Sciencemadness Discussion Board

Bromine.

Cou - 19-5-2013 at 16:59

Are there any online stores that ship elemental bromine? United nuclear and elemental scientific don't have it. I can get all the other halogens though; I can buy fluorine and chlorine from the Airgas store next to me, and iodine from elemental scientific, but no bromine. What is the easiest way to make it?

elementcollector1 - 19-5-2013 at 17:24

There's a thread on bromine over in the "Chemistry in General" section - check that for a good prep.
Also, what kind of Airgas sells fluorine (and just how expensive is it?)

Dr.Bob - 19-5-2013 at 18:16

Any Airgas, Linde, or Praxair location would be able to provide fluorine, provided that you can afford the cylinder deposit, and that they trust you not to be a terrorist or likely kill yourself with it. They also can get HF.

But neither of those would be ideal to have around your house. Even at the old fluorochemical company I worked at 30 years ago, they kept the fluorine outside in a cabinet with piping to bring it into the building. I just heard yet another story about someone trying to do some chemistry with F2 who nearly killed themselves even outside on a porch, and he had worked with it for years, but was trying to moonlight making some compounds after the main company closed. He ended up in the hospital with pneumonia when his system leaked a little. I could see doing small scale F work i the proper fume hood, but a cylinder of F2 or HF could take out a good part of a neighborhood.

neptunium - 19-5-2013 at 19:29

also fluorine will explode or burst into flame with a lot of compound....leaving toxic fluoride behind...yeah always small amount of it!

woelen - 20-5-2013 at 06:01

Yeah, buying fluorine at the store at the next corner....

If you can get fluorine, then you certainly can get bromine.

This question is comparable to saying: "Where can I buy a toy gun? I can buy AK47's and Kalashnikovs, but I cannot find toy guns anywhere.".

Cou - 20-5-2013 at 13:16

Quote: Originally posted by woelen  
Yeah, buying fluorine at the store at the next corner....

If you can get fluorine, then you certainly can get bromine.

This question is comparable to saying: "Where can I buy a toy gun? I can buy AK47's and Kalashnikovs, but I cannot find toy guns anywhere.".

The problem is that you can get fluorine and chlorine from the gas store because they can be stored in canisters, iodine is a solid so you can just buy it in a bottle, but bromine is a liquid and they don't have that

Pyro - 20-5-2013 at 13:58

so? Br2 can be stored in both bottles and canisters if they are made of the appropriate material. how about making it? NaBr+KMnO4+H2SO4, NaBr+H2SO4, NaBr+Cl2, ...
2kg NaBr will give you 400ml Br2 at 80% yield (realistic yield for NaBr+KMnO4+H2SO4, Ive had higher but 80% is average)

Ps:Woelen, an AK-47 is a Kalashnikov :) one of the many weapons designed by Antonin Kalashnikov

radagast - 20-5-2013 at 14:05

Not that I was exactly the model of safety at your age, but nobody is going to sell bromine or fluorine to anyone under the age of 18, and for good reason, too :o

I'm not a safety nut but if you're interested in working with bromine, I would highly advise you to reach out to your chemistry instructor so he can supervise the process. When working with such a volatile and dangerous reagent, even small errors can injure/maim/kill you!

Cou - 20-5-2013 at 16:09

Quote: Originally posted by radagast  
Not that I was exactly the model of safety at your age, but nobody is going to sell bromine or fluorine to anyone under the age of 18, and for good reason, too :o

I'm not a safety nut but if you're interested in working with bromine, I would highly advise you to reach out to your chemistry instructor so he can supervise the process. When working with such a volatile and dangerous reagent, even small errors can injure/maim/kill you!

That's why my parents are buying it.
Also i've worked with chlorine before, isn't chlorine more dangerous?

Finnnicus - 20-5-2013 at 16:14

May I ask how much flourine is? Not that I'm thinking of buying any... :o

[Edited on 21-5-2013 by Finnnicus]

Cou - 20-5-2013 at 16:15

Quote: Originally posted by Finnnicus  
May I ask how much flourine is? Not that I'm thinking of buying any... :o

[Edited on 21-5-2013 by Finnnicus]

I don't know, probably very expensive, if they even have it. I looked on their website, i don't know if it's in the retail store

Finnnicus - 20-5-2013 at 16:22

Quote: Originally posted by Cou  

I don't know, probably very expensive, if they even have it. I looked on their website, i don't know if it's in the retail store

Well, if you buy bromine, could you check for us?
BTW, I really think making your own would be more... economical.

Cou - 20-5-2013 at 16:25

Quote: Originally posted by Finnnicus  
Quote: Originally posted by Cou  

I don't know, probably very expensive, if they even have it. I looked on their website, i don't know if it's in the retail store

Well, if you buy bromine, could you check for us?
BTW, I really think making your own would be more... economical.

They don't have bromine. And I might not get to go to Airgas because they they are only open on weekdays, and close at ****ing 5:00 PM, and my parents are too lazy to drive me there, and they probably won't let me ride my bicycle for 17 miles just to check what they have

Mixell - 20-5-2013 at 16:50

A quick suggestion:
Don't buy chlorine and especially fluorine by the cylinder. Better not to buy fluorine at all...
Be careful with bromine as well, it has a relatively high vapor pressure.

