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Author: Subject: Bromine Source and Synthesis
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[*] posted on 9-7-2006 at 11:03


Some will still remain dissolved. Imagine crystallizing a salt from a solution and removing the crystals. Some salt will remain in the resultant solution.

Why not boil down some acid to concentrate it? With volumes this small, it shouldn't be too hard.




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[*] posted on 9-7-2006 at 11:33


I was thinking the other day while distilling bromine, that if the exit of the condensor was run through a tube full of calcium chloride, that the bromine would come out much dryer. Mainly for convenience as it would reduce the handling of the bromine.

I did the pour off ice thing yesterday. I got back around half of the bromine I started with. My bromine may have been damper than yours however.




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[*] posted on 9-7-2006 at 15:05


I am planing on preparing some con. sulfuric acid from my Rooto. Why should I be the only one who hasn't yet had the fun of doing this.

I don't think I have too big a fraction of ice in my bromine. But I may be surprised. I'll find out when I pour it into my con. acid.




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[*] posted on 12-7-2006 at 12:25


Today I made some bromine. To 6% H2O2 I added some KBr and diluted sulfuric acid (battery acid). The solution first turned green yellow than yellow than yellow orange orange than orange than orange red and now it is still orange red. During the evolution of bromine the solution heated up. I don't know how much reactants I used since I didn't measure anything.



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[*] posted on 13-7-2006 at 02:33


Today the solution is yellow. Probbably most of the bromine has evaporated.



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[*] posted on 13-7-2006 at 09:14


Today I made bromine again. I made a saturated solution of KBr ant to it I added some 12.5% Sodium hypochlorite solution (bleach). Then the solution first turned green because the bleach was green. A few minutes after that the solution turned from green to yellow and the smell of bromine appeared. Then to it I added 19% HCl. Instantly the solution turned from yellow to red. 2-3 minutes after adding the HCl I noticed some bromine vapour above the liquid.

Can this mixture be keept or does the bromine ned to be distilled imidiently out of the mixture? If it can be keept how long can it be keept?(1 year). I have to keep it because I do not have a distillation apartus right now and I t think I will get one in the near future.

[Edited on 13-7-2006 by Zinc]




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[*] posted on 13-7-2006 at 14:28


It can be kept if you can keep the bromine from evaporating. Bromine evaporates much more easily than water. The trick would be finding something to keep it in. Bromine attacks plastic and metals. You would need a glass bottle - not sure what you could use for a cap. A plastic cap might work for a few days.

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[*] posted on 13-7-2006 at 16:42


Bromine slowly reacts with water. Bromine water will slowly decompose into HBr solution and oxygen. I had some concentrated Br2 solution in a tightly closed bottle (teflon cap) and after a few weeks the color of the solution had lightened up very noticeably.
The decomposition can be slowed down by protecting the solution from light, as light speeds up the reaction of bromine with water.

To store your bromine, you have to isolate it by distillation, dry it by shaking with concentrated H2SO4 and redistill in a dried distillation setup.




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[*] posted on 13-7-2006 at 16:55


Also see:

http://www.sciencemadness.org/talk/viewthread.php?tid=5572#p...




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[*] posted on 31-8-2006 at 19:15


I was making a few mL's of bromine today in the garage, not distilling it, just sucking a few drops off the bottom of the reaction vessel. I wore a gasmask and opened the big garage door when the fumes built up too much. Could smell the bromine on my clothes after. According to someone else, there was a distinct 'chlorine like' smell in the garage, and I don't notice a thing. Later in the day I was using dilute ammonia when I realized 'oh shit, I can't even smell it'.
Halogens don't seem too good for ones sense of smell. I cannot even smell iodine anymore.

[Edited on 1-9-2006 by rogue chemist]
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[*] posted on 1-9-2006 at 01:09


It is temporary. Your sense of smell will return, I once had this while working with Cl2. It did not really irritate me (concentration was low), but the smell for a somewhat longer time apparently did suppress my sense of smell. Since then I have become more careful.



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[*] posted on 4-9-2006 at 07:15


Heh. Another thing to keep in mind. Even if you seal bromine into a glass ampoule, over time it will eventually eat through the weak point and start to leach out. I had my bromine in a sealed glass ampoule and after about two years it has started to leach out. I can tell because the smell of it is quite strong in the cabinet I have it stored in.



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[*] posted on 30-10-2006 at 10:24
1-Bromo-3-Chloro-5,5-dimethylhydantoin


This substance is easily found as "brominating tablets" and is used typically in pools or spas as a source of HOBr for decontamination.

