woelen
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storage of PCl5 and AlCl3
I have 2 specific chemicals, which I find really troublesome to store for a longer time. I have a bottle of anhydrous AlCl3 and a bottle of anhydrous
PCl5. Both are stored in a Schott Duran bottle, with a red PTFE lined cap. These caps are more than 10 euro a piece, the bottles also had a similar
price. But even these caps do not keep well. After one year or so, the liner starts blistering and dirty dark brown goop leaks from the cap. I need to
replace the cap every year :-(
Even stuff like SOCl2 or Br2 is easier on storage than these two chemicals. The only other chemicals, which come close to being as problematic as PCl5
and AlCl3 are SO2Cl2 and SO2(OH)Cl.
What kind of cap remains well for many years? I have seen Schott Duran Premium caps (with shipping, more than 20 euros per piece when at GL45 size).
These are somewhat transparent, are without dye, and can withstand temperatures from -200 to +250 C or so. For these, you also need a Schott Duran
Premium bottle, which also is very expensive. I consider buying two of such bottles with caps, but only if they provide a solution to my storage
problem.
https://www.laboratoriumdiscounter.nl/en/screw-closures-dura...
[Edited on 11-9-25 by woelen]
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Keras
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I have PCl₅ I ordered several years ago when I was beginning to set up my lab, it’s in an iron cylindrical box with a very tight metallic lid (the
kind you must use a screwer to pop up). I never opened it. The box is rusty outside, but I surmise there is a bottle inside enclosed in a sealed
plastic wrap.
As for AlCl₃, I have a fresh bottle wrapped into a thermally sealed plastic wrap, and it seems to get along fine. I have one opened bottle, I can
check it next time I get to go to the lab. I don’t think any of my aluminium chloride bottles had any kind of special lid.
Didn't you try 'old' ways, namely storing them into some sort of erlenmeyer with a PTFE lined glass stopper?
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teodor
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You can buy those caps per 5 EUR / stuk. I will tell you where after fixing some problem with the last delivery from that shop.
What I observed storing such type of compounds they don't like adsorbent which decreases the HCl concentration. Keeping with such adsorbent increases
decomposition.
So, probably it would be perfect to store it in an old apothecary ground-glass bottle (the ancient bottles have a very good grounded glass stoppers
which is not comparable with chinese or indian made, Adrian who has a great collection of bottles said me when I asked him about grounding). I mean
something you can buy on ebay for 20 EUR or more. No guarantee but I don't see how to make comparable sealing. May be taking a small Duran elrenmeyer
with a glass stopper? We can make a group purchase probably. Some flask with a big neck. I believe there also storage full-glass bottles in the Duran
line. They sell it by boxes.
My 98% sulfuric acid after 5 years of storage in duran bottle with a plastic cap in our fresh marine air became 89%+. I had a sad day when I realized
I have no concentrated acid anymore. I believe my measurement was a bit wrong, but if not I am not really surprised.
So, the most important thing would be adsorbent for the second bottle. It should adsorb water but not HCl. To keep proper equilibrium of high HCl
concentration.
Well, this is my idea. I have no those compounds. But I want to have. So, if I will try I will be able to tell more.
[Edited on 11-9-2025 by teodor]
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woelen
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Quote: Originally posted by teodor  | You can buy those caps per 5 EUR / stuk. I will tell you where after fixing some problem with the last delivery from that shop.[...]
[Edited on 11-9-2025 by teodor] |
That would be interesting for me. The high price of these caps makes me
hesitant to buy them, but for 5 euros I can buy a nice set of them and store some of my really corrosive chemicals in bottles with such caps.
Amazingly, storing oleum is not that hard. The same is true for P4O10 and "HPO3". Apparently, it is the chloride in PCl5, AlCl3, SO2Cl2 and SO2(OH)Cl,
which makes storage so hard. SOCl2, however, also is easier on storage. Most likely, the somewhat reducing properties of SOCl2 make storage somewhat
easier. The worst is PCl5, which is really really hard to keep well, if it is not put in a glass ampoule.
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Keras
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Out of curiosity, have you also wrapped the bottleneck threading in PTFE tape to help the lid be tighter?
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teodor
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| Quote: Originally posted by woelen | | Quote: Originally posted by teodor | You can buy those caps per 5 EUR / stuk. I will tell you where after fixing some problem with the last delivery from that shop.[...]
[Edited on 11-9-2025 by teodor] |
That would be interesting for me. The high price of these caps makes me
hesitant to buy them, but for 5 euros I can buy a nice set of them and store some of my really corrosive chemicals in bottles with such caps.
Amazingly, storing oleum is not that hard. The same is true for P4O10 and "HPO3". Apparently, it is the chloride in PCl5, AlCl3, SO2Cl2 and SO2(OH)Cl,
which makes storage so hard. SOCl2, however, also is easier on storage. Most likely, the somewhat reducing properties of SOCl2 make storage somewhat
easier. The worst is PCl5, which is really really hard to keep well, if it is not put in a glass ampoule. |
When SOCl2 destroys something on storage it mostly destroys itself. Do you have the same color of SOCl2 as I've got here: https://www.sciencemadness.org/whisper/viewthread.php?tid=15...
