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Author Topic: Boron Tribromide Synthesis Route (Low Temp)  (Read 130 times)

no1uno

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Boron Tribromide Synthesis Route (Low Temp)
« on: July 30, 2010, 04:41:28 AM »
Righto boys and girls, we finally have a low-ish temperature route to BBr3 that doesn't require Boron to be made - it proceeds via AlBr3 (Go to SM, the Bromine thread by Len1 and get the Bromine), then drop aluminium into the DRY bromine and collect the result.

Then follow this paper (Has the preparation of both BF3 and the potassium salt) from boric acid (fuse it & crush it first), then into 47% HF to get the BF3, neutralize it with potassium carbonate and collect the salt. Release it again with H2SO4/H3PO4 and let it react with the AlBr3. How fucking easy is that? Especially given the Rice, et al procedure (see Rhodium/Erowid) using it to get morphine from codeine in what, 91% yield?

Really, I wonder why the fuck I go looking for references, that fuckers been up for 2 days and not 1 download
"...     "A little learning is a dang'rous thing;
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Sedit

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Re: Boron Tribromide Synthesis Route (Low Temp)
« Reply #1 on: July 30, 2010, 05:24:38 AM »
I figured you went looking for references for your own use like everyone else to be quite honest dude. If it makes you feel anybetter I planed on reading some of the Lithium papers this weekend when I had some peace and quite else I wouldn't remember them anyway trying to read them now. I its appriciated man and sooner or later someone will find great use in them even if you yourself does not.
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Vesp

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Re: Boron Tribromide Synthesis Route (Low Temp)
« Reply #2 on: July 30, 2010, 05:26:25 AM »
How is it you plan to get the AlBr3 from the resulting explosion/fire with Al and Br2?
It seems like a rather difficult one to slow down considering how fast the wound up Al foil was - it isn't the most reactive form of Al out there, and that didn't have much surface area.

AlBr3 is useful alone so that is a good find but looks tricky.

Quote
Really, I wonder why the fuck I go looking for references, that fuckers been up for 2 days and not 1 download

ah perhaps this subject just doesn't interest the majority of the people who post here? I don't know, but this DIY borohydride stuff is very interesting and I hope it turns out.  It just probably isn't something everyone is very interested in doing... Either way, they are useful and a great thing to have around IMO.

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no1uno

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Re: Boron Tribromide Synthesis Route (Low Temp)
« Reply #3 on: July 30, 2010, 05:30:29 AM »
Vesp & Sedit, it ain't just the borohydride stuff - this is the SIMPLEST route ever to BBr3 - thus morphine from codeine in great yields, the fact the clown who did it (and reported it) didn't grab the gas in an ammonia solution (thus methylamine bromide and ammonium bromide can be collected and the fumes can be dealt with, water was never going to do it...



Potassium Fluoroborate

Potassium Fluoroborate was prepared by dissolving boric acid in 48% hydrofluoric acid and adding potassium carbonate. The product was recrystallized from hot water and dried at 110'C.

Boron Fluoride

Boron Fluoride was prepared by the action of hot concentrated sulfuric acid on a mixture of potassium fluoroborate and boric oxide.

Aluminium Boride

Aluminium Boride was prepared by slowly adding bromine to an excess of aluminium in an ordinary distilling flask.

Boron Tribromide

The Boron Fluoride generator was connected to the reaction flask by means of a small bubbler containing concentrated sulfuric acid. The rate of flow was comparatively rapid, about 30 minutes for 2 moles of gas. After the apparatus was swept with boron fluoride, the large flask containing the aluminium halide was heated gently by means of a free flame whereupon the reaction soon started. For the preparation of boron bromide the aluminium bromide was refluxed gently in a stream of boron fluoride. The effluent gasses were passed into a U-tube cooled with solid carbon dioxide and alcohol, protected by a drying tube. When the reaction was over the U-tube was sealed off and its contents distilled. In the preparation of boron bromide small amounts of bromine were obtained but were readily removed by shaking with mercury (NB not a good plan, I hate fucking Hg). A little metallic aluminium added to the preparation flask decreased the amount of bromine formed... From one-half a mole of aluminium bromide and two moles of bromine fluoride, 70% yields of boron bromide have been obtained.
« Last Edit: July 30, 2010, 05:32:10 AM by no1uno »
"...     "A little learning is a dang'rous thing;
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    There shallow draughts intoxicate the brain,
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no1uno

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Re: Boron Tribromide Synthesis Route (Low Temp)
« Reply #4 on: July 30, 2010, 05:38:58 AM »
I mean, if you don't have ammonia solutions - preferably ones of known molarity - to hand when trying to fuck around with codeine, then you'd have to be a lost cause to begin with. Why the person who reported on this was not condensing the off gases or passing them into even a beaker full of ammonia solution, is fucking beyond me. Bromine & Bromomethane are going to react a fucking lot quicker with that than with water.

What has stopped everyone without an account from trying this method, is the acquisition or preparation of BBr3 - the high temperature method of making anything with Bromine would scare the fucking devil himself, bromine is a biatch at RT it would be wonderful at 400C.