I've been thinking of ways to utilize this as a bromine source and have done a few test tube scale reactions to show the liberation of Br is feasible.

The compound is only sparingly soluble in water but when placed in a test tube and boiled, a chlorine like odor is first noted (hypohalous acids) with much solid remaining undissolved. When NaNO2 is added to this solution, there is first the evolution of red gas which quickly dissolves in the water and creates a red solution. After a minute or so, the solution becomes clear with the dissolution of the initial undissolved substance (which releases colorless gas as it dissolves). Eventually a clear solution is obtained that shows slow evolution of colorless gas.

I am curious as to what is happening here. The in situ formation of ClNO2 and BrNO2 is possible with their quick reaction with excess NO2- and formation of transient N2O4.

Is is possible there is diazotization occuring on the nitrogens of dehalogenated 5,5-dimethylhydantoin? Could the colorless gas be N2 arising from the decomposition of this diazo compound? If so what would be the product?

1-Bromo-3-Chloro-5,5-dimethylhydantoin has potential as an interesting source of bromine IMHO.

I guess I'm just not certain what happens with hypohalous acids and nitrite ions in aqueous media.
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[*] posted on 30-10-2006 at 11:03


You would need to reduce 1-Bromo-3-Chloro-5,5-dimethylhydantoin with KBr, NaBr or other bromides in the presence of an acid in order to efficiently use it as a bromine source:

1-Bromo-3-Chloro-5,5-dimethylhydantoin(s) + 3KBr(aq) + H2SO4(aq) => 2Br2(l) + K2SO4(aq) + KCl(aq) + 5,5-dimethylhydantoin(s)

Using this exact stoichiometry is very important else you get other pathways reduce the yield of Br2.
If you want only the Br in 1-Bromo-3-Chloro-5,5-dimethylhydantoin you could reduce it with other reductants instead of bromides, but then you would obtain only half mol Br2 per one mol 1-Bromo-3-Chloro-5,5-dimethylhydantoin. For example, like you did with NaNO2, forming NaCl, NaNO3 and Br2. Sulfites and similar reducing agents would also work. However, like I said, it would be a waste of the oxidative power to do so while the reagent can be used to oxidize bromides instead.

Anyway, this has been discussed ad nauseam already. There was no need to open a new thread. UTFSE!




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[*] posted on 11-11-2006 at 08:50


I would think when bromine is chilled it can be stored in a glass flask. I have made a small HTML to the bromine and
chlorine synthesis. I hope it looks not to simple.
The HTML contains a chapther to the chlorine production per
electrolysis. I will not open e extra topic because of the
document. Somewhat a probelm is to prepare the layer in the
electrolysis cell. Have someone a idea to design the layer ? I
would guess you can produce bromine with this method. (NaBr in 5% H2SO4)

[Edited on 11-11-2006 by Mason_Grand_ANNdrews]

Attachment: Cl2-Br2.zip (571kB)
This file has been downloaded 853 times

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[*] posted on 22-11-2006 at 19:54


hi. I haven't got a clue 'bout chemistry, but I love this site! As I like to expand my knovledge radially, as far as I can get. I can grasp most "basic" concept, due to my backgroun, elsewhere I'm learning everyday STOP
Just for the press, sodium bromide was used MANY years ago as mild sedative/anaphrodisiac to prevent trooper gettin' crazy for sex abstinence! It was served insice milk/caffe/tea for breakfast.




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[*] posted on 29-11-2006 at 21:58


I used to react 2KBr + 2HNO3 -> 2KNO3 + Br2

I forget where the hydrogen went, probably excess water?

This was done in a glass retort which was heated in boiling water.

The distilled Br2 was collected in a test tube sitting in ice.

This was very effective. But you must empty out the potassium nitrate solution before it cools down as the KNO3 will crystalize in the retort.

On occasions, I noticed that when the KNO3 solution cooled, the solution crystalized and there was very little water left.

This is also a handy source of KNO3!

daryl
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[*] posted on 29-11-2006 at 22:10


In order for you to be oxidizing bromide to bromine the nitric has to be getting reduced. NO/NO2 was likely the result, completly unnoticable amidst the bromine vapours. Your bromine distillate may have contained an ammount of nitrosyl bromide as a result of this.



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[*] posted on 30-11-2006 at 01:09


Yes, I have done this experiment also. In fact, I found it to be unsuitable for making bromine of accetably purity. The bromine is increadibly impure and difficult to clean. I think that you obtain a mix of Br2, ONBr, NO2 and HNO3. When you add a drop of that bromine to water, it makes a very acid solution, while pure bromine should make an almost neutral solution.

