SURFACTANT EFFECTS UPON CYCLIZATION OF O-(OMEGA-HALOALKOXY)PHENOXIDE IONS - THE ROLE OF PREMICELLAR ASSEMBLIES

Aqueous cationic micelles of R'NR(3)Br (R' = C12H25, R = Me, DoTABr; R' = C16H33, R = Me, CTABr; R' = C16H33, R = Bu, CTBABr) and R'NMe(2)(CH2)(4)NMe(2)R'2Br (R' = C16H33) increase rates of cyclization of o-(OC6H4O)-O--(CH2)(n-4)Y (X = Br, I) designated PhXn. Rate increases are small, except for PhI7 in CTBABr(1), and activation parameters are similar to those in water or 75% aqueous EtOH. In very dilute surfactant there are large rate increases, by factors of up to 39 with PhI16 in CTABr, but CTBABr is less effective. These rate increases are ascribed to formation of substrate-premicellar complexes of PhBr10, PhBr12, and PhX16 with all the surfactants. These complexes dissolve into normal micelles at higher [surfactant], and the unusual rate effects disappear.