Sciencemadness Discussion Board

AlCl3 synthesis

Otter - 5-8-2011 at 19:29

Two days ago a friend and I tried to make Aluminum Chloride.

We mixed bleach and fuming HCl to generate chlorine gas, which we diverted into a flask containing shredded aluminum foil. We didn't heat the aluminum foil in any way, however we did conduct the whole venture in the sunlight, hoping that some UV light might break down some chlorine to atomic chlorine which is much more reactive.

However after waiting for a long time (~30 minutes) nothing reacted.

Can anyone tell me what exactly went wrong? :(

bob800 - 5-8-2011 at 20:24

According to Wikipedia,
Quote:
Aluminium chloride is manufactured on a large scale by the exothermic reaction of aluminium metal with chlorine or hydrogen chloride at temperatures between 650 to 750 °C.


So, you would need to heat your Al to at least 650 degrees C for the reaction to proceed.

Otter - 5-8-2011 at 20:31

Okay, so it's exothermic. It doesn't necessarily have to be heated to 650C, just high enough to get the reaction going.

Nicodem - 6-8-2011 at 02:55

Anhydrous Aluminum Chloride prepration

User - 6-8-2011 at 03:12

Nevertheless every source that ive seen so far speaks of a high temp, never below 600/650 degrees.
Lower temp reaction are possible with use of FeCl3, but the direct route seems rather efficient.

UV radiation would take a long time unless one uses way higher levels, if it even works in the real world.
I like the idea though.

(There are numerous posts on this subject already, couple a topics also.)

Otter - 6-8-2011 at 04:42

Are there other Lewis acids that I could make without needing to work with chlorine gas just needing HCl(aq) instead?

bbartlog - 6-8-2011 at 05:01

ZnCl2? But obtaining anhydrous ZnCl2 from the hydrated form that you will get if you just put zinc in aqueous HCl is also a bit of a challenge, and anyway it may not be a strong enough Lewis acid for whatever you're trying to do.

User - 6-8-2011 at 09:11

You can actually make AlCl3 with dried hydrochloric gas.
2 Al + 6 HCl → 2 AlCl3 + 3 H2
;)



edit
ouch this might be faulty
Ill look it up.

[Edited on 6-8-2011 by User]

MeSynth - 6-8-2011 at 15:04

There is a topic on this. AlCl3 is the anhydrous form of the chem. From what I have read and figured out myself the best way to make produce this stuff is by passing anhydrous hydrogen cloride over the surface of aluminum heated up close to 400 degrees. You cant do this in a glass tube (I tried) and it is not smart to do this in a metal BBQ held together with aluminum nuts and bolts. (they melted when i tried). I did, however, have the pleasure of watching the reaction take place before the glass tube started to melt. The gas was passing over the aluminum and then white powdery trails started to form off of the aluminum down wind through the tube. It was a bright white powder. The whole experiment when sour when the BBQ was so hot that nuts and bolts were melting. So I removed the glass tubing and threw it on the grass and squirted it with water... and then the BBQ which took 5 minutes of hosing to cool down.

It would be smarter to dig a small ditch and line it with bricks and line the walls with bricks if you make it rectangular. And it would also be wise to use an aluminum tube instead of glass. I haven't done this experiment again due to the cost of charcoal and propane and the low chance of success that I think I have. No your best bet is to search the net and find a supplier that sells it to individuals. They are out there.

OR you can get a small peice of aluminum tube and a blow torch as the reactor. Sulfuric acid and salt for hydrogen chloride. Calcium chloride in the drying tube. And then another metal tube that is slightly wider than your reactor tube that you can fit over the end to catch the AlCl3. If i did it again I would try it like that. ur brain will figure it out.

MeSynth - 6-8-2011 at 15:11

PS keep in mind that when you generate HC from table salt it tends to foam really bad. Pool salt foams too. In fact I have not figured out how to prevent foaming. the foam can get up into the tubing and then into the reactor contaminating your experiment.

