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Author: Subject: Gluey mess won't quit in the flask
Schleimsäure
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[*] posted on 25-4-2015 at 12:51
Gluey mess won't quit in the flask


So I decided to work up my methylated spirit a bit, because as it is the smell is a pain. It's not the cheapest, 2,5 l from S3, a chemical supllier. It's 99%, denatured with 1% MEK and a few ppm of denatonium benzoate.

Firstly I put 600ml in a 1l flask and refluxed with 10g of NaOH for 3 hours or so. It went from clear to light orange.
Then, after simple destillation the destillate was clear and smelled a lot less then the original product, almost absolute alcohol. So success.

Anyway, I decided to do that with the rest and just built up my 4l 3-neck flask with 1,9l methylated spirit and 31g of NaOH for reflux in a water bath.

Problem is, the 1l-flask of the first run has a very gluey mass on the ground. Could it be that hot NaOH melted even with the glass?
I put in some chromo sulfuric acid and a short neutralisation took place, after a few minutes most of it is still solid.

I will wait a little longer for the chromo sulfuric to work, but I'm a little afraid I could ruin my 4l 3 neck flask.

Thanks for consideration.
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Chemosynthesis
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[*] posted on 25-4-2015 at 13:16


What does the "gluey mass" look like? White? Might very well be sodium silicate. Next time, you may wish to seal your glassware better. As for cleaning, a cool/cold base bath overnight shouldn't show any visibly appreciable etching on non-analytical equipment, however if you are really concerned about chromic acid etching (as per Can J. Chem. (1962) Vol .40 p), you might look into just using sulfuric acid and/or getting an ultrasonic cleaner.
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Schleimsäure
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[*] posted on 25-4-2015 at 13:18


All clear. The whole clump just got off after some pushing with a glas rod. Chromo sulfuric acid is the best:D

I highly recommend on this method for working up stinky methylated spirit. The end product is not 100% ketone free, but the method is cheap and easy. The result satisfying for use of cleaning and even as a "better" solvent.

For best results hydroxylamine is needed, which is more expensive and for some hard to aquire.
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[*] posted on 25-4-2015 at 13:23


Quote: Originally posted by Chemosynthesis  
What does the "gluey mass" look like? White? Might very well be sodium silicate. Next time, you may wish to seal your glassware better. As for cleaning, a cool/cold base bath overnight shouldn't show any visibly appreciable etching on non-analytical equipment, however if you are really concerned about chromic acid etching (as per Can J. Chem. (1962) Vol .40 p), you might look into just using sulfuric acid and/or getting an ultrasonic cleaner.


Actually it's kind of orange with clear chrystal like on the borders. And stinks abnormally. But now with the chromo sulfuric acid it has finally detached from the bottom:)

I was not concerned about chromic acid etching, but rather about hot NaOH as the rest of the boiling NaOH/EtOH solution.
Excuse my ignorance, what do you mean by sealing the glasware better in that context?


[Edited on 25-4-2015 by Schleimsäure]
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[*] posted on 25-4-2015 at 13:33


MEK, like acetone, will polymerize and make bad smelling, sticky and annoying compounds when exposed to a strong base over time. I'd try to pour in some gasoline (or equivalent) and leave it on the magnetic stirrer for a while.



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[*] posted on 25-4-2015 at 13:35


Thank you! So I don't necessarily have to use Chromic acid then.
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[*] posted on 25-4-2015 at 16:46


Oh, I misunderstood. I though you had a gluey mass on the ground glass joint area.
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