trans 1,2-dibromocyclohexane

[andyjl]

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This is from the eliminations quiz on kaplan and the problem says that adding Bromine gas to cyclohexane results in trans-1,2-dibromocyclohexane which is a chiral compound. Chiral compounds are suppose to have different substituents on all the carbon atoms aren't they?

The answer says that "try superimposing it's mirror image on itself"

 

[Lonely Sol]

This is from the eliminations quiz on kaplan and the problem says that adding Bromine gas to cyclohexane results in trans-1,2-dibromocyclohexane which is a chiral compound. Chiral compounds are suppose to have different substituents on all the carbon atoms aren't they?

The answer says that "try superimposing it's mirror image on itself"

No, chiral compound can have same compound on 2 carbons. The only thing that would make it achiral is if it is symmtrical and if 2 of the same compounds are on the specific carbon. For example, if a carbon has 2-H's attached to it then it is achiral carbon.

when you get 1,2-dibromocyclohexane, both carbons where bromine is attached to have different suubstituents on each. Therefore it is chiral molecule.

 

[andyjl]

No, chiral compound can have same compound on 2 carbons. The only thing that would make it achiral is if it is symmtrical and if 2 of the same compounds are on the specific carbon. For example, if a carbon has 2-H's attached to it then it is achiral carbon.

when you get 1,2-dibromocyclohexane, both carbons where bromine is attached to have different suubstituents on each. Therefore it is chiral molecule.

but the remaining 4 carbons all have 2 Hs each..so wouldn't that make the whole compound achiral?

 

[hoak]

A compound is chiral, i.e is opitcally active, when it has at least one chiral center (except for meso compounds). Because if one Carbon is chiral, it will alter the angle of the light go through that compound. trans-1,2-dibromocyclohexane has 2 chiral centers and it asymmetrical. Therefore, it should be a chiral compound. 4 other achiral carbons are irrelevant.

 

[touroden]

I think it is chiral because it is in the trans formation. If it were cis it would be achiral.