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Author: Subject: Bromine Source and Synthesis
Blind Angel
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[*] posted on 10-4-2003 at 12:57
Bromine Source and Synthesis


I was wondering, is there any OTC source of bromine that can give good yield if we try to isolate it?
I know that most cough syrup contain DMX.HBr but i don't think that the bromine quantitie is enough to be useful...
any idea?


Edit: Merged with bromine thread as this contains plenty synthesis info :)

[Edited on 18-8-2004 by chemoleo]




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DDTea
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[*] posted on 10-4-2003 at 16:06


Sodium Bromide is sold at Pool and Patio stores under that very name: "Sodium Bromide." I don't remember specifically what it is used for though. However, some Pool and Patio guy was selling some of the stuff on eBay. It comes in a cylindrical container, and costs $9.99.

From there, the way I would go about isolating Bromine would be the same way as isolating Iodine from Iodide salts...

First react the NaBr with Sulfuric Acid to make Hydrogen Bromide, and then react the Hydrogen Bromide with a strong oxidizer to separate H2 and Br2.
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Blind Angel
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[*] posted on 10-4-2003 at 19:27


cool, didn't thought it was that easy lol



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PHILOU Zrealone
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smile.gif posted on 11-4-2003 at 05:01


NaBr + H2SO4 --> NaHSO4 + HBr(g)
8HBr + KMnO4 --> KBr + MnBr2 + 5/2 Br2(l/g) + 4H2O
KBr + H2SO4 --> KHSO4 + HBr(g)
MnBr2 + 2H2SO4 --> Mn(HSO4)2 + 2HBr(g)

So:
5NaBr + 5H2SO4 --> 5NaHSO4 + 5HBr(g)
5HBr +3H2SO4 + KMnO4 --> KHSO4 + Mg(HSO4)2 + 5/2Br2 + 4H2O

And in a one pot reaction:
5NaBr + 8H2SO4 + KMnO4 --> 5NaHSO4 + KHSO4 + Mg(HSO4)2 + 5/2 Br2 + 4H2O

Br2 can be extracted with CH2Cl2, CCl4, CHCl3, CCl3-CH3, ...

Beware of its low boiling point and heavy gaseous fumes that makes it very concentrate much more than Cl2; so even if a little less reactive the concentration can make it very dangerous to handle, to inhale or to get on the skin!!!!


:cool:




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[*] posted on 11-4-2003 at 07:54


How about bubbling chlorine gas through a sodium bromide solution. The chlorine should knock out the bromine and for sodium chloride with the bromine free. There are many methods for generating chlorine gas, but common bleach and sodium bisulfate does the trick.
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[*] posted on 11-4-2003 at 21:37


Yes that method does work 2 NaBr(aq)+Cl2 = 2NaCl(aq)+Br2. Watch out for the undissolved chlorine.



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[*] posted on 13-4-2003 at 21:34
Home Depot


sells NaBr soln ~35%. It comes as a part A and part B set meant for brominating the pool IIRC. The other part contains K2SO5 soln. ~ 33%. There .... mix the 2 and you get bromine water .:D
You might also find brominating tabs .... they, IIRC are cyanuric tribromide. I suppose you bubble Cl2 through a soln. of that to get Br2.




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[*] posted on 14-4-2003 at 20:10


Bubbling Cl2 through an NaBr solution does seem like a much cleaner way to go. However, with me, I avoid working with straight Chlorine gas whenever possible; it's really not something I enjoy being around, partly because of its irritating nature, and partly because i just don't like the smell :) .

However, from what I've read, straight Br2 doesn't seem much nicer...
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[*] posted on 15-4-2003 at 07:59


Yea, bromine gas smells quite like chlorine. They do sell respirators at the hardware store for 29.99 that will filter chlorine along with acid gases, vapors and mists. How about running the residual gas through a drying tube full of activated carbon or into a container with activated carbon in it. The chlorine should be absorbed and trapped in the pores of the charcoal.
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[*] posted on 15-4-2003 at 12:42
Is it not possible


for the free Br2 to react with the bubbling Cl2 in the solution to form other weird Halo-halides etc ???
Once you get Br2*H2O is it possible to distill it to get pure bromine ??
What do you need the Br2 for anyways ... Blind Angel ??
Oh and a Bromine burn ...... Hurts like a bitch and for a long time.




