Enantiomer/Diasteriomer quick question

[imbackasd]

Problem: http://tinypic.com/r/33ljcbn/6

Hey so for this problem, you need to tell if the chair conformation is either Identical,Enantiomer, Diasteriomer, or Completely Different to the drawing given (The one the far left)

My teacher says its an Enantiomer, which I find interesting since they both (if you name them are the same exact compound) seem identical as they both are trans too.

Can something be trans yet be enantiomers like that???

THIS IS NOT FROM ANY MCAT BOOK, so no copyright issue or w.e

Thanks

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[V5RED]

They do not have the same name.

The one on the left is (1R,2R)1-Bromo-2-Iodo-Cyclohexane.
The one on the right is (1S,2S)1-Bromo-2-Iodo-Cyclohexane.

They are mirror images. Mirror image chiral molecules that are not meso are enantiomers.
They are both trans because the mirror image of a trans molecule will still be trans.

 

[Singhp03]

Problem: http://tinypic.com/r/33ljcbn/6

Hey so for this problem, you need to tell if the chair conformation is either Identical,Enantiomer, Diasteriomer, or Completely Different to the drawing given (The one the far left)

My teacher says its an Enantiomer, which I find interesting since they both (if you name them are the same exact compound) seem identical as they both are trans too.

Can something be trans yet be enantiomers like that???

THIS IS NOT FROM ANY MCAT BOOK, so no copyright issue or w.e

Thanks

you can use absolute configuration to see if you have an enantiomer or a the same compound. for example, a same compound would retain the same configuration of its chirality(RS-->RS) as opposed to enantiomers, in which the chirality configuration inverts(RS-->SR).

Also remember isomers have the same empirical formula, steroisomers differ in arrangement while structural isomer differ in bond linkage

check out this flow chart:http://ww2.chemistry.gatech.edu/class/2311/marder/Stereochem.pdf

 

[Singhp03]

They do not have the same name.

The one on the left is (1R,2R)1-Bromo-2-Iodo-Cyclohexane.
The one on the right is (1S,2S)1-Bromo-2-Iodo-Cyclohexane.

They are mirror images. Mirror image chiral molecules that are not meso are enantiomers.
They are both trans because the mirror image of a trans molecule will still be trans.

bingo, notice the inversion in chiral center configuration (1R,2R)->(1S,2S)

 

[05silvergt]

They do not have the same name.

The one on the left is (1R,2R)1-Bromo-2-Iodo-Cyclohexane.
The one on the right is (1S,2S)1-Bromo-2-Iodo-Cyclohexane.

They are mirror images. Mirror image chiral molecules that are not meso are enantiomers.
They are both trans because the mirror image of a trans molecule will still be trans.

Exactly. If you rotate them so that the I and Br are on the same carbons, you will see (or visualize, rather) that each molecule has an I pointing out of and into the page and a Br that points out of and into the page.

Always remember that enantiomers are mirror images, and diasteromers are compounds that are the same, but are not mirror images.