies on the distribution of N-phenylanthranilic acid in two-phase system: Aromatic solvent–water

The detailed description of equilibria of N-phenylanthranilic acid in the aqueous solutions and in the two-phase systems: aromatic solvent–aqueous solution were obtained. The isoelectric point, pH I, the dissociation constants of the protonated form, K a1, and the neutral form, K a2, in the aqueous solutions were determined from the apparent ionization constant in methanol–water solutions of various proportions by extrapolation to zero co-solvent using Yasuda–Shedlovsky procedure. On the basis of the spectrophotometric investigations, the values of the distribution ratio, D, of N-phenylanthranilic acid in the two-phase systems: aromatic solvent (benzene, ethylbenzene, toluene, chlorobenzene, bromobenzene)–aqueous solution were obtained. Employing the results of the potentiometric titration in the two-phase systems: aromatic solvent–aqueous solution, and using models of singular and multistep equilibria the values of the distribution constants, K D, dimerization constants, K dim, were calculated. The significant influence of the polarity of the applied aromatic solvents and pH of the aqueous phase on the percentage of the particular forms of N-phenylanthranilic acid in the two-phase systems was proved.

Evaluation of Nonaqueous Solvent Systems for Countercurrent Chromatography Using an HPLC Assay to Determine Partition Coefficients of a Mixture of Compounds

Abstract A reversed phase HPLC assay was used to measure partition coefficients for salicylic acid, salicylamide and salicyluric acid in two-phase systems employing neat or aqueous ethylene glycol, formamide, or methanol and the organic solvents: ethylene dichloride, ethyl acetate, diethyl ether and methyl isobutyl ketone. These solvent systems permit preparative separation by countercurrent chromatography of compounds with limited aqueous solubility. Salicylic acid, salicylamide and salicyluric acid are readily separated in the system employing ethylene glycol as the stationary phase and diethyl ether as the mobile phase.