Colloid and Polymer Science

, Volume 278, Issue 1, pp 8–14

Complexation in the heptanoic acid–heptylamine system

  • S. Karlsson
  • S. Backlund
  • R. Friman
ORIGINAL CONTRIBUTION

DOI: 10.1007/s003960050002

Cite this article as:
Karlsson, S., Backlund, S. & Friman, R. Colloid Polym Sci (2000) 278: 8. doi:10.1007/s003960050002

Abstract

The complexation between heptylamine and heptanoic acid has been elucidated at 298.15 K using spectroscopic methods and also by measuring macroscopic quantities such as viscosity, conductivity and surface tension. Fourier transform IR and 13C NMR measurements point towards the existence of a compound consisting of one amine molecule and one acid molecule in an equimolecular mixing ratio. These suggestions are supported by viscosity and surface tension measurements. This compound is further able to interact with excess acid, but similar behaviour is not observed with excess amine. The equimolecular compound behaves like a catanionic surfactant; this is seen in the phase diagram for the heptylamine–heptanoic acid–water system at 298.15 K, where the dominating phase is the lamellar liquid-crystalline phase. This phase is in equilibrium with almost pure water. At low water content a solution phase extending from the binary heptylamine–heptanoic acid axis and covering all mixing ratios between the amine and the acid is also present.

Key words Alkanoic acidAlkylamineCatanionic surfactantTernary phase diagram

Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • S. Karlsson
    • 1
  • S. Backlund
    • 1
  • R. Friman
    • 1
  1. 1.Department of Physical Chemistry Åbo Akademi University Porthaninkatu 3-5 FIN-20500 Turku, Finland e-mail: jkarlsso@abo.fiFI