- #1
Nick tringali
- 71
- 13
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The discussion centers on the concept of enantiomers, specifically addressing the confusion surrounding their structural differences. One participant emphasizes the importance of using molecular modeling tools to better understand stereoisomers in three dimensions. The key point made is that enantiomers, while appearing similar, cannot be superimposed on one another due to their distinct spatial arrangements. The explanation highlights that flipping the molecule involves more than just rotating it; it requires considering the orientation of functional groups, such as hydroxyls, which change position relative to the viewer. This spatial distinction is what defines them as enantiomers, underscoring the necessity of visualizing molecular structures to grasp their differences fully.
- #2
TeethWhitener
Science Advisor
Gold Member
- 2,630
- 2,244
Get a hold of a good molecular modeling kit or a visualization program (there are a few good free ones online). It’s a lot easier to wrap your head around stereoisomers when you can play with the 3D representations of molecules.
- #3
snorkack
- 2,388
- 536
No, they are not.Nick tringali said:
Even without getting a model - how can you flip them around one into another?
You cannot rotate it around horizontal axis - because this would flip the M-shaped carbon backbone into W. So the rotation which leaves the pentane backbone unchanged M would be the rotation around vertical axis.
But what happens to the hydroxyls then?
The upper form starts off having the left, say 2 hydroxyl group towards viewer and the right, then 4 hydroxyl group away from viewer.
When you flip the sheet, the 2-hydroxyl group will be on the right... but because you are now looking at it from the opposite side of sheet, it is now away from you. So you again have the left hydroxyl (now 4) towards you and the right hydroxyl away from you. The molecule is NOT converted to the form below where the left hydroxyl is away from you and right hydroxyl towards you.
Which is why they are enantiomers.
- #4
Mayhem
- 421
- 311
When you flip these mentally, you have to think of it as you are flipping a page of a book, not simply interchange the groups.