According to Thomas, TlBr3 ? 4H2O is prepared by treating an aqueous suspension of TIBr with excess Br2 until solution is complete and concentrating at 30-40°C (it starts to decomposeat higher temperatures as well as at too great concentrations,turning yellow). The concentrate is cooled until crystallization occurs. Persistent supersaturation, which occurs readily, is most easily remedied by abrupt cooling of one point in the solution with a stream of CO2 gas.
