Oops, yes I was off by an order of magnitude there
0.015 ppm in a H NMR is typically not a significant issue when
characterizing compounds but when monitoring reactions by NMR it is very
significant in spectral overlays. We have to be very careful to perfectly
zero the TMS in the JCAMP files.
Although we do have some C NMR in our monitoring runs, we don't have many
because it takes too long to get a quantitative carbon spectrum - relaxation
times have to be on the order of 80s.
On 9/16/07, peter murray-rust <[EMAIL PROTECTED]> wrote:
>
> At 11:37 16/09/2007, Jean-Claude Bradley wrote:
> >Peter,
>
> Thanks very much - this is exactly the sort of hidden science we
> should be able to extract
>
> >For a simple example I am attaching the view of adding a solution of
> >veratraldehyde to a solution of 5-methylfurfurylamine, both in
> >methanol-d4 - taken from overlay 1 of EXP046
> ><http://usefulchem.wikispaces.com/Exp046>
> http://usefulchem.wikispaces.com/Exp046
> >(the most recent version of Java is not supported by JSpecView so
> >uninstall the last Java update to get this to work) Anyway here is
> >an image of the methoxy region attached
> >
> >The methoxys of veratraldehyde are the tall blue peaks then after
> >about 85% conversion to the imine they shift by 0.1 to 0.15 ppm
> >upfield giving the residual smaller red peaks. This may be due to
> >water being generated since the peaks shift gradually over the
> >course of imine formation. (see monitoring peaks in the results
> >section 46A) It would be nice to be able to model this.
>
> In the current project we will only be looking at 13C I think...
>
> Also - did you mean 0.15 or 0.015? The whole spectrum is only 0.15
>
> P.
>
>
> Peter Murray-Rust
> Unilever Centre for Molecular Sciences Informatics
> University of Cambridge,
> Lensfield Road, Cambridge CB2 1EW, UK
> +44-1223-763069
>
>
--
Jean-Claude Bradley, Ph. D.
E-Learning Coordinator for the College of Arts and Sciences
Associate Professor of Chemistry
Drexel University
http://drexel-coas-elearning.blogspot.com
http://drexel-coas-talks-mp3-podcast.blogspot.com/
http://usefulchem.blogspot.com
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