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Blind Angel
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[*] posted on 15-4-2003 at 13:35


Oh, i dont really need it, i just know source for Chlorine, (theoricly) for Fluorine and for Iodine but i didn't knew for bromine



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[*] posted on 12-7-2003 at 22:51


Coulden't you use HCl instead of pure Cl2 gas? I had used HCl and Ca(OCl)2 as a source of chlorine gas before. So HCl seems like a good possability maybe the Cl will displace the Br as its more electro negeative. HCl is OTC and very cheap its $3.79 a gallon (3785ml) 31% soloution.
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[*] posted on 13-7-2003 at 17:43


To avoid the cholorine gas all together I usually dissolve my sodium bromide in water and add calcium hypochlorite then once the two are mixed I add a bit of hydrochloric acid. The mix instantly turns red from bromine liberation and if the concentration is high enough you get some rewarding drops of dark red in the bottom of the reaction mixture. Then the bromine can be distilled off of course.
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[*] posted on 28-7-2003 at 00:30
Recent post at the Hive


Taken from the Hive:

Taken from 'Chemische experimente, die gelingen', dr. Hermann Rצmmp, 1939 p 49-50 :


BROMINE


In its pure form bromine is a deep red-brown coloured liquid from which evolve at room temperature redbrown, heavy, poisonous fumes that smell sharp and chlorine-like. Bromine fumes colour (potato-)starch yellow.

Bromine is very poisonous, 0.001% bromine fumes in the air are already dangerous by inhalation for a couple of hours. It also causes serious burns on the skin.
For storage use a bottle with a tightly-closing ground-glass stopcock. Do not use cork.

It is best to prepare pure bromine when needed, what is not used can then be dissolved in water, to make bromine-water which can be stored with much less dangers.

(Small scale) preparation:

In a mortar 5 grams of potassium bromide (KBr) is grinded to a powder, and this is mixed with 10 grams of manganese dioxide (MnO2) powder. This is then carefully added through the tubus to the retort , making sure no powder adheres to the neck of the retort. 150 cc of dilute sulfuric acid (1 part H2SO4 with 5 parts water) is then also added through the tubus of the retort.

In a fume-hood or in front of an open window the retort is carefully heated, and the recieving flask is well cooled in ice. The bromine fumes cool and liquify to form a small amount of liquid bromine.
Note: better use the fume-hood, especially for larger scale experiments.

1000 cc water can dissolve 35 g Br2, to make bromine-water.
This preparation is not adviced for the beginning experimenter !




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[*] posted on 18-8-2004 at 09:23
Bromine


Recently, I tried to make some bromine. I added NaOCl (bleach w/6% NaOCl), NaBr, and NaHSO4 to a flask and saw a nice reddish-tan color in the solution. Upon allowing it to sit for a few minutes, I noticed reddish-tan fumes above the solution and a black drop on the bottom, which I took to be bromine. I then put the flask in an ice bath in an attempt to condense some of the fumes and keep more of the stuff from evaporating. Wanting more bromine, I added more bleach to the solution. Nothing happened. Then, I added some more bisulfate. Still nothing. Thinking the solution had run out of Br- ions, I added some more NaBr. Now, this is the weird part: the salt dissolved and the bromine on the bottom disappeared! Does anyone know what happened? I know that I- forms the I3- ion, does bromine do anything similar?

Edit: Merged with existing thread.

[Edited on 18-8-2004 by chemoleo]
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[*] posted on 18-8-2004 at 10:14


It looks that way. Such a Br3- anion, like I3-, would be linear, with the central Br being trivalent and bearing the negative charge.

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[*] posted on 18-8-2004 at 11:51


Has anyone seen proof that such an ion definitely exists?
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[*] posted on 18-8-2004 at 12:21


A quick Google search for "tribromide ion" reveals a number of references to it.



