Collect. Czech. Chem. Commun. 1997, 62, 1853-1862

An Influence of the Spatial Arrangement, Length of the Alkyl Chain and Temperature on Micellar Properties of N-Alkyl-N-{[2-(benzyloxy)cyclohexylmethyl]}-N,N-dimethylammonium Bromides in Aqueous Solutions

Jarmila Oremusová and Veronika Mislovičová

Institute of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University, 832 32 Bratislava, Slovak Republic


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 (∆Gm0, ∆Hm0, ∆Sm0) 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 ∆Gm0 values (ca 1 kJ mol-1) due to increasing temperature was found, the decrease in ∆Hm0 is much more pronounced.

Keywords: Phenylcarbamates; Micelles; Micellization; Temperature dependence.