Viscosity B-coefficients between 5° and 20° for glycolamide, glycine, and N-methylated glycines in aqueous solution
Abstract
The significance of viscosity B-coefficients for solutions of dipolar ions and non-electrolytes in water is discussed in the light of hydrodynamic theories of viscosity and the usefulness of the ratio B/Φ°2(Φ°2 is the limiting apparent molar volume of the solute) is stressed. Viscosity and density measurements have been made at 5°, 10°, 15°, and 20° on aqueous solutions of glycolamide, glycine, sarcosine, dimethyglycine, and betaine. Apparent molal volumes and viscosity B-coefficients have been calculated from these data. The results suggest that a charged nitrogen atom bearing 3 or 2 hydrogen atoms interacts strongly with the solvent water to form a primary solvation sheath. Substitution of two of the three hydrogen atoms, as in dimethylglycine, leads to a considerable reduction in solvation, and complete substitution, as in betaine, seems to prevent it entirely.
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