abolt (Hive Addict)
03-09-04 19:32
No 494095
       Dewar Condenser     

Has anyone had any experience utilising a Dewar condenser and/or dry ice for condensing a nitro Al/Hg?

Theoretical advice welcome.smile
Audacious enough to shred the U.S. Constitution, even while he imposes one on Iraq


 
 
 
 
    hypo
(Hive Addict)
03-10-04 04:07
No 494171
       huh?     

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.
filter(lambda W : W not in 'ILLITERATE','BULLSHIT') 		 
 
 
 
    hypo
(Hive Addict)
03-10-04 04:33
No 494172
       UTFSE you stupid BITCH!!!!!     

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...
filter(lambda W : W not in 'ILLITERATE','BULLSHIT') 		 
 
 
 
    ApprenticeCook
(Hive Bee)
03-10-04 20:39
No 494307
       Well apart from hypo going spaz, hypo is ...     

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
(Hive Addict)
03-10-04 22:05
No 494318
       heh...     

just for the record: the bitch was to myself for not checking
google. laugh (feeling weird)

and yes, you fill them with a cooling mixture. usually dry ice/
acetone or something like that
filter(lambda W : W not in 'ILLITERATE','BULLSHIT') 		 
 
 
 
    abolt
(Hive Addict)
03-12-04 21:24
No 494790
       unnecessary. i'd fear that the condensor ...     

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.
Mr. Bush has not yet attended a single funeral for anyone killed in Iraq.
 		 
 
 
 
    Rhodium
(Chief Bee)
03-12-04 21:30
No 494791
       thermal shock     

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...
The Hive - Clandestine Chemists Without Borders 		 
 
 
 
    abolt
(Hive Addict)
03-12-04 21:46
No 494792
       Good point chief     

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.
Mr. Bush has not yet attended a single funeral for anyone killed in Iraq.