RE: ORGLIST: Oxime degradation

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From: will jones (willjones46$##$hotmail.com)
Date: Mon Dec 05 2005 - 04:54:53 EST


oximes at pH 7 are usually stable, at least in the literature I have seen
and from my experience.

You should always extract from the reaction mixture in order to get rid of
your unreacted reagents. I clean up unreacted hydroxylamine by acidifying
the reaction mixture, and extracting with water.

If you are worried about degradation, but are not sure what is going on,
then the only way of knowing what is happening is to look at your compound.
TLC should suffice to see whether there is a 'change' regardless of what
that change is. If you have NMR that is accessible, then use that.

Whilst not scientific, if you see a change, then just make your compound up
fresh each time. If you are curious as to what is going on, then look at the
TLC and separate out the compounds by chromatography and then NMR them.

You probably wanted a 'do this' answer...

Hope that helps

Will





>From: "Nalini Patel" <nalini.patel$##$rediffmail.com>
>Reply-To: Nalini Patel <nalini.patel$##$rediffmail.com>
>To: everybody$##$orglist.net
>Subject: ORGLIST: Oxime degradation
>Date: 4 Dec 2005 06:32:31 -0000
>
>Hi to all ORGLIST friends !
>
>I made very well the OXIME of 4-Methyl cyclohexanone with Hydroxylamine HCl
>in caustic media. Here my question is, is it necessary to give this oxime
>washes of satd. brine after reaction completion, even if the pH of the
>media comes neutral ?  
>
>The reason of asking this, because when after 2 weeks & 4 weeks, I used
>this oxime for my further steps, the yield of my final product was
>consequently being lower & lower comparing to using fresh oxime in the next
>step.
>
>Can anyone pls advice me, this result may be due to not giving washes of
>brine or may be due to degradation of the oxime ?
>
>Awaiting your replies, soon !
>
>
>
>
>Thanking you,
>NALINI
>
>
>
>
>
>


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