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Author: Subject: Distillation of Paint Thinner and Parent Problems
Trevor9424
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[*] posted on 5-7-2016 at 09:39
Distillation of Paint Thinner and Parent Problems


For the past few weeks, I've been attempting to convince my parents to allow me to distill (using an alcohol burner) paint thinner for the solvents in it (it contains DCM, xylene, methanol, ethanol, and acetone, all of which I want for extractions or other experiments). However, they don't like the sound of raising something flammable like paint thinner to the boiling point (they thought raising something to the boiling point like a solvent was the same as combustion or an explosion by the way :mad: ).

For the heat distillation I did plan to try to implement safety precautions:
-goggles, gloves, and a respirator for fumes
-a pipe connected to the receiving flask that leads stray fumes to the ground away from the flame (since the fumes are heavier than air in weight I thought this would help a lot)
-An ice bath for the receiving flask to sit in to reduce fumes from the distillate
____________________________________________________________________

However, I do have a hand vacuum pump and I was thinking that maybe I could try a vacuum distillation. The filtering flask I'm using as a receiving flask has thick walls but the round bottom I'm using doesn't. I do have an extra thick walled filtering flask however. Would vacuum distillation be preferable over a heat distillation and should I swap out my round bottom for another thick walled filtering flask?

Thank you! :)


-I did want to add a picture of what my distillation setup looked like for vacuum distillation but for some reason, the picture increased the webpage's size by like 4 times :o


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argyrium
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[*] posted on 5-7-2016 at 09:47


Hi.
Just a big word of caution. You do NOT want to use an open flame for this. Too great a chance of serious problems.

Please be careful and read, read, read and then read more before attempting even what might seem like a simple procedure.
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Trevor9424
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[*] posted on 5-7-2016 at 09:54


Quote: Originally posted by argyrium  
Hi.
Just a big word of caution. You do NOT want to use an open flame for this. Too great a chance of serious problems.

Please be careful and read, read, read and then read more before attempting even what might seem like a simple procedure.


Would a hotplate be better maybe :o ? Unless it can still make due for the flash point of vapors...

I could also try to use a hot water bath for the lower boiling point solvents like DCM.

-Thank you for the very quick reply by the way :)

[Edited on 7-5-2016 by Trevor9424]
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Deathunter88
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[*] posted on 5-7-2016 at 10:07


First things first, your parents have a right to not let you distill flammable solvents with an alcohol burner. That's extreamly dangerous from a variety of reasons. The flame may ignite leaking vapors causing an explosion. Even if the flame does not touch the vapors directly it may still cause an explosion by reaching the compounds auto ignition temperature. Finally, heating flasks with a naked flame may cause it to break open due to thermal expansion resulting in a fireball. Use a hotplate and regulate the temperature. Ventilation is still essential even with a hot plate.

PS. I know all about parents not being reasonable (see the thread called 'parents getting in the way of chemistry' for tips on dealing with this problem). However in this situation your parents are right.
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Trevor9424
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[*] posted on 5-7-2016 at 12:00


Quote: Originally posted by Deathunter88  
First things first, your parents have a right to not let you distill flammable solvents with an alcohol burner. That's extreamly dangerous from a variety of reasons. The flame may ignite leaking vapors causing an explosion. Even if the flame does not touch the vapors directly it may still cause an explosion by reaching the compounds auto ignition temperature. Finally, heating flasks with a naked flame may cause it to break open due to thermal expansion resulting in a fireball. Use a hotplate and regulate the temperature. Ventilation is still essential even with a hot plate.

PS. I know all about parents not being reasonable (see the thread called 'parents getting in the way of chemistry' for tips on dealing with this problem). However in this situation your parents are right.


Yes, you're right... I don't think they'd be happy to see part of their house on fire/burnt down or if I got glass shards sent through me with complimentary burns to go with them. :(

I guess an alcohol burner for distillation is out of the question. So would vacuum distillation work? Or is that out of the question too due to implosion risk...
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macckone
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[*] posted on 5-7-2016 at 12:33


When distilling flamable solvents, good ventilation is mandatory.
never use flat bottom flasks or improper glassware for vaccuum work.
never use damaged glassware for anything removely dangerous.
avoid open flames with flammable liquids.
use electric heaters that are designed for labs with the correct control systems.
these are generally explosion resistant designs.
lexan shields are a good investment. They will stop all but the most energetic shrapnel.
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aga
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[*] posted on 5-7-2016 at 13:55


Boiling points:-

DCM: 40 C
Acetone: 56 C
Methanol: 65 C
Ethanol: 78 C
Xylenes: 140 C

What's the spirit burner for ?

A pan of boiling water will drive the first 4 fractions out.

When the mixture in the pot stops boiling, it would be mostly Xylenes.

Probably easier to convince people about boiling a pan of water than the OP's attempt to convince anybody of anything else.

