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Author Topic: Sources of Bromine/Bromide.  (Read 1008 times)

jon

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Re: Sources of Bromine/Bromide.
« Reply #40 on: August 10, 2010, 11:58:25 PM »
yes it can be washed with sodium thiosulfate why would you want to distill bromine?
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drone1240

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Re: Sources of Bromine/Bromide.
« Reply #41 on: August 11, 2010, 01:04:00 PM »
I am ready to do another technique experiment. I have only seen Br2 in the science museum and never had the pleasure to work with it. I want to brominate something.
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Sedit

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Re: Sources of Bromine/Bromide.
« Reply #42 on: August 12, 2010, 12:19:50 AM »
Pleasure to work with it? Well we will see about that wont we.
Its like Chlorines evil twin and I would take alot of caution when using it because it is some potant stuff. Im pretty sure you understand the dangers and all so just take care ok.
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jon

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Re: Sources of Bromine/Bromide.
« Reply #43 on: August 12, 2010, 12:59:50 AM »
use good ventilation wear gloves eye protection it will burn the shit out of your eyes glycerin can be kept around as a salve in case of burns which are quite unpleasant.
i would'nt even bother to distill it just extract into dcm less fuss you want to do as little manipulation with this shit as possible.
keep 5% sodiumthiosulfate handy.

Vesp

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Re: Sources of Bromine/Bromide.
« Reply #44 on: August 13, 2010, 07:37:19 PM »
I've never seen bromine stain glass. It rolls right off of it for the most part. After all it is a pretty reactive and volatile liquid, rinsing the glass with water should get rid of any bromine present on it as far as I know.
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lugh

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Re: Sources of Bromine/Bromide.
« Reply #45 on: August 13, 2010, 09:31:45 PM »
Bromine doesn't adhere to glass, but it will stain polymers  ;)  It's best prepared in cold weather, that tames it's nasty nature  ;D  A stopper can be fabricated from polyethylene tubing and polytetrafluoroethylene plumbing tape that won't deteriorate like rubber does in it's presence  8)
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drone1240

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Re: Sources of Bromine/Bromide.
« Reply #46 on: August 14, 2010, 04:51:02 PM »
Thank you guys for your insight. I will report back with my results as soon as I have them. Thanks for the warning Sedit.
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poisoninthestain

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Re: Sources of Bromine/Bromide.
« Reply #47 on: August 14, 2010, 08:03:22 PM »
a couple cold water washes always seemed to remove the color completely and even the smell of bromine after i was done cleaning glass.

drone1240

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Re: Sources of Bromine/Bromide.
« Reply #48 on: August 18, 2010, 03:23:00 PM »
I read the MSDS for Br2 and I got a knot in my stomach. I knew it was bad stuff but not as toxic as it is.
Money is a limiting factor in my experiments and safety is my top priority. 2 questions: do I need a full face respirator or can I get by with a half face respirator with halogen cartridges and goggles? Also would it be wise to have a buddy near by in case I get over exposed? I dont think I will but that MSDS made it clear that I have no room for error with this stuff.

PS I watched a video on you tube where the kids were making it wearing shorts and no respirators. I guess the MSDS's blow stuff a little outta proportion. Will report back soon.
« Last Edit: August 18, 2010, 04:07:36 PM by drone1240 »
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TooCold

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Re: Sources of Bromine/Bromide.
« Reply #49 on: August 26, 2010, 03:35:23 PM »
MSDS sheets present warnings for the worse case scenario. But that doesn't mean one can be careless with bromine either. Just use your hand and practise normal safety procedures and you'll be fine.

atara

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Re: Sources of Bromine/Bromide.
« Reply #50 on: September 24, 2010, 07:25:03 AM »
It looks as though DBDMH should be useful for bromination in its own right; I mean, it actually doesn't look very far removed from N-bromosuccinimide.

poisoninthestain

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Re: Sources of Bromine/Bromide.
« Reply #51 on: September 27, 2010, 01:13:00 AM »
TCCA or even bleach decently chlorinates 2C-H in aqueous solution prior to workup though the equalibrium could be better..haven't tried DBDMH...intuition tells me it's a thumbs up. Always had bromine on hand so never thought to experiment with the bromo's.

