In the following questions a statement of assertion (A) followed by a statement of reason (R) is given. Choose the correct option out of the choices given below each question.
Assertion (A) : The compound cyclooctane has the following structural formula :
It is cyclic and has conjugated 8π-electron system but it is not an aromatic compound.
Reason (R) : (4n + 2) π electrons rule does not hold good and ring is not planar.
(i) Both A and R are correct and R is the correct explanation of A.
(ii) Both A and R are correct but R is not the correct explanation of A.
(iii) Both A and R are not correct.
(iv) A is not correct but R is correct.
Correct option is - (i) Both A and R are correct and R is the correct explanation of A.
Cyclooctatetraene do not obey (4n+2)π e’s rule; i.e. huckel rule and given cyclooctatetraene is non planar molecule. Huckel rule says a molecule is aromatic/ antiaromatic/ nonaromatic.
According to huckel rule –
For a compound to be aromatic it should be following:
1. Cyclic
2. Planar ring (sp2 hybridized)
3. (4n+2) π bond e’s where n= 0,1,2,3,…..
4. Molecule must have continuous ring of p-orbitals.
In case of cyclooctatetraene 8 π e’s are present (4 pi bond) of the ring So, it has 4nπ e’s not (4nπ +2) e’s.
