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Jor
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bromine
Hello,
Im thinking about buying some bromine.
Im cuite worried about the stories , that i is almost impossible to keep this beast of a chemical inside. It will eat through anything. So I was
thinking , Let buy it from Merck, because I cant imagine Merck packs it wrong? Or is it really that nasty, that it will go through anything (I would
expect Merck to put in TEFLON)? Have you guys had experience with this?
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kilowatt
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Glass is completely impervious to bromine, as are passivated metals under normal conditions (as long as the bromine is dry) like nickel or monel,
chrome, titanium, etc. The difficulty in containing it is due only to its volatility. It will slowly diffuse through all but the densest grades of
teflon and other plastics due to their porosity. Just keep it in a glass bottle with a ground glass stopper and some fluorosilicone grease or teflon
tape to help make the seal. Refrigeration helps keep the volatility down but beware that even when a small amount leaks out the fridge will smell
like bromine forever.
I'm pretty sure there is at least one thread on this site regarding ampouling bromine, which may be your best bet if you just want to keep a small
amount. If you aren't using it any time soon you may as well just keep it in a salt form from such as ammonium bromide or alkali bromide, and extract
it when you need it. It's MUCH easier and cheaper to buy that way too. It isn't any harder to isolate than chlorine or iodine.
The real moral of the story is that if you don't know how to store or handle it properly you probably shouldn't be using it.
The mind cannot decide the truth; it can only find the truth.
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ScienceGeek
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I bought some Bromine from Aldrich, and it came in a sealed tin- can in a glass bottle with a teflon- lined cap. I store it in an airtight space, and
everytime I open the door, small amounts of Bromine smell seeps out.
Although it doesn't pose a risk of inhalation, it does smell up the place.
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MagicJigPipe
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"It isn't any harder to isolate than chlorine or iodine. "
I beg to differ. Aside from fluorine and astatine, bromine is the hardest halogen to isolate. Mostly because it's a liquid.
IMO it is in this order from easiest to hardest to isolate:
Iodine
Chlorine
Bromine
Fluorine
Astatine
I've never messed with fluorine or astatine but at least fluorine can be obtained via electrolysis. I'm sure astatine would be easier to isolate but
it's virtually unatainable.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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kilowatt
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My point is that it isn't that difficult, and especially not difficult enough to make it worth purchasing in elemental form when its salts are so
readily available. Electrolysis in a separatory funnel followed by distillation of the liquid that sinks out works. IMO electrolysis in a membrane
cell or amalgam cell followed by purification is the easiest way to isolate any halogen (except fluorine which requires a special cell at low
temperature); even the popular chemical methods of iodine extraction are finicky and leave much to be desired.
The mind cannot decide the truth; it can only find the truth.
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Sauron
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The volatility is a function of temperature. Refrigerate the Br2 and it is tame as a kitten. Even if you don't refrigerate (In which case you will get
some diffusion losses) you chould chill the bottle in an ice bath prior to opening.
I have a 100 ml Hamilton glass syringe with PTFE Luer-lok 'needle" for transfer of this sort of thing.
Sic gorgeamus a los subjectatus nunc.
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woelen
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Buying Merck bromine is NOT a guarantee for a good bottle. I read a thread on www.versuchschemie.de about really rotten bromine bottles, which were purchased from Merck. Things were so bad, that after some time, there even
appeared crystals in the bromine, and that can only be a big impurity. Bromnine never forms crystals at room temperature.
I have made my bromine from bromate and bromide, using an all glass distillation setup and drying it with conc. H2SO4. I posted a thread about that
some time ago, it is here on sciencemadness.
I now have appr. 200 ml of bromine in a glass bottle, with a screw-cap, which has a PTFE liner inside, and teflon tape wrapped around the rim of the
bottle. It stores well, but around the cap, I notice a faint smell of Br2. Summer still has to come...
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Nicodem
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Standard Fluka reagent bottles (the brown ones with the famous blue stoppers) are great for storing bromine and other such nasties. Never noticed any
leak and hold a fair amount of internal overpressure. They are also easy to find since for some reason most labs just throw them away.
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YT2095
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| Quote: | Originally posted by MagicJigPipe
I beg to differ. Aside from fluorine and astatine, bromine is the hardest halogen to isolate. Mostly because it's a liquid.
IMO it is in this order from easiest to hardest to isolate:
Iodine
Chlorine
Bromine
Fluorine
Astatine
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actually I beg to differ here, Bromine is Very easy to isolate!
more so than Iodine.
in fact I would go far as to say it`s one of the "Nicer" halogens to isolate and use, and for the Most part it`s very "Well Behaved", although storage
for some Can present problems.
a Nice way to do it however is to use the method Woelen has outlined on his site.