Hardware store wheel-rim cleaner, normally ammonium fluoride with H2SO4, will give you HF if you put some sand in it, pass the off-gas into distilled water, the hydrolysis of the SiF4 will give HF and SiO2. Sodium fluoride is used as flux for aluminium welding. Yes, HF is not nice, neither are HI/HBr for that matter. Hot tip, don't use glass to collect the HF, use one of those horrible copper bowl's (seems everyone has one somewhere) or make something basic out of Copper tubing & plumbing parts. Alternatively, a PTFE/PEEK bottle (they are often on ebay) will do nicely.

Vesp - add Bromine to aluminium balls in a distilling flask (either use a 2/3 neck flask or a Claisen head) using a dropping funnel, also have a distillation head on and collect the distillate (mainly bromine)* and the residue (mainly AlBr3 and Al) and redistill it over excess Al. The AlBr3 has a BP of 265'C, so it will be mainly in the original flask. Distillation of it into the reaction flask provided you have kept it dry, then reflux in the stream of BF3, apparently the AlF3 builds up on the sides of the flask, so we can reclaim the Fluoride.

* You could also just grab the fumes (most of it is going to be bromine) in an ammonia solution. Any AlBr3 that comes over will react with the water anyway.

PS I have added two cognate preparations from Schlesinger's "Inorganic Laboratory Preparations" (1962), one is for the fluoroborates and the other for anhydrous aluminium bromide. I'm sure there is another version of Schlesinger's Textbook that contains a very similar schema for the preparation of boron trihalides (ie. from the Aluminium Halides & BF3). I'll keep looking for that one.
« Last Edit: July 31, 2010, 05:55:51 AM by no1uno »
"...     "A little learning is a dang'rous thing;
    Drink deep, or taste not the Pierian spring:
    There shallow draughts intoxicate the brain,
    And drinking largely sobers us again.
..."

Vesp

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Re: Boron Tribromide Synthesis Route (Low Temp)
« Reply #5 on: August 02, 2010, 04:13:52 AM »
Quote
Vesp - add Bromine to aluminium balls in a distilling flask (either use a 2/3 neck flask or a Claisen head) using a dropping funnel, also have a distillation head on and collect the distillate (mainly bromine)* and the residue (mainly AlBr3 and Al) and redistill it over excess Al. The AlBr3 has a BP of 265'C, so it will be mainly in the original flask. Distillation of it into the reaction flask provided you have kept it dry, then reflux in the stream of BF3, apparently the AlF3 builds up on the sides of the flask, so we can reclaim the Fluoride.

Oh that is smart, I didn't even think of that for some reason, but now that I have that picture,  It seems like a reflux condenser attached to a flask via a claisen adapter, with an addition funnel of dry Br2(l) would be pretty effective when dripping it slowly onto aluminum balls. This would be nice since everything could be kept with in the reaction flask since the bromine that did evaporate could be condensed again and drip back onto it.

OK so AlBr3 sounds very easy to make. This is good news. I don't know why I don't hear more about that?
One thing that might be worth worrying about is that the heat of the reaction might cause thermal instability with the flask - but this could easily be remedied by adding very pure sand to the bottom of the flask with the aluminum balls - I guess the sand would work sort of as a heat sink. It may not be needed though, but burning Al in a bromine atmosphere does sound pretty exothermic, regardless how slowly you added it (at some point it would catch fire, it doesn't seem like something that would easily reach an equilibrium)
The sand and AlBr3 mixture could be used as is, or purified via a solvent that is dry and unreactive towards AlBr3. 
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shroomedalice

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Re: Boron Tribromide Synthesis Route (Low Temp)
« Reply #6 on: August 22, 2010, 09:48:14 AM »
nice on no1 :)

ye I would drip the bromine into a stirred solution of xylene and al foil balls to stop

runnaway.

oh well when I finally get a place in the country I can try some of this way out shit.

Buzzoff

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Re: Boron Tribromide Synthesis Route (Low Temp)
« Reply #7 on: August 26, 2010, 07:03:35 AM »
Interesting, I recently read a preparation in Vogel's 5th Ed. Practical Organic Chemistry.  Wherein, a benzene-diazonium chloride, is reacted with Sodium Fluoroborate, and the resultant Diazonium fluoroborate salt is dried, and then heated until it slowly decomposes.  The product?  A Fluorobenzene.  The by-product?  Boron Trifluoride.

Interesting for two reasons. The first reason is, that generally speaking, drying and heating a diazonium salt is suicidal....It's a good way to blow yourself off of the face of the planet.  Apparently, Diazonium Fluoroborates are unusually stable, allowing them to be isolated as solids. The second reason, the reaction is interesting, is that it produces "free" Boron trifluoride.

no1uno

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Re: Boron Tribromide Synthesis Route (Low Temp)
« Reply #8 on: August 26, 2010, 02:17:56 PM »
There are less suicidal routes to BF3, which have the benefit of not attracting the wrong sorts of attention from all sides of the street.
"...     "A little learning is a dang'rous thing;
    Drink deep, or taste not the Pierian spring:
    There shallow draughts intoxicate the brain,
    And drinking largely sobers us again.
..."

Buzzoff

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Re: Boron Tribromide Synthesis Route (Low Temp)
« Reply #9 on: August 26, 2010, 11:01:58 PM »
Not suicidal.  Fairly easy.  Check Vogel.
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