Enantiomers vs. Optical Isomers

[kryptonxenon]

Are all enantiomers considered optical isomers? Can diastereomers also rotate plane-polarized light?

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[theonlytycrane]

yep! For enantiomers the optical activity is opposite with equal magnitude. For diastereomers the optical activity is different in both sign and magnitude.

 

[aalamruad]

yep! For enantiomers the optical activity is opposite with equal magnitude. For diastereomers the optical activity is different in both sign and magnitude.

Quick correction: There's actually no way to predict a relationship of optical activity between diastereomers, so it's not quite right to say that the optical activity of diastereomers is different in sign and magnitude, because they could have the same sign (rotate light in the same direction).

 

[BerkReviewTeach]

Not all enantiomers are optical active, so they are not automatically optical isomers. Probably 99.9% of the time enantiomers are also optical isomers, but substituted allenes are a typical example of mirror images that are not superimposable, and are not optically active. Consider H(Cl)C=C=CH(Cl). You can draw the structure with the two Cls two different ways, which come out to be mirror images. But neither enantiomer is optically active.