Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The standard enthalpies of dilution (dilH) and isentropic compressibilities (Ks,2) of some saccharides and their derivatives; ()-D-ribose, (+)-D-glucose, 2-deoxy-D-glucose, (+)-methyl -Dglucopyranoside, (+)-maltose monohydrate, and (+)-raffinose pentahydrate (solutes) have been determined from heat change (q) and speed of sound (u) data measured respectively in (0.05, 0.15, 0.25 and 0.35) molkg-1 and (0.5, 1.0, 1.5 and 2.0) molkg-1 aqueous solutions of sodium phosphate (NaH2PO4), ammonium phosphate (NH4H2PO4) monobasic salts, and potassium phosphate (K3PO4) tribasic salt at T = 288.15-318.15 K at P = 0.1 MPa. Other parameters such as transfer values (t(dilH), tKs,2), change in heat capacity (dilCop,2,m), and hydration numbers (nw) have also been derived to rationalize the molecular interactions in mixtures of saccharide and derivative and phosphate based salts.These studies are important to understand various interactions in terms of changing cation (Na+, NH4+ and K+) and anion (H2PO4- and PO43-) size, ionic strength and influence of salts on water structure. 1. INTRODUCTION Saccharides being integral parts of bio-macromolecules (glycoproteins, glycolipids, nucleic acids, polysaccharides, etc.) play key roles in control of various life processes like cell-cell communication, biosynthesis, protein folding, immunology, fertilization, etc. For example, L-fucose (deoxyhexose) residues in the carbohydrate chains of glycoconjugates act as cell-cell recognition sites and as important antigenic determinants such as blood group antigens. Fucosylation is one of the most important oligosaccharide modifications in cancer. A number of important polymers which occur in the living cells are composed of glucose, hyaluronic acid and other saccharides. Polysaccharides such as cellulose and chitin, are renewable natural resources and one of the most important materials for life and energy. These have been used as raw materials for bulk chemicals through fermentation as well as chemical transformations.1-4 Thermodynamic studies of saccharides in electrolyte solutions have importance in several fields of catalysis, biology, medicine and environment. Since the metabolism, synthesis, and transmembrane transport of saccharides are closely related to the concentration of various ions (H+, Na+, K+) in body fluids, so these physicochemical studies are quite helpful in understanding the biological processes.5-8 The phosphate salts being components of ADP, ATP, nucleic acids, etc., play important roles in biological processes. Therefore, the study of interactions of saccharides and their derivatives