Cou - 20-5-2013 at 17:21

I just make chlorine with HCl and bleach anyway

Pyro - 21-5-2013 at 05:40

F2 is a LOT more toxic than Cl2. halogens get worse going up the periodic table. I2 is least toxic/irritating, then Br2 then Cl2 then F2. I believe it's got to do with electronegativity. F2 is 4, Cl is 3,16 ,Br2 is 2,96, I2 is 2,66.

MrHomeScientist - 21-5-2013 at 07:38

Bromine may be less toxic/reactive than chlorine, but it is extremely dangerous for different reasons. The fact that it is a liquid means that accidents can be quite a bit worse than with chlorine. There are very few materials that can stand up to liquid bromine, so it will wreak havoc on gloves if spilled. Spilling some on your skin leaves very painful, deep wounds that take a very long time to heal. Think of it like bromine is inherently extremely concentrated, so it's always a strong oxidizer and carries a lot of risk if you aren't extremely careful.

woelen - 21-5-2013 at 09:28

Bromine is quite toxic and one certainly has to be careful with this, but its toxicity and danger is somewhat exaggerated. I have personal experience with Br2 running over my skin. I blew on my skin to have it evaporated quickly and after that, I used a solution of Na2S2O3 to reduce remains of bromine on my skin. I had no adverse effects at all, except that I had yellow stains on the area of skin which was covered by bromine.

You certainly must not allow bromine to act on your skin for prolonged time. Have a bottle of solution of Na2S2O3 or Na2SO3 at hand when you experiment with bromine.

Bromine vapor is less acutely toxic than chlorine gas at the same molar concentration. But again, try to avoid as much as possible to inhale bromine vapor. It is highly irritating and leads to damage of the respiratory tract. Systemic toxicity of bromine is somewhat higher than systemic toxicity of chlorine and iodine, but overall I think that bromine is of comparable toxicity as chlorine.

I would say that toxicity of halogen can be ordered as follows:

F ≫ Cl ≈ Br > I

Toxicity of halide can be ordered as follows:

F(-) ≫ Br(-) ≈ I(-) > Cl(-)

All of bromide, iodide and chloride are only marginally toxic and in practical situations they can be considered non-toxic as long as you do not ingest the compounds. Fluoride on the other hand is very toxic and can lead to really serious wounds and really serious health effects, which also can have severe long-term effects. I feel more comfortable working with cyanides than with fluorides.

Working with chlorine, bromine and iodine can be done safely in a home setting, provided that you take some reasonable measures to prevent inhalation of vapor/gas and to prevent prolonged contact with skin. Working with fluorine is out of the question in a home setting. Even many professional labs do not have the equipment to safely handle fluorine.


[Edited on 21-5-13 by woelen]

radagast - 21-5-2013 at 09:36

Quote: Originally posted by MrHomeScientist  
Bromine may be less toxic/reactive than chlorine, but it is extremely dangerous for different reasons. The fact that it is a liquid means that accidents can be quite a bit worse than with chlorine. There are very few materials that can stand up to liquid bromine, so it will wreak havoc on gloves if spilled. Spilling some on your skin leaves very painful, deep wounds that take a very long time to heal. Think of it like bromine is inherently extremely concentrated, so it's always a strong oxidizer and carries a lot of risk if you aren't extremely careful.


I think you hit the nail on the head here. Chlorine would be even more hazardous than bromine if you were using it in the liquid phase, but most amateurs generate small amounts of chlorine gas instead. In fact, I recall reading a J. Chem. Edu. article recently where they brominated a pyrimidine by bubbling generated chlorine gas through a NaBr solution so the students didn't need to risk working with bromine.

Which is not to discourage the OP from pursuing safer experiments, since he clearly has advanced interests for a 14-year old -- just that this isn't exactly the sort of thing I'd want my kid doing without some serious supervision :D

MrHomeScientist - 21-5-2013 at 10:24

Quote: Originally posted by woelen  
Bromine is quite toxic and one certainly has to be careful with this, but its toxicity and danger is somewhat exaggerated. I have personal experience with Br2 running over my skin. I blew on my skin to have it evaporated quickly and after that, I used a solution of Na2S2O3 to reduce remains of bromine on my skin. I had no adverse effects at all, except that I had yellow stains on the area of skin which was covered by bromine.


Wow really? Everything I've ever heard about bromine says it leaves nasty, painful injuries, which I assumed appeared rather quickly. Your story makes me feel a little more at ease, but doesn't (and shouldn't) change the amount of respect I'll give bromine in the future. I know it's still capable of nasty things.

Before making bromine for the first time, I made up a 1M solution of sodium thiosulfate just like you suggest. It came in handy when I very stupidly opened the stopcock more instead of closing it, and some bromine spilled out onto my table :/

woelen - 21-5-2013 at 10:59

You must respect the chemical bromine (like most other chemicals), but you should not be afraid of it. Bromine can produce very nasty wounds, but not in a few seconds. Most dangerous situation is that you do not notice having your skin covered by bromine and just work on. Then it has time to do its nasty thing. But if you notice as soon as it happens and take counter measures immediately (sodium thiosulfate or sodium sulfite on the affected skin) then the effects are not that bad. It is as with many chemicals. The amount of time of exposure determines the seriousness of the injury.

