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Question 1

What is steric hindrance?
A:

Answer 1

A decrease in reactivity caused by bulky groups at the reaction site, reducing accessibility to the nucleophile.

Question 2

How does steric hindrance affect nucleophilicity?

Answer 2

A: It decreases nucleophilicity by making it harder for the nucleophile to access the electrophilic carbon.

Question 3

Does steric hindrance affect basicity?

Answer 3

A: No, steric hindrance does not affect basicity because basicity depends on the ability to accept or donate protons.

Question 4

What are nonnucleophilic bases?

Answer 4

A: Bases that are sterically hindered, making them poor nucleophiles.

Question 5

Give an example of a nonnucleophilic base.

Answer 5

A: Tert-butoxide (CH₃)₃C⁻O⁻.

Question 6

Compare the nucleophilicity of ethoxide and tert-butoxide

Answer 6

.
A: Ethoxide (CH₃CH₂⁻O⁻) is a stronger nucleophile than tert-butoxide due to less steric hindrance.

Question 7

Why is tert-butoxide less nucleophilic than ethoxide?

Answer 7

A: The bulky methyl groups in tert-butoxide hinder its ability to approach the electrophilic carbon.

Question 8

Is a sterically hindered base still effective in deprotonation reactions?

Answer 8

A: Yes, because basicity is not affected by steric hindrance.

Question 9

Which property—basicity or nucleophilicity—is more impacted by steric hindrance?

Answer 9

A: Nucleophilicity is more affected by steric hindrance

Question 10

What makes a nucleophile strong despite steric hindrance?

Answer 10

A: Small size and low steric bulk allow easier approach to the electrophile.

Question 11

How do steric effects help differentiate between nucleophilicity and basicity?

Answer 11

A: Steric effects reduce nucleophilicity without significantly altering basicity, highlighting their distinct nature.

Question 12

What is the nucleophilic strength trend for CH₃CH₂⁻O⁻ and (CH₃)₃C⁻O⁻?

Answer 12

A: CH₃CH₂⁻O⁻ > (CH₃)₃C⁻O⁻ because CH₃CH₂⁻O⁻ has less steric hindrance.

Question 13

What happens to a nucleophile’s effectiveness in substitution reactions when steric hindrance increases?

Answer 13

A: Its effectiveness decreases due to reduced ability to approach and react with the substrate.

Question 14

Define “sterically hindered bases” in simple terms

Answer 14

.
A: Bases with bulky groups around the reactive site, making them poor at attacking carbon atoms.