Etilefrine HCl was found to be a surface active molecule. Using
the dependence of conductivity values on concentration, critical
micelle concentrations (CMC) and degree of ionization (a) of etilefrine
HCl in absence and presence of NaCl at different temperatures
were calculated. The presence of different concentrations of NaCl
was found to decrease the CMC while increasing the temperature
leads to an increase followed by a decrease in the CMC values
(inverted U-shaped pattern). 1H NMR was also applied to
determine the CMC of etilefrine HCl. Applying the classical charged
pseudophase separation model and using the obtained CMC and
(a) values, various thermodynamic parameters, such as standard
Gibbs free energy, DG
m, enthalpy, DH
m, and entropy, DS
m, of
micellization were also calculated. The self-association of etilefrine
HCl was found to be a thermodynamically favored and entropy
driven process. The enthalpy–entropy compensation phenomenon
was observed in the investigated systems.