Absolute vs relative configuration

[phattestlewt]

What's the difference between absolute vs relative configuration?

I'm confused here.

R and S applies to chiral centers of stereoisomers.


D and L is the rotation of plane polarized light.


D/L and R/S are in no way related.

Absolute configuration is the R or S that we assign to a chiral center, but what is relative configuration?

---

Members don't see this ad.

 

[icedragon]

Someone correct me if I am wrong, but I think of the absolute configuration as the orientation of the chiral center and which way it will rotate light (found experimentally). The relative configuration can be seen after say a reaction where only the chirality of it will be known, but which way it rotates light is still unknown (because it still needs to be found experimentally) so it is relative.

 

[sps27]

What's the difference between absolute vs relative configuration?

I'm confused here.

R and S applies to chiral centers of stereoisomers.


D and L is the rotation of plane polarized light.


D/L and R/S are in no way related.

Absolute configuration is the R or S that we assign to a chiral center, but what is relative configuration?

http://en.wikipedia.org/wiki/Chirality_(chemistry)

This link does a good job at explaining things. What I got from the link was that R/S and (+)(-) are basically absolute configurations. R/S is based on predetermined rules and (+)(-) is based on experimental observations. But D/L is a relative configuration because it is based on orientation of glyceraldehyde molecule ---- so it can be thought of as relative. The three systems though are totally independent and not related to one another.

 

[chill3]

D and L is the rotation of plane polarized light.

Be careful. d/l and +/- refer to optical activity but D/L is relative configuration as previous posts have explained.