enthalpy

The temperature dependences of the solubility of 2-methyl-5-(2-chloro-5-trifluoromethylphenyl)-furan-3-carboxylic acid and 2-methyl-5-(2,5-dichlorophenyl)-furan-3-carboxylic acid in acetonitrile, dimethyl ketone, isopropanol and ethyl acetate have been experimentally determined. The enthalpies of fusion of the investigated substances, as well as their enthalpies and entropies of mixing at 298 K have been calculated. The dependence of the saturated solution concentration on the values of enthalpy and entropy of solubility at 298 K has been determined.

2-Cyano-3-[5-(2-oxy-methyl-4-nitrophenyl)-2-furyl]-2-propenamide is a biologically active derivative of furan with reactive centers of donor and acceptor type that is used as a starting material in the synthesis of drugs.

The structure of the substance was confirmed by NMR spectroscopy. The purity of the substance was determined using a system of high-efficiency liquid chromatograph Agilent 1100 HPLC.

The temperature dependencies of both acids solubility in acetonitrile, dimethylketone, isopropanol, ethylacetate and benzene were investigated. The results were represented by Shredder’s equation according to which enthalpies, entropies and Gibbs energy of solubility at 298 K were determined. Fusion heats of the acids were determined using differential thermal analysis. In accordance with obtained values the enthalpies, entropies and Gibbs energy of mixing were calculated. The compensating effect of mixing was observed for al solvents with carboxy group.

The investigation of thermodynamic peculiarities of bromphenol blue (BB) elimination from aqueous solutions using solvent sublation technique has been carried out. Thermodynamic properties of acid dye (BB) interaction with cationic surfactant cetylpyridinium chloride (CPC), applying Kharash method and HyperСube HyperСhem Professional software were studied. It was proven that dye-surfactant ion complex formation is a spontaneous process and does not require any external forces for its run.

On the basis of literature data the constancy of heat capacity change during vaporization ( 2 %) and sublimation ( 8 %) has been determined at 298 K for different organic compounds. The obtained equations allow to recalculate the enthalpy according to Kirchhoff’s law easier compared with present techniques based on the increments method. The vaporization and sublimation enthalpies of 5-(2-nitrophenyl)-furan-2-carbaldehyde have been determined and recalculated for 298 K for the reliability proofing of the suggested method.