Solvent‐Free Fluorination of Electron‐Rich Aromatic Compounds with F‐TEDA‐BF₄: Toward “Dry” Processes

Abstract

An effective protocol for the solvent‐free fluorination of electron‐rich aromatic compounds with 1‐chloromethyl‐4‐fluoro‐1,4‐diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (F‐TEDA‐BF 4 ) is described. The protocol allows the easy and efficient isolation of fluorinated products in high yields and purities with low E factors (kg waste kg product –1 ) by vacuum‐sublimation without the use of any solvent. The solid‐state fluorination of naphthalen‐2‐ol was studied by differential thermal analysis, and scanning electron microscopy was used to obtain evidence for the solid‐state process. The crucial influence of alkali‐metal carbonates on the rate of the solvent‐free fluorination of hydroxynaphthalenes and estrone was demonstrated.