Not a lot of point attempting a vac distillation without doing a normal distillation first, as there'd be nothing to compare it with.

A vac distillation for a couple of hours using a hand-pump would leave you looking like a Fiddler Crab.

Edit:

Editing the size of an image with something like 'Paint' is trivially easy, especially for young people, so don't even try to claim otherwise, or the complexity of Chemistry will be so far out of reach to not be worth bothering with in the first place.

[Edited on 5-7-2016 by aga]




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Metacelsus
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[*] posted on 5-7-2016 at 14:43


You're going to need a good fractionating column to separate those solvents. Also, if you use vacuum, you won't be able to condense the lower boiling solvents (not to mention that a hand pump would be impractical).



As below, so above.
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Trevor9424
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[*] posted on 6-7-2016 at 10:48


Quote: Originally posted by macckone  
When distilling flamable solvents, good ventilation is mandatory.
never use flat bottom flasks or improper glassware for vaccuum work.
never use damaged glassware for anything removely dangerous.
avoid open flames with flammable liquids.
use electric heaters that are designed for labs with the correct control systems.
these are generally explosion resistant designs.
lexan shields are a good investment. They will stop all but the most energetic shrapnel.


I do all the experiments I do outside. Are flat-bottom flasks not suitable for vacuum? They sell them for vacuum filtration.

Quote: Originally posted by Metacelsus  
You're going to need a good fractionating column to separate those solvents. Also, if you use vacuum, you won't be able to condense the lower boiling solvents (not to mention that a hand pump would be impractical).


So hot water bath it is and not sitting on my head with a hand vacuum pump. Thank you! :)

Quote: Originally posted by aga  
Edit:

Editing the size of an image with something like 'Paint' is trivially easy, especially for young people, so don't even try to claim otherwise, or the complexity of Chemistry will be so far out of reach to not be worth bothering with in the first place.

[Edited on 5-7-2016 by aga]


I know how to edit an image using paint, I've done it before to crop pictures.

Though I guess the "Picture-dilemma" info above is unnecessary. :(

Thanks
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[*] posted on 6-7-2016 at 12:42


If all you wanted was the DCM, the separation is almost trivially easy: distill using a hot water bath until the stillhead temperature reaches 60 C (at normal atmospheric pressure), and then wash out everything but the DCM with water. Getting the xylene out shouldn't be too hard either: if you collect from 100 C to near dryness (use an oil bath!), you will collect xylene, some water-soluble organic stragglers, and almost no DCM. These too can be washed out easily with water. However, attempting to separate and use the ethanol, acetone, and methanol seems like an exercise in futility: not only are those solvents so cheap as to make the endeavor pointless, they are very difficult to separate from each other without a good fractionating column. In addition, acetone and methanol form an azeotrope of about 88% acetone, so even with a good column separating these two solvents will be very difficult.

My advice is to extract the DCM, the xylene (assuming the xylene content is more than a few percent), and throw the rest away.
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tandpasta
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[*] posted on 6-7-2016 at 15:07


Why at 60C? DCM boils at 39.6C. Won't you get more impurities if you distill at that high of a temperature?

[Edited on 6-7-2016 by tandpasta]
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[*] posted on 6-7-2016 at 16:17


Not all of the DCM will come over at exactly 40 C-- there's typically a temperature rise as the distillation of the DCM fraction proceeds. 60 C is a significantly higher temperature than what is even needed in practice, but it ensures all of the DCM has come over, and plus all of the impurities coming over at that point are water soluble and can be washed out.

Even if you only took the fraction boiling at 40 C, you would still have to wash the DCM collected-- it and methanol form a low-boiling azeotrope at around 37 C.

[Edited on 7-7-2016 by Cryolite.]
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[*] posted on 6-7-2016 at 21:45


Quote: Originally posted by Trevor9424  
Quote: Originally posted by macckone  
When distilling flamable solvents, good ventilation is mandatory.
never use flat bottom flasks or improper glassware for vaccuum work.
never use damaged glassware for anything removely dangerous.
avoid open flames with flammable liquids.
use electric heaters that are designed for labs with the correct control systems.
these are generally explosion resistant designs.
lexan shields are a good investment. They will stop all but the most energetic shrapnel.


I do all the experiments I do outside. Are flat-bottom flasks not suitable for vacuum? They sell them for vacuum filtration.



They are fine for filtration but not real vacuum work.
Filtration is usually not a high vacuum. The vacuum
during filtration is only sufficient to force the filtrate
through the sediment and the filter. You don't want too
much vacuum during filtration. Usually you are only
going down to 600mmHg. Of course at my altitude
it is, I go down to about 450mmHg since I start at 600mmHg.

Vacuum distillation is usually much higher vacuum.
ie. near 50mmHg or less. The strain difference on the
glass is substantial.
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