xwinorb
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Anhydrous AlCl3 handling and storage
Some issues with anhydrous AlCl3 ( I have recently received 500 g I have just purchased ) :
It arrived in a cardboard box, the box was soft and wet and smelling of HCl. I initially though it might be leaking a bit. I removed the old package
and conditioned it better.
After looking some more in MSDS's, and exchanging emails with a friend that reported similar experience, I started to figure out that this is a
chemical difficult to store.
Looks like, no matter what you do, water sneaks in and starts to react with the chemical and then it produces HCl vapour.
Right now, I have the original bottle, top screw on cap taped ( it was taped when it arrived, I taped it a bit better ), inside a big ziplock plastic
bag, then inside a plastic container with snap-on lids ( supposedly air proof ), then inside a second similar container, with snap-on lids also,
slightly bigger.
Inside the bigger container, I am regularly placing DampRid ( cheap dessicant found at hardware store ).
Despite all this, it is still slowly releasing HCl. Every few days I remove the lids and relieve any HCl pressure on the small container ( I have seen
this procedure recomemended in one MSDS, other wise the HCl pressure might explode out the lid or bottle cap ).
Is there any way to avoid the slow HCl release ? Seems to be generated by AlCl3 reacting with ambient moisture.
One MSDS says SELF REACTIVE.
Just curious :
Does it means the AlCl3 reacting with the hexahydrate salt, or with Al(OH)3 ? Or with external moisture that gets inside ?
Also, does the HCl release gets worse after opening / loading / weighting the AlCl3 ? Have not done it yet.
I am planning my first Friedel-Crafts, a few weeks form now maybe.
For this reaction :
Just in case, my friend has advised me to mix the reactants slowly, gradually, with cooling and directing any possible HCl gas output down the drain
or to inside a water container.
Also, how long will the AlCl3 last ?
Any other tips on this subject will be greatly appreciated.
Thanks.
xw.
[Edited on 18-4-2012 by xwinorb]
[Edited on 18-4-2012 by xwinorb]
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woelen
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You should not release HCl every few days. Each time when you do that, the pressure inside will be lowered and new moisture is allowed to get inside
the container. Once there is a certain pressure of HCl inside the container, the reaction will stop and a steady state is reached.
You need a container with a very good seal. Only in such a container you can keep the chemical for any length of time. In other containers it will
degrade.
I personally would take a very good container and use that as main stock and besides that you take a small container (e.g. holding 50 grams), which
you use for experiments. The small container is opened more frequently for experimenting and the main stock only is opened when the small container is
empty.
For my own corrosive chemicals I use Schott-Duran bottles with GL 45 caps (just google on these terms and you see many examples), the blue ones if
just a good seal is needed for very air-sensitive compounds, the red ones if the compound itself is highly corrosive as well. For AlCl3 I would
recommend the red ones.
These bottles are fantastic and you can keep very sensitive chemicals in them indefinately. They also withstand pressure inside and certainly the
moderate pressure of AlCl3 is no problem at all. The pressure does not build up without limit, the buildup stops if all water vapor inside the bottle
has reacted.
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xwinorb
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THX
I wil look for the suggested bottles and caps right now.
I am quite happy to know that long term storage is possible.
Many thanks.
xw.
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mr.crow
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How about anhydrous FeCl3? It seems pretty sedate
And yes, media bottles are great for storage
You can also place an open container of NaOH next to the bottle in your bag to absorb HCl fumes
Double, double toil and trouble; Fire burn, and caldron bubble
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xwinorb
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Sorry for the late reply.
I am not sure if FeCl3 would substitute well for AlCl3. I guess no, other wise, why to use AlCl3 at all.
On the storage :
Schott Duran are kind of expensive, hard to find, and sold in boxes of 10. I have seen both GL 45 and GL 80.
Indeed, I found one pyrex, GL 45, blue cap, at my local chemistry store. I bought one.
I am planning to transfer the AlCl3 to the new bottle soon.
