[maverick1996]

Hey!

Can somebody confirm the chiral centre is R in this molecule?


Thanks

[kriggy]

I think its S. O is priority 1, isopropyl is 2 and ethyl is 3 and the rotation is counterclockwise

[maverick1996]

But the Hydrogen is on a wedged bond so the molecule has to be rotated so its on a hashed as lowest priority has to be pointing back - thus making the clockwise and therefore R

Please correct me if I'm wrong

Thanks

[spirochete]

You are correct, Maverick. You can also bypass the visual rotation you describe and think to yourself "if the #4 priority is going toward from viewer (on a wedge), then the rule are reversed".

The only time when you can't use the same trick would be when the #4 priority is on a line (in the plane of the page, or computer screen, etc). Then you would have to consider a 3-D visualization, or use a more elaborate trick.

[kriggy]

But the Hydrogen is on a wedged bond so the molecule has to be rotated so its on a hashed as lowest priority has to be pointing back - thus making the clockwise and therefore R

Please correct me if I'm wrong

Thanks

Of course, I forgot to rotate 

[maverick1996]

You are correct, Maverick. You can also bypass the visual rotation you describe and think to yourself "if the #4 priority is going toward from viewer (on a wedge), then the rule are reversed".

The only time when you can't use the same trick would be when the #4 priority is on a line (in the plane of the page, or computer screen, etc). Then you would have to consider a 3-D visualization, or use a more elaborate trick.

Yeah I have heard about this trick but our Prof wants us to rotate the molecule otherwise we won't get full marks

But thanks

[AWK]

Such rotation is very easy. You rotate molecule along horizontal axis in the plane of picture by 180 degree. Then C- - -O bond (downward) will be upward and C to hydrogen - downward. That's all.

[Babcock_Hall]

I find it helpful to rotate around the axis of one bond, usually a bond that is in the plane of the paper.  The rotation can be chosen in such a way that the lowest priority group is in the back.
EDT
In this case the bond between the central carbon atom and R₂ is rotating.

[maverick1996]

Thanks for all your help


Yeah this is relatively easy - some people got different answers so I just wanted to check


Thanks again

[OCSaviour]

You can use Jsmol software. It helps a lot to understand how rotation changes the spatial arrangement of the atoms/groups.