Which of the following hydrocarbons readily loses a hydride ion (to a reagent such as Ph3C+) because the resulting cation is aromatic?

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JEE Advanced levelSingle correct optionDifficulty 3 of 3g1157

Which of the following hydrocarbons readily loses a hydride ion (to a reagent such as $Ph X_{3} C X^{+}$ ) because the resulting cation is aromatic?

Acyclopenta-1,3-diene
Bcyclopentane
Ccyclohepta-1,3,5-triene
Dcyclohexa-1,3-diene

Answer: C

Loss of

H X^{-}

from the sp3

CH X_{2}

of cyclohepta-1,3,5-triene gives the planar tropylium cation with 6 pi electrons, which is aromatic. Cyclopenta-1,3-diene would give the antiaromatic cyclopentadienyl cation (4 pi e), and the other two give non-aromatic cations.

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Which of the following hydrocarbons readily loses a hydride ion (to a reagent such as PhX3​CX+) because the resulting cation is aromatic?

Answer: C

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Which of the following hydrocarbons readily loses a hydride ion (to a reagent such as $Ph X_{3} C X^{+}$ ) because the resulting cation is aromatic?