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Post Closed as "Needs details or clarity" by Mithoron, Mathew Mahindaratne, Nuclear Chemist, user55119, Todd Minehardt
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Karsten ♦
Karsten ♦
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For a molecule with 2 chiral centres, there are four possible combinations, (R,R), (R,S), (S,R) and (S,S). For example, 3-bromo-2-butanol has four stereoisomers: (2R,3R)-3-bromo-2-butanol, (2R,3S)-3-bromo-2-butanol, (2S,3R)-3-bromo-2-butanol and (2S,3S)-3-bromo-2-butanol.

Of these combinations, the following pairs are diastereomers:

S,R and S,S

S,R and R,R

R,S and S,S

R,S and R,R

I notice that only one chiral centre has been flipped to form these pairs.

The following pairs are either enantiomers or meso compounds (e.g. for (2R,3S)-tartaric acid):

S,R and R,S

S,S and R,R

I notice that both chiral centres have been flipped to form these pairs.

Could we generalise that flipping an even number of chiral centres always gives either an enantiomer or the same molecule if it's a meso compound, and flipping an odd number of chiral centres always gives a diastereomer?

For a molecule with 2 chiral centres, the following are diastereomers:

S,R and S,S

S,R and R,R

R,S and S,S

R,S and R,R

I notice that only one chiral centre has been flipped to form these pairs.

The following are either enantiomers or meso compounds:

S,R and R,S

S,S and R,R

I notice that both chiral centres have been flipped to form these pairs.

Could we generalise that flipping an even number of chiral centres always gives either an enantiomer or the same molecule if it's a meso compound, and flipping an odd number of chiral centres always gives a diastereomer?

For a molecule with 2 chiral centres, there are four possible combinations, (R,R), (R,S), (S,R) and (S,S). For example, 3-bromo-2-butanol has four stereoisomers: (2R,3R)-3-bromo-2-butanol, (2R,3S)-3-bromo-2-butanol, (2S,3R)-3-bromo-2-butanol and (2S,3S)-3-bromo-2-butanol.

Of these combinations, the following pairs are diastereomers:

S,R and S,S

S,R and R,R

R,S and S,S

R,S and R,R

I notice that only one chiral centre has been flipped to form these pairs.

The following pairs are either enantiomers or meso compounds (e.g. for (2R,3S)-tartaric acid):

S,R and R,S

S,S and R,R

I notice that both chiral centres have been flipped to form these pairs.

Could we generalise that flipping an even number of chiral centres always gives either an enantiomer or the same molecule if it's a meso compound, and flipping an odd number of chiral centres always gives a diastereomer?

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ETS
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Diastereomers, enantiomers, and meso compounds of molecules with lots of chiral centres

For a molecule with 2 chiral centres, the following are diastereomers:

S,R and S,S

S,R and R,R

R,S and S,S

R,S and R,R

I notice that only one chiral centre has been flipped to form these pairs.

The following are either enantiomers or meso compounds:

S,R and R,S

S,S and R,R

I notice that both chiral centres have been flipped to form these pairs.

Could we generalise that flipping an even number of chiral centres always gives either an enantiomer or the same molecule if it's a meso compound, and flipping an odd number of chiral centres always gives a diastereomer?