AbstractPhenols containing a freeorthoposition can be alkylated byortho‐t‐butyl‐phenols in the presence of catalytic amounts ofp‐toluenesulfonic acid at temperatures between ∼ 60 and 100°.Using,e.g., 2,6‐di‐t‐butyl‐p‐cresol as an alkylating agent, trans‐t‐butylations were carried out with a number ofpara‐ andortho‐substituted phenols.The above mentioned reactions lead to equilibria of the type: 2,6‐di‐t‐butyl‐p‐ZC6H2OH +p‐ZC6H4OH ⇄ 2 (2‐t‐butyl‐p‐ZC6H3OH)The equilibrium constant (K= 43 at 80°C) is independent of the substituent present in the phenolic nucleus.For Z =p‐CH3the energy of activation of the forward reaction amounts to 18.5 kcal/mole.Ortho‐paraisomerization occurs, when the 3, 4 and 5 positions are free. Several differences between the catalytic effects o