Kinetic demonstration of premicellar aggregation. The alkaline hydrolysis of N-hexadecyl-4-cyanopyridinium bromide

✍ Scribed by N. Hioka; M.J. Politi; H. Chaimovich

• Publisher: Elsevier Science
• Year: 1989
• Tongue: French
• Weight: 214 KB
• Volume: 30
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)80356-7

✦ Synopsis

The critical micelle concentration (CMC) of N-hexadecyl-4-cyanopyridinium (HCP) bromide, determined by conductivity or fluorescence quenching, was 7-8 * 10-4 M. The observed rate constants for the hydrolysis of HCP below the CMC increased with the concentration of this amphiphile from 2 * 10-b M up to the CMC. The product ratio (pyridone/amide) also varied with HCP concentration.

The analysis of both concentration-rate profiles and product composition demonstrated that HCP undergoes premicellar aggregation at concentrations one hundred fold lower than its CMC.

Micelle formation has been generally analyzed using two state models in which monomers and micelles constitute the two relevant states (1,Z). However, there is evidence for the