[Question from NMRWiki Q&A forum] paramagnetic oxygen in solution NMR

[nmrlearner]

paramagnetic oxygen in solution NMR

A student is running a kinetics experiment in a J-Young tube under 5-10 atm of oxygen, much like in this journal article:http://pubs.acs.org/doi/abs/10.1021/ja9061932

1. Student is seeing reduction in signal from his compound (slightly polar) and his internal standard (non-polar). Obviously paramagnetic oxygen?
2. The part I can't figure out: student is NOT seeing a reduction in his solvent peak. Solvent is benzene or toluene. I am assuming he is using at least some deuterated solvent.

I have found a lot of literature on the interaction of paramagnetic O2 with membrane proteins, etc., but the paper the student sent to me makes no mention of accounting for this in the kinetics calculations. Assuming the relaxation of his compound and the internal standard are affected similarly by the paramagnetic O2, the relative integration should be correct? Is the relaxation of the solvent just too long to be affected much by paramagnetic O2? The issue with the kinetics runs is that they typically do one scan per time point since the reaction occurs somewhat quickly and they do not want to average over several scans. If the relaxation is short enough can we just do several scans with very short delay times?



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