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Author: Subject: Anhydrous Aluminum Chloride prepration
byko3y
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[*] posted on 24-6-2015 at 00:35


Considering you can obtain at least 60% yield using a regular chlorine-foil method, I doubt the ZnCl2 way is viable.
Pretty much the only major problem is to move the product all the way through the tube to the receiving vessel and stop it right there. I'm sure this was a major issue in your case.
Asbestos/glass wool/PTFE plug will shield the receiving flask from water.
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[*] posted on 24-6-2015 at 07:37


Quote: Originally posted by ChemPlayer_  
So I sneaked in the time quickly to do another run, this time using 100g of anhydrous zinc chloride and 25g of aluminium powder (~25% molar excess).
[snip]
3. I saw the liquid mentioned refluxing back into the flask (which didn't violently react with anything, hence I assume you must be right and this is AlCl3 or ZnCl3 as opposed to anything aqueous in nature - not that I imagine water can survive long in those conditions anyway).
[snip]
I can only conclude that a lot of the product must be retained in the reaction flask (or the reaction didn't go to completion).

Ok so now I've got the basic set-up nailed (I think) my thoughts on next steps are to see if I can grind up the ZnCl2 into a finer powder (at the risk of atmospheric moisture absorption however) and hence a better surface area with the Al (and maybe slightly greater excess of Al to temper the likely faster reaction a bit).

I have to replenish my ZnCl2 stocks first however as this is quite an 'expensive' process unoptimised! I do have a beautiful 100g+ of AlCl3 collected now though and I may do some more FC experimentation in the interim.


25 % molar excess is still not really a lot. Of course increasing it further may increase yield but will also waste Al powder.

ZnCl3?

Try heating stronger when the reaction appears to be tailing off. Try and actually liquefy completely towards the end. I think the reaction is not running to completion, due to poor reagent/reagent contact. Even if you reached the BP of ZnCl2 (756 C), it would condense back in the higher, cooler part of the flask.

Quote: Originally posted by byko3y  
Considering you can obtain at least 60% yield using a regular chlorine-foil method, I doubt the ZnCl2 way is viable.
Pretty much the only major problem is to move the product all the way through the tube to the receiving vessel and stop it right there. I'm sure this was a major issue in your case.


Depends what you call viable: it’s not intended as an industrial process. As a set up it’s a lot easier than having to deal with HCl or Cl2. That’s why I tried it.

You wouldn't be writing that second sentence if you had witnessed it yourself. Losses through the gap are quite modest but could be further reduced, for sure. Condensing AlCl3 w/o losses with the HCl/Cl2 method faces the same problems.

[Edited on 24-6-2015 by blogfast25]




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[*] posted on 24-6-2015 at 17:40


I think you're both right.

Losses from the gap are now really minimal using the larger bottle so it's a challenge of moving the product into the collection vessel, or getting the reaction to run to completion; I suspect both are the issue.

For me this process feels like it holds a lot of potential, having played around with Cl2 gas and Al and nearly gone crazy in the process. If this can product 50-60% then I will be very happy, but I agree that even with 30-40% this is still somewhat useful for the home chemist considering the alternative.

Ultimately though I like the challenge of trying to really understand what's going on here and seeing if this can be optimised. I'm on about reaction 15 now and I don't expect that I've unlocked all the secrets if they are there to be discovered just yet. This is as much for the challenge and understanding as for the end product of having a nice useful anhydrous AlCl3 source.

I will post any more useful findings as and when I get them...
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[*] posted on 24-6-2015 at 20:47


I wholeheartedly agree that these "solid" reactions are really interesting and present unique challenges for recovery of the product.

The economics are not good as ZnCl2 cost is similar to that for AlCl3. But since AlCl3 is such a powerful and useful reagent who knows if its availability might someday be restricted. I consider the development of OTC procedures for making such reagents to be a high calling for our hobby.

For these "solid" reactions it seems that they really don't take off until some amount of liquid is formed. I'm thinking specifically about the following, of which I do have experience:

1. phosphorus: from (NaPO3)6 (MP = 628°C)
2. benzene: from Na benzoate (MP = 410°)
3. pyridine: from nicotinic acid (MP = 237°C)


[Edited on 25-6-2015 by Magpie]

[Edited on 25-6-2015 by Magpie]




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[*] posted on 27-6-2020 at 08:49


Age old topic, but I made a quartz tube reactor ages ago which I packed with two flanges with aluminosilicate cement housings and cast-in smaller borosilicate tubes for inlet and outlet. If this whole apparatus was heated above 200C and the center to 600-700C, it could be used to batch produce aluminum chloride. It would exit the other tubing and sublimate into a receiving flask, which could be kept under drying tube.

