Exchange of Chloride for Bromide

Via Anion Exchange Reactions 10.1.3.1. Exchange of Chloride for Bromide 

Addition of a concentrated solution of potassium bromide to an aqueous solution of a triaryl or a methyl diaryl telluronium chloride precipitates the telluronium bromides  

Examples of telluronium bromides prepared in this manner are  

The exchange of chloride for bromide can also be accomplished in methanolic medium, in which potassium chloride is insoluble  

Tris[4-hydroxy-2-methylphenyl] Telluronium Bromide An excess of a solution of potassium bromide in methanol is added to a saturated methanolic solution of the telluronium chloride and mixed thoroughly. Diethyl ether is added to the mixture to complete precipitation of potassium chloride and excess potassium bromide. The mixture is filtered, the filtrate is concentrated under vacuum, and the residue is recrystallized from diethyl ether or acetone yield 90%, m.p. 180 183°. 

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