Geometrical Isomer and calculation of Geometrical Isomers

  • Geometrical Isomer

Geometrical isomer arises because of the restricted rotation about the bond
The band may be sigma and π.

Restricted








  • π bond : azo , alkene, oxime
  • Sigma bond :- in cyclic compound

For sigma bond GI condition :- in order to represent geometrical isomerism by the compound two group at each stereocenter should be different
For substituent almost should be in same plane


Calculation of Geometrical Isomers


  1. Find first n = Number of site for geometrical isomer
  2. Classified the molecule -- symmetric and unsymmetrical
  3. For Unsymmetrical = 2^n
  4. For symmetrical = 2^n-1 + 2^p-1
  5. Mid point of molecule are both side check environment , when same environment = symmetric and different environment = unsymmetric

Shown fig...



2 Due to chiral center


  1. Calculate n = No. Of Chiral Center
  2. Cheked - Chiral compound (POS =X and COS =X) x= absent
  3. Shown fig....





3 Calculation of total isomer if molecule contains more than one type of steroisogenic center



  1. Direct method 2^n
  2. Indirect method

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