User - 7-8-2011 at 03:49

Or one could just use an Al pipe, this way you can consume the apparatus itself.
Foaming can in some cases be held down by using a little alcohol, dont know if this is safe in this setup.

[Edited on 7-8-2011 by User]

unionised - 7-8-2011 at 04:12

Why are people suggesting using an Al tube?
At temperatures between 650 and 750 C the stuff will melt.
Even if it doesn't melt then it will be burned through by the chlorine.

I suspect adding alcohol won't help much in conc H2SO4. It would be potentially dangerous in a chlorine generator.

Also, unless you dry the gas, the major product will be Al2O3


Mildronate - 7-8-2011 at 04:36

You can use quartz or ceramic tube with nicrome wire over it.

Otter - 7-8-2011 at 20:23

Quote: Originally posted by unionised  
Why are people suggesting using an Al tube?
At temperatures between 650 and 750 C the stuff will melt.
Even if it doesn't melt then it will be burned through by the chlorine.

I suspect adding alcohol won't help much in conc H2SO4. It would be potentially dangerous in a chlorine generator.

Also, unless you dry the gas, the major product will be Al2O3




How about using a steel tube?

I don't think it necessarily has to be heated to so high a temperature. Possibly 200C (I don't mind a slower reaction), this way I suppose I could also cover the inside of the tube with some petroleum jelly to stop the tube being eaten up, and then just wash out the whole thing with dry ethanol, add a bit of gasoline to dissolve and extract petroleum jelly from the ethanol and then crystallize the AlCl3 by just evaporating the ethanol?

According to wikipedia AlCl3 IS soluble in ethanol.

http://en.wikipedia.org/wiki/Aluminium_chloride

Retard-3000 - 8-8-2011 at 00:24

Could AlCl3 be produced by bubbling dry chlorine gas through anhydrous liquid aluminium triiodide ?, The melting point of AlI3 is stated as 189.4C (wikipedia) which is easily achieved, or maybe even using aluminium tribromide which has an even lower melting point of 97.8C ?

Arthur Dent - 8-8-2011 at 03:58

I tried the synthesis of hydrated AlCl<sub>3</sub> over the weekend, by dropping a big chunk of heat sink in a erlenmeyer with a sidearm, filled with 32% HCl.

Wow, talk about exothermic!!! the erlenmeyer was so hot i needed cooking gloves to handle it, and some furiously corrosive vapor of water/HCl/hydrogen was coming out of the sidearm. The reaction evolved much dark gray froth and when it settled, gave a dark gray solution with lots of precipitate.

So then I filtered the solution and threw away the precipitate left in the filter. The filtered solution was light bluish and very thick, like syrup. I'll let the stuff settle for a couple of days to see if there are phase separations or settling of sediments. The solution is still acidic so I guess there's still some unreacted HCl in there.

Anhydrous stuff would have been interesting to prepare but it is way beyond the realm of possibility for me. :(

Robert

[Edited on 8-8-2011 by Arthur Dent]

Picric-A - 8-8-2011 at 06:05

Dont forget all aluminium chloride solutions are acidic due to the equilibrium;

AlCl3 + 3H20 <--> Al(OH)3 + HCl

Mixell - 8-8-2011 at 06:28

You sure thats right? Anhydrous AlCl3 reacts like this with water.
But as far as I know, the Al(H2O)6 3+ cation, present in aqueous solutions of aluminium salts, dissociation of this ion is as follows: Al(H2O)6 3+ <-->Al(H2O)5OH 2+ + H+. This is the cause of the acidity of Al 3+ solutions.

Otter - 8-8-2011 at 07:43

Due to Al3+ ions hydrating to form the Al(H2O)1OH 2+ ligand, when you dry the products from reacting hydrochloric acid and aluminum metal you'll be left with a whole lot of alumina or aluminum hydroxide, with all the chlorine leaving the solution in the form of HCl. That huge positive charge of the aluminum ion combined with the tiny size of the ion makes it bind itself very strongly to the very negative dipole with water.

