From: Starcrown (stch8002$##$bureau.ucc.ie)
Date: Fri Jun 11 1999 - 11:08:46 EDT
I have been trying to characterise a curious 'isomer' of what is
essentially acetylacetone with a large transition metal organometallic
'substituent' attached to the central (i.e. 3-) carbon. I use the word
'isomer' loosely because we don't actually know what this species is - just
that it can be readily formed from the 'normal' substituted-acac in a
variety of ways and very easily reverts to the latter - e.g. if a
dichloromethane solution is filtered through silica or treated briefly with
very dilute aqueous acid. One possibility that we are following is that it
may be a labile hydrogen-bonded adduct with water, other polar solvents or
whatever acceptor happens to be present when it is generated. If so, it
seems that less than one mole of acceptor is required per mole of our
potential donor. We have, for instance, detected the presence of equimolar
Et3N under one set of preparative conditions but - curiously - can leach
out almost 2/3 of the amine without destroying the 'isomer' or 'adduct'. We
would like to test the hydrogen bonding hypothesis by using an extremely
strong acceptor in the hope of isolating an 'adduct' (if that is what our
mysterious species is) stable enough th be fully characterised. All
suggestions will be most gratefully received as we are quite tired of
banging our heads against this particular brick wall 8->)
TIA -
Fergus Lalor
--------------------------------------------------
Dr. Fergus Lalor, Chemistry Dept., University
College, Cork, IRELAND.
Telephone: 353-(0)21-902317. Fax: 353-(0)21-274097
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