Insights on tert-butyl alkylation effects on fluorobenzene

Abstract

Directing effects of substituents on the benzene ring, ortho and para directors by electron donating groups and meta directors using electron withdrawing groups have been studied and reported widely. In particular and for many years, the directing effect of substituent groups in benzene have provided important basic under-standing of electrophilic aromatic substitution reactions. However, some deviations from what is known and expected from literature about electrophilic aromatic substitution is not adequately reported. This study reports two interesting products 1-tert-butyl-4-fluoro-2-methoxybenzene and 2-(tert-butyl)-5-fluorophenol for which the tert-butyl group are attached to unfavourable position, the ortho irrespective of the steric hindrance. The results indicate that steric hindrance sometimes is not only a sufficient factor in determining the directing effect of substituents and hence, this tendency compels for consideration of other factors including the resonance and inductive effects of fluorobenzene.