Re: ORGLIST:Information on the xidation/oxygenation of carbanions by molecula r oxygen?

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From: Jacob Zabicky (zabicky$##$bgumail.bgu.ac.il)
Date: Wed Oct 27 2004 - 03:42:50 EDT


Dear Lalor,

1. The following reaction is supposed to proceed via carbanions
effecting a nucleophilic attack on the carbonyl group of the aromatic
aldehyde:

CH2XY + ArCH=O --(base)--> ArCH=CXY + H2O

X and Y are electronegative groups such as -CO2Et, -CONH2, -CN. In
mechanistic studies we performed in air with CH2(CN)2 the yields were
excellent, pointing to a relatively slow reaction with O2.

2. I maintain concentrate solutions of EtOMgCH(CO2Et)2 for long periods
in the refrigerator without apparent change. Although protection from
moisture is needed, air does not seem to affect the reagent.

3. The sluggishness of putative carbanions towards oxygen shown in the
items above does not preclude a more extensive reaction with O2 when
the carbanion sources are dissolved in concentrate base. Perhaps
looking up in Beilstein the various CH2XY compounds mentioned in item
1, or even CHXYZ, where Z is similar to X and Y, and some possible
salts derived from such compounds, will yield the desired information.

All the best,

Jacob

Prof. Jacob Zabicky
Institutes for Applied Researcfh
Ben-Gurion University of the Negev
P. O. Box 653
Beer-Sheva, 84105
Israel
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Tel. +972-8-6461271
Fax. +972-8-6472969
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Private: P. O. Box 12366
Beer-Sheva, 84863
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Tel. +972-8-6496792

On Oct 26, 2004, at 16:40, Lalor, Fergus wrote:

> I'd be most grateful for any pointers to any source of information -
> book,
> review article, research paper etc. - on the oxidation and/or
> oxygenation of
> carbanions by molecular oxygen.
> TIA -
> Fergus Lalor
>
> Dr. Fergus John Lalor
> Senior Lecturer
> Department of Chemistry
> University College
> Cork
> Ireland.
> Telephone: 00353-21-4902317
> Fax: 00353-21-4274097
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