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Author: Subject: Bromine Source and Synthesis
verode
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[*] posted on 22-3-2005 at 06:29


the NaBr with ice + Cl2+ some HCl
You get Br2 Its should be acid becose it could happen Br->HBrO3
The Br2(l) is heavy than water
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[*] posted on 18-5-2005 at 20:26


I'm working on a method that allows absolutely no formation of halohalides. I also don't want to use H2SO4 because the heat spike volitalizes so much Bromine. So, the current results.

I was not in a mood to measure very carefully and I didn't have my scale there, so its pinch of this, dash of that chemistry. I used Sodium Bromide, then added 6% bleach and swirled the mixture until it dissolved all the sodium bromide to form an orange solution. To this was added citric acid. Fizzing started immediately, but died down quickly, and the solution turned a deeper orange. Remembering H2O2 as an oxidizing agent, some was added. The solution turned white and what little bromine was on the bottom dissolved. More citric acid was added, but the orange color did not reappear. So, to decompose the peroxide, potassium permanganate was added (~5g). The solution turned purple, then a pond scum color, as a dense oily <b>ORGANIC</b> settled to the bottom. That is when I left. Did I manage to make bromoform? Or is it some other chlorinated/brominated organic? I don't know. The work continues.
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Rosco Bodine
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[*] posted on 18-5-2005 at 20:49


Anybody tried the reaction of TCCA with sodium bromide solution ?

Evidently what results is sodium cyanurate
in solution , and bromine on the bottom .

See the patent GB1401120 . The file is attached to one of the recent posts in the hydrazine thread .
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[*] posted on 19-5-2005 at 00:16


I tried the reaction. According to the patent, the TCCA/NaCl reaction produces appreciable free halogen only when the solution is heated, strongly illuminated, or placed under reduced pressure. There isn't a lot of free halogen produced otherwise. The same seems to be true with bromine: the sodium bromide/TCCA mixture instantly turns orange on addition of water, and you can smell the bromine, but there is no liquid bromine formed, nor any visible bromine fumes. The liquid isn't the dark color expected of saturated bromine water.

On acidification with H2SO4, the reaction began with more vigor. This is not especially surprising; the TCCA seems to act like more conventional oxidizers in the production of bromine. The addition of conc. H2SO4 heated the mixture, and after a couple small pipettes of acid, the mixture was merrily fizzing out vapors. I would be interested in seeing what the effects of heating alone without acid addition are, but that will have to wait until the fumes have cleared out of my workspace.




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Rosco Bodine
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[*] posted on 19-5-2005 at 00:28


You might try putting a layer of ether
or methylene chloride on top of the mixture and setting it in sunlight .

The solvent should move the equilibrium to the right the same as heating or vacuum , and so will the sunlight .

Of course shaking it up once in awhile or stirring it should help too and the color and the bromine should end up in the solvent .
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[*] posted on 23-5-2005 at 15:05


Many ethers are oxidised to esters by bromine, the reaction product HBr being also able to cleave ether bonds, so methylene chloride is better.
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[*] posted on 24-5-2005 at 02:26


The problem here is separating the two afterwards. They're both nonpolar and have about the same boiling point. Separation would be very difficult without a good fractionating setup.
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[*] posted on 24-5-2005 at 04:24


Just make sure you don't get bromine onto your hands. I once was helping to move a few items off a bench in a friends lab at work one day. I grabbed the capped bottle of bromine to move it to the shelves. The lid wasn't on tight and it ran over my fingers. Lots of water washing didn't help much. My fingers were actually the minor pain. The thinner skin of the webbing was eaten away. First orange, then white, now a scarred pink. This is one of those memories I won't soon forget.



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[*] posted on 24-5-2005 at 13:14


Don’t worry, I’m sure that most of us here know what we’re doing. Still, bromine burns are definitely something to avoid.
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[*] posted on 11-6-2005 at 01:59


Nice :D Looking forward to reading more about it.



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[*] posted on 13-7-2005 at 19:04


In to route to hydrogen bromide gas the reaction occurs in the following way:

NaBr + H2SO4 --> NaHSO4 + HBr(g)

My question: When one does this reaction wouldn't the HBr react with the remaining H2SO4 and since HBr is such a strong reducer, wouldn't it be oxidized by the H2SO4 and free the bromine?
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[*] posted on 13-7-2005 at 19:14


Yes, that is what happens to some extent. Small samples of bromine are commonly prepared like this.
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[*] posted on 13-7-2005 at 19:55


If that is the case, is there a more desirable way to produce HBr gas without the contamination of free bromine?

