CLEAVAGE OF 4-NITROPHENYL DIPHENYL PHOSPHATE BY ISOMERIC QUATERNARY PYRIDINIUM KETOXIMES-HOW CAN STRUCTURE AND LIPOPHILICITY OF FUNCTIONAL SURFACTANTS INFLUENCE THEIR REACTIVITY IN MICELLES AND MICROEMULSIONS?

摘要

Amphiphilic pyridinium ketoximes 4-[1-(hydroxyimino)alkyl]-1-methylpyridinium bromides (1) and 1-alkyl-4-[1-(hydroxyimino)ethyl]pyridinium bromides (2) are isomeric cationic surfactants bearing the nucleophilic hydroxyimino group.They differ in the position of the nucleophilic function relative to polar head group and hydrophobic alkyl chain.The 4-nitrophenyl diphenyl phosphate (PNPDPP) cleavage by the oximate anions generated from 1 and 2 was used as a model reaction for the investigation of the influence of the structure and lipophilicity of functional surfactants on their reactivity in micelles and micro-emulsions.The investigation of the model reaction in cationic micelles of hexadecyl-trimethylammonium bromide (CTAB),in non-ionic micelles (Triton X-100 and Bri] 35) and in o/w microemulsion (isooctane/phosphate buffer/CTAB and butan-1-ol) has revealed that it is the lipophilicity which is the most important factor influencing the localization and reactivity of functional surfactants in nanoaggregates.