Re: ORGLIST:Benzylic Oxidation of Methylated Polyhalogenated Cresol

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From: Jacob Zabicky (zabicky$##$bgumail.bgu.ac.il)
Date: Fri Mar 19 2004 - 11:46:54 EST


Hello Brad,

Try bromination adding a bromine solution with illumination, it may be
sunlight. be careful to scrub the evolving HBr because it is quite
corrosive when it sticks to anything in the vicinity of the reaction
flask. You'll probably ge easily up to two bromine atoms on the
benzylic site, but maybe even three. Mildly basic hydrolysis may finish
on an aldehyde or the acid. In the former case, oxidation with
bichromate or permanganate will finnish the proceedings. My experience
is that you cannot avoid alpha bromination when adding bromine to
toluene, unless you cover your reaction flask to avoid light... So...

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 Mar 18, 2004, at 17:08, <support$##$cussyn.com> wrote:

> Greetings,
>
> I am looking for a decent method for making 2-Bromo-4-chloro-
> 5-methoxy-benzoic acid from 1-Bromo-5-chloro-4-methoxy-2-
> methyl-benzene by direct oxidation. We have tried standard
> Chromium and KMnO4 based methods but they all suffer from
> poor yields. I would appreciate any suggestions. If anyone
> has another suggestion for an easy route from cheap available
> materials I would appreciate it. I
>
> Thanks in advance,
>
> Brad
>
> Senior Chemist
> Manager of Scientific Operations
> Custom Synthesis Services
> support$##$cussyn.com
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