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greenimp
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Easy anhydrous AlCl3 production
I wanted to post something I have been thinking about recently. I have spent alot of tie trying to produce 100 gram scale quantities of anhydrous
AlCL3. I have experimented with Al powder is a variety of solvents, with dry HCL gas bubbled through the solution. I have achieved success with this
procedure, but rejected it for larger scale production.
Al and Cl2 gas has also rejected for reason of scale/cost
I know someone will say, anhydrous AlCl3 is not that expensive, or hard to purchase. This is true, but the hazardous shipping costs are often greater
than 50% the cost of the item. A method that allows medium scale production at low cost would be a boon to my pocket book.
Recently, this patent, US patent 3471250, link has come to my attention. It has been mentioned here a few years ago in relation to creating anhydrous FeCl3. After reading the patent, I
think it might suit my needs nicely. One can make hexahydrate AlCl3 easily enough from HCl and Al foil.
Moreover, the AlCl3-DMSO precipitate that forms is also a really nice way to store AlCL3 long term, as it can quickly be heated under vacuum to
generate fresh anhydrous AlCl3 as needed.
I will post my experiences with the process soon. If anyone has experience with this method, and wants to comment , have at it.
Green Imp
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Klute
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Nice find! Using triethylamine looks like a good alternative, with a lower bp, and it's pretty cheap...
It's pretty surprising that even the dihydrate of magnesium can be deshydrated without hydrolysis..
Let us know how it goes!
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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greenimp
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To be true it was not me that found the patent. It was bought to my attention by another.
I have a gallon of 99% DMSO that is left over from other experiments, so I will be trying it first.
Plus I can probably recover most of it, if I do a large batch.
Green Imp
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chemrox
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I also found that one .. right after finding a vendor with a decent price. Did you make the 99% DMSO from cruder stuff by distillation or buy it that
pure?
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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greenimp
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My local health food store stocks the 250ml and 500ml bottles of 99% DMSO. I asked the manager if they could order me a gallon, because I was buying
so much, and they did it.
I have used it when I was going crazy trying to get my methyleneation experiment to work. It works fine in those reactions.
If this procedure works I am going to be really upset, because I spent a lot of weekends with my gas generator with very little to show for it, save a
lot of spent solvent.
This is just silly easy if it works. Oh, and it was 2bfrank that brought the patent back to the surface. He should get the credit for tracking it
down.
Green Imp
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starman
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I'm assuming you have a capable vacuum pump.The one example they ran at less than savage vacuum(the one @3mm Hg) required 10 hours on a scale 1/100th
what you are looking at.
Do let us know how you go.DMSO is at least readily available.
Chemistry- The journey from the end of physics to the beginning of life.(starman)
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Polverone
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Anhydrous aluminum chloride sublimes pretty readily even at atmospheric pressure. It seems a lot more volatile than any of the example compounds in
the patent.
PGP Key and corresponding e-mail address
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greenimp
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Good point. I encountered that with my previous experiments. Actually, you might be able to use the sublimation to purify it. Heat it under vacuum,
get it to sublime, and recover the vapor. I'll have to get my notebook out, but I think I saw sublimation around 60C with my vacuum at full for
AlCl3. Sublimation might not work at the large scale, but for 50-100g it might work just fine.
I also wounder it just re-suspending the AlCl3-DMSO in something like DCM would dissociate the two? Maybe another solvent?
Also the vacuum times seem to change with the halide, so 10 hours might not be norm.
Also, having read the patent again in more detail, it says up to a 50% aqueous solution of DMSO can be used. So apparently a little water in the
drying reaction is not too critical.
Green Imp
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len1
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AlCl3 is a stronger Lewis acid - due to the fact that Al3+ ion charge to size ratio is greater, therefore it is harder to dehydrate - than any of the
other Lewis acids used in the examples. I do not think thats an accident, but might be worth a try. My advice to many here is - do not boast of what
you are going to do, do first, post later, to avoid looking silly.
