Hatsuho Uedaira

Sugar-Water Interaction from Diffusion Measurements

The diffusion coefficients of deoxyribose and ribose in water were measured at 25°C. The Stokes-Einstein relation for mono-, di-, and tri-saccharides are discussed. The diffusion coefficient at infinite dilution Do for deoxyribose was the largest among these sugars. It appears that the deoxyribose breaks local water structure but the ribose hardly affects the structure. Do correlates well with the mean number of e-OH groups in the sugar molecule. It is suggested that the mean number of e-OH groups is a good parameter to describe the properties of sugar hydration.

Association of azo dyes and effect of sucrose on the association in the aqueous solution

SummaryThe electrolytic conductances of two dyes, Zambesi Black D (dye D) and Aniline-p-cresidine-γ-acid sodium salt (dye A) in the aqueous and the aqueous sucrose solutions have been investigated. The dye A is more aggregated and its self-association is more affected by sucrose than dye D. From these results, it is shown that the hydrophobic bonding plays an important part in association of dye, and that difference of the self-association between dyes, which have similar molecular structure, is explained by the difference of hydrophobic bonding.ZusammenfassungDie elektrolytischen Leitfähigkeiten zweier Farbstoff Zambesi Schwarz D und Anilin-p-Cresidin-γ-Säure als Na-Salz (Farbstoff A) in Wasser und wäßrigen Zuckerlösungen wurden untersucht. Farbstoff A ist stärker aggregiert und seine Selbstassoziation stärker von Zucker beeinflußt als der von D. Aus diesen Resultaten wird gezeigt, daß die Wasserstoffbrückenbindung eine wichtige Rolle in der Assoziation von Farbstoff besitzt und daß der Unterschied in der Eigenassoziation zwischen Farbstoffen von ähnlicher molekularer Struktur durch die Verschiedenheit der Wasserstoff brückenbindung erklärbar ist.