Optical Isomers

[Maverick56]

Optical Isomers cannot be rotated or manipulated to assume the structure of another isomer.

Why are (R)-2-chloropentane & (2)-2-chloropentane optical isomers when all I have to do is just rotate the sigma bond between Carbon 2 &3 to convert between them?

I am having such an difficult time with stereochemistry. I even have the molecular model set out. Thinking about a tutor

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[sdm33]

Optical Isomers cannot be rotated or manipulated to assume the structure of another isomer.

Why are (R)-2-chloropentane & (2)-2-chloropentane optical isomers when all I have to do is just rotate the sigma bond between Carbon 2 &3 to convert between them?

I am having such an difficult time with stereochemistry. I even have the molecular model set out. Thinking about a tutor

optical isomers are not the same as S/R configuration
Absolute configuration is the (R) or (S) that's labeled on the chiral centers.

Relative configuration is always defined in relationship to another chiral center. The direction that a molecule rotates plane-polarized light is the prime example of relative configuration.

Before the mid-1800s, people did not have an understanding of the tetrahedral carbon atom, so they did not have absolute configurations. Instead, they used the relative configurations of which way a compound rotates plane-polarized light.