lollerskatez
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Drying Acetone with Desiccant in Nylon Mesh Bags
I'm trying to devise a good solution to dry out a large amount of acetone (~4 gallons in a 5 a gallon bucket) with a desiccant (decided to go with
magnesium sulfate anhydrous). However, given that I'm using 5 gallon buckets to hold the acetone, decanting isn't really a viable option—too much
risk of accidental spilling, also concerned about losing acetone to evaporation over the long term.
So, I've found these nylon mesh filter bags to go over top of the bucket and hold the magnesium sulfate. Only thing I'm concerned about is whether or not the
acetone will eat through the nylon, and I'm getting conflicting information about that.
Any advice about a better set-up would also be appreciated, if anyone has ever had to deal with a similar situation.
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Herr Haber
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Leave it alone for a few days, syphon as much of the acetone as you can and filter what's left the usual way maybe ?
The spirit of adventure was upon me. Having nitric acid and copper, I had only to learn what the words 'act upon' meant. - Ira Remsen
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outer_limits
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https://www.sciencedirect.com/science/article/pii/B978012805...
https://doi.org/10.1016/B978-0-12-805457-4.50003-3
This one says that MgSO4 is not a good choice for acetone
| Quote: |
Acetone [67-64-1] C3H6O, M 58.1, b 56.2o/atm, d € 4 20 0.791, n € D 25 1.35880, pK € 1 25 -6.1 (basic, monoprotonated), pK € 2 25 20.0
(acidic) The commercial preparation of acetone by catalytic dehydrogenation of isopropyl alcohol gives relatively pure material. Analytical reagent
quality generally contains less than 1% of organic impurities but may have up to about 1% of H2O. Dry acetone is appreciably hygroscopic. The main
organic impurity in acetone is mesityl oxide, formed by aldol condensation. It can be dried with anhydrous CaSO4, K2CO3 or type 4A Linde molecular
sieves, and then distilled. Silica gel and alumina, or mildly acidic or basic desiccants cause acetone to undergo the aldol condensation, so that its
water content is increased by pass98 age through these reagents. This also occurs to some extent when P2O5 or sodium amalgam is used. Anhydrous MgSO4
is an inefficient drying agent, and CaCl2 forms an addition compound. Drierite (anhydrous CaSO4) offers minimum acid and base catalysis for aldol
formation and is the recommended drying agent for this solvent [Riddick & Bunger Organic Solvents Wiley-Interscience, NY, 3rd edn, 1970]. Acetone
can be shaken with Drierite (25g/L) for several hours before it is decanted and distilled from fresh Drierite (10g/L) through an efficient column,
maintaining atmospheric contact through a Drierite drying tube. The equilibrium water content is about 10-2M. Anhydrous Mg(ClO4)2 should not be used
as drying agent as there is a high risk of EXPLOSION with acetone vapour. Organic impurities have been removed from acetone by adding 4g of AgNO3 in
30ml of water to 1L of acetone, followed by 10ml of M NaOH, shaking for 10 minutes, filtering, drying with anhydrous CaSO4 and distilling [Hawley et
al. Analyst (London) 58 333 1933, DOI: 10.1039/AN9335800333]. Alternatively, successive small portions of KMnO4 have been added to acetone at reflux,
until the violet colour persists, followed by drying and distilling. Refluxing with chromium trioxide (CrO3) has also been used. Methanol has been
removed from acetone by azeotropic distillation (at 35o) with methyl bromide, and treatment with acetyl chloride. Small amounts of acetone can be
purified as the NaI addition compound, by dissolving 100g of finely powdered NaI in 400g of boiling acetone, then cooling in ice and salt to -8o.
Crystals of NaI.3Me2CO are filtered off and, on warming in a flask, acetone distils off readily. [This method is more convenient than the one using
the bisulfite addition compound.] It has also been purified by gas chromatography on a 20% free fatty acid phthalate (on Chromosorb P) column at 100o.
