####46. The restricted rotation about carbon carbon double bond in 2-butene is due to
[1993]
(a) Overlap of one - and - hybridized orbitals
(b) Overlap of two - hybridized orbitals
(c) Overlap of one - and one - hybridized orbitals
(d) Sideways overlap of two -orbitals.
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Solution:
- (d) Restricted rotation about carbon carbon double bond in 2-butene is due to sideways overlap of two -orbital.
Rotation around bond is not possible. If any attempt is made to rotate one of the carbon atoms, the lobes of -orbital will no longer remain coplanar i.e no parallel overlap will be possible and thus -bond will break . This is known as concept of restricted rotation. In other words the presence of -bonds fix the position of two carbon atoms.