A more serious device could be made with a flask with gas inlet and outlet, the system kept in housing that is heated above 200C at all times, and the flask itself kept at 600-700C holding molten Al and Cl2 lead in. AlCl3 would sublime away through the exit tube and sublimate to the receiving vessel. If excess chlorine were to vent, it could be exhausted properly through a drying tube.
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[*] posted on 29-6-2020 at 20:44


I’ve been curious as to if loss of the alcl3 can be mitigated using anhydrous ethanol or methanol. Per US1647446A, the patent states that solvents can be used to suppress the powder alcl3

A787867A-954D-4E49-B09E-D3BE2C999113.png - 65kB

I’ve been finding a mix of information. Some sources say that ethanol reacts with alcl3 at room temperature. I can’t find anything about the recovery of alcl3 from anhydrous solutions of ethanol

[Edited on 30-6-2020 by Opylation]
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[*] posted on 30-6-2020 at 05:27


The ethanol will react with the AlCl3, since AlCl3 is a very strong Lewis acid. The final products will likely be ethyl chloride and aluminum oxychlorides.



As below, so above.
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[*] posted on 30-6-2020 at 08:30


I have made small amounts of aluminum chloride from hydrogen chloride and aluminum in a quartz tube. I never managed to make very much of it that way due to flaws in my equipment that I wasn't aware of and also my relative lack of skill at the time. I was not exactly unskilled, but I had never used such a complex piece of apparatus before, and the experience of actually doing things like gas drying and temperature control was fairly new to me. I had one run that resulted in maybe half a gram of apparently fairly pure product and another run that was too hot that resulted in a lot of unreacted aluminum getting into the product (which was a few grams). Both times I had hydrogen chloride leaking from a completely invisible pinhole in one of my pieces of equipment.

The major advantage of hydrogen chloride over chlorine, of course, is that hydrogen chloride is much less toxic. A disadvantage is that the apparatus will generate hydrogen. Hydrogen can drive air out of the apparatus, but it's also extremely flammable, especially at 700 C, so several precautions must be taken.

I think it would be practical for a skilled chemist to make hundreds of grams of aluminum chloride that way with good equipment.



[Edited on 30-6-2020 by JJay]
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[*] posted on 6-7-2020 at 18:50


I just completed a successful reaction of Aluminum with Chlorine gas. The first go-around worked but got ruined due to blowback from the chlorine trap. The second go worked but was ruined because I did not continue the chlorine generation. The third and final go worked perfectly.

I started by getting a chlorine generator ready, hooked it up with a short path condenser, and had it empty into a flask with small chips of aluminum foil. The vacuum adapter was then hooked up to a base scrubber to capture excess Cl2 gas. The aluminum was heated with a large propane torch set to almost closed (very weak stream, lower temp), which equated to roughly 700 degrees celsius. It was held away from glass (I have broken so many flasks because of heat shock) and slowly warmed. When it was too hot to touch, I then heated it much more rapidly and waited until I saw reddish-pink coloring of the glass. I stopped and shook the flask as best I could, and within seconds, it flashed and rapidly sublime out white substance. Once settled, it was exactly the consistency expected from the literature. I am very surprised I did not break my glassware during this reaction. That propane torch can reach 2000C if I opened it to full.

I must note that there should be catalyst added in future to help heat and begin the reaction. I have read about FeO2/CuCl2 mixture, like a powder that can be mixed. I will probably invest in a coffee grinder to help increase the surface area of the aluminum. If I was to require more however, more than 5-10g, then I would use some of the methods already posted here, as they seem to be geared towards larger amounts. Quartz tube was suggested, and maybe a doped quartz wool (FeCu/C) would be nice. Maybe a Fe-Fe(CN)6 complex would work?

alcl3-sublime-h2o-impurity_yellow.jpg - 69kB

alcl3-sublime-h2o-impurity_yellow.jpg - 64kB




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clearly_not_atara
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[*] posted on 7-7-2020 at 07:46


So apparently CuCl2 produces too much heat when you use it? We switched to ZnCl2 for this reason?

MnCl2 can be dried by heating and should give a less exothermic process than CuCl2 while being easier to make than ZnCl2. Just a thought.




[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 7-7-2020 at 09:28


It's probably possible to get Al-CuCl2 to work to produce useful amounts of AlCl3, but as far as I am aware, no one has worked out all of the details yet. There have been a few attempts. When the reactants are dry and finely powdered, the reaction is extremely vigorous, like setting a flame to gunpowder. When the aluminum is in coarse granules, continuous application of a propane torch is necessary to sustain the reaction.

A prominent member of this forum mentioned in the exotic thermites section some results from wrapping copper (ii) chloride in aluminum foil.

MnCl2 is an interesting idea... MnCl2 and Al melt at about the same temperature....
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[*] posted on 7-7-2020 at 09:52


Doesnt the chlorine generator and quartz tube with al-foil procedure work ok?
Below is a procedure i saved from somewhere.
I add a pdf with another variant that i also found somewhere.

Concentrated (37%) hydrochloric acid (20 mL, 658 mmol) was added dropwise to hydrated calcium hypochlorite (22.0 g, 102 mmol) generating a steady stream of chlorine gas.
The chlorine gas was passed through a glass column filled with aluminium foil (1.00 g, 37.1 mmol) and then into a water trap. Once the apparatus had been filled with chlorine gas the aluminium foil was heated with a bunsen burner to facilitate the reaction. Upon sufficient heating, the aluminium foil burnt with a bright white light signifying the reaction had commenced.
At this point the bunsen burner was removed and the reaction self propagated along the column with occasional flickers of red-orange embers. When the vigorous reaction had subsided, a black residue remained in the column and a yellow powder (AlCl3) was deposited in the receiving flask.
Yield: 4.05 g (82%).

