The reduction of fluorine-containing triarylmethanols by formic acid

Adrian F. Andrews, Raymond K. Mackie, John C. Walton*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

Triarylmethanols containing one or more fluorine substituants in the para-positions are converted by 90% formic acid into a mixture of the fluorine-containing triarylmethane, and a second component in which one fluorine has been replaced by a hydroxy-group. A mechanism is proposed which involves nucleophilic attack by water on the initial carbonium ion (4) with subsequent loss of hydrogen fluoride, to give the diphenyl-p-hydroxyphenylmethyl carbonium ion (6) which undergoes hydride transfer with formate to give the product. This mechanism was supported by the isolation of 4-hydroxytriphenylmethanol from the reaction involving 4-fluorotriphenylmethanol. Pentafluorophenyldiphenylmethanol on similar treatment gave 9-(pentafluorophenyl)fluorene, and 2-(trifluoromethyl)triphenylmethanol gave 9-(2-trifluoromethylphenyl)fluorene. Both reactions presumably occur via an intramolecular electrophilic aromatic substitution. The 19F and 13C n.m.r. spectra of the triarylmethanes and 9-aryl-fluorenes are reported and discussed.

Original languageEnglish
Pages (from-to)96-102
Number of pages7
JournalJournal of the Chemical Society, Perkin Transactions 2
Issue number1
Publication statusPublished - 1 Dec 1980

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