SYNTHESIS OF ALKYLPHENYL ETHERS IN AQUEOUS SURFACTANT SOLUTIONS BY MICELLAR PHASE-TRANSFER CATALYSIS .1. SINGLE-PHASE SYSTEMS

Phase-transfer catalysis and micellar catalysis are two conventional m ethods of promoting reactions between lipophilic and hydrophilic react ants. Phase-transfer catalysis employs organic solvents that may be un desirable for both economic and:environmental reasons, while applicati on of micellar catalysis is limited by the relatively low solubilizati on capacities of surfactant solutions. Micellar phase-transfer catalys is is a process that combines the best aspects of both conventional me thods while avoiding some of the associated problems. Reaction systems consist of reactants, water, surfactant and a phase-transfer catalyst --no organic solvent is used. The surfactant acts to solubilize and em ulsify the lipophilic reactant, while the role of phase-transfer catal yst is to shuttle the hydrophilic reactant from the aqueous phase into the micellar environment where the reaction primarily takes place. Al kylation of phenol with 1-bromobutane was studied under phase-transfer , micellar, and micellar phase-transfer conditions in single-phase sol utions at relatively high reactant loadings. Cationic (dodecyltrimethy lammonium bromide), anionic (sodium dodecyl sulfate), and nonionic (di methyldodecylamine oxide) surfactants were compared. Higher conversion s with micellar phase-transfer catalysis over conventional micellar an d phase-transfer catalysis were observed in nonionic and anionic surfa ctant systems. For cationic surfactant systems, no significant advanta ge was observed for micellar phase-transfer catalysis in comparison to conventional micellar catalysis. The effect of cationic surfactant co ncentration was studied and an optimum surfactant concentration was ob served. Effects of initial reactant concentrations and two types of mi xing were also studied. Mixing effects were significant, suggesting th at mass transport rates of components between the aqueous and micellar pseudophases in these microheterogeneous systems at high reactant con centrations may affect reaction kinetics.