theimplaer
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Help with drying acetone
Hello, I am trying to dry store bought acetone with dried magnesium sulfate.
I baked the sulfate until it was dry, and then added some to the acetone. I mixed the bottle well, but there solution seems extremely cloudy with some
of the sulfate at the bottom, not necessarily clump, some clumps. Did I do something wrong?
How to i remove the cloudiness? Well it go away after 24 hours?
Thank you.
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fusso
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Filter it.
Is the dried MgSO4 powdery or lumpy?
What temperature you dried MgSO4?
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theimplaer
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It wasn't too powdery, i dried it from 300 -500 over the course of about 2 hours. I then powder it a bit, but not fully before dumping into the
acetone. How long should i wait before i filter the acetone? Thank you for your reply.
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macckone
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Let it settle then decant and filter.
Then you can try filtering the undecanted portion.
Use good filter paper, not a coffee filter.
Acetone is not particularly hygroscopic but cover to avoid contaminants while settling.
Most OTC acetone is basically dry to begin if bought as straight acetone.
It is made via cumene process which requires anhydrous conditions.
The resulting acetone is boiled off the phenol and then packaged.
I would be more concerned about phenol contamination than water.
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theimplaer
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ohh interesting, thank you for your reply, i will then decant and filter it. Thank you!
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SWIM
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I thought acetone was a lot harder to dry than that.
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macckone
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Acetone is made anhydrous, it is the nature of the process.
It is highly flammable and stored in metal cans.
Adding water would lead to rust and leakage.
Unless it is in another mix the only likely contaminant is phenol.
Acetone isn't very polar and hence not hygroscopic.
Acetone doesn't dissolve magnesium sulfate in significant quantity.
Lower alcohols can't be dried effectively with magnesium sulfate
but non-polar substances and ketones are generally fine.
Calcium chloride is slightly soluble in acetone (.1g/L).
Magnesium chloride is also slightly soluble in acetone and
it could be in your magnesium sulfate if it isn't FDA grade.
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AvBaeyer
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Sodium sulfate is probably a more practical drying agent if you think you need one since as macckone says commercial acetone is quite dry to begin
with. The dried acetone can be decanted from the drying agent which avoids the filtration problem associated with magnesium sulfate. It is then best
to distill the dried acetone and collect a very narrow fraction around the boiling point which for all practical purposes provides a pure and
anhydrous material.
In my experience hardware store acetone (Home Depot, ACE) is very clean and virtually all of it distills very sharply without any need for pre-drying.
AvB
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nimgoldman
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Cloudiness is actually a good sign your acetone is dry.
Usually when drying solvents, you add desiccant, swirl it a bit and observe clumping - when no more clumping happens, the powder is mobile and creates
a "snowstorm effect" upon swirling.
The powder will settle sooner of later and thenyou can carefully decant and/or filter the solvent.
Be aware that acetone is hygroscopic, especially when cold.
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XeonTheMGPony
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Quote: Originally posted by AvBaeyer  |
In my experience hardware store acetone (Home Depot, ACE) is very clean and virtually all of it distills very sharply without any need for pre-drying.
AvB |
I have often found trace oil impurities and solid impurities in my locally sourced acetone, but in terms of H2O it is quite dry, so I all ways
recommend distilling.
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macckone
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Acetone is not particularly hygroscopic as nimgoldman claims.
Given enough time it will absorb some water but that doesn't make it hygroscopic.
All substances below dew point will collect water this is not unique to acetone.
As xeon stated, there can be impurities from the manufacture of the can and inadvertent debris.
If I got an organic solid after distilling I would suspect phenol.
The oils derive from the lubricant used in making the can when bending and crimping.
You can get metal debris from the same process.
Understanding how the chemical is made and packaged can be very helpful in determining what kind of impurities to expect.
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SWIM
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I'm seeing quite a few references that say magnesium sulfate is not intense enough.
Think I'll stick to calcium sulfate or boron trioxide
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macckone
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You don't need intense for acetone.
It seriously is not that hygroscopic.
Acid anhydrides probably are a bad choice for ketones given aldol condensation.
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