Tuesday, February 03, 2009

Sigma-Aldrich ships ONS solubility challenge batch

A while back I reported that Sigma-Aldrich was sponsoring the Open Notebook Science challenge by donating compounds when necessary. That was a very generous offer and we have just made use of it. The first batch has shipped yesterday to Jenny Hale at Southampton University. Since she is using a SpeedVac to measure solubility, we made a list of lower cost Ugi product reactants with higher boiling points. Here is the collection:

Every solubility measurement technique has its pros and cons. Evaporation based methods are very direct but are limited to high boiling solutes. UV is sensitive to low concentrations but requires a calibration curve and a chromophore. (for example EXP024)

NMR is less sensitive than UV but has the advantage that it can handle solutes of any volatility and does not require a chromophore - and from an efficiency standpoint - it does not require a calibration curve. At our concentration range of interest (>0.1M), NMR does seem to be the most convenient method in my lab: make a saturated solution in the solvent of interest then dilute with a deuterated solvent (generally CDCl3) then add an internal standard (acetonitrile is handy) then take one spectrum and analyse. For an example see Khalid's EXP030.

For an sampling of all the methods see our experiment list.

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