Bandil (Hive Bee)
12-10-01 19:37
No 246146
      Distillation of bromine  Bookmark   


Just though of an experiment swim did some time ago. He had a aq. soln of elemental bromine. Swim decided to get rid of that nasty bromine, so he distilled it! After some time the bromine stated giving of vapors, but did not really condense in the condesor. Damn, what a shame swim thought, but then he applied just a tiny-tiny amount of vacuum to suck over a lot of bromine and when the vapours was just about to enter the pump, he shut it of and a lot of bromine condesed in the condesor immediately. After that the bromine distilliation was a breeze. At the vacuum inlet of his setup, he plugged in a long hose, and ran it down the toilet. The vapors from the distilled bromine ran over in this hose and very slowly into the toilet(actually, most of the bromine stayed in the hose). Anyway, as the temp rose, swim thought the water was coming over, so he replaced the flask with a clean one and threw the lidded bromine flask into the freezer. After cooling, it actually looked quite clean. No water floating on top etc. Swim had no use for the bromine, so he just dumped it down the drain(dissolved in gassoline...).

The point of this tale is that bromine CAN be distilled with success. I do not know how pure the bromine in the receiver flask was, but i looked ok and was VERY heavy. After the vac-no.vac trick, the bromine condensed just fine. I suppose one could generate bromine from sulfuric acid/peroxide/bromide and distill to get pure bromine. Swims could hardly smell the bromine during the work and after, so it did not make a big mess..

12-12-01 17:46
No 246815
      Re: Distillation of bromine  Bookmark   

Preparation of bromine from potassium bromide, potassium permanganate and sulfuric acid (they collect the bromine under H2SO4):

J.Meyer, K.Pukall, Ph. Ch. (A) 145, 364 (1929)

Nach J.Meyer und K.Pukall wird ein besonders reines Brom durch Einwirkung von verd. Schwefelsäure auf ein Gemisch von Kaliumbromid und Kaliumpermanganat hergestellt. Das übergehende Brom wird unter konz. Schwefelsäure aufgefangen, nochmals über Kaliumbromid destilliert, um Chlor zu entfernen, und dann zur Beseitigung der letzten Reste von Schwefelsäure und Jod über Bariumoxid und Zinkoxid destilliert.