From: peter walla (peter.walla$##$post.sk)
Date: Tue Jul 22 2003 - 11:33:02 EDT
Dear Kollegues!
In our lab we have performed a set of Negishi cross-coupling reactions stating from aryliodide and 4-tolylzinciumchloride (prepared from 4-Tolylmagnesiumbromide and Zinc(II)chloride 1:1, 4-tolylmagnesiumbromide was prepared from 4-bromotoluene with 1,1 equiv Mg in THF, reflux 2 hrs to obtain around 1M solution). What is so interesting, we have observed the cross-coupling reaction takes around 2 days to complete consumption of aryliodide, when we have used freshly prepared tolylmagnesiumbromide. When we reproduced more times the same reaction at the same conditions, but with 3 days old 4-tolylmagnesiumbromide, the reaction did not proceed!
We are suspicious, that the reagent tolylmagnesiumbromide somehow with the progress of time losses its activity or is gone. Please, tell me, If you also had such an experience. We have found no special notices in Encyclopedia of organometallic coumpounds regarding the Tolylmagnesiumbromide, so we store it at room temperature under argone atmosphere.
We would very appreciate and be thankfull to anyone, who response just wih one sentence.
Best regards
Peter Walla
________
Bezplatny webmail, forum, PaciNepaci, e-pohladnice - www.POST.sk
_______________________________________________
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)
This archive was generated by hypermail 2.1.4 : Fri Sep 19 2003 - 12:17:26 EDT