From: C. Oliver Kappe (oliver.kappe$##$uni-graz.at)
Date: Fri Aug 09 2002 - 03:37:31 EDT
Hi!
I would agree that it would be worthwhile to try this sort of
bromination chemistry under microwave conditions. Of course, there could
be alternative sources for bromine apart from elemental bromine for this
chemistry. Most modern microwave reactors allow you to carry out
reactions up to 20 bars in sealed vessels (250 °C). With more
specialized equipment you could go much higher, i.e. to 80 bars/300 °C
in quarz vessels. For more info on microwave reactors in general, check
out our microwave chemistry website:
http://www-ang.kfunigraz.ac.at/~kappeco/microwave.htm
Oliver
-- C. Oliver Kappe Institute of Chemistry Karl-Franzens-University Graz Phone: +43-316-3805352 Heinrichstrasse 28, A-8010 Graz Fax: +43-316-3809840 AUSTRIA e-mail: oliver.kappe$##$uni-graz.at http://www-ang.kfunigraz.ac.at/~kappecoDarren Rhodes schrieb: > > It would be interesting to this sort of thing under microwave conditions ... > This should bring down your reaction time and if you wanted to do the work > on a larger scale you could use a continuous flow microwave reactor ... For > the batch microwave work talk to http://www.personalchemistry.com/ (the web > page seems a bit bloated but it should give you contact details). For the > continuous flow ... maybe the personalchemistry people again ??? Perhaps > someone else on the list could give appropriate details and refs and perhaps > their own experiences of these techniques ..... > > Darren. > > ----- Original Message ----- > From: "Jacob Zabicky" <zabicky$##$bgumail.bgu.ac.il> > To: <suzukicar$##$belais.freesurf.fr>; <everybody$##$orglist.net> > Sent: Thursday, August 08, 2002 12:32 PM > Subject: Re: ORGLIST:Bromination > > Hello Bel, > > The pressure in the vessel will be somewhat lower than 4 bar. If your > reaction mixture is over a couple of mL, you should carry out the process > in a Teflon-lined pressure vessel. If you can do it in small batches, > then you can prepare thick-walled test tubes, of outer diameter not bigger > than say 10 mm, place your mixture, freeze it with ice-salt or other > cooling medium (below -10C), and seal the tubes while slightly evacuating > at the end. > > You can place the tubes in boiling water or in a temperature-controlled > heating block, all this, of course in a well protected hood. Thick-walled > tubes of small diameter withold some pressure quite well. > > Good luck, > > Jacob > > At 16:23 7/8/2, Bel wrote: > >Dear all, > > > >I would like to know If any has experience with bromination in harsh > >conditions, using sealed tube at high temperature. I found one procedure > >concerning the bromination of an electronically poor aromatic (pyridinium > >derivative) which must be done by heating during 3 days at 180C. The > >bromine's boiling point is 58.7C, which means a very high pressure in the > >tube at 180C. So does anyone know how to make such reaction in a safe way, > >and which kind of tube may resist to such pressure? > > > >Regards > > > >Bel > _______________________________________________ ORGLIST - Organic Chemistry Mailing List Website / Archive / FAQ: http://www.orglist.net To post a message (TO EVERYBODY) send to everybody$##$orglist.net To unsubscribe, send to everybody-request$##$orglist.net the message: unsubscribe your_orglist_password your_address List coordinator: Joao Aires de Sousa (coordinator$##$orglist.net)
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