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Author: Subject: soxhlet modification
chemrox
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[*] posted on 23-6-2012 at 17:47
soxhlet modification


I want to modify one of my smaller soxhlets for leaching a gummy product into a boiling LAH solution. I suppose I could dilute the material in THF and add it the normal way but I'm copying a procedure most of us have read in PiKHAL using very similar ingredients and it seems to work well and conserve solvents too. Rather than have the soxhlet collect and dump the idea is to have it continuously drip and I think the way to do this to take a torch with a fine flame and shrink the siphon tube until it closes. It would probably be best to do the shrinking closest to the bottom of the lower end. Is this they way you would do it? (The glass shop takes too long for small jobs I can do myself.)



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peach
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[*] posted on 23-6-2012 at 20:37


Be really careful with the soxhlet thing. If you can dissolve whatever you're adding in one go and use an addition funnel, that'll be a lot easier to control and safer. If you haven't already, I'd recommend you try dissolving some in warm THF to check out the solubility for yourself. There are examples of people using the soxhlet and it dumping a lot of their substrate straight in; it'll get real hot, real quick. The reaction will start pouring heat out and the soxhlet will only speed up in those cases.
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watson.fawkes
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[*] posted on 24-6-2012 at 06:48


Look up the Gregar extractor. It has a mode of operation much like you're describing.
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[*] posted on 25-6-2012 at 13:58


Trying a pipperine extraction from black pepper I observed that a small cotton wool plug at the the bottom of the extraction chamber produced this effect. the solvent drips slowly and steadily throughout the extraction. if the substance is not too viscous it might work. You have to regulate the heating or the thickness of the material a bit but it would probably work just as well with glass wool or something else non reactive. Hope it helps :)

[Edited on 25-6-2012 by safety first]
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Paddywhacker
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[*] posted on 25-6-2012 at 23:08


That's a waste of a good soxhlet, which is OK only if you can afford it.
But, for a continuous extraction, how about suspending your soxhlet thimble in a wide diameter air condenser or chromatography column with a regular condenser on top, the whole lot mounted above your boiling flask.
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Mildronate
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[*] posted on 25-6-2012 at 23:42


Interesting, i have something similar to Gregar extractor, its old soviet custom extrator from radiochemistry lab, it also had porous glass.
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chemrox
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[*] posted on 1-7-2012 at 13:20


@Paddywhacker (I hope the username doesn't imply disdain for those of us of Irish descent!?) Thanks! That's a good idea and one I've been thinking about it. A cylinder wide enough for a 50mm glass thimble, a 24/40 and a 55/50 joint should do it. The glass thimble would sit inside no need to suspend. Cool!



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