The incorrect statement regarding the geometrical isomers of 2-butene is :
- cis-2-butene and trans-2-butene are not interconvertible at room temperature.
- trans-2-butene is more stable than cis-2-butene.
- cis-2-butene has less dipole moment than trans-2-butene.
- cis-2-butene and trans-2-butene are stereoisomers.
Answer
(3) cis-2-butene has less dipole moment than trans-2-butene.
Solution
(1): rotation about C=C needs breaking of the π bond ⇒ no interconversion at room temperature ⇒ (1) is correct
(2): in trans the two CH3 groups are far apart (less steric strain) ⇒ (2) is correct
(3): trans – the two C–CH3 bond moments cancel ( = 0); cis – they add ( 0.33 D) ⇒ cis has more dipole moment ⇒ (3) is incorrect
(4): same connectivity, different arrangement in space ⇒ (4) is correct
Answer: (3)