Cleaning the Br2 is hard, because the impurities also are dark brown in the gas phase, and their boiling points also are fairly close (IIRC NO2: 26 C, Br2: 57 C). Repeated fractional distillation may give you purer Br2, but then there are easier ways to obtain relatively pure Br2.




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[*] posted on 30-11-2006 at 10:36


I have probably mentioned this earlier in this very thread, but I made it via oxidation by peroxysulfuric acid (caro's acid). The reaction is exothermic, enough so that the bromine readily distills over. An excess of sulfuric acid prevents much water being carried over, but the resultant bromine must still be shaken in a separatory funnel with concentrated sulfuric to rid it of residual water (as well as separate any HBr)

[Edited on 30-11-2006 by Fleaker]




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[*] posted on 30-11-2006 at 11:47


Quote:
Originally posted by woelen
When you add a drop of that bromine to water, it makes a very acid solution, while pure bromine should make an almost neutral solution.


Would washing it be any faster than fractional distillation, then? Water has a good affinity for HBr and HNO3, while the Br2 would tend to oxidize the other bits (NO2, ONBr?), or they would oxidize HBr... The result being some disproportion between Br2 <--> HBr and lower NOX <--> HNO3, if any of them be particularly favorable...

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[*] posted on 30-11-2006 at 12:09
your friend electrolysis


http://www.crscientific.com/article-bromine.html


it slides right off the graphite!!!!
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[*] posted on 1-1-2007 at 09:12


Quote:
Originally posted by daryl
I used to react 2KBr + 2HNO3 -> 2KNO3 + Br2

I forget where the hydrogen went, probably excess water?

This was done in a glass retort which was heated in boiling water.

The distilled Br2 was collected in a test tube sitting in ice.

This was very effective. But you must empty out the potassium nitrate solution before it cools down as the KNO3 will crystalize in the retort.

On occasions, I noticed that when the KNO3 solution cooled, the solution crystalized and there was very little water left.

This is also a handy source of KNO3!

daryl

you can make it with cold conc. HNO3 just add some NaNO2
and reaction starts at once even at 0ºC you can get bromine from the bottom of flask
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[*] posted on 4-1-2007 at 15:52


Quote:
Originally posted by evil_lurker
BCDMH is definately an interesting chemical and a darn hard one to figure out how to reduce.

The only literature on it, is what is provided by the pool and spa industry which is generally written for "those not skilled in the art".

The only practical way I can think of reducing BCDMH is by adding NaOH and heating then reducing the formed halogen compounds by adding sulfuric acid... which may or may not work.

When BCDMH is placed into water, it dissolves into hypohalous acids and hypohalic ions whose equilibrium is based upon temperature.

The addition of NaOH neutralizes the acids formed and turns them into hypohalites.

Adding heat causes the BCDMH to dissolve more readily and the hypohalite salts to undergo an auto-oxidation-decomposition into halides and halates.

The reaction would be:

BCDMH + 2 NaOH = 1 NaBr + 1 NaCl + 1 NaBrO + 1 NaClO

1 NaBrO + 1 NaClO ---- heat ---> 2 NaBr + 1 NaBrO3 + 2 NaCl + 1 NaClO3

(X represents a halogen)

6NaX + 2 NaXO3 + 3 H2SO4 = 4Br

I know the equation is unbalanced but it should liberate most of the available bromine due to the chlorine liberated at the same time as the bromine... the free chlorine would undergoes substitution reactions with the bromo compounds.

It is unknown whether or not the NaOH or Sulfuric acid would react with the spent DMH.


Would a simple substitution reaction work?

Cl2 + NaBrO3 => Br2 + NaClO3

I believe that NaBrO3 react with the HCl. That reaction takes place? I don't believe that it produces this reaction because it detach a gas:

NaBrO3 + HCl => NaCl + HBrO3

[Edited on 4-1-2007 by Filemon]
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[*] posted on 5-1-2007 at 01:40


Cl2 + NaBrO3 => Br2 + NaClO3
This reaction does not occur. Chorine replaces bromine from bromide, but not from bromate, because bromate is a stronger oxidizer than chlorine.

NaBrO3 + HCl => NaCl + HBrO3
This also does not occur. HCl reacts with bromate, forming chlorine gas, bromine chloride and water. The reverse also happens, an equilibrium is reached with bromate, bromine, chlorine and water. In fact, the precise conditions and reaction are fairly complex.




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