likely a reallllly easy question about optical activity

[Kneecoal]

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dumb question - kaplan doesn't really make it too clear and it's been a while since i learned this stuff.

are only chiral molecules optically active? i know that enantiomers, which are chiral, have opposite optical rotation, but can achiral molecules be optically active? my gut is telling me duh, no, but i just wanted to make sure.

thanks peeps.

 

[nze82]

dumb question - kaplan doesn't really make it too clear and it's been a while since i learned this stuff.

are only chiral molecules optically active? i know that enantiomers, which are chiral, have opposite optical rotation, but can achiral molecules be optically active? my gut is telling me duh, no, but i just wanted to make sure.

thanks peeps.

Chiral molecules always have optical activity. Achiral molecules can never be optically active.
Molecules that possess a single chiral center have optical activity.
Molecules that possess two or more chiral centers MAY be optically active.

 

[tdkyun]

Glycine is inactive because it has no chiral center!

 

[DoctaWalnuts]

Glycine is inactive because it has no chiral center!

Right, Glycine is the only amino acid that is achiral and it has two of the same substituents right? That would be the extent of my knowledge when it comes to sugars.

 

[tdkyun]

Right, Glycine is the only amino acid that is achiral and it has two of the same substituents right? That would be the extent of my knowledge when it comes to sugars.

you mean amino acids 🙂

 

[miedvied]

Chiral molecules always have optical activity. Achiral molecules can never be optically active.
Molecules that possess a single chiral center have optical activity.
Molecules that possess two or more chiral centers MAY be optically active.

To elaborate on that last bit: a molecule with two opposing chiral centers (i.e., an R and an S) which have the same substituents will not be optically active (and are called "meso".)

IF the chiral centers are not opposing, or if they're opposing but have different subs, they're not meso, and are active.