JEE Advanced 2017 · Paper 1 · Chemistry Q12 · Dronacharya Exams

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ChemistryInteger+3Question 30 of 54

Among the following, the number of aromatic compound(s) is

Nine structures: cyclooctatetraene; cyclopropenyl anion; cyclopropenyl cation; 1,3-cyclohexadiene; cycloheptatrienyl (tropylium) cation; cyclopentadienyl cation; cyclopentadienyl anion; 1,2-dihydronaphthalene; phenanthrene.

Your answer

Answer and worked solution

Official answer: 5

Apply the Hückel rule (planar, cyclic, fully conjugated, $4n+2$ π electrons):

Structure	π electrons	Aromatic?
cyclooctatetraene	8, tub-shaped	no
cyclopropenyl anion	4	no (antiaromatic)
cyclopropenyl cation	2	yes
1,3-cyclohexadiene	not cyclic conjugation	no
tropylium cation	6	yes
cyclopentadienyl cation	4	no
cyclopentadienyl anion	6	yes
1,2-dihydronaphthalene	has a benzene ring	yes
phenanthrene	14	yes

Total: 5.

Answer: 5

Topics:Aromaticity

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