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Author: Subject: Cheap and simple stirrer?
WaveFront
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[*] posted on 9-3-2009 at 11:42
Cheap and simple stirrer?


Have any of you considered the possibility of trying a sonic or ultrasonic buzzer (properly isolated of reagents) as a efective "stirrer" for some reactions?
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Saerynide
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[*] posted on 9-3-2009 at 13:07


I've always had an aversion to ultrasonics as I always feel like the glass is going to explode (also, sound at those frequencies really bother me.. its like fingernails on blackboards ack!)



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kclo4
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[*] posted on 9-3-2009 at 14:42


Hmm what is an ultrasonic buzzer? I googled but I don't see anything that looks like it can stir.



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Space_Milk
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[*] posted on 10-3-2009 at 12:31


I think he means something like a sonic bath http://en.wikipedia.org/wiki/Ultrasonic_cleaner which uses an ultrasonic transducer/buzzer to create turbulence in the liquid medium. I like the idea although I don't think it would be as effective as a magnetic stirrer but I could be wrong. I put my finger in a sonic bath used to clean glassware and it feels kinda like being electrocuted lol
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kclo4
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[*] posted on 10-3-2009 at 13:56


At least it would be useful to get the magnesium to react in a grignard reagent. :P



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watson.fawkes
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[*] posted on 10-3-2009 at 15:00


Quote:
Originally posted by WaveFront
Have any of you considered the possibility of trying a sonic or ultrasonic buzzer (properly isolated of reagents) as a efective "stirrer" for some reactions?
Please see Sonochemistry on Wikipedia.
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chemrox
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[*] posted on 10-3-2009 at 16:30


All my Grignards have been with alkyl bromides or bromobenzene and they have been easy to start. An I2 crystal sometimes helps .. fresh Mg helps ..anyway I'v managed many a Grignard without any kind of stirrer. I always have ice and a pair of turkey baisters for when the reax really take off.



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kclo4
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[*] posted on 10-3-2009 at 16:42


What do the turkey baisters do?



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UnintentionalChaos
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[*] posted on 10-3-2009 at 18:34


Quote:
Originally posted by kclo4
What do the turkey baisters do?


Squirt the ice bath over the flask to keep the temperature down I imagine. I believe I read about him doing this in a thread a long time ago.




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kclo4
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[*] posted on 10-3-2009 at 18:53


Makes sense! thanks.



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Globey
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[*] posted on 11-3-2009 at 11:20


Just keep in mind you would probably be creating tiny areas of extreme temperature.


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WaveFront
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[*] posted on 11-3-2009 at 13:23


Quote:
Originally posted by watson.fawkes
Please see Sonochemistry on Wikipedia.


That sounds too much energetic (cavitation, points of extreme temperature...)
I was thinking in something less severe, some kind of device inducing vibrations, from a cheap home device, like a cell phone, an alarm of clock or similar, to acelerate reactions in a similar way to stirring:

For example, this link from your link:

http://en.wikipedia.org/wiki/Sonication
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Globey
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[*] posted on 11-3-2009 at 13:29


If you manually initiate stirring, you *may* be able to sustain it with some sort of resonance. doubt you can go from zero to stirring though.
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WaveFront
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[*] posted on 11-3-2009 at 13:58


Well, it would not be exactly stirring, but maybe similar in the effects accelerating some reactions, perhaps it is not worth in some cases. Just can be interesting to try one day "sonicated reaction versus control" :)
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jokull
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[*] posted on 11-3-2009 at 16:32


at gigapedia you can find a book series concerning:

Uses of ultrasound in chemistry...

I can't check it right now, but I think is called "Advances in Sonochemistry"

All of you interested in will find them useful.
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ProChem
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[*] posted on 12-3-2009 at 10:31


I do sonochemistry and found out that if you are sonicating without an inert atmosphere you will oxidize your subsrtate. I would not use an ultrasonic buzzer for stirring. try somthing else.
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watson.fawkes
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[*] posted on 12-3-2009 at 12:42


Quote:
Originally posted by Globey
If you manually initiate stirring, you *may* be able to sustain it with some sort of resonance. doubt you can go from zero to stirring though.
You won't get either from a single transducer, because you can't create curl in the pressure gradient field from only a single source. You need at least two sources and phase-interlocked supplies for each of them, at minimum. And then you've got to figure out what percentage of the excitation is going into standing waves vs. stirring action. To cut to the chase, not simple and/or not cheap.
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