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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Shadow on April 05, 2013, 10:45:36 AM

Title: 1-bromine-2-methylcyclohexane isomers
Post by: Shadow on April 05, 2013, 10:45:36 AM
Is there a plane of symmetry in (1R,2S)-1-bromine-2-methylcyclohexane? I think that there is, so it isn't optically active. It should be meso, but I need a confirmation from someone else.
Title: Re: 1-bromine-2-methylcyclohexane isomers
Post by: sjb on April 05, 2013, 10:48:12 AM
Is there a plane of symmetry in (1R,2S)-1-bromine-2-methylcyclohexane? I think that there is, so it isn't optically active. It should be meso, but I need a confirmation from someone else.

Can you draw a picture showing where your proposed plane of symmetry is?
Title: Re: 1-bromine-2-methylcyclohexane isomers
Post by: discodermolide on April 05, 2013, 10:50:26 AM
Surely meso compounds have the same substituents on adjacent carbons?
Title: Re: 1-bromine-2-methylcyclohexane isomers
Post by: Shadow on April 05, 2013, 11:27:11 AM
So it is not meso. Then I have the (1S,2R) isomer, too?
Title: Re: 1-bromine-2-methylcyclohexane isomers
Post by: discodermolide on April 05, 2013, 11:30:18 AM
Yes, I would expect as well.
Title: Re: 1-bromine-2-methylcyclohexane isomers
Post by: Shadow on April 05, 2013, 11:54:54 AM
There are four compounds then: (1S,2R), (1R,2S), (1R,2R), (1S,2S) and not two are superimposable, right?
Title: Re: 1-bromine-2-methylcyclohexane isomers
Post by: discodermolide on April 05, 2013, 12:05:49 PM
Yes that's correct, 4 possible diastereoisomers, two enantiomeric pairs.
Title: Re: 1-bromine-2-methylcyclohexane isomers
Post by: Rutherford on April 05, 2013, 12:49:10 PM
Have to ask, if the substituents were the same, these would be meso?
Title: Re: 1-bromine-2-methylcyclohexane isomers
Post by: discodermolide on April 05, 2013, 01:11:43 PM
Have to ask, if the substituents were the same, these would be meso?


Look here:
http://en.wikipedia.org/wiki/Meso_compound (http://en.wikipedia.org/wiki/Meso_compound)