The Nature of the Cosolvent Effects of Sugars on the Aqueous Solubilities of Hydrocarbons

Abstract

Pentoses (d-arabinose, d-xylose, and d-ribose) and hexoses (d-glucose, d-galactose, and d-mannose) increased appreciably the aqueous solubilities of naphthalene and biphenyl, but all the sugars except ribose caused solubility depression of 1-octanol. Ribose increased most effectively the hydrocarbon solubilities while glucose showed the least effect. Deoxy sugars and methyl glycosides were more effective than the corresponding unsubstituted sugars. As to maltodextrins the solubility-increasing effect per glucose unit is cooperatively enhanced as the number of glucose residue increases. On the basis of these data, it was concluded that the cosolvent effects of the sugars are primarily brought about by their nonpolar interactions with hydrocarbons that occur at the structure-breaking sites of the sugar molecules.