Actually a 1M solution of Al(H2O)6 3+ is very acidic, with a pH of around 1!

Sorry Arthur Dent, that precipitate isn't AlCl3. Only way to make AlCl3 is to use chlorine or HCl gas I'm afraid. :(

Retard-3000 - 8-8-2011 at 09:03

Anyone ?

Otter - 8-8-2011 at 09:42

Quote: Originally posted by Retard-3000  
Anyone ?


Yes... however where will I get Aluminum iodide? Just as hard to get as the chloride salt. :P

I will work though, chlorine will oxidize iodine and make it back into a gas as chlorine's more reactive. But if I can get AlI3 I can certainly get AlCl3

Mixell - 8-8-2011 at 10:00

Anhydrous AlI3 can be made by reacting aluminium and iodide, with chlorine its a lot harder since its a gas.

Mildronate - 8-8-2011 at 10:12

Annybody had synth AlBr3 or AlI3 ir large amounts?

Retard-3000 - 8-8-2011 at 14:37

The reaction between aluminium and iodine or bromine is very exothermic so an excess of halogen should be used, also it'd be recommended to maybe use a condenser to condense any bromine or iodine back into the reaction.

smaerd - 8-8-2011 at 21:43

Now I'm a pretty dumb dude but wikipedia shows something interesting on the AlBr3 page.

(DRY) 2Al + 3Br2 ==> Al2Br6
(DRY) 2Al2Br6 + 3CCl4 =heat=> 4AlCl3 + 3CBr4

Now the actual feasibility of preparing CCl4 from chloroform/dichloromethane and Cl2 gas I'm not really aware. This is the only way around the furnace I could find.

Drying Br2 is a pretty unnerving task without a fume-hood/blast shield.

Will this actually work? I don't know... Also there is like 10 AlCl3 threads, this is getting out of hand... Wish I could find a supplier that didn't only sell it by the kg(and overseas).

[Edited on 9-8-2011 by smaerd]

redox - 9-8-2011 at 05:43

Quote: Originally posted by smaerd  
Now I'm a pretty dumb dude but wikipedia shows something interesting on the AlBr3 page.

(DRY) 2Al + 3Br2 ==> Al2Br6
(DRY) 2Al2Br6 + 3CCl4 =heat=> 4AlCl3 + 3CBr4

Now the actual feasibility of preparing CCl4 from chloroform/dichloromethane and Cl2 gas I'm not really aware. This is the only way around the furnace I could find.

Drying Br2 is a pretty unnerving task without a fume-hood/blast shield.

Will this actually work? I don't know... Also there is like 10 AlCl3 threads, this is getting out of hand... Wish I could find a supplier that didn't only sell it by the kg(and overseas).

[Edited on 9-8-2011 by smaerd]


When I get back from vacation in a couple weeks, I will attempt this, as I have both CCl4 and AlBr3. :cool:

Mildronate - 10-8-2011 at 01:51

But why you need it? You can use alBr instead of AlCl3?

Bitburger - 19-8-2011 at 11:26

It's pretty easy to make AlBr3, but once you made it under reflux with toluene as a solvent you should see that clouds will form immediately when exposed to air. It's caused by the reaction of this substance with water in the air, I think that AlBr3.6H2O might be formed in the first phase.

I choose toluene because both bromine and AlBr3 are soluble in it. However, the mixture have a brown colour.

I can do two things: a one pot reaction without isolating AlBr3
OR
Try to isolate AlBr3 by destillation.
I prefer the first one.
---------------------------------------------------------------------------------
AlBr3 forms yellow-white hygroscopic monoclinic crystalls
mp.97.5°C
bp.255°C
Ref; Handbook of Chemistry and physics 2010-2011

MeSynth - 21-8-2011 at 19:12

I just found a listing on ebay for this chemical.

http://www.ebay.com/itm/Aluminium-chloride-anhydrous-100g-98...