For efficiency of desiccants in drying acetone see Burfield and Smithers [J Org Chem 43 3966 1978, DOI: 10.1021/jo00414a038]. The water content of
acetone can be determined by a modified Karl Fischer titration [Koupparis & Malmstadt Anal Chem 54 1914 1982, DOI: 10.1021/ac00248a072].
[Beilstein 1 IV 3180.] Rapid procedure: Dry over anhydrous CaSO4 and distil. Acetoxime (acetone oxime) [127-06-0] C3H7NO, M 73.1, m 63o, b 135o/760mm,
d 0.901, pK40 0.99, crystallises from petroleum ether (b 40-60o) and can be sublimed. [Beilstein 1 H 649, 1 IV 3202.] Acetone semicarbazone [110-20-3]
C4H10N3O, M 115.1, m 187o, pK25 1.33, crystallises from water or from aqueous EtOH. [Beilstein 3 H 101, 3 I 48, 3 II 81, 3 III 189, 3 IV 179.]
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lollerskatez
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| Quote: | | This one says that MgSO4 is not a good choice for acetone |
Yeah, but since the only problem is inefficiency (which I'm assuming is time; MgSO4 can absorb a lot of water compared to CaSO4), that's acceptable.
It was also cheaper than Drierite—unless I wanted 50lbs of desiccant. Another consideration is that the acetone is going to have a lot of water in
it, so high capacity desiccants are more important than efficient ones.
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macckone
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nylon is not a good material with acetone.
Acetone doesn't dissolve it quickly but it does dissolve it.
If you are trying to get pure acetone, nylon isn't the way to go.
Cotton fabric is going to be way more resistant.
Metal screen or glass frit would be ideal.
Fiberglass cloth without binders would also work.
If your bucket is metal then you shouldn't have a problem.
But if it is plastic it is probably polyethylene and that will be a problem.
It is going to leach.
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lollerskatez
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Quote: Originally posted by macckone  | nylon is not a good material with acetone.
Acetone doesn't dissolve it quickly but it does dissolve it.
If you are trying to get pure acetone, nylon isn't the way to go.
Cotton fabric is going to be way more resistant.
Metal screen or glass frit would be ideal.
Fiberglass cloth without binders would also work.
If your bucket is metal then you shouldn't have a problem.
But if it is plastic it is probably polyethylene and that will be a problem.
It is going to leach. |
How long will it take to dissolve the nylon? It's going to be left in there for ~6 days. Same with the HDPE bucket, though ideally I'd be using
metal—pure acetone isn't the goal though, just anhydrous. That said, I'd like to avoid ruining buckets over the long-term... and buy more nylon
meshes.
Appreciate the other tips, didn't even think of fiberglass cloth filter.
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macckone
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6 days is enough to ruin a nylon mesh bag.
It won't survive.
The HDPE bucket will definitely soften in 6 days.
Not sure how many times you could do that.
Your acetone will have a definite color change in that length of time from material absorbed from the bucket.
MgSO4 is adequate for drying acetone.
Treat it several times with that then get some plaster of paris, use that for the final drying. CaSO4 is plaster. A box is a couple of bucks at any
hardware store ($3 at wally world).
Plaster is redried at 266F (130C). Heating it too hot, above 180C, will convert it to a form that doesn't absorb water.
Epsom salt is dried at 200C (392F) to achieve monohydrate. It will absorb a lot of water.
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Fyndium
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I've distilled acetone a few too many times in recent weeks. I've got a question regarding it's distillation. When I distill acetone or a solution
that contains acetone and aromatic substance with bp of 194C, the vapor temp always starts from 56-58C and generally remains between 58-60 for the
first half, and then it starts to slowly climb to lower 60's, and by the end it starts to go past that, and only at temp 70-80C the apparent
condensate of acetone seems to be stalling. This effect is especially pronounced when extracting acetone from water. Acetone is not very expensive,
but some reactions mix it with water or the resulting compound can be instantly polarized out from the acetone with simple addition of water.
