Question 1

Which enzyme catalyzes the aldol reaction in the conversion of fructose-1,6-bisphosphate to two triose phosphates in glycolysis?

Accepted Answer

Aldolase

Question 2

In the fatty acid synthesis pathway, which step involves the reduction of a 3-ketoacyl-ACP to a 3-hydroxyacyl-ACP, and what is the required cofactor?

Accepted Answer

Reduction by 3-ketoacyl-ACP reductase using NADPH

Question 3

Which of the following best describes the role of Mg2+ or Zn2+ in the aldolase-catalyzed reaction shown in glycolysis?

Accepted Answer

They stabilize the negative charge on the intermediate during the reaction.

Question 4

In the fatty acid synthesis pathway, which step is responsible for the formation of a double bond in the acyl chain?

Accepted Answer

Dehydration by 3-hydroxyacyl-ACP dehydrase

Question 5

What is the net result of the enoyl-ACP reductase reaction in fatty acid synthesis?

Accepted Answer

Reduction of a double bond to a single bond using NADPH

Question 6

Which of the following statements about keto-enol tautomerism is correct?

Accepted Answer

The equilibrium generally favors the keto form unless structural factors stabilize the enol form.

Question 7

Given the following pKa values: $$pK_a = 9$$, $$pK_a = 11$$, $$pK_a = 13$$, $$pK_a = 17$$, $$pK_a = 19$$, $$pK_a = 25$$, which compound is the most acidic?

Accepted Answer

The compound with $$pK_a = 9$$

Question 8

Why does the bromination of ketones exhibit an induction period before the reaction rate increases dramatically?

Accepted Answer

The reaction is autocatalytic; the product catalyzes further reaction.

Question 9

Which of the following best explains why para-substituted phenol is more acidic than phenol?

Accepted Answer

Resonance stabilization of the anion is more significant in the para position.

Question 10

Which reaction is used to brominate carboxylic acids that are otherwise difficult to brominate due to low enol content?

Accepted Answer

Hell-Volhard-Zelinsky reaction

Question 11

In the fatty acid synthesis pathway, which step involves the removal of water to form a double bond?

Accepted Answer

Dehydration by 3-hydroxyacyl-ACP dehydrase

Question 12

Which of the following is a key difference between the Claisen condensation and the aldol reaction?

Accepted Answer

Claisen condensation involves esters, while aldol reaction involves aldehydes or ketones.

Question 13

Which reagent is commonly used to generate a kinetic enolate for alkylation reactions?

Accepted Answer

LDA (lithium diisopropylamide)

Question 14

What is the main advantage of using enamines over enolates for alkylation reactions?

Accepted Answer

Enamines are more nucleophilic and less basic than enolates.

Question 15

Which of the following best describes the mechanism of the Claisen condensation?

Accepted Answer

Addition-elimination mechanism with deprotonation driving the reaction

Question 16

Which type of addition do organolithium and Grignard reagents typically undergo with α,β-unsaturated carbonyl compounds?

Accepted Answer

1,2-addition

Question 17

Which reagent would you use to selectively reduce a double bond in an enoyl-ACP intermediate during fatty acid synthesis?

Accepted Answer

NADPH

Question 18

Which of the following is a real-world application of the aldol reaction in biochemistry?

Accepted Answer

Cleavage of fructose-1,6-bisphosphate in glycolysis

Question 19

Which step in fatty acid synthesis is analogous to the dehydration step in the aldol condensation?

Accepted Answer

Dehydration by 3-hydroxyacyl-ACP dehydrase

Question 20

Which of the following best explains why the equilibrium for keto-enol tautomerism generally favors the keto form?

Accepted Answer

The keto form is usually more thermodynamically stable due to stronger C=O bonds.

Alpha Carbon Chemistry and Enolate Reactions in Organic Synthesis

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