ARENEDIAZONIUM SALTS - NEW PROBES OF THE INTERFACIAL COMPOSITIONS OF ASSOCIATION COLLOIDS .3. DISTRIBUTIONS OF BUTANOL, HEXANOL, AND WATER IN 4-COMPONENT CATIONIC MICROEMULSIONS

Product yields from dediazoniation of 4-hexadecyl-2,6-dimethylbenzened iazonium tetrafluoroborate, 16-ArN2BF4, bound to aggregates of four-co mponent microemulsions composed of cetyltrimethylammonium bromide, (CT A)Br, H2O, hexadecane, and an alcohol, R'OH, either 1-butanol, BuOH, o r 1-hexanol, HexOH, were used to estimate changes in H2O and R'OH comp ositions at the microemulsion interface over a range of microemulsion compositions. Analysis of % 16-ArOR'/% 16-ArOH product percent yield r atios obtained in the water-in-oil microemulsion region of the phase d iagram at low water content show that mass action binding constants fo r the distributions of BuOH and HexOH between the interfacial and oil regions in these microemulsions are independent of [R'OH]. These resul ts indicate that (CTA)Br mixes ideally with both alcohols and that alc ohol binding is driven primarily by the hydrophobic effect with minima l contributions from specific interactions between R'OH and (CTA)Br. W e also show that our approach provides estimates of molar concentratio ns of BuOH and H2O in the oil, interfacial, and water regions at any c omposition of these 4-component microemulsions. Changes in the molar c oncentrations of H2O and BuOH mark the oil-in-water droplets to bicont inuous to water-in-oil droplets transitions. Potential applications of the dediazoniation method are discussed.