Question

In question when number of stereoisomer is asked then generally I've seen number if optical isomers is calculated and geometrical if double bond and then added to give total stereoisomers but no conformational is counted. Why? Is conformational a rare case?

Answer 1

Dear student

The conformational isomers arise when ever there can be a rotation about a single bond. In general a molecule can be rotated about a single bond in infinite number of ways. Thus we can not take into account all those infinite ways. So we consider only a few of them which will be maximum stable. Now the stereoisomers are generally considered for the compounds like ethane, butane etc. and not for the complicated compounds as the energy difference between the various structures will not be appreciable and thus the isolation of such structures will not be easy.

Regards