distillation of pyrrole: need advice
Scott
I'm trying to distill pyrrole (98%) using a sand bath but I cant seem
to get the solution up to the desired temperature using a conventional
hot plate. My boss said something about a thermal wrap that I could
place around the distillation kit. Im not having much luck sourcing
one of these.
Does anyone know of a source (preferably UK) for thermal wraps and
thermostats? Or, alternatively, a better way to distill pyrrole.
Thanks
Scott
Chris Murray
> Hi,
> I'm trying to distill pyrrole (98%) using a sand bath but I cant seem
> to get the solution up to the desired temperature using a conventional
> hot plate. My boss said something about a thermal wrap that I could
> place around the distillation kit. Im not having much luck sourcing
> one of these.
> Thanks
> Scott
Pyrrole boils at about 130 degrees - your hotplate should be capable of
much more than that. Is it working properly?
We use hotplates with silicone oil baths which are good for nearly 200 deg
C if you wrap the top of the bath with baking foil to insulate. Have you
measured the temp of your sand bath?
If you can't raise the temperature then what about lowering the pressure?
__________________________________________________________________________
Chris Murray #
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PhD student #
Organofluorine research group # The views expressed in this message
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__________________________________________________________________________
Ian Gilmore
so you can immerse the flask(probably best to use a pear-shaped one). Use
aluminium foil to wrap around the bath and stillhead.
Regards,
Ian Gilmore
"Scott" <scott...@aol.com> wrote in message
news:699ca499.02021...@posting.google.com...
Uncle Al
Pyrrole boils at 130 C and is exceedingly sensitive to acid and
oxygen. Use an oil bath, possibly at lower pressure using a water
aspirator and controllable inert gas leak. Magnetic stirrer! If all
you wish to separate is involatile crud, pump it down on a vac line
then transfer trap to trap (magnetic stirrer!) with the cold side in
Dry Ice/acetone or liquid nitrogen.
You wrap the distillation column in a few layers of cheezecloth, or
glass wool held in pace with aluminum foil. You want the column to be
adiabatic and in mixing equilbirium for maximum theoretical plates.
Don't flood the column. If you run at lowered pressure you need a cow
so you can collect fractions without breaking to air.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!
William Penrose
>Hi,
>I'm trying to distill pyrrole (98%) using a sand bath but I cant seem
>to get the solution up to the desired temperature using a conventional
>hot plate. My boss said something about a thermal wrap that I could
>place around the distillation kit. Im not having much luck sourcing
>one of these.
Just pack glass wool or even domestic insulation around the sides of
the flask. Hold in place with soft iron wire.
Don't forget to flush with nitrogen, or you'll end up with
coffee-colored muck.
Bill Penrose
Grim
Chris Murray
> Do you use cotton inside the foil? [on a jacket for an oil bath]
No, it's basically just a shield to reduce the cooling effect of the air
flow in the fume hood. If you want to tightly insulate a glass oil-filled
bath with cotton wool, be my guest. It will be messy and if it touches the
hotplate it'll be smokey too. Accidentally touching hot, oil-soaked cotton
wool is the sort of thing that you only do once.
If you're talking about a column then foil (shiny side in) with a tight
cotton wool wrap works well. Better is a vacuum insulated silvered column
(expensive but worth it). Fisher sell some very nice ones.
Grim
André Ferreira
I've worked with pyrrole for quite a time (4 years) and I need to have
it very pure. Pyrrole darkens very quickly in contact with air. The
best way to distill it it's by using a vacuum/inert gas line. You
should first evacuate your assembly and make 3 cycles vacuum/inert
gas. Then you introduce the pyrrole and let it stir for some time with
a little bit of CaH2 to remove water, with agitation and under inert
gas (nitrogen or argon). After that, you start the vacuum and you
should distill it around 30ºC (depending on your vacuum pump). Collect
it and in the end introduce inert gas to the whole system and keep
your pyrrole on the freezer.
It's a sure method.
By the way, what are you working with pyrrole with?
Best regards
André