I keep a jar with the correct mixture of KBr and KBrO3 as a fine powder.
for Me this is Instant-Bromine-Just-Add-Acid.
from there you can make as Little or as Much as you like at any time and it`s done within a minute or 2.
there`s no storage issues and it will last forever like this, and if I can`t wait the 1-2 minutes for the bromine liquid to form, then I have no
business being in the Lab doing Any experiment that will use it anyway! 
edit: as for Astatine, you wouldn`t want it anyway, it`s radioactive!
[Edited on 7-3-2008 by YT2095]
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
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woelen
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Yes, I agree with YT2095. If you acidify the 5 : 1 molar mix of KBr and KBrO3 with a suitable amount of 30% H2SO4 (for each mol of KBrO3 use well over
3 mols of H2SO4) , then within a few minutes you have a nice blob of bromine at the bottom, which can be collected using a pipette. In this way, you
isolate approximately 75% of the bromine. If you want all bromine, then you need a distillation setup.
I make the following list of ease of separation of the halogens:
1) Br2 and Cl2
2) I2
3) F2
[Edited on 7-3-08 by woelen]
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MagicJigPipe
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Okay, I suppose I meant decent amounts of pure Br2. That is much more difficult than iodine or any gas. How could it be easier than I2? I consider
filtering and washing a solid the simplest of all tasks in the lab.
All I'm saying is the only halogen I have EVER had any problems getting by itself, pure, is Br2. Chlorine is easily seperated from liquid because
it's a gas and iodine is easily seperated from a liquid because it's a solid. This makes perfect sense to me.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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woelen
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No, I still do not agree. Iodine is formed as a fine precipitate, which is wet. Separating it from the adhering water is not that easy, although it
certainly can be done. Simply heating it in order to get rid of the water is no option, the iodine also evaporates quite a lot. You need to sublime
the iodine at least two times in order to het rid of the water. I do not know a highly volatile solvent, which easily rinses off the water and does
not dissolve the iodine. Stuff like ether, acetone, alcohol etc. are of no use here.
Bromine, which separates as liquid, is easily pipetted without any water. The bromine, made this way already is quite pure. Solubility of water in
bromine is very low (only appr. 0.05% by weight). The biggest problem is not the water, dissolved in the bromine, but the drops of water, which always
will stick to your pipette and float on top of the bromine. If you accept another 10% loss of the bromine, then you could make almost perfectly dry
bromine simply by pipetting it.
Getting it really dry can be done by pouring concentrated sulphuric acid on the bromine and keeping it that way:
[Edited on 7-3-08 by woelen]
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YT2095
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Bromine`s a gas too with a little heat (and I mean a Little!).
what do you need to get a pure Br2 liquid?
1) make it as outlined above
2) either turn it to a gas and treat like Cl2 OR...
3) pipette it out into a test tube and add conc sulphuric.
it really gives you the best of Both worlds, as the gas is Clearly visible as is the liquid.
Fl2 would be the last on the list, and I would agree with, and you may as well forget At2, think Beta decay of Polonium!
anyway, we`re going Slightly off topic here, I strongly recommend the method Woelen and I employ (and probably a good many others here too), if it
aint broken... Don`t fix it!
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
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-jeffB
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| Quote: | Originally posted by kilowatt
IMO electrolysis in a membrane cell or amalgam cell followed by purification is the easiest way to isolate any halogen (except fluorine which requires
a special cell at low temperature); even the popular chemical methods of iodine extraction are finicky and leave much to be desired.
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If I electrolyze NaI or KI, I produce iodine, but it immediately complexes with the remaining iodide and goes into solution. How do you isolate it?
I produced Br2 and I2 by chemical oxidation of bromides and iodides, then extracted them in CCl4. (Back in the good old days, when I had a gallon of
technical CCl4, and was dumb enough to use it with mediocre ventilation.) This worked well, and the CCl4 solutions were always pretty...
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Jor
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| Quote: | Originally posted by woelen
No, I still do not agree. Iodine is formed as a fine precipitate, which is wet. Separating it from the adhering water is not that easy, although it
certainly can be done. Simply heating it in order to get rid of the water is no option, the iodine also evaporates quite a lot. You need to sublime
the iodine at least two times in order to het rid of the water. I do not know a highly volatile solvent, which easily rinses off the water and does
not dissolve the iodine. Stuff like ether, acetone, alcohol etc. are of no use here.
Bromine, which separates as liquid, is easily pipetted without any water. The bromine, made this way already is quite pure. Solubility of water in
bromine is very low (only appr. 0.05% by weight). The biggest problem is not the water, dissolved in the bromine, but the drops of water, which always
will stick to your pipette and float on top of the bromine. If you accept another 10% loss of the bromine, then you could make almost perfectly dry
bromine simply by pipetting it.
