NEETChemistryGeneral Organic Chemistry
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The cycloheptatrienyl (tropylium) cation is exceptionally stable compared to typical alkyl carbocations. Reason (R): It contains six electrons delocalized over a non-planar seven-membered ring, which makes it aromatic. In the light of the above statements, choose the most appropriate answer from th
Options
- A(A) is true but (R) is false.
- BBoth (A) and (R) are true and (R) is the correct explanation of (A).
- CBoth (A) and (R) are true but (R) is not the correct explanation of (A).
- DBoth (A) and (R) are false.
Correct answer
A. (A) is true but (R) is false.
Step-by-step solution
Assertion (A) is true. The cycloheptatrienyl (tropylium) cation is exceptionally stable because it is an aromatic carbocation. Reason (R) is false. While the tropylium cation does contain six electrons ( 4n+2 where n=1 ), a strict requirement for aromaticity according to Hückel's rule is that the ring must be planar to allow for continuous delocalization of the electrons. The reason incorrectly states that the ring is non-planar. Therefore, (A) is true but (R) is false. Answer: (A) is true but (R) is false.