Question 1

Which of the following functional groups is present in ezetimibe, as indicated by the red-highlighted atoms in the structure provided?

Accepted Answer

Hydroxyl, amide, and aromatic ring

Question 2

In the structure of escitalopram, the stereocenter in the red circle is best described as which configuration?

Accepted Answer

$(S)$

Question 3

Which of the following statements best explains why the O–H bond in ezetimibe is more acidic than the N–H bond?

Accepted Answer

Oxygen is more electronegative than nitrogen, stabilizing the conjugate base via negative charge delocalization.

Question 4

In escitalopram, which nitrogen atom is a stronger Brønsted–Lowry base and why?

Accepted Answer

The aliphatic nitrogen, because its lone pair is not delocalized into the aromatic ring.

Question 5

Consider the reaction of cis-but-2-ene with bromine in water, followed by treatment with NaOH. Which product is formed and why is only one product observed?

Accepted Answer

A single epoxide is formed due to anti addition and stereospecificity of the reaction.

Question 6

In the hydroboration–oxidation of methylcyclohexene, which of the following best describes the regioselectivity and stereochemistry of the alcohol product?

Accepted Answer

Anti-Markovnikov addition with syn stereochemistry

Question 7

Which category of stereoisomerism do the products F and G from the hydroboration–oxidation of methylcyclohexene represent?

Accepted Answer

Diastereomers

Question 8

When comparing the two possible chair conformations of a cyclohexanol derivative, which conformation is generally more stable and why?

Accepted Answer

The conformation with the bulky substituent in the equatorial position, due to minimized 1,3-diaxial interactions.

Question 9

Which product is formed when 1-butyne (H) is treated with $\mathrm{H_2O}$, $\mathrm{H_2SO_4}$, and $\mathrm{HgSO_4}$?

Accepted Answer

Butan-2-one

Question 10

Which product is formed when 1-butyne (H) is treated with $\mathrm{9-BBN}$ followed by $\mathrm{H_2O_2}$ and $\mathrm{NaOH}$?

Accepted Answer

Butanal

Question 11

Which of the following statements best describes the selectivity of hydration of alkynes using $\mathrm{H_2O}$, $\mathrm{H_2SO_4}$, and $\mathrm{HgSO_4}$ compared to hydroboration–oxidation?

Accepted Answer

Acid-catalyzed hydration follows Markovnikov selectivity, while hydroboration–oxidation follows anti-Markovnikov selectivity.

Question 12

In a retrosynthetic analysis, which reagent would you use to convert phenylacetylene to 1-phenyl-1-butanol via a multi-step synthesis?

Accepted Answer

$\mathrm{1. NaNH_2, 2. 1-bromopropane, 3. BH_3, 4. H_2O_2, NaOH}$

Question 13

Which of the following best explains why, in the reaction sequence involving cis-but-2-ene and bromine in water, the reaction is described as 'stereospecific'?

Accepted Answer

The stereochemistry of the starting alkene determines the stereochemistry of the product due to anti addition.

Question 14

Which of the following statements is true regarding the hybridization of the oxygen and nitrogen atoms in escitalopram?

Accepted Answer

The oxygen is $sp^3$ hybridized and the nitrogen is $sp^3$ hybridized.

Question 15

In the multi-step synthesis of 1-phenyl-2-propanone from ethylbenzene, which sequence of reactions would be most appropriate?

Accepted Answer

$\mathrm{1. Br_2, hv; 2. NaCN; 3. H_3O^+}$

Question 16

Which of the following best explains why, in the formation of D/E from the reaction of an acetylide anion with an epoxide, the addition must occur sequentially rather than mixing all reagents at once?

Accepted Answer

The acetylide anion would be quenched by water if added simultaneously, preventing nucleophilic attack.

Organic Chemistry Exam Practice: Functional Groups, Stereochemistry, Reaction Mechanisms, and Synthesis

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