Author Topic: Dewar Condenser  (Read 1411 times)

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abolt

  • Guest
Dewar Condenser
« on: March 09, 2004, 07:32:00 PM »
Has anyone had any experience utilising a Dewar condenser and/or dry ice for condensing a nitro Al/Hg?

Theoretical advice welcome. :)


hypo

  • Guest
huh?
« Reply #1 on: March 10, 2004, 04:07:00 AM »
what is a dewar condensor, for the ignorants (like me) who never
heard of such a thing?
the dewar i know of does the opposite of what a condensor does:
it keeps heat inside (or outside).

> and/or dry ice for condensing a nitro Al/Hg?

unnecessary. i'd fear that the condensor breaks due to termal stress.
(it should survive, but why risk?)
don't take the MM-document too serious.


hypo

  • Guest
UTFSE you stupid BITCH!!!!!
« Reply #2 on: March 10, 2004, 04:33:00 AM »
ok, i see. those are nice thingies, but overkill for an Al/Hg.
they are nice if you want to condense NH3 or stuff like that...


ApprenticeCook

  • Guest
Well apart from hypo going spaz, hypo is ...
« Reply #3 on: March 10, 2004, 08:39:00 PM »
Well apart from hypo going spaz, hypo is correct, total overkill for the Al/Hg rxn, dewar condenser as far as swim knows is like a bucket, fill the bucket with collant and the vapours go up inside the "walls" of the bucket, right?

A normal condenser is fine for it, dont get too stressed, just ice water flowing through the condenser is all that is required.

hypo

  • Guest
heh...
« Reply #4 on: March 10, 2004, 10:05:00 PM »
just for the record: the bitch was to myself for not checking
google.  ;D  (feeling weird)

and yes, you fill them with a cooling mixture. usually dry ice/
acetone or something like that


abolt

  • Guest
unnecessary. i'd fear that the condensor ...
« Reply #5 on: March 12, 2004, 09:24:00 PM »
unnecessary. i'd fear that the condensor breaks due to termal stress.
(it should survive, but why risk?)


I don't think thermal stress would be an issue. A solution of dry ice/IPA (much safer than dry ice/acetone) would give a solution of ~ minus 78 Celcius. The reflux temp of an Al/Hg would be 65-70 Celcius, using MeOH as the solvent.

Pyrex has a thermal shock rating of around 160 Celcius so I think thermal stress would not be an issue.

The M.P. of MeOH is minus 98 Celcius and the M.P. of Methylamine is minus 93 Celcius. So this should not be a problem

I was just wondering if the buildup of pressure in the reaction could be a problem, otherwise I think this would be the best way to do an Al/Hg as no Methylamine would be lost out of the condenser and Nitromethane could be added in one go.


Rhodium

  • Guest
thermal shock
« Reply #6 on: March 12, 2004, 09:30:00 PM »
A solution of dry ice/IPA (much safer than dry ice/acetone) would give a solution of ~ minus 78 Celcius. The reflux temp of an Al/Hg would be 65-70 Celcius, using MeOH as the solvent.

Pyrex has a thermal shock rating of around 160 Celcius so I think thermal stress would not be an issue.


The temp difference you give is ~150°C, so that's not too far off. And I'm not sure that rating is the same if the glass is at cryogenic temps...


abolt

  • Guest
Good point chief
« Reply #7 on: March 12, 2004, 09:46:00 PM »
Either another material (stainless steel) or a standard condenser in between the reaction vessel and the Dewar condenser, in order to spread out the thermal stress, would probably be the best way to go.