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Author: Subject: Bumping hell.
Chordate
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[*] posted on 27-4-2011 at 23:21
Bumping hell.


I'm trying to recover a solvent from a system which has no small amount of sodium chloride dissolved in it, and I am having the worst bumping issues I've ever had. Chips seem to work for a few minutes, but then quickly cease working. I think their pores are being clogged with precipitating salt. Magnetic stirring is out, because my stirrer is glitching out (why does such a simple device need a microcontroller?)

Does anyone have any creative techniques for dealing with bumping?
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Ramiel
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[*] posted on 28-4-2011 at 00:04


Could you tell us which solvents are in the system, it would make it much easier. I guess it's a polar solvent, and that it is not water you want to recover (since your location is not Arakkis). Can you precipitate the salts and filter them out?

If it's a mix of solvents, I would chill, add an alcohol, filter and if your scale is small enough to warrant the trouble, wash with dry alcohol. Then distill and recover the solvents.




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Chordate
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[*] posted on 28-4-2011 at 00:22


It's water and 2-pyrollidone. I am about ready to just pack the damn flask full of steel wool and throw in some sulfuric acid.

My original goal here was to avoid having to do a second precipitation step. I think I may just have to bite the bullet and double distill.

[Edited on 28-4-2011 by Chordate]
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azo
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[*] posted on 28-4-2011 at 01:00


I find that crushed up car spark plugs works very good as boiling chips easy to get and cheep.


regards azo
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[*] posted on 28-4-2011 at 02:52


Steel wool and a very small amount of acid worked BEAUTIFULLY, I have never had such an even boil. Obviously the application of this is somewhat limited to situation where your material isn't particularly acid sensitive or reduction prone, but damn if it wasn't a miracle cure in this case.
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Arthur Dent
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[*] posted on 28-4-2011 at 04:26


I've been using glass beads, like the ones sold at craft stores. They have a hole in the middle, are made of soda glass and are about 3 to 4 mm in size.

I throw a handful of those in a boiling flask and even at high temp, it's quite controlled. Best of all, they're a dollar a bag and three bags fill nicely a 200 ml beaker right to the top! And after a reaction, they're quite easy to wash and reuse, if they're too gunky, you just throw them away!

Check out the crafts section of your local dollar store, you'll be surprised at the quantity of useful stuff there!

Robert




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[*] posted on 28-4-2011 at 07:30


If you have solids laying on the bottom of the flask you are providing a layer of insulation that prevents effective heat transfer to the liquid. When the situation on the bottom gets really hot then you get a huge bump. You've got to get those solids stirred up somehow.



The single most important condition for a successful synthesis is good mixing - Nicodem
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