I guess this has to do with vapor pressure equilibrium. Now that I generally need only as anhydrous acetone as possible, this becomes an issue. How to
alter the distillation, and how to determine if acetone contains any significant amounts of water? My general procedure has been using CaSO4 as drying
agent. I have used so far only sculpturing gypsum because I'm not sure if hardware store gypsum plaster has additives that could be detrimental and
would appreciate if someone had knowledge about this.
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macckone
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Stop the distillation at 60C if you are trying to get a pure product.
It depends on what it is mixed with but you want narrow fractions.
You can redistill the portion that comes over between 60 and 80.
You can do a liquid/liquid extraction on the wide fraction then salt out the acetone from the water. Table salt will work ok. The redistill it.
If you have a lot of water, epsom salt works well for drying.
If you are trying to get the last little bit then CaSO4 is going to work better.
There probably isn't any difference between hardware store and sculpting plaster. There are a variety of impurities depending on the source but they
aren't likely to distill with acetone and they aren't likely to be different between the two. After you dry the acetone, you should redistill it and
store over 3a molecular sieves.
https://smile.amazon.com/Molecular-Sieve-500g-Poly-Purity/dp...
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Fyndium
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I was always under impression that acetone cannot be salted out. It's good to learn new things everyday. So I suppose I could first strip the acetone,
then salt out the excess of water, dry it with CaSO4 and redistill it. According to a quotation somewhere, it said to dry acetone over 25g/L and then
redistill it over 10g/L of CaSO4.
You're right about the impurities left behind, in this instance it is of no worry. I though more of an instance where the desiccant is simply decanted
and filtered out of the liquid. The hardware store stuff is declared to contain some sort of lightweight filler.
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lollerskatez
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Thought I'd give an update:
The nylon mesh didn't dissolve and there didn't appear to be any obvious damage after 6 days. That said, it may have weakened slightly; I definitely
wouldn't leave it in longer than a month (if for whatever reason that was necessary).
The magnesium sulfate was highly effective at removing the water, granted I didn't need to remove all traces of water (in which case I would have used
CaSO4 afterwards).
I have two questions about MgSO4—I can't seem to find good answers anywhere else:
1. Any way to tell the saturation of MgSO4 by visual inspection? It just seems to get "clumpy" and stick together after saturation, I guess I was
expecting a more crystalline structure to arise, or at least some type of more visual change to it. I suppose weighing it would work to tell how much
water was absorbed.
2. What is the actual water absorption capacity of MgSO4? Assuming it forms MgSO4·7H2O, then its capacity is something like ~104% of its anhydrous
weight. I don't know if that's actually achievable, however, and if it isn't, then what its more realistic capacity is.
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Fyndium
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I tried to dry IPA with MgSO4 anhydrite a time ago, and it just clumped and clumped, and finally I gave up because I had drained a substantial amount
of the liquid mass. I need to layer it with NaOH, but either it also clumps with other substances than only water, or the IPA was REALLY wet.
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macckone
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MgSO4 forms a variety of hydrates.
The ones involved in drying acetone are going to be the monohydrate (unless you dry the crap out of it at 350C), and the hexahydrate (unless you have
a lot more water than it is capable of absorbing). So it can remove 5 moles of water for each mole of monohydrate.
MgSO4 will absorb some IPA but it shouldn't absorb much if any acetone.
Acetone does not readily form hydrogen bonds while isopropyl alcohol does.
Hence the lower boiling point and less absorption.
There is no way to tell if MgSO4 is hydrated or not unless you add an indicator.
The following article uses congo red and citric acid for water determination between 0.5 and 12% in acetone.
https://link.springer.com/article/10.1134/S1061934810030184
I was incorrect, I was thinking rayon, nylon should be 'ok'.
Fyndium,
IPA can be 99, 91 or 70%. Depending on where you got it, it may just be listed as rubbing alcohol with no percentage.
99% should be easy to dry but it is less common than 91 and 70%.
Potassium carbonate to salt it out is your friend.
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