Diastereomers vs Enantiomers

[EpicDentist]

When comparing 2 compounds to determine whether they are diastereomers or enantiomers, do I simply compare the R and S?

For example, if Compound A is R,S and Compound B is S,R, then the two must be enantiomers. (Since the R/S are both completely different)

However, in another example, if Compund C is S,R and Compound D is R,R then the two must be diastereomers. (Since the R/S is the same in for the second stereocenter - R)

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[spoog74]

When comparing 2 compounds to determine whether they are diastereomers or enantiomers, do I simply compare the R and S?

For example, if Compound A is R,S and Compound B is S,R, then the two must be enantiomers. (Since the R/S are both completely different)

However, in another example, if Compund C is S,R and Compound D is R,R then the two must be diastereomers. (Since the R/S is the same in for the second stereocenter - R)

yeah you seem to get the idea. If you compare the r and s, if they both are switched, then they are enantiomers, if only one, then it is a diastereomer.

BUT ALSO BEWARE

If you have a structure that has 3 or 4 chiral centers, and it has for example R R S and then they give you another structure R R R, then THIS IS AN EPIMER , which can also be a diastereomer . DOnt forget this, if they give you an answerr choice as epimer, and if the molecule in comparison is ONLY different in ONE chiral center, then its an epimer. If its different in more than one, then its a diastereomer.

 

[bharat008]

yeah you seem to get the idea. If you compare the r and s, if they both are switched, then they are enantiomers, if only one, then it is a diastereomer.

BUT ALSO BEWARE

If you have a structure that has 3 or 4 chiral centers, and it has for example R R S and then they give you another structure R R R, then THIS IS AN EPIMER , which can also be a diastereomer . DOnt forget this, if they give you an answerr choice as epimer, and if the molecule in comparison is ONLY different in ONE chiral center, then its an epimer. If its different in more than one, then its a diastereomer.

When is your test??

 

[spoog74]

When is your test??

wednesday why

 

[bharat008]

wednesday why

No reason. Btw, best of luck...👍👍

 

[spoog74]

No reason. Btw, best of luck...👍👍

thanks man, im about to call it a night.


gd bless and good night

 

[UBCStudent128]

yeah you seem to get the idea. If you compare the r and s, if they both are switched, then they are enantiomers, if only one, then it is a diastereomer.

BUT ALSO BEWARE

If you have a structure that has 3 or 4 chiral centers, and it has for example R R S and then they give you another structure R R R, then THIS IS AN EPIMER , which can also be a diastereomer . DOnt forget this, if they give you an answerr choice as epimer, and if the molecule in comparison is ONLY different in ONE chiral center, then its an epimer. If its different in more than one, then its a diastereomer.

If it's a carbohydrate in open form, then you could have TWO different chirality centers but still be an epimer.
This question was on our organic chem final and killed so many students... :'(

But to OP's question, that is the general idea but you should look at whether the compound is symmetrical or not as well. R / S having internal symmetry can be meso. Then the relation ship between Compound A (R /S ) and Compound B ( S/ R) can be identical compounds

 

[spoog74]

If it's a carbohydrate in open form, then you could have TWO different chirality centers but still be an epimer.
This question was on our organic chem final and killed so many students... :'(

But to OP's question, that is the general idea but you should look at whether the compound is symmetrical or not as well. R / S having internal symmetry can be meso. Then the relation ship between Compound A (R /S ) and Compound B ( S/ R) can be identical compounds

'

you're probably right but i was trying to give him info in the context of the dat. I dont think he needs to be confused any more then he is lol. Thanks for the info though