Preparation of Elemental Bromine

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• published: 25 Oct 2012
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Liquid bromine is prepared in 95.2% yield from sodium bromide on a 1.5 mole scale. To a solution of NaBr in a minimum of water is added potassium permanganate, with stirring to keep it suspended since most of it will not dissolve immediately. After setting up the rest of the distillation apparatus, an excess of concentrated sulfuric acid is very slowly dripped in. Due to the exothermic nature of this process, the resulting heat causes bromine to self-distill. When water begins distilling over, the addition is stopped and the reaction mixture allowed to cool before resuming addition. These are reaction-size dependent and scaled-down preparations may not overheat or self-distill. External heating is applied toward the end to expel all bromine from the reaction mixture and maximize yield. The distillate consists of a biphasic mixture of bromine and water. The water is removed as completely as possible with a pipette and the bromine is then dried with concentrated sulfuric acid in a separatory funnel. Points on safety, storage, and decontamination of apparatus (for those lacking a fume hood) are covered. The intro music clip is from "Stealing Fat" by The Dust Brothers. I believe this falls under fair use.