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24th November 2014 @ 10:40

Solubility is becoming an increasingly crucial aspect of design in OSM Series 4, and a major outcome of the latest meeting

OSM Online Project Meeting 9 (24th Nov 2014)

was to ensure that all compounds being made have a healthy predicted logP value of below 3.5 or so.

It's important we are predicting these values accurately for proposed molecules. I'll shortly post what we know of the correlation between reality and prediction for OSM compounds. We have Chemdraw available to us, and are typically using this, and typically looking at the CLogP value. In tinkering with these calculations I previously noticed that drawing in explicit H's can give striking differences in these predicted values, in what is a known Chemdraw bug.

Explicit H's and Chemdraw ClogP

In tinkering a little more just now I also found that the predicted values are sensitive to explict H's on heteroatoms too, i.e. whether the H is draw as attached (N-H) or implicit (NH). Which tautomer is drawn also impacts significantly on the calculated value, though less so for LogP (rather than CLogP). This is more reasonable, but given that we have, below, four representations of what is one compound in solution, it's important we are aware of such variance (3.32 to 6.50) when using calculated values as a criterion for whether to make a given compound.

Chemdraw CLogP and Tautomers

Attached Files
Tautomers and CLogP.cdxml
LogP Calcs.cdxml
LogP Calcs.png
Tautomers and CLogP.png