[Edited on 22-7-2009 by len1]
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chloric1
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This is completely off the DMSO track but here is another approach. Heating aluminum powder with anhydrous cupric chloride. Anhydrous cupric
chloride is easily obtained from the dihydrate by simply heating to 102 Celsius. The reaction is fast and thermite-like but if you have an efficient
means of collecting the AlCl3 fumes, you are good to go.
Fellow molecular manipulator
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kclo4
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If the AlCl3 is to hard to get from the AlCl3-DMSO via vacuum and heating, maybe a compound that could trap the DMSO and free the AlCl3 could be
used/found?
I think a lewis acid that has a significantly higher sublimation temperature could allow the reaction to shift towards the free AlCl3 as it is
heated, having the AlCl3 sublimate away leaving the lewis acid-DMSO behind.
AlCl3-DMSO + X = X-DMSO + AlCl3
X = suitable lewis acid, such as FeCl3, MgCl2, etc.
Also would the AlCl3-DMSO itself work as a lewis acid at all? It seems it may if it were in boiling xylene or toluene, as at 110+*C, as it may break
down a bit giving up free AlCl3 and DMSO, this might allow for some other method of separating it.
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greenimp
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Well gave this a try today.
7g AlCl3-6H20 was dissolved in 50 ml 95% EtOH. To this was added slowly 50 ml of 99.9% DMSO. The DMSO was added slowly in 1ml aliquots to see if
precipitation would occur. After 50 ml had been added, no precipitate had formed. The solution was clear at the end of the DMSO addition.
The solution was then heated to remove the EtOH at atmospheric pressure. As the EtOH was removed, the solution took on a yellow color that increased
as the EtOH was removed. When about 45 ml of EtOH had been evaporated, the solution turned cloudy and a fluffy/snowy white precipitate formed. The
was removed with vacuum filtration. The weight if the vacuum material was 16.5g.
The 8g of this material was then placed in a round bottom flask and vacuum of 26 inHg was applied while heating to 120C for 2 hours. Noticeable vapor
was seen leaving the material can condensing on the inside of the flask. Later inspection of the condensate showed it to be DMSO. After 2H some of
the material had taken a yellow color, and the rest was a crunchy white solid, where as the starting material was a fluffy white-soft solid.
Also I should add the precipitate will re suspend in water.
I am going to try a longer vacuum treatment in a smaller flask tomorrow.
[Edited on 24-7-2009 by greenimp]
Green Imp
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Klute
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You should have tried to sublim the solid! So is it anhydrous AlCl3? What was the weight loss?
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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greenimp
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No I don't think it is anhydrous yet, I think all I did was remove some more un-complexed DMSO that had not been removed during filtration. I suspect
all my vacuum treatment did was dry the material further.
But I do think I was able to get the AlCl3-DMSO complex to form. To what extent will require more testing.
The material does not react "violently" with water, it just re suspends in it.
Green Imp
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Maja
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What about heating AlCl3-DMSO complex in a flask till the complex decomposed, then pour some dry organic solvent to extract DMSO ? And you are left
with AlCl3 with some organic solvent(in most cases AlCl3 is suspended in solvent, so I don't even know who would like to evaporate solvent from
AlCl3)?
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kmno4
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Many years ago I did experiment with heating ( 300-400 C as far i remember) of Al pieces (~2x2x2 mm) in stream of HCl (from H2SO4/NaCl) in glass pipe.
I prepared about 50g AlCl3 in this way, just to see if it works at all.
Simple, rapid and the cheapest method I know.
Next I threw this AlCl3 into water in water-closet ....
Good thing for a show 
I also remember specific smell of anhydrous AlCl3.
AlCl3 is strongy coordinated especially by substances containing oxygen, so preparing it by DMSO method is rather losing the time. But for same
experimenting.... why not.
ps. 80% of patents (especially old ones) is a bullshit.