With my actual storage ( two plastic boxes with snap-on lids, air tight, one inside another, plus a bit of DampRid inside each ) I have no problem
with HCl fumes outside. Indeed, it keeps on showing up inside both boxes. When I start to see moisture on the inside, I open the boxes and replace the
DampRid. Sort of once a week or so. I am not opening the bottle though.
My friend told me he has kept his anhydrous AlCl3 for years using a similar setup. Indeed, I definetely would prefer to have something more long term
stable and requiring less attention.
I am planning to try to transfer it on my apt. balcony, when no one is looking, using a gas mask, protective glasses and rubber gloves. I have all of
the above, have not used it too much though. I mean it.
I hope I can do it fast, before it starts to make up too much HCl fumes.
One question :
Looks like the powder density of AlCl3 ( anhydrous ) is something like 2.5. Indeed, mine is inside a 500 ml bottle, pretty much like the pyrex one I
just bought. And looks like it is full close to the top. It weights something like 750 g, including the bottle weight.
So, looks like the density of my AlCl3 is more like 1 or so. I just emailed my friend, he said his also looks like mine.
Does anybody know why ? I think it is probably because of the way the density is measured, but no sure. If someone knows please post.
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xwinorb
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Powder density
I think I found out what's up with the powder density. Looks like the stated number is something called "Particle density", and it does not takes into
account empty space in between grains of the powder.
Please see this link :
http://en.wikipedia.org/wiki/Particle_density
So, I think the volume taken up by the powder can be significantly more than the volume estimated using the particle density number.
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woelen
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Anhydrous FeCl3 is a lot easier on storage than AlCl3. FeCl3 does not fume and is much less reactive. FeCl3 does attract water from the air though and
changes color from black to mustard yellow/brown while doing so. I keep mine in a sturdy HDPE bottle with a good screw cap and this works quite well.
AlCl3 I certainly would not keep in a HDPE bottle, you need glass for that.
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mr.crow
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Thanks Woelen. My anh FeCl3 comes in a plastic bottle so now I know thats ok.
When it reacts with water the iron hydroxide is probably a much better base than aluminia so it can absorb HCl and make hydrated FeCl3
Double, double toil and trouble; Fire burn, and caldron bubble
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xwinorb
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Moved to new bottle
I have just moved the AlCl3 to the new bottle, looking good, doing fine. No HCl release noticed.
The handling of the AlCl3 was easier than what I imagined. I used a powder funnel, I could just pour down the powder into the new bottle. I used a
funnel that fitted almost exactly on the GL 45. Twice I clogged the funnel, but it was quite easy to push the powder down with a teflon bar. Don't
pour too fast, easy.
My old bottle was indeed a bit larger than my pyrex 500 ml bottle. I transfered some 450 g, then it almost filled my new bottle. I then stoppered it,
placed inside a ziplock bag. After a few hours, no HCl smell noticed.
No HCl fumes noticed while doing the transfer. I was indeed wearing a mask, protective glasses and rubber gloves. No HCl smelled nor seen.
The old bottle still has some 50 g left, and it is just like before, slowly releasing HCl fumes. I am going to buy another 250 ml bottle and will move
the rest of the AlCl3 a few days from now.
Inside my new bottle, looking almost white, a very slight tint of green.
I am glad to know that it seems easier to handle than what I though. My friend told me to take care with the main reaction and with the quenching,
when most HCl fumes are released.
I hope to keep everything closed inside a reflux setup, any HCl output directed to a water container or down the drain.
