Collection of Czechoslovak Chemical Communications - digital archive 

Abstract

In this work we study influence of the length of the alkyl chain and temperature on critical micellar concentration (CMC) for cis and trans diastereoisomers of the N-alkyl-N-{[2-(benzyloxy)cyclohexylmethyl]}-N,N-dimethylammonium bromides in aqueous solutions using conductometric and spectrophotometric techniques. From the measured dependences, the degree of the counterion binding (β) and thermodynamic parameters of micellization (∆G_m⁰, ∆H_m⁰, ∆S_m⁰) were calculated and compared with the literature data on similar compounds. The results show that lengthening of the alkyl chain by one methylene group causes approximately a two-fold reduction in CMC. The β values decrease with temperature and with increasing length of the alkyl chain. While only a small decrease in the ∆G_m⁰ values (ca 1 kJ mol^-1) due to increasing temperature was found, the decrease in ∆H_m⁰ is much more pronounced.

Keywords: Phenylcarbamates; Micelles; Micellization; Temperature dependence.