Also, when pure it doesn't fume much.
PCl5 probably must be kept under guard of chlorosulfonic acid. They will have interesting talking. The problem is I don't know the reliable way to
store chlorosulfonic acid. The same group as SO2Cl2 I assume.
P.S. May be PCl5 it should be kept under PCl3? This is the same group as SOCl2, self-eating compound. A bit of phosphorus in the second container
probably can also help. Not sure about P2O5, but may be also can create some buffer.
[Edited on 12-9-2025 by teodor]
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woelen
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My SOCl2 is pale yellow/brown. Probably coming from some sulfur-compounds.
My SO2Cl2 is pale green, this most likely is due to equilibrium with SO2+Cl2, where the Cl2 gives it the pale green color.
My PCl5 is off-white, with a yellow/green tinge. Most likely also due to some Cl2. Maybe it is in equilibrium with PCl3+Cl2. The equilibrium, however,
if it indeed is the cause of the color, is far to the side of PCl5. The color is very weak. The Cl2, however, may be enough to eat away caps and
liners of storage bottles in a relatively short time.
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davidfetter
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| Quote: Originally posted by Keras |
Out of curiosity, have you also wrapped the bottleneck threading in PTFE tape to help the lid be tighter? |
Sadly, quite a few halogenated compounds including their molecular forms can and do attack PTFE. Some of the others are listed here.
Just generally, it's good to look to look at charts like the attached one when selecting parts of a containment system.
Attachment: LG CC.pdf (1017kB)
This file has been downloaded 67 times
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Keras
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Fruit juice?????
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Deathunter88
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As alluded to by teodor, it is my experience that GL45 media bottles (no matter if they are Duran or other brands) are some of the worst reagent
storage bottles. I've used the standard blue PP caps, the red PBT caps, and even the premium Duran clear caps, but none do a great job of making a
seal. If you turn your GL45 bottles upside down then right side up again there is a good chance liquid will start seeping out!! They seem to be more
aimed at short term storage of stock solutions for biological labs rather than harsh chemicals for chemistry labs.
I'm not sure why this is the case, I believe it has to do with the complex and large sealing surface of the glass bottle, pour ring, and the top of
the cap. Also, due to their size it is difficult to get the cap torqued down well, and if you torque too hard you risk deforming the pour ring
unevenly and causing a leak. It's a PITA.
What I find works much better are the "cheap" looking boston round amber bottles. Pair it with one of the green PTFE lined phenolic caps and you can
get fuming nitric acid to last a few years without noticable degradation. My AlCl3 still looks brand new after 3 years inside one of these bottles.
For milder reagents, the default LDPE "polycone" black phenolic caps that come with these are superior in my experience to GL45 media bottles, even
the ones that came on cheap no-name bottles I got off Amazon.
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teodor
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I can confirm that my chemicals I've got from poland in bottles with a small cap which are looking cheap really provided better storage. For example I
had sodium stored under ether in GL45 bottle and all ether was gone. On the same shelf the level of ether in that narrow-neck bottle is on the same
mark as when I put it there.
But in case of corrosive substances it is not so. They just destroy the cap. And this is not about teflon, it is about the part with a thread.
[Edited on 13-9-2025 by teodor]
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Dr.Bob
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The Qorpak bottles are very good, and the PTFE lined lids do well, mostly as there is WAY less thread space than on media bottles. Hard to use for
solids, but they do have medium mouth qorpaks with PTFE lids as well which are OK for most corrisives. I had a bottle of AlCl3 in one for years and
it only slowly went bad after dozens of openings (I did try to blow N2 into it each time...)
But solids are also hard as they often get on the threads and keep them from sealing well or make them seize up. I have a few white PTFE lined lids
for GL45 media bottles which are pretty good, but still will fail eventually with some things, but cheaper at $2 each.
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Schleimsäure
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I have my PCl5 in the original Sigma bottle (500g). For about 5 years or so on shelf. Wrapped some extra tape arround the cap end back then. Also
vaccum sealed the whole thing with normal plastc vaccum seal bag.
Result: The vaccum seal bag is quite destroyed. Cap looks still okish, PCl5 inside got one big hard lump, but that is ok I think. Just got rid of the
old fleddered outer plastic bag. Bottle had some HCl film on the glass, label has darkened much.
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MrDoctor
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i saw this thread and quickly went out to check my AlCl3 bottle from sigma, since it isnt even in a plastic bag, just rawdogging it on a shelf, and
has been for about 4 years. seems fine.
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Radiums Lab
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In my college we have AlCl3. It is kept in a normal reagent bottle with yellow stuff around the neck
Water is dangerous if you don't know how to handle it, elemental fluorine (F₂) on the other hand is pretty tame if you know what you are doing.
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Radiums Lab
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I dont know what that yellow stuff is, the whole bottle is in a thin plastic cover. It is pretty old
Water is dangerous if you don't know how to handle it, elemental fluorine (F₂) on the other hand is pretty tame if you know what you are doing.
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