Question

Ordinarily the barrier to rotation about a carbon-carbon double bond is quite high but in compound P, the double bond between the two rings was observed by NMR to have a rotational barrier of only about 20 cal/mol, showing that it has lot of single bond character.

The reason for this is:

• A. The double bond has a partial triple bond character due to resonance
• B. The double bond undergoes flipping
• C. The aromaticity attained by both the three membered and the five membered rings
• D. The $+I$ effect exhibited by the $n{C}_3{H}_7$ groups induces the double bond to have a partial single bond character

Answer 1

The correct option is C The aromaticity attained by both the three membered and the five membered rings