User talk:KingGeezer

Mismatched structures (cyclic hemiketal shown in one)

The line-drawing, and the 3d-mol-graphics of the structure don't quite match; it appears that they are (if I remember the terminology correctly?) tautomers of each other. The 4-hydroxy hydrogen shown in the line-drawing appears to have moved over to the methyl-C=O group, and a ring-closure has happened. Chemists may think this is trivial, the two structures probably are in equil in solution, but to the 'normal human' looking at the two structures, they appear confusing, and so would defeat the purpose of effective science communication; IMO. Having now seen the rest of the comments, I see this subject was brought up before; so I would like to emphasize my point is more about useful/effective communication to non-experts, rather than claiming which structure is 'correct'. I would only suggest the two representation be consistent? KingGeezer (talk) 15:09, 9 June 2010 (UTC)

You're right-- the ball and stick model should look like the line drawing and it doesn't. The ball and stick form probably IS a tautomer, like the cyclic hemiketal tautomers in ketone sugars like fructose. In coumadin, what is shown is also a cyclic hemiketal form where the coumarin 4' alcohol has attacked the ketone carbon in the 3' substituent, probably/possibly reversibly. But whether reversible or not, somebody needs to re-do the ball and stick model. Not least because it is surely 4-hydroxycoumarin ring-open form that is needed for the molecule to be active. How do we know? Because there is a whole class of 4-hydroxycoumarin anticoagulants, and many of them, for example phenprocoumon, have no chance of any hemiketal forming, because the 3-substituent contains no ketone! So if this ring-closed hemiketal forms for warfarin, it's incidental to the molecule's function, and has to be undone before the molecule is active as an enzyme inhibitor. SBHarris 17:49, 9 June 2010 (UTC)