Sciencemadness Discussion Board

What to do with this HBr?

CrimpJiggler - 31-1-2012 at 07:08

I made some hydrobromic acid and was planning on distilling it but I no longer have any use for hydrobromic acid. I don't want to waste it though since bromine is hard to obtain OTC in my country. I made the HBr by reaction KBr with H2SO4. I'm thinking the best thing to do would be to make elemental bromine. How should I go about turning HBr into Br2?

Hexavalent - 31-1-2012 at 08:23

Make a satured solution of it and bubble chlorine into it, as per;

http://www.youtube.com/watch?v=OB4MmPTOBxg

Also, you could make some nice alkyl halides and other organics with it if you have the right materials and time.

GreenD - 31-1-2012 at 08:24

mix it in a pot with ethanol and reflux. then pour it into a nother good ole pot with some tryptamine, stir. Eat.

Hexavalent - 31-1-2012 at 08:25

Ok, you show us first GreenD!:)

Lambda-Eyde - 2-2-2012 at 15:47

Why don't you just distill it and keep it? If you're into organic chemistry at all, you will be using it some time or another. It won't be wasted. On the contrary, it will save you time when you decide to synthesize an alkyl bromide, for example.

entropy51 - 2-2-2012 at 17:14

Quote: Originally posted by Lambda-Eyde  
Why don't you just distill it and keep it? If you're into organic chemistry at all, you will be using it some time or another. It won't be wasted. On the contrary, it will save you time when you decide to synthesize an alkyl bromide, for example.
I have to agree Lambda-Eyde. I have never disposed of a chemical that I didn't later regret having done so. Except maybe the mercaptans.

Lambda-Eyde - 2-2-2012 at 17:24

Quote: Originally posted by entropy51  
I have to agree Lambda-Eyde. I have never disposed of a chemical that I didn't later regret having done so. Except maybe the mercaptans.

Don't forget the isonitriles and low molecular weight phosphines..!

As for the original question: If you have HBr and want bromine, all you have to do is add some sulfuric acid and a slight excess of hydrogen peroxide. There are several threads on this.

Sedit - 2-2-2012 at 17:27

Either save it or find another synthesis like Lambda suggested in order to use it up. Ethyl bromide is so simple I was able to make it with acceptable yields and if I had distilled it slower I feel I would have had even greater yields then I got.

GreenD - 3-2-2012 at 06:41

Quote: Originally posted by Sedit  
Either save it or find another synthesis like Lambda suggested in order to use it up. Ethyl bromide is so simple I was able to make it with acceptable yields and if I had distilled it slower I feel I would have had even greater yields then I got.


its a very friendly synth! you just need some good ol' parafilm for keeping it around for any length of time (from what I hear)

CrimpJiggler - 4-2-2012 at 05:18

Quote: Originally posted by GreenD  
mix it in a pot with ethanol and reflux. then pour it into a nother good ole pot with some tryptamine, stir. Eat.


lol, I'm a bit reluctant to try that. What would it yield, a brominated tryptamine? i.e. a 2C-B type compound?

Quote: Originally posted by Lambda-Eyde  
Why don't you just distill it and keep it? If you're into organic chemistry at all, you will be using it some time or another. It won't be wasted. On the contrary, it will save you time when you decide to synthesize an alkyl bromide, for example.

Thats what I ended up doing. I went to the trouble of making the acid in the first place so I might as well go all the way and distil it. I'm wondering how to store it now though. I have no decent sized glass storage containers. Does 40% HBr react with HDPE?

bahamuth - 4-2-2012 at 06:25

Quote: Originally posted by CrimpJiggler  
Quote: Originally posted by GreenD  
mix it in a pot with ethanol and reflux. then pour it into a nother good ole pot with some tryptamine, stir. Eat.


lol, I'm a bit reluctant to try that. What would it yield, a brominated tryptamine? i.e. a 2C-B type compound?


GreenD was probably refering to N,N-diethyltryptamine produced by amine alkylation, though I doubt it is just that easy...
Quote: Originally posted by CrimpJiggler  
Does 40% HBr react with HDPE?


Never had the guts to store HBr in HDPE or any plastic for that matter.
Guess it, as its sibling HCl, will work its way through the plastic and give all nearby corrodable (is that even a word?) surfaces that rusty finish we all love so much.

CrimpJiggler - 4-2-2012 at 15:04

Quote: Originally posted by bahamuth  

Never had the guts to store HBr in HDPE or any plastic for that matter.
Guess it, as its sibling HCl, will work its way through the plastic and give all nearby corrodable (is that even a word?) surfaces that rusty finish we all love so much.

Some 40% HBr splashed onto the perspex (polymethylmethacrylate) window of my fume hood and I didn't bother to clean it off. A couple of weeks later I noticed the perspex had turned brown where the HBr landed.

This is probably a stupid question but I noticed that when I distilled my HBr solution, the contents of the boiling flask went from yellow to dark red. Theres clearly some free bromine in the flask. Why doesn't it distil over? Does Br2 form a high boiling point azeotrope with water? I also noticed some big black things floating around in the boiling flask. They weren't there when I started distilling. I had carelessly left the crude hydrobromic acid in an open container for a few weeks so maybe contaminants landing in the flask but this is the first time I've seen big solid black things form out of nowhere like that.

GreenD - 6-2-2012 at 07:01

yeah the free bromine is going to stay in solution... I don't know why but I've done a lot of bromination reactions and they always turn very deep brown. Don't roto-vap that shit - its very bad for you, stings the eyes like crazy too. Always wash organic phases with thiosulfates. Or is it sulfites?