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In case of checking for the optical activity of cyclohexane or its derivative why we check for POS and COS in its cyclic 6 membered planar eclipsed state but not by its real conformation it forms chair, boat,twist boat etc) .

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  • Are you asking why we determine if the compound is chiral from the simplified planar hexagonal drawing, rather than its true conformation drawing? – H.Linkhorn Jun 03 '20 at 16:23
  • Yes I am asking this –  Jun 03 '20 at 17:22
  • Why might you think? Which drawing is easy to show and visualise planes of symmetry? Remember the drawings are saying the same thing - the chair conformation is implied in the drawing of a hexagon. – H.Linkhorn Jun 03 '20 at 17:23
  • It is not about being visualised easily but it is about the real structures which should be seen for the molecule.The complete planar form doenot exist in any of its conformation.Check out for finding the plane of symmetry of a simple molecule 1,2 cis dimethyl cyclo hexane which has POS according to planar structure,If there is no problem with this then the actual conformer should also have POS ,but where it is –  Jun 03 '20 at 18:35
  • So with the specific example of cis - 1,2 - dimethylcyclohexane, the molecule is achiral not because it has a plane of symmetry. Each of the conformations of the ring are chiral, but they interconvert rapidly at room temperature and so the overall compound is said to be achiral. – H.Linkhorn Jun 03 '20 at 18:41
  • The idea of a compound being achiral doesn't mean it has to contain a plane of symmetry. – H.Linkhorn Jun 03 '20 at 18:41
  • Can you explain it further –  Jun 04 '20 at 05:31
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    So each of the conformation is chiral because they have no plane of symmetry like you suggested. However the ring is constant flipping between the two chiral conformations, which are enantiomers of each other. So at room temp you moving between each enantiomer so fast you can call the overall compound achiral. But at very low temp when there isn’t the energy to ring flip it is technically a chiral compound as you stuck in one conformation – H.Linkhorn Jun 04 '20 at 05:33
  • You can add this one in the answer section –  Jun 04 '20 at 05:42

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