Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

The standard partial molar volumes, V12 at infinite dilution of monosaccharides; D(+)-xylose, D( )-arabinose, D( )-ribose, D(+)-mannose, D(+)-galactose, D( )-fructose and D(+)-glucose, disaccharides; D(+)-melibiose, D(+)-cellobiose, D(+)-maltose monohydrate, D(+)-trehalose dihydrate, D(+)-lactose monohydrate and sucrose, trisaccharide; D(+)-raffinose pentahydrate, methylglycosides; a-methyl-D(+)-glucoside, methyl-a-D-xylopyranoside and methyl-b-D-xylopyranoside have been determined in water and in aqueous solutions of potassium chloride (0.5, 1.0, 2.0, and 3.0) mol kg 1 at T = (288.15, 298.15, 308.15, and 318.15) K from density measurements employing a vibrating-tube densimeter. These results have been utilized to determine the corresponding standard partial molar volumes of transfer, DtV12 for the transfer of various saccharides from water to aqueous potassium chloride solutions. The standard transfer volumes have been found to be positive (except for a- and b-methyl xylopyranosides in 0.5 mol kg 1 solutions of potassium chloride) whose magnitude increase with the concentration of potassium chloride as well as temperature for all the saccharides. Partial molar expansion coefficients, ooV12 =oTPp and the second derivative oo2V12 =oT2Pp values have been estimated. Pair and higher order volumetric interaction coefficients have also been calculated from DtV12 by using the McMillan Mayer theory. These parameters have been discussed in terms of the solute cosolute interactions and are used to understand various mixing effects due to these interactions. The effect of substitution of OH by glycosidic group, OCH3 is also discussed. Attempt has also been made to discuss the stereochemical effects which are controlled mostly by the dominant conformations of the saccharides in water.