[Edited on 26-7-2009 by kmno4]
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Vogelzang
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Look at the aluminum chloride patents here:
https://www.hyperlab.info/inv/index.php?s=309f6d356ac3dee658...
Хорошая мысль!
[Edited on 25-7-2009 by Vogelzang]
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len1
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The fact that far too many patents are bullshit can be vouched for from my many experimental pages on this site. But the above patent I dont believe
lies in this class. Good idea indeed, why didnt I think of that. AlCl3 must sublime out of a melt mixture of low b.p. chlorides, such as the
sodium-calcium eutectic of the downs cell, and aluminium sulphate by LeChatliers. Who wants to mess with HCl at 700C? On the contrary, the DMSO
method, apart from being economically silly, does not have thermodynamics on its side either.
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kmno4
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700 C is too much, there is no need for such heating and it is above melting point of aluminum.
Al quickly reacts with hot HCl, AlCl3 sublimates above 200 C, surface impurities of Al (mainly oxide) just leave in pipe, product is pure and ready to
use. The only messy thing is strong corrosive effect of HCl when it is out of aparaturus. Just every metal item close to HCl sourse will cover with
rust soon. Unfortunately it was tested 
But it happens only if you let HCl go out.
Al, H2SO4, NaCl - what can be cheaper ?
Glass pipe - I used laboratory glass pipe 3 cm in diameter, ~40 cm long, filled in central part with Al pellets (cut 2mm wire), heating wire around
the pipe....
One of the earliest experiments of mine, so cannot be difficult to do. I do not force anyone to do this but it seems to be the only good method for
preparing AlCl3 on multigram scale.
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len1
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You are right, I exaggerated for effect. Its more like, 400-500C in a tube oven.
But to answer your question, NaCl, CaCl2, and Al2SO43 is cheaper. You dont have to adjust HCl rate with possibility of generating too much effluxing
you product and corroding everything. The former method you can do completely hermatically on a large scale in a box oven, the later as you say needs
a tube so yield is limited. Plus this method is new. AlCl3 often comes from reputable suppliers (like my last batch from sigma, partly hydrated.
Its a problem if you want it to make LiAlH4 to get around the high cost of the latter. This is in fact the topic for which it was suggested, but my
understanding is noone tried it out.
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Sedit
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This appears to be a nice way to produce AlCl3 len and I wouldn't mind attempting a small amount just for fun but I must ask about Aluminum sulfate
and how does one obtain it anhydrous? Will simple heating suffice or should desiccation or other means be used?
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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len1
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Thats very easy. Al sulphate melts and undergoes various hydrates of decreasing water content, starting at 86C, until by 250C or so its essentially
anhydrous.
But its even easier than that, because alum, the dirty variety sold in gardening supplies will do even if you want your AlCl3 99%. The AlCl3 will
purify itself by fractional distillation.
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Sedit
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Very nice, Thank you much len.
I can't help but wounder why this is not more popular though considering everything that gets spoke of on these forums talk about feeding dry HCl
over hot Al and condensing the vapors IIRC. Seems rather trouble some when put into perspective against this process.
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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len1
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Ah yes, I was rather thinking that two. Two possibilities come to mind
1) The patent is obscure - so those passing HCl over Al dont know better
2) It doesnt work and the patent author is a lier - my concern is the Al sulphate getting covered by insoluble CaSO4 stopping reaction.
Which is it? You cant rule this one out on theory, so the only way is to do it. If you or someone else dont get there first, Ill find out myself.
Thats why science is more fun than watching crap on TV.
[Edited on 27-7-2009 by len1]
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Magpie
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Thats why science is more fun than watching crap on TV.
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TV's crap is about to reach a new low. Nadya Suleman is getting a "reality" show where each of her 14 children will be paid $250/day.
Sorry for dumping in this important thread, but I couldn't help it.
The single most important condition for a successful synthesis is good mixing - Nicodem
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