Possible variety of Stereoisomers

In general, a framework with n stereocenters will have 2n different stereoisomers. (We are not considering, for the time being, the stereoaltoalsimce.orgistry of twin bonds – that will certainly come later). Because that example, let"s take into consideration the glucose molecule in that open-chain type (recall that countless sugar molecules can exist in one of two people an open-chain or a cyclic form). There room two enantiomers of glucose, dubbed D-glucose and L-glucose. The D-enantiomer is the typical sugar the our bodies usage for energy. It has actually n = 4 stereocenters, so because of this there space 2n = 24 = 16 feasible stereoisomers (including D-glucose itself).

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Now, let"s expand our analysis to a sugar molecule with three chiral centers. Going with all the feasible combinations, us come up v eight full stereoisomers - 4 pairs that enantiomers.

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Let"s draw the RRR stereoisomer. Being careful to attract the wedge bonds appropriately so the they match the RRR configurations, we get:

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Now, utilizing the over drawing as our model, drawing any kind of other stereoisomer is easy. If we want to attract the enantiomer the RRR, we don"t require to try to visualize the winter image, we simply start v the RRR structure and also invert the configuration at every chiral center to get SSS.

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Try making models the RRR and also SSS and confirm that they are in fact nonsuperimposable mirror pictures of every other.

There are six diastereomers the RRR. To attract one that them, we just invert the construction of at least one, however not all three, that the chiral centers. Let"s invert the configuration at chiral facility 1 and 2, however leave chiral facility 3 unchanged. This provides us the SSR configuration.

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One more definition at this point: diastereomers which differ at just a solitary chiral facility are called epimers. Because that example, RRR and also SRR are epimers:

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The RRR and also SSR stereoisomers shown earlier are diastereomers however not epimers because they differ at two of the three chiral centers.


Example (PageIndex2)

The sugar below is one of the stereoisomers that we have been discussing.

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