The Preparation of TlBF4

Abstract

Thallium tetrafluoroborate is a useful reagent in chemistry labs for preparing tetrafluoroborate salts via abstraction of coordinated halide ions. Although many of these species can be isolated as perchlorates by reacting the appropriate parent halocompound with silver perchlorate, the explosive nature of many perchlorate salts prompted a search for substitutes. Tl[BF4], a good alternative to AgClO4, can be prepared by treating the metal or carbonate with aqueous tetrafluoroboric acid. However, the procedure outlined here, based on the reaction of thallium with hydrogen peroxide and tetrafluoroboric acid, is specially appropriate for teaching purposes.