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Magpie
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| Quote: |
Quote: Originally posted by AvBaeyer:
I applaud Elemental for being able to supply many extremely useful reagents. Unfortunately, they make far too much use of poorly sealing plastic
containers which obviously helps with shipping costs. I transfer most things I receive from them into quality glass bottles with good sealing
properties upon receipt.I have used aluminum chloride in the past (when I was gainfully employed) from very old but well sealed glass bottles. These
bottles were sealed with many layers of Parafilm or had been dipped in wax. Sometimes the AlCl3 had a bit of yellow tinge but never black and always
worked as intended....AvB |
Unfortunately I have another breached bottle of AlCl3 to report. This is the same situation as I reported before. I received this bottle 6-9 months
ago and just got around to using some of the AlCl3 2 days ago. Upon opening the outer bottle and 2 layers of plastic bagging I found that the plastic
bottle cap was completely destroyed and a large black glob about 1" in diameter was attached to what used to be the cap top. It seems the AlCl3
reacted with the plastic reducing it to carbon. See picture below.
Taking AvB and woelen's advice, this morning I transfered the AlCl3 to a GL45 Shott-Duran bottle (thanks Dr Bob). Hopefully this will provide a better
lid. Time will tell.
I'm not real confident this is the best solution, however. I'm thinking that a ground glass stopper would be better. The lid could then be dipped in
parrafin and the bottle placed in a desiccator having a powerful desiccant.
I know that Shott Duran has two more lid types that might be better, ie, the red cap, and the clear premium cap.
Does anyone else have any suggestions to solve this difficult storage problem?
repackaged AlCl3.jpg - 135kB
I have reposted this in this thread as I felt it more appropriate than in the "Friedel-Crafts acylation" thread here: link
[Edited on 6-8-2016 by Magpie]
[Edited on 6-8-2016 by Magpie]
The single most important condition for a successful synthesis is good mixing - Nicodem
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Rob Lavington
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I have kept my AlCl3 in an amber glass jar with a PP lid lined with a PTFE seal.
I had an initial release of HCL after a few months. After two years I opened the jar again (slightly) and no release this time.
The only other chemical I have found so difficult to store was a small amount of anhydrous, crystal clear HNO3. I stored this in an FEP bottle in the
bottom of the freezer, even with an air tight seal a trace found it's wat out into the secondary container. It is unbelievably mobile. It eats PP for
breakfast!
Fluorinated containers are your friend!! searched for months to get the few I have.
[Edited on 8-8-2016 by Rob Lavington]
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woelen
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@Magpie: You definitely need the red caps. The blue ones are good for temporary storage of AlCl3, but in the long run they will degrade and be
destroyed. First they turn white, next, they start blistering on the inside and then they crack. The red ones are much better for storage of extremely
corrosive material. But, in the long run, even the red caps degrade. You will have to replace them once every three years or so.
If you want really long-lasting storage (indefinite), then you need to ampoule the AlCl3. I have done so with my PCl5 (which is comparably nasty on
storage), NbCl5, SOCl2, POCl3 and PCl3. Only a small working stock is kept outside of glass ampoules, the rest of it is in ampoules now.
The blue caps are very good for storing chemicals, which themselves are not very corrosive, but which do degrade on exposure to air. I store lumps of
calcium metal, lithium metal, KCN, P4S6, H2SO4 (96%) in Schott Duran bottles with blue caps. These chemicals remain good. The caps are not attacked at
all. I use the red caps for storage of Br2, HBr (48%), HCl (37%), HNO3 (90%), oleum (20%). These chemicals do not attack the red caps. Only the 37%
HCl is somewhat problematic. Dilution to 30%, however, solves the problem. Remarkably, oleum does not attack the cap at all, apparently the teflon
liner in the red cap is not porous for SO3.
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mr.crow
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Why is AlCl3 so hard to store? Is it just the HCl gas?
I have a large bottle from Elemental Scientfic that is still factory sealed and seems OK. Its in a plastic box with an open container of NaOH.
Blue caps are polypropylene. Why would HCl degrade this?
Red caps have a nice teflon liner but are made of PBT, which is a polyester.
Double, double toil and trouble; Fire burn, and caldron bubble
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Magpie
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I've been asking myself the same question.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Ozone
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Mine keeps well with a wax seal on the lid in a drybox.
O3
-Anyone who never made a mistake never tried anything new.
--Albert Einstein
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