Getting it really dry can be done by pouring concentrated sulphuric acid on the bromine and keeping it that way:
[Edited on 7-3-08 by woelen] |
exactly, I made some iodine as well from KI, and it was very wet. It not that hard to isolate dry though. Just heat in an erlenmeyer with a watchglass
on it, and you will het quite dry iodine on the watchglass.
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MagicJigPipe
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I still completely disagree. Bromine is a pain in the ass to isolate IMO.
"I produced Br2 and I2 by chemical oxidation of bromides and iodides, then extracted them in CCl4. (Back in the good old days, when I had a gallon of
technical CCl4, and was dumb enough to use it with mediocre ventilation.) This worked well, and the CCl4 solutions were always pretty"
If Br2 is so easy to isolate, why would you need something like CCl4? Anyway, with oxidation of iodides, yields are always great. Oxidation of
bromides (or electrolysis) that involves any water seems to have low yields. I see you made a small amount of Br2. But how long did that take?
Also, I have never attempted to dry I2 by this method but couldn't you used a dessicator while cooling the I2 to just above 0C? This should prevent
excessive sublimation and dry it at the same time.
I always just used dry filter paper. Seems to work well. Probably not dry enough for moisture sensitive applications but still reasonably dry.
I just hate messing with Br2. It mixes with water too easily and once it does it's a pain to remove from the water.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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woelen
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No need to use CCl4. Simply use the method, mentioned above where the Br2 drops out. Easy, simple and effective. Yield of oxidation is 100%, no
incomplete oxidation as mentioned by MagicJigPipe. If you have incomplete oxidation, then it is time to find a better oxidizer. Every oxidizer like
chlorate, permanganate, hypochlorite, bromate completely oxidizes bromide to bromine in acidic environment. Only thing is that one should be careful
using fairly precise stoichiometric amounts. Especially the chlorine-based oxidizers tend to form Cl2 when used in excess and then mixed halogen
compounds and bromic acid are formed.
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Fleaker
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You'll have proof of Br2 being easy to isolate quite soon. There are ample examples already on the forum of how to make bromine, but the most direct
is to use bromate, bromide, and an acid (sulfuric or hydrochloric). The reaction is almost quantitative from HBr and and bromate. Distill the bromine,
dry with sulfuric in a sep funnel.
I am working on a 10 kilogram synth of bromine, it's already late, but I'm waiting on the rest of my sodium bromate to arrive. I'll probably be doing
it in either a 12 or a 22L flask. It will be stored in a large 2L FETFE bottle.
[Edited on 7-3-2008 by Fleaker]
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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-jeffB
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| Quote: | Originally posted by MagicJigPipe
If Br2 is so easy to isolate, why would you need something like CCl4? Anyway, with oxidation of iodides, yields are always great. Oxidation of
bromides (or electrolysis) that involves any water seems to have low yields. I see you made a small amount of Br2. But how long did that take?
Also, I have never attempted to dry I2 by this method but couldn't you used a dessicator while cooling the I2 to just above 0C? This should prevent
excessive sublimation and dry it at the same time.
I always just used dry filter paper. Seems to work well. Probably not dry enough for moisture sensitive applications but still reasonably dry.
I just hate messing with Br2. It mixes with water too easily and once it does it's a pain to remove from the water. |
As I recall, Br2 and I2 partitioned into CCl4 from the aqueous I3-/Br3- solution. But this was all thirty-odd years ago, so I may be misremembering
critical details.
I had neither distillation apparatus nor dessicators at the time, and I was working with sub-gram quantities anyhow.
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theobromacacao
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I'm not sure if anyone would be interested in this, but I have acquired a 2ml ampoule of bromine which is too large for my periodic table. I was
wondering if any members on here (based in UK) would be interested in this for their use and experiments? I have already approached my local
university to see if they would like it for their stock, but all they wanted to do with it was store it with their waste and dispose of it!!! If
anyone is interested, please let me know.
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YT2095
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I`ll take it off your hands if it`s Free (I`ll pay postage), a 2ml would be smaller than my Current element sample.
or even do a trade if you`re after an element that I have enough of to share.
\"In a world full of wonders mankind has managed to invent boredom\" - Death
Twinkies don\'t have a shelf life. They have a half-life! -Caine (a friend of mine)
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MagicJigPipe
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I suppose once I find a cheap source of BrO3 then it will be easy for me as well. 'Till then it remains annoying.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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StevenRS
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I just oxidize bromide with 30% H2O2, using H2SO4, and the heat produced in enough to distill the bromine into a sep funnel, then I just pour out the
bromine. Easy, and very dry product.
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Klute
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So you use a distn setup, but connect a sep funnel instead of a receiver flask?
Do you add the H2O2 to the KBr/NaBr and H2SO4, or H2O2 and H2SO4 to the salt?
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MagicJigPipe
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Distillation of Br2 is not easy, IMO. How does one obtain NaBrO3 for a decent price? I believe IT is a pain in the ass to synthesize, as well.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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