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[*] posted on 18-8-2004 at 13:12
oops


I was just searching "Br3-". Curse my lack of googling (sp?) skills. :(

:edit:
Okay, I just added more hypochlorite/bisulfate to the solution. instead of giving me liquid bromine, I got a piss yellow solution! :mad: So, I've concluded that a slight excess of Br- in solution will destroy some Br2 and that an excess of Cl2 will also destroy it! :mad: Oh, well

[Edited on 18-8-2004 by procrastinator]
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[*] posted on 18-8-2004 at 13:38


I'd suggest you'd carefully boil down (not to dryness ofcourse)the solution outside to destroy all the hypochlorite that might still be in there.

Then put it in the freezer for a night and see what happens. If that doesn't work, KMnO4 + H2SO4 time baby! :D




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[*] posted on 18-8-2004 at 14:55


Quote:
Originally posted by vulture
I'd suggest you'd carefully boil down (not to dryness ofcourse)the solution outside to destroy all the hypochlorite that might still be in there.


I'm pretty sure that'll also make most of the bromine evaporate as well. Remember that I started out with only 6% NaOCl. Also I unfortunately don't have an expendable freezer. :P Although I'm putting a good deal of ice into it. Anyway, if I finally do get anything from this batch, I'll store it in a glass vial. Unfortunately, the underside of the cap is made of some junk which will no doubt liquefy on contact with the bromine just like it did with iodine. Does anyone have any ideas about insulating it with something inert? PE & PP probably won’t work and my PTFE tape is completely permeable to corrosive vapors.:(
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[*] posted on 18-8-2004 at 18:07


Bromine preparations:

Bromine presents a challenge different from producing chlorine as hydrobromic acid is not readily available.

As mentioned, permanganate, bromide, and acid produce bromine.

Hypochlorite, bromide, and acid produce bromine. (Either by the insitu production of chlorine and it's action on the bromide, or by the liberation of free bromine by hypochlorite oxidation and the bromine, or by the liberation of free bromine by one of the two aforementioned methods, followed by the replacement of the chloride in the hypochlorite with bromine, and the decomposition of the hypobromite anion.)

As shown in the picture that is attached to this, H2O2, H2SO4, and bromide produce bromine.

I've heard that adding concentrated H2SO4 to a bromide also produces an appreciable amount of free bromine by oxidizing the bromide anion in addition to the HBr produced.

Another source of bromine that is over the counter is 1-Bromo-3-chloro-5, 5-dimethylhydantoin which is one of the bromine carriers that is available for treating spas. But I'm not sure how one would recover the bromine from this.

Bromine is my favorite halogen. My method with H2O2 and H2SO4 only gives a 50% or so yeild with respect to sodium bromide, some of this is due to inefficent condensing and evaporations from my receiving flask, but these really are not acceptable looses.

Br2setup.jpg - 49kB




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[*] posted on 18-8-2004 at 18:28
H2O2 method


So, adding caro's acid to a bromide should give free Br2. Couldn't it just be decanted instead of having to be distilled? NaHSO4, HBr, H2O, H2SO4, H2SO5 should form a separate layer from the nonpolar Br2, right?

OT, I'm slowly realizing that my name may make me seem kind of...dumb. Is there any way to change it or do I have to re-register?
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[*] posted on 18-8-2004 at 18:41


The bromine could probably be siphoned off, but my main reason for distilling is that the reaction is exothermic so distilling actually requires no heat. I dissolve my NaBr in 35% H2O2 and add the H2SO4 (conc.) slowly with stirring, the Br2 comes off.

So if you keep the reaction mixture very cool it should keep the Br2 in the main mix though.

And yes procrastinator, I believe you have to reregister.

One other thing that I mentioned before, the activity series of the halogens when it comes to oxocompounds is reversed. Therefore free bromine will replace chlorine in hypochlorite.

Addition of hydrobromic acid to a solution of bromate results in very high, almost quantitative bromine yields.




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[*] posted on 19-8-2004 at 11:52
bromine


When I was young, I used to love distilling bromine, I think it came from potassium bromide and I collected it under water cooled with an ice bath. A lower layer of bromine formed once the water was saturated with bromine. Makes you cough.
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