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Abstract: In the scope of investigating new solvents as potential replacements for chlorocarbons or aromatic hydrocarbons for separation of carboxylic acids from dilute aqueous solution, we have focused on the dibasic esters, which have perfect properties for industrial applications. For this purpose, liquid–liquid equilibrium data for water+formic acid+solvent (diethyl carbonate or diethyl malonate or diethyl fumarate) ternary systems were investigated at 298.15K and atmospheric pressure. The equilibrium results consisted of solubility data and tie-lines were presented in ternary phase diagrams. The reliability of the experimental tie-lines was confirmed by using Othmer–Tobias correlation. The experimental tie-line data were correlated by UNIQUAC model, which gave satisfactory representation for the systems. It is concluded that diethyl carbonate, diethyl malonate and diethyl fumarate may be adequate solvents to extract formic acid from its dilute aqueous solutions. [Copyright &y& Elsevier]

Abstract: The recovery of propionic acid from aqueous solutions such as fermentation broth and wastewater is an important problem where liquid extraction is the favorite process. Liquid–liquid equilibrium (LLE) data were investigated for mixtures of water+propionic acid+diethyl carbonate or diethyl malonate or diethyl fumarate at 298.15K. The solubility curves and the tie-line end compositions of liquid phases at equilibrium were determined experimentally, and the tie-line results compared with the data correlated by means of UNIQUAC model. The phase diagrams for the ternary mixtures including both the experimental and correlated tie-lines are presented. The reliability of the experimental tie-lines was confirmed by using Othmer–Tobias correlation. The distribution coefficients and the separation factors for the immiscibility region are calculated. In order to boost the distribution of propionic acid between aqueous and organic phases, the distribution was investigated by using organic solutions composed of amine {tributylamine (TBA)} and phosphorus containing compounds {trioctylphosphine oxide (TOPO) or tributyl phosphate (TBP)} dissolved in diethyl carbonate, diethyl malonate and diethyl fumarate, in the concentration range of about 0.06–1.00mol/l. It was observed that the used solvents may serve individually as adequate agents to extract propionic acid from its dilute aqueous solution; however, the extraction performance can be improved by using phosphorus containing compounds or amines, mostly by using tributylamine dissolved in diethylmalonate. [Copyright &y& Elsevier]

Abstract: Radical polymerization of cyclodextrin (CD) complexed diethyl fumarate (1) and diethyl maleate (2) was investigated using redox initiator in aqueous media at room temperature. Control experiments were carried out showing that 2 does not homopolymerize using radical initiator in bulk at 60°C. Complex 2 undergoes homopolymerization with a cis/trans-isomerization in the presence of both CD and redox initiator. The obtained polymers have a similar structure and molecular weight as polymer obtained from the corresponding 1-CD complex. Additionally, the X-ray structure of a α-cyclodextrin complex of monomer 1 is represented. [Copyright &y& Elsevier]