Synthesis of 6,13-difluoropentacene

Abstract

6,13-Difluoropentacene was synthesized from 1,4-difluorobenzene. Friedel-Crafts annulation of the latter with phthalic anhydride and subsequent reduction of the anthraquinone gave 1,4-difluoroanthracene. After ortho-lithiation and reaction with phthalic anhydride a carboxylic acid was obtained whose Friedel-Crafts acylation and subsequent reductive removal of the oxygen-functionalities resulted in the formation of the target compound. The HOMO-LUMO gap of 6,13-difluoropentacene was determined via UV-vis spectroscopy and compared to other fluorinated pentacenes.

Keywords: Friedel–Crafts reaction; fluorinated acenes; ortho-lithiation; synthesis.