Attachment: Preparation of aluminum chloride.pdf (160kB)
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[*] posted on 7-7-2020 at 09:54


Another approach would be to dissolve CuCl in acetonitrile... obviously you get half the molar yield vs the dichloride but the whole reaction is "cool" and liquid-phase, CuCl doesn't even form hydrates, and the solubility of CuCl in MeCN is apparently 20%:

https://www.researchgate.net/post/Solvent_to_dissolve_Copper...

Unfortunately the solution of CuCl in MeCN is unstable to aerobic oxidation, but this occurs slowly so just prepare it immediately when needed for use. It should be easy to recover the copper this way so the process can be repeated.




[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 7-7-2020 at 10:46


Quote: Originally posted by Mateo_swe  
Doesnt the chlorine generator and quartz tube with al-foil procedure work ok?
Below is a procedure i saved from somewhere.
I add a pdf with another variant that i also found somewhere.

Concentrated (37%) hydrochloric acid (20 mL, 658 mmol) was added dropwise to hydrated calcium hypochlorite (22.0 g, 102 mmol) generating a steady stream of chlorine gas.
The chlorine gas was passed through a glass column filled with aluminium foil (1.00 g, 37.1 mmol) and then into a water trap. Once the apparatus had been filled with chlorine gas the aluminium foil was heated with a bunsen burner to facilitate the reaction. Upon sufficient heating, the aluminium foil burnt with a bright white light signifying the reaction had commenced.
At this point the bunsen burner was removed and the reaction self propagated along the column with occasional flickers of red-orange embers. When the vigorous reaction had subsided, a black residue remained in the column and a yellow powder (AlCl3) was deposited in the receiving flask.
Yield: 4.05 g (82%).



I think I will try this one today and swap the quartz with my cheapo glass. I have gotten the cheap glass to work, but only on hot days and with low humidity. Also, I thought it was yellow because of Fe impurity?




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[*] posted on 7-7-2020 at 20:52


Good luck.
Dont put too much Al-foil in the glass tube as the produced AlCl3 can block the tube.
If that happens the chlorine gas will need to find another way out of the device.
Do it outside or if you have a flowhood.
I will also try this when my ordered quartz tubes arrives.
In the pdf variant they bubble the chlorine gas through 2 flasks before going into the glass tube with Al-foil.
The first with water to remove any HCL in the chlorine gas and the second with some conc. sulfuric acid to dry the chlorine gas.
I dont know how much this will improve things, but skipping this will obviously work also.
Maybe if you need high purity AlCl3 its something to consider.

[Edited on 2020-7-8 by Mateo_swe]
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[*] posted on 7-7-2020 at 21:01


Decided I am going to wait one more day. Tonight I prepped the chlorine, the sulfuric acid scrub, and I prepared a small 25mL flask. The hope is to load about .01g of Aluminum after its been cleaned, dried, and slightly warmed to evaporate any weird stuff. At about 7am, Ill rerun the reaction.

PS... does anyone have any clue what that black solid might be in the pictures above? The reaction auto-ignited and flew up the neck of the flask but quickly turned black from a white substance. Some of it turned yellow, but I'm not sure why. I had not run a iron reaction before in that flask. As far as I know, the only things in the flask were HCl gas, Cl2 gas, and the Aluminum.




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[*] posted on 9-7-2020 at 17:16


Okay, so that was a total failure. I tried three times again, and each time I was much too impatient and hasty. I heated the aluminum for away too long after the autoignition. However, had I successfully heated it properly, I would have attained beautiful yellow powder. Next time, sometime next week probably, I will work on a slower workup.

I think I am going to try ordering some catalysts, my professor from the Inorganic class said that Fe2O3 and CoCO3 are good to throw in. But everything needs to be fairly grinded. I suggest that anyone else use the powdered aluminum as it is easier to ignite. Only warning is that it is much quicker and needs to be done in a larger tube or container.




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[*] posted on 11-7-2020 at 03:36


The more solid the Al is the slower the reaction is going to be.
I would use a larger diameter tube if using thin or powdered Al, so it doesnt get blocked.
Maybe do a small test with not so much Al first to get a feel how fast the reaction is.
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[*] posted on 12-7-2020 at 15:49


Thats a good idea M... I am going to set up a gas adapter to my test tube and put one solid piece of foil in there, probably semi wound into a roll. Im not sure how much chlorine will be since my scale has broken, but I will make excess and add a air trap determine the usage of gas. I also heard that putting carbon inside the reaction chamber may increase the efficiency; came from the last inorganic lecture I sat in before the virus hit. If I recall correctly, the professor said that activated carbon could help homolytically cleave the Cl2 bond forming 2 radicals...

Anyone know if this claim holds any water?




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