Arenediazonium salts: New probes of the interfacial compositions of association colloids. 2. Binding constants of butanol and hexanol in aqueous three-component cetyltrimethylammonium bromide microemulsions

Article abstract of DOI:10.1021/ja00071a051

Yields of aryl ether products, 16-ArOR′, were determined by HPLC with excellent reproducibility from dediazoniation of 4-hexadecyl-2,6-dimethylbenzenediazonium tetrafluoroborate (16-ArN₂BF₄) bound to surfactant aggregates in three-component microemulsions of cetyltrimethylammonium bromide ((CTA)Br), H₂O, and an alcohol (R′OH), either 1-butanol (BuOH) or 1-hexanol (HexOH). The results were used to estimate the mole fractions (X_A) of R′OH bound to the microemulsions, their mole fraction partition constants (K_A), and mass action binding constants (K^A′). Values of K_A decrease with added R′OH consistent with literature results. Unexpectedly, values of A_A′ are constant at all values of X_A, indicating that (CTA)Br mixes ideally with both BuOH and HexOH in aqueous microemulsions and that binding of R′OH to (CTA)Br microemulsions is driven by a hydrophobic effect with minimal contributions from specific interactions between R′OH and (CTA)Br.