Sydenhams chorea

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Re: Sources of Bromine/Bromide.
« Reply #52 on: May 30, 2012, 07:02:52 PM »
The following variation works satisfactorily for brominating 2C-H:

Dissolve 1 mol.eq. KBr in methanol and add 1.1 mol. eq. oxone as instructed in the article, but don't add the mol.eq. 2C-H yet, let it stir for 1 hour. An orange solution of bromine is obtained. To this add your 2C-H dissolved in acetic or propionic acid. Let stir for 1 hour and work up by acid/base extraction.

The amine group needs to be protonated or it will be destroyed by the oxybromination process as described in the original article.
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fractal

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Re: Sources of Bromine/Bromide.
« Reply #53 on: July 02, 2012, 08:07:31 PM »
I hate working with Cl2 even more than working with Br2. The way I usually make bromine is via the route magpie posted over at SM. You can find it there. Basically dissolve NaBr in water, add a slight molar excess of concentrated H2SO4 SLOWLY (to form HBr). Then drip in slightly over .5mol:1mol of 35% H2O2 to NaBr you are using. May need to heat a little at first just to get it going but once it does you can turn it off. The heat from the reaction distills the Br2 as it's formed.

carl_nnabis

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Re: Sources of Bromine/Bromide.
« Reply #54 on: July 03, 2012, 03:52:24 PM »
ive done it in a similiar manner, just the other way round because i used KMnO4 as oxidator instead hydrogen peroxide, so ive dripped sulfuric acid in a solution of sodium bromide and permanganate, distilled it off then but i had to heat to get it completely over to the end.
but i am talking about "test tube amounts" yielding less than very few grams, so i would guess this is way too small to distill itself without external heating over ;D
i agree totally with fractal about Cl2, chlorine is way more nastier, bromine has also some of chlorine volatile components, but very good cooled or even frozen is it nearly as harmless to handle as iodine in my opinion. (but the possible reader of this should always remind, bromine is a lot more toxic and corrosive as I2  ::))
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Tsathoggua

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Re: Sources of Bromine/Bromide.
« Reply #55 on: July 04, 2012, 02:56:27 AM »
Bee careful. If Conc. H2SO4 contacts KMnO3...It forms the EXTREMELY sensitive HIGHLY EXPLOSIVE compound MnO7. this stuff can be handled, under certain circumstances. BUT it is such a powerful oxidizer, and  SO fucking sensitive that it canandorwill detonate, under the merest speck of atmospheric dust/airborne oxidizable particle.
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carl_nnabis

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Re: Sources of Bromine/Bromide.
« Reply #56 on: July 04, 2012, 07:14:36 PM »
Thank you good to know, better not distill it to dryness ;D Ive used diluted sulfuric acid anyway, i would have a vague bad feeling just intuatively to mix such strong oxidants as concentratred sulfuric and permanganate are ;D
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Wizard X

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Re: Sources of Bromine/Bromide.
« Reply #57 on: July 04, 2012, 11:15:25 PM »
2 KMnO4 + H2SO4 => K2SO4 + Mn2O7 + H2O
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carl_nnabis

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Re: Sources of Bromine/Bromide.
« Reply #58 on: July 04, 2012, 11:28:19 PM »
yeah obviously, but the equation is another one if one uses diluted sulfuric acid which is dripped into a KMnO4/NaBr solution because of the whole lot parts H2O isnt it? I have taken the write up with pictures from some german side and because it was not mentioned and i did it with amount scaled down from the example except water as solvent so i never worried about mangan heptoxide at all.
or am i wrong with the assumption it does not appear in an aqueous system?
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Tsathoggua

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Re: Sources of Bromine/Bromide.
« Reply #59 on: July 05, 2012, 01:17:48 AM »
It decomps in H2O.

Dangerous stuff, toady played with Mn2)7 a bit as a kid. It appears as a dark, kinda oily looking liquid. Very, very powerful oxidant.And when it dets, it decomps into enough ozone gas to set fire to EtoH, dripped onto a substrate. It can be prepared as a solution in anhydrous CCl4 however, or in dichlor. Do NOT try distilling it though. The elder toad has been meaning to try playing about with it in soln. as an oxidant sometime.
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