Nucleophilic C-Alkylation of Phenols with Alcohols Promoted by Anatase TiO₂

Key words

aromatic alkylation - anatase TiO₂ - nucleophilic aromatic functionalization

Significance

C-alkylation of phenols with alcohols was promoted by anatase TiO₂ at 300 °C. Phenol reacted with n-propyl alcohol to give 2-propylphenol with 87% selectivity. Rutile TiO₂, a stable polymorphs titania, did not promote the C-alkylation (ca. 0% phenol conversion). Phenols bearing 3-chloro and 3-methyl substituents showed a similar trend of selectivity for the alkylation, although they have opposite electronic effects.

Comment

DFT calculations as well as experimental observations indicate that the main reaction pathway of C-alkylation is different from the conventional Friedel-Crafts alkylation. The authors have proposed that the reaction proceeds via a Ti=C intermediate which reacted with a Ti-activated phenol nucleophilically at the ortho-position.

Publication History

Article published online:
14 October 2023