There are very few chemicals which give nasty wounds at once (within a second). Some examples are
- oleum (solution of SO3 in H2SO4)
- anhydrous perchloric acid
- high concentration hydrofluoric acid (not immediately visible, but after some time becomes extremely painful and 'rots' underlying tissue)
Bromine is not one of them.

[Edited on 21-5-13 by woelen]

Dr.Bob - 21-5-2013 at 12:06

And to think that nowadays (when I can get most chemicals) I go out of my way to avoid certain reagents due to their hazards...

Once you work in industry or even most good academic or gov. labs, you are taught, trained, and badgered to do everything in the safest way possible. All it takes is one fire, spill, or other incident to have OSHA, etc inspecting you and fining you for every extension cord, ladder, or other trivial thing not properly documented, labelled, or used. So we make a reasonable effort to avoid t-butyl lithium, metallic sodium or potassium, cylinders of hazardous gases, etc. I try to generate HCl from acetyl chloride and methanol, brominate with NBS, and use milder sources of "HF" like pyridine-HF or tetrabutylammonium fluoride for silyl group removal. Not to say that I can't or don't work with hazardous chemicals, but it is just to costly to do it when you can avoid it.

This is not as relevant for most home scientists, I know, but I do hope that people will be careful not to create situations that only make it harder for people to do home science, as fires, poisonings, and other home lab emergencies will only make things worse for all involved.

woelen - 21-5-2013 at 12:49

Professional labs can do such things, but home scientists don't have such options. E.g. bromine can be made fairly easily by home chemists, but NBS is unavailable. Making HCl from acetyl chloride and some alcohol sounds ridiculous to me. Acetyl chloride is a very valuable reagent in a home lab, while HCl is nothing special at all. Use of "milder" sources of HF sounds interesting, it would make experimenting with fluorides more accessible for home chemists. I have 48% HF but I hardly did any experiment with this, due to the very high risk and I do not feel comfortable using that chemical.

LanthanumK - 21-5-2013 at 13:06

Bromine is often more dangerous to materials than flesh. Just a solution of bromine water is capable of eating away plastic over time, as I experienced. Bromine dissolves many plastics, rubber seals, and many other substances. Storage must be in all glass apparatus, or leakage of fumes will result, causing corrosion on metal surfaces.

Dr.Bob - 22-5-2013 at 05:18

Another source of HF that might be more accessible would be ammonium bifluoride, which is the salt of ammonia and 2 mols of HF, thus acidic, but still a crystalline solid. It is used as a glass etchant as well as by some people to wash wheels in car washes, as it cleans aluminum well. So it may well be more readily available. I did try it once, and it will slowly etch glass, so it is used by the glass industry when they want to make custom etched glass.

And using a small amount of acetyl chloride to generate HCl in situ is a classic way to run Fischer esterifications, for example, as you want anhydrous HCl, and it is a real pain to set up a HCl cylinder and bubbler to get a few grams of HCl into a reaction. It usually only takes a few ml of acetyl chloride, verses the cost of a cylinder rental for HCl, which can be quite a bit per month. So costs are all relative. A 1L bottle of AcCl is only a few dollars, since it is a commodity chemical. Thionyl Chloride works about the same, but likely also generates dimethyl sulfate in situ also, but that would not hurt an esterification at all.

I would certainly agree that some reagents, like NBS, are not readily available, but being aware of them is certainly useful, as there are some reactions that it works better for. I have found that N-hydroxysuccinimide is a very useful reagent, in general, for making activated esters, buffering halogens, and other unique uses, much like HOBT is useful in some peptide chemistry (but sometimes used when not needed as well, like in achiral amide forming reactions).

MrHomeScientist - 22-5-2013 at 06:15

I have about 500g of ammonium bifluoride that I bought for my neodymium magnet experiments (smallest size I could find, unfortunately), and I did my own experiment to see how well it etched glass. I dissolved maybe 0.5g in 10mL of water or so, and poured this on the bottom of an overturned glass bottle. I didn't want to etch the inside so I figured I'd try it that way. I left it there for a few hours, but observed almost no etching. Maybe my solution wasn't concentrated enough.

I'm with woelen, though - HF-related chemicals make me very nervous.

Dr.Bob - 22-5-2013 at 11:42

It is buffered by the ammonia, so it takes a conc. solution and some time to etch glass. That is why is it safer and preferred, as you can control the amount of etching very precisely by the time you wait, whereas with aq. HF it would be much harder to control the amount of etching. Even strong HF does not dissolve glass like toluene does styofoam.

MrHomeScientist - 22-5-2013 at 13:19

Ahhh that makes a lot of sense, thanks for the clarification. Currently my stuff is stored in a plastic bottle with one of those child-safety caps, but I think i'm going to nest that in a bucket or something lined with baking soda, as I do with my other acids.