Bromine synthesis from Potassium Bromide + H2O2

[ChemMang]

SWIM dreamt they had plenty of GAA and 2CH; This Bee wanted Bee Honey.  SWIM needed elemental Bromine for this to become a reality.  SWIM also has a few grams of Potassium Bromide and has solution of 3% Aqueous H2O2.  SWIM was told that Bromine can be rxn'd from Potassium Bromide + 3% H2O2 Solution.  Can someone help SWIM??  I know SWIM's getting stung by bee's right around the corner..once the bromine is synthed all holy will manifest!  

[Bandil]

It is possible to make elemental bromine from a mixture of potassium bromide, H2O2 and a little sulfuric acid. However, it is NOT recomended as bromine is evil to work with, and especially distilling! Swim has successfully distilled bromine from that mixture before, but the entire glassware, exhaust pipes etc are next to impossible to clean afterwards. 3% H2O2 is also a little bit to diluted. 10% is probably better to use.

But you can do the reaction in situ, meaning that you add the whole thing(2CH, GAA, KBr, H2O2, Sulf.Acid), but the yeilds are not terribly good afaik. Read up on the oxone reaction with bromine. It should work perfectly for your needs.

Regards
Bandil

[moo]

How about oxidising the bromide to bromine in a two-phase system of water/DCM and then using the DCM layer in the bromination? Yes, it is bromine but at least it's diluted.

Bandil: In what way was it next to impossible to clean the glassware? If it was the bromine fumes still inside the system, one might try to distill some solvent (but not acetone or MEK , I would pick DCM) with the same setup after having distilled the bromine, to get rid of the nasty fumes and all.

[ChemMang]

I've used TFSE to no avail, can you outline the specifics of the rxn Bandil, for bromine via KBr+H2O2+H2SO4?

[Bandil]

I can't find that either, but i know how i would perform it:

make the GAA/2CH soln. as usual when brominating. Add equimolar amounts of KBr and H2SO4 to another GAA solution and then add 1.5(50% excess) times as mant moles of 30-40% H2O2. This should oxidize everything to elemental bromine. Then just pour the bromine soln. into the 2CH soln. That should work. I am not totally sure of the procedure, so if anyone have better ideas; bring them on

After the reaction i can't say if the 2CB.HBr / 2CB.HSO4 will precipitate, so you might have to perform a workup in the usual manner of the reaction mixture if it does not.

Regards
Bandil

[Rhodium]

Is aquiring NBS (N-Bromosuccinimide) out of the question? It is not bad at all to handle, and it brominates activated aromatics (such as 2C-H) easily, see my page in the section about aromatic halogenation.

[ChemMang]

Thanks Rhodium and Bandil I appreciate your priceless aid! Both of you guys are true iron clad soldiers in the story of psychoactive chemistry!

[Oxygen69]

I have been thinking about brominating with NBS for a while.  It is not hard to obtain at this time.

Oxygen69