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Studying thermodynamic aspects of sublimation, solubility and solvation processes and crystal structure analysis of some sulfonamides.

Perlovich GL, Strakhova NN, Kazachenko VP, Volkova TV, Tkachev VV, Schaper KJ, Raevsky OA

Department of Computer-Aided Molecular Design, Institute of Physiologically Active Compounds, Russian Academy of Sciences, 142432 Chernogolovka, Russia. glp@isc-ras.ru

Crystal structures of N-(2-chlorophenyl)-benzene-sulfonamide (I), N-(2,3-dichlorophenyl)-benzene-sulfonamide (II), N-(4-chlorophenyl)-benzene-sulfonamide (III) were solved by X-ray diffraction method. Temperature dependencies of saturated vapor pressure and thermodynamic functions of sublimation process were calculated (I: DeltaG(sub)(298)=50.4kJmol(-1); DeltaH(sub)(298)=114+/-1kJmol(-1); DeltaS(sub)(298)=213+/-3Jmol(-1)K(-1); II: DeltaG(sub)(298)=54.1kJmol(-1); DeltaH(sub)(298)=124.9+/-1.6kJmol(-1); DeltaS(sub)(298)=237+/-5Jmol(-1)K(-1); III: DeltaG(sub)(298)=49.9kJmol(-1); DeltaH(sub)(298)=98.6+/-1.9kJmol(-1); DeltaS(sub)(298)=163+/-5Jmol(-1)K(-1)). Thermochemical parameters of fusion process for the compounds were obtained. Enthalpies of evaporation were estimated from enthalpies of sublimation and fusion. Temperature dependencies of the solubility in water, n-octanol and n-hexane were measured. The thermodynamic functions of solubility and solvation processes were deduced. Specific and non-specific solvation terms were distinguished using the transfer from the "inert"n-hexane to the other solvents. The transfer processes of the molecules from water to n-octanol were analyzed and main driven forces were established.

Published 19 March 2007 in Int J Pharm, 334(1): 115-24.
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