Question 1

Which of the following statements best explains why benzene is significantly less reactive toward bromine addition than cyclohexene?

Accepted Answer

Benzene is stabilized by resonance, and addition reactions would disrupt its aromaticity.

Question 2

Which of the following compounds is aromatic according to Hückel’s rule?

Accepted Answer

Benzene ($$C_6H_6)$$

Question 3

A compound has a planar, fully conjugated ring system with 10 π electrons. According to Hückel’s rule, is this compound aromatic, antiaromatic, or nonaromatic?

Accepted Answer

Aromatic, because $$4n+2=10$$ when $$n=2$$

Question 4

Which of the following best describes the molecular orbital configuration of benzene?

Accepted Answer

All six π electrons occupy three bonding molecular orbitals, forming a closed-shell configuration.

Question 5

Which of the following is the correct systematic name for the compound commonly known as TNT?

Accepted Answer

2,4,6-Trinitrotoluene

Question 6

Which of the following statements about the benzylic position is FALSE?

Accepted Answer

A quaternary benzylic carbon is readily oxidized to benzoic acid.

Question 7

Which of the following best explains why [10]annulene is not aromatic?

Accepted Answer

It does not have a continuous system of p orbitals due to steric interactions that force it out of planarity.

Question 8

Which of the following best describes the difference between pyridine and pyrrole regarding aromaticity?

Accepted Answer

The lone pair on pyridine nitrogen is localized and does not participate in aromaticity, while the lone pair on pyrrole nitrogen is delocalized and does.

Question 9

Which of the following is the expected product when ethylbenzene is oxidized with excess chromic acid ($$Na_2Cr_2O_7$$, $$H_2SO_4$$, $$H_2O$$)?

Accepted Answer

Benzoic acid ($$C_6H_5COOH)$$

Question 10

Which of the following statements about the Birch reduction is correct?

Accepted Answer

The carbon atom attached to an electron-donating group is not reduced.

Question 11

A compound with the molecular formula $$C_8H_{10}$$ exhibits a $$6H$$ singlet at $$2.2$$ ppm and a $$4H$$ multiplet at $$7.1$$ ppm in its $$^1H$$ NMR spectrum. What is the structure of this compound?

Accepted Answer

para-Xylene

Question 12

Which of the following is NOT a criterion for aromaticity?

Accepted Answer

The molecule must have an even number of π electrons.

Question 13

Which of the following best explains why C$$_{60}$$ fullerene (buckyball) is not aromatic?

Accepted Answer

The curvature of the sphere prevents all p orbitals from overlapping continuously.

Question 14

Which of the following IR absorption regions is characteristic of aromatic C–H stretching?

Accepted Answer

$$3000-3100\ \mathrm{cm}^{-1}$$

Question 15

Which of the following best describes the effect of aromatic rings on the chemical shift of protons in $$^1H $$NMR spectroscopy?

Accepted Answer

Aromatic protons are deshielded and appear downfield, typically between $$6.5$$ and $$8$$ ppm.

Question 16

Which of the following best explains why first-generation antihistamines often cause drowsiness?

Accepted Answer

They can cross the blood-brain barrier and bind to receptors in the central nervous system.

Question 17

Which of the following structural features is necessary for a compound to function as an H1 antihistamine?

Accepted Answer

Two aromatic rings in close proximity and a tertiary amine.

Question 18

Which of the following is a correct statement about the acidity of cyclopentadiene?

Accepted Answer

Cyclopentadiene is unusually acidic for a hydrocarbon because its conjugate base is aromatic.

Aromatic Compounds: Structure, Stability, and Reactions

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