Studies of viscosities of dilute solutions of alkylamines in non-electrolyte solvents: III. Alkylamines in butanols at 303.15 K

Viscosities η of dilute solutions of n-propylamine, n-butylamine, di-n-propylamine, di-n-butylamine, triethylamine, tri-n-propylamine, and tri-n-butylamine in 1-butanol and 2-butanol at 303.15 K have been measured. The specific viscosities (η−ηSo)/ηSo and viscosity deviations Δη   have been calculated. The values of (η−ηSo)/ηSo and Δη are negative and their magnitude increases with the increase in concentration of alkylamine. The values of excess Gibbs energy of activation ΔG*E of viscous flow determined based on Eyring's theory of absolute reaction rates are positive for alkylamine solutions in both the butanols. The strong solute–solvent interactions leading to the structure formation between butanol and alkylamine molecules through H-bondings are observed. The results have been further analyzed in terms of Herskovits and Kelly equation and Nakagawa equation. The values of viscosity increment (   in Herskovits and Kelly equation and coefficient B′intB′int in Nakagawa equation are negative for all presently investigated alkylamine solutions.