Effects of charge separation, effective concentration, and aggregate formation on the phase transfer catalyzed alkylation of phenol.

The factors that influence the rate of alkylation of phenol under phase transfer catalysis (PTC) have been investigated in detail. Six linear, symmetrical tetraalkylammonium cations, Me(4)N(+), Et(4)N(+), (n-Pr)(4)N(+), (n-Bu)(4)N(+), (n-Hex)(4)N(+), and (n-Oct)(4)N(+), were examined to compare the effects of cationic radius and lipophilicity on the rate of alkylation. Tetraalkylammonium phenoxide·phenol salts were prepared, and their intrinsic reactivity was determined from initial alkylation rates with n-butyl bromide in homogeneous solution.