Master Organic Synthesis: A Comprehensive Guide for MSc Chemistry Students

Question 1

Which of the following is NOT a commonly used protecting group for alcohols in organic synthesis?

Accepted Answer

Acetyl

Answer

TBDMS

Answer

TBS

Answer

MOM

Question 2

Retrosynthesis primarily involves:

Accepted Answer

Working backwards from a target molecule to identify potential starting materials

Answer

Synthesizing a target molecule from readily available starting materials

Answer

Using protecting groups to selectively modify functional groups

Answer

Catalyzing a reaction to increase its yield

Question 3

Which of the following is a crucial element in asymmetric synthesis?

Accepted Answer

Employing a chiral catalyst or reagent

Answer

Protecting the reactive sites of the molecule

Answer

Employing a multi-step synthesis

Answer

Using a high-pressure reaction vessel

Question 4

Which of the following reagents can be used to convert an alcohol to an alkyl halide?

Accepted Answer

SOCl2

Answer

NaBH4

Answer

H2SO4

Answer

NaOH

Question 5

Protecting groups are primarily used in organic synthesis to:

Accepted Answer

Prevent unwanted reactions at specific functional groups

Answer

Increase the solubility of the molecule in organic solvents

Answer

Catalyze specific reactions

Answer

Improve the yield of the final product

Question 6

Which of the following is a chiral molecule?

Accepted Answer

2-Butanol

Answer

Ethane

Answer

Propane

Answer

Butane

Question 7

Asymmetric synthesis is significant because it enables:

Accepted Answer

Synthesis of enantiopure compounds

Answer

Synthesis of racemic compounds

Answer

Synthesis of diastereomeric compounds

Answer

Synthesis of achiral compounds

Question 8

What is the central principle of retrosynthesis?

Accepted Answer

Decomposing target molecules into simpler starting materials

Answer

Employing only forward reactions to build the target molecule

Answer

Prioritizing the use of protecting groups in the synthesis

Answer

Maximizing the yield of the final product

Question 9

What is the purpose of using a chiral auxiliary in asymmetric synthesis?

Accepted Answer

To induce a specific stereochemistry in the product

Answer

To increase the reaction rate

Answer

To prevent racemization

Answer

To purify the product

Question 10

What is the main difference between a protecting group and a directing group?

Accepted Answer

Protecting groups prevent unwanted reactions, while directing groups guide regioselectivity

Answer

Directing groups prevent unwanted reactions, while protecting groups guide regioselectivity

Answer

Protecting groups are temporary, while directing groups are permanent

Answer

There is no difference between protecting groups and directing groups

Question 11

Which of the following reactions is a classic example of a pericyclic reaction?

Accepted Answer

Diels-Alder reaction

Answer

Michael addition

Answer

Grignard reaction

Answer

SN2 reaction

Question 12

What is the mechanism of the Friedel-Crafts acylation reaction?

Accepted Answer

Electrophilic aromatic substitution

Answer

Nucleophilic aromatic substitution

Answer

Radical addition

Answer

Pericyclic reaction

Question 13

Which of the following reagents is commonly used to perform a Wittig reaction?

Accepted Answer

Triphenylphosphine

Answer

Sodium borohydride

Answer

Lithium diisopropylamide

Answer

Potassium permanganate

Question 14

What is the product of the following reaction: 1-Bromopropane + Sodium azide?

Accepted Answer

1-Azidopropane

Answer

1-Propanol

Answer

1-Propylamine

Answer

Propionitrile

Question 15

Which of the following defines retrosynthesis?

Accepted Answer

Working backward from the target molecule to identify synthetically accessible starting materials

Answer

Optimizing the number of steps in a synthesis

Answer

Using protecting groups to prevent unwanted reactions

Answer

Employing asymmetric synthesis to control the stereochemistry of products

Question 16

What is the primary purpose of employing protecting groups in organic synthesis?

Accepted Answer

To prevent nucleophilic attack on sensitive functional groups

Answer

To increase the solubility of organic compounds in water

Answer

To direct reactions to specific sites on a molecule

Answer

To enhance the reactivity of specific functional groups

Question 17

Asymmetric synthesis is a powerful tool in organic chemistry. What is its primary application?

Accepted Answer

Enantioselective synthesis of chiral compounds

Answer

Stereospecific synthesis of alkenes

Answer

Regioselective synthesis of functionalized compounds

Answer

Protecting groups in organic chemistry

Question 18

Protecting groups that can be easily removed under mild conditions are known as:

Accepted Answer

Temporary

Answer

Permanent

Answer

Selective

Answer

Unstable

Question 19

In asymmetric synthesis, the use of a chiral catalyst offers a key advantage. Which of the following is this advantage?

Accepted Answer

High enantioselectivity

Answer

Increased reaction rates

Answer

Improved yields

Answer

Reduced side product formation

Question 20

In organic synthesis, the yield of a reaction is typically expressed as:

Accepted Answer

Percentage of the theoretical yield obtained

Answer

Mass of the product obtained

Answer

Moles of the product obtained

Answer

Volume of the product obtained

Question 21

Discuss the advantages and disadvantages of modern protecting group strategies, such as orthogonal protecting groups and photolabile protecting groups.

Accepted Answer

Orthogonal protecting groups allow for selective removal under different reaction conditions.

Accepted Answer

Photolabile protecting groups can be removed easily using light.

Answer

Modern protecting group strategies are more expensive than traditional methods.

Answer

Modern protecting group strategies offer no benefits over traditional methods.

Question 22

Which protecting group is most commonly used to protect primary amines?

Accepted Answer

t-Butyloxycarbonyl (Boc)

Answer

Triphenylmethyl (Trt)

Answer

Acetyl (Ac)

Answer

Benzyl (Bn)

Question 23

In retrosynthesis, what is the primary goal when selecting a functional group disconnection?

Accepted Answer

Identifying the target functional group and its precursors.

Answer

Ensuring the stability of the starting materials.

Answer

Maximizing the number of synthetic steps.

Question 24

What is the chiral auxiliary employed in Sharpless asymmetric epoxidation?

Accepted Answer

Dihydroquinine (DHQD) or Dihydroquinidine (DHQ)

Answer

Evans' auxiliary

Answer

Corey's auxiliary

Answer

Masamune's auxiliary

Question 25

Which approach is NOT commonly employed to increase the yield of a reaction in organic synthesis?

Accepted Answer

Using a large excess of one reactant

Answer

Removing by-products as they are formed

Answer

Employing a catalyst

Answer

Optimizing reaction conditions (temperature, solvent)

Question 26

What is the primary purpose of using a protecting group in organic synthesis?

Accepted Answer

To prevent undesired reactions at specific functional groups

Answer

To stabilize reactive intermediates

Answer

To enhance the reactivity of a functional group

Question 27

Which step is crucial in the synthesis of complex molecules?

Accepted Answer

Disconnecting the target molecule into simpler building blocks

Answer

Identifying the starting materials

Answer

Optimizing reaction conditions

Question 28

What is the chief advantage of utilizing a chiral catalyst in organic synthesis?

Accepted Answer

Enantioselective synthesis of chiral products

Answer

Reduced side reactions

Answer

Improved yield

Answer

Increased reaction rate

Question 29

What is a primary consideration when designing a multi-step synthesis?

Accepted Answer

Minimizing steps and maximizing overall yield

Answer

Employing only highly efficient reactions

Answer

Avoiding hazardous reagents