Author Topic: initiating Grignards with ultrasonic ...  (Read 1475 times)

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psyloxy

  • Guest
initiating Grignards with ultrasonic ...
« on: December 13, 2001, 10:52:00 PM »
Does anyone here have any experience with the great looking procedure
to initiate Grignard-reactions in wet ether with ultrasonic, as outlined
in

https://www.thevespiary.org/rhodium/Rhodium/chemistry/grignard.wet.html

?

On the other hand some discussion of the topic is also appreciated, since
I don't semm to fully understand the whole thing... because it looks so
microscale and I don't seem to find the passage in the text where they say
"after you've got the micro-reaction going, slowly add more R-MgBr and R-COH
to get the real rxn started..."

I don't need a 40L ultrasonic bath for that purpose, do I ?

--psyloxy--

hest

  • Guest
Re: initiating Grignards with ultrasonic ...
« Reply #1 on: December 13, 2001, 11:12:00 PM »
Ultrasound clean's the Mg surface, and as usual the more power you put in the more fun you get's out.
But the juveler cleaner (small U.S. bath) works greath too.
A Iodine xtal is also greath to promote the Gr.
If you use Mg turning, stirring the raw turnings for 12 houers works greath too. (Gives them a big clean surface)

Rhodium

  • Guest
Re: initiating Grignards with ultrasonic ...
« Reply #2 on: December 13, 2001, 11:14:00 PM »
It is probably preferable to have an ultrasonic bath the size of your reaction flask, as you need to shake off the oxide layer of all the Mg turnings you are using, but in my opinion it is only necessary to sonicate all the magnesium with say 10% of the alkyl halide, the other 90% of the halide can be added in another flask, if you figure out a clever way of transferring a reacting grignard solution from one flask to another.

An alternative for large reactions is to use an ultrasonic probe, which you dip into the reaction flask, instead of having the whole flask in a sonicating bath.

hest

  • Guest
Re: initiating Grignards with ultrasonic ...
« Reply #3 on: December 14, 2001, 12:22:00 AM »
Yep, an 150W old ultrasoundwelding prope is greath ;D
A seldisrupter is a great tool too

Rhodium

  • Guest
Re: initiating Grignards with ultrasonic ...
« Reply #4 on: December 14, 2001, 12:37:00 AM »
Hest: What is that? It sounds interesting.

hest

  • Guest
Re: initiating Grignards with ultrasonic ...
« Reply #5 on: December 14, 2001, 01:19:00 AM »
I'm not sure, some old ultrasound probe in a box, I found it in a elektr. shop for app 60 euro (yes we have to get use to it  ;D )
I was told that  it was used for weldering small Alluminium pises together. Ill dick up the name.

Aurelius

  • Guest
Re: initiating Grignards with ultrasonic ...
« Reply #6 on: December 14, 2001, 05:59:00 AM »
Bwiti, where are your comments for this thread?

hest

  • Guest
Re: initiating Grignards with ultrasonic ...
« Reply #7 on: December 17, 2001, 09:31:00 PM »
I't turns out that it is not a weldering machine, but a cell disrupter.
Here is a pic.

http://www.integratedservices.com/soniprep.htm


Rhodium

  • Guest
Re: initiating Grignards with ultrasonic ...
« Reply #8 on: December 17, 2001, 09:34:00 PM »
Oh, that one looks cheap!  :P

hest

  • Guest
Re: initiating Grignards with ultrasonic ...
« Reply #9 on: December 17, 2001, 09:43:00 PM »
54$ (used one)

psyloxy

  • Guest
Re: initiating Grignards with ultrasonic ...
« Reply #10 on: December 18, 2001, 01:21:00 AM »
There's also quite a lot on ebay, affordable us-cleaners that can hold a gallon...
didn't think so with the article speaking of 470$ for such a real small unit... well
it's been a while since then.


--psyloxy--