I guess one could always perform the reaction and then heat the reagents until the HBr comes out of the solution. Also perhaps the H2SO4 could be dilluted as well the the NaBr be aqueous solution
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[*] posted on 14-7-2005 at 06:13
Non-oxidising acid


The use of the non-oxidising phosphoric acid and a potassium or sodium bromide salt should produce bromine free hydrogen bromide gas.

H3PO4 + KBr ---> HBr + KH2PO4
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[*] posted on 14-7-2005 at 08:53


Whaddabout plain HCl?

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[*] posted on 14-7-2005 at 10:05


Probably quite a lot of HCl impurities mixed with the HBr.
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[*] posted on 14-7-2005 at 10:30


Wa gwan thanks for the info I should have thought of that.
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[*] posted on 17-7-2005 at 01:54


You can produce bromine with conc. sulphuric acid and potasium bromide.
It reacts in two steps:
H2SO4+2KBr-->2HBr+K2SO4
now the concentrated sulphuric acid will oxidise the HBr to water and bromine.
H2SO4+2HBr-->Br2+SO2+2H2O
All in all you can say:
2H2SO4+2KBr-->K2SO4+2H2O+SO2+Br2
You can save oxidation agents like KMnO4, MnO2, H2O2, etc. It´s a very cheap producing methode.

[Edited on 17-7-2005 by mantis]
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[*] posted on 24-2-2006 at 15:19


Quote:
Originally posted by rogue chemist
"Causes irritation to the gastrointestinal tract. Symptoms may include nausea, vomiting and diarrhea. May cause abdominal pain, reduced urinary output, low blood pressure, methemoglobinemia, convulsions, liver and kidney damage, and coma. Cyanosis may occur as a later symptom. Death may occur from renal failure, within 1 to 2 weeks. Estimated lethal dose is 4 grams."

Sounds like something really great to have in food products. :o The MSDS must be exagerating...
Source:
http://www.jtbaker.com/msds/englishhtml/p5576.htm


I bought a loaf of "White Enriched Bread" at the supermarket recently. I happened to notice on the label:
BROMATE FREE
UNBLEACHED FLOUR
NO ARTIFICIAL PRESERVATIVES

So apparently bromates are used in baking some types of white bread.
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[*] posted on 24-2-2006 at 19:14


Well, bromate is a reasonable oxidizer, no? Probably serves the same purpose as OCl, bleaching (hence unbleached flour).

Tim




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[*] posted on 25-2-2006 at 14:41


Quote:
Well, bromate is a reasonable oxidizer, no?

yes, but it need a acid medium.
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[*] posted on 5-3-2006 at 00:01
Safer Bromine Source


This isn't exactly OTC, but pyridinium hydrobromide perbromide makes a good brominating agent, and it is also much safer to use if you have limited space/ don't have a fume hood. The perbromide forms a rapid equilibrium with pyridinium hydrobromide and bromine, so the bromine concentration is fairly low. However, it is convenient, safe, and easy to work with. I'm not sure what it costs, but I imagine that it will be worth it. It might not be the best for working on a large scale, but I know that it's perfect for my purposes. You can run the bromination in GAA and you'll be all set.

Djerassi, C.; Scholz, C.R. J. Am. Chem. Soc. 1948, 70, 417.
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[*] posted on 5-3-2006 at 15:08


The only bromine source I can get hold of is 1-bromo-3-chloro-5,5-dimethylhydantoin (BrClC<sub>5</sub>H<sub>6</sub>O<sub>2</sub>N<sub>2</sub>;). Can this be used to produce bromine?


Mike.
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[*] posted on 5-3-2006 at 16:43
1-bromo-3-chloro-5,5-dimethylhydantoin


Sure, it looks like a strong brominating agent. The trouble is, that it will also be a chlorinating agent. Interesting chemical, actually, I would very much like know if it would be useful. Some reactions don't require a specific halogen, just that the molecule be halogenated... so if a few chlorines mucking about aren't a problem.... I imagine that you could put this to use, though I am hesitant to comment on the synthetic utility of it.

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[*] posted on 5-3-2006 at 16:56


And if nothing else, the chlorine should displace the bromine and get you pure bromine, no?

Interesting molecule, looks like a variation on TCCA I'd say?

Tim




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