Sciencemadness Discussion Board

Aluminum bromide, AlBr3

TheMrbunGee - 17-12-2016 at 05:31

Hey, so I opened ampule of AlBr3, and I have done all the things I wanted, I still have about 100g left. Because of shity labware it is now sitting in a jar, slowly decomposing - so - any cool suggestions for a good use of it?

j_sum1 - 17-12-2016 at 05:36

Make bromine? I mean, why wouldn't you?

Deathunter88 - 17-12-2016 at 08:05

Re-ampoule it?

TheMrbunGee - 17-12-2016 at 08:26

Quote: Originally posted by Deathunter88  
Re-ampoule it?


I have more ampules, and this one is already dirty and partly decomposed! :D

Also for bromine - same problem with storage! Bromine would be last thing I would make from it!

Isn't there really nothing interesting to do with it? :?

JJay - 17-12-2016 at 09:17

You can use it as a catalyst for Friedel-Crafts alkylations and acylations. With the bromoacetone you have, you could make some interesting aromatic ketones... do be careful, though, because it is easy to get into some legal grey areas with those... you don't want to have to explain to a judge why you just so happened to whip up a batch of phenylacetone.

myristicinaldehyde - 17-12-2016 at 09:24

AlBr3 can also cleave ethers- my new research group will be using it for that purpose. Maybe it will work on vanillin?

JJay - 17-12-2016 at 18:13

I wish I had fancy chemicals like AlBr3. I'm not even really sure how to make it... the reaction between bromine and aluminum is extremely vigorous.... Perhaps by slowly dropping a very dilute bromine/chloroform solution into a stirred chloroform/aluminum turnings mixture and then distilling off the chloroform? Or maybe leading an excess of bromine vapors into a room temperature tube lined with aluminum foil... that is likely a good method, actually... it would be easy enough to recover any extra bromine... and if you used a quartz tube, you could heat it with a torch to kick off the reaction if necessary.

[Edited on 18-12-2016 by JJay]

Texium - 17-12-2016 at 18:33

Depending on what you're doing with it, it can sometimes be prepared in situ. For instance, I made bromobenzene from benzene and bromine once, and I just used a slight excess of bromine and added a couple little scraps of aluminum foil to the flask. The excess bromine reacted with the aluminum and the bromination proceeded successfully.

Melgar - 17-12-2016 at 18:57

Quote: Originally posted by JJay  
I wish I had fancy chemicals like AlBr3. I'm not even really sure how to make it... the reaction between bromine and aluminum is extremely vigorous.... Perhaps by slowly dropping a very dilute bromine/chloroform solution into a stirred chloroform/aluminum turnings mixture and then distilling off the chloroform? Or maybe leading an excess of bromine vapors into a room temperature tube lined with aluminum foil... that is likely a good method, actually... it would be easy enough to recover any extra bromine... and if you used a quartz tube, you could heat it with a torch to kick off the reaction if necessary.


Not only does aluminum react readily with MeCl and chloroform, AlBr3 can be used to displace chlorine with bromine in organochloride compounds. This can be a convenient way to make dibromomethane, which might be interesting to OP. A lot of people on this site tend to be interested in dibromomethane and diiodomethane for some strange, incomprehensible reason.

byko3y - 17-12-2016 at 20:30

I think you can use pretty much any inert solvent that is capable of dissolving the AlBr3, benzene is a good example already mentioned, but chlorobenzene and nitrobenzene also work well. Chloroform is not an inert solvent, and the main products of reaction with it are dibromochloromethane (CClBr2) and AlCl3.
Unlike AlCl3, AlBr3 can be distilled, has a high melting point of 97.8 °C though.
Interest for dihalomethanes arizes from those interested in MDA/MDMA.
Ampouling aluminium bromide is pretty tough task, because traces of water in the amoule might lead to a critical buildup of pressure and cracking of the amouple, because HBr has higher vapour pressure than H2O. Sealing at high temperature (100°C) and storing in cold might resolve the problem.

JJay - 18-12-2016 at 03:03

Hmm... I wonder how hard it would be to remove glacial acetic acid from AlBr3... GAA is not exactly a dessert topping (it's pretty nasty stuff, actually), but it is less flammable than benzene and not carcinogenic.

byko3y - 18-12-2016 at 05:05

Aluminium has a high affinity for oxygen. Products of reaction of acetic acid with AlBr3 in anhydrous conditions are aluminium acetate and HBr.

Ozone - 18-12-2016 at 07:49

Hmm. I'd seal the jar (with a PTFE seal, under an inert atmosphere, if possible), tape it up (teflon helps), and put that into a sealed container with a bunch of Dririte (I prefer the indicating type). I have AlCl3 that has remained dry this way--just make sure the rocks stay blue.

Aside, I always made AlBr3 in-situ for Friedel Crafts, as described by zts16--I ball up the needed mass of aluminum foil, put that into a flask and set up for reflux with a vapor trap. Then, the apparatus is flamed, and stoichiometric bromine is slowly added with a dropping funnel. Even with slow addition, the reaction is exciting, and yields a highly active catalyst.

O3

JJay - 18-12-2016 at 09:04

It sounds like in-situ is definitely the way to go for most reactions involving AlBr3. I've seen a few videos of the reaction between Al and Br2, and it looks pretty spectacular.