Choosing Between SN1/SN2/E1/E2 Mechanisms

The video tutorial explains SN2, SN1, E2, and E1 mechanisms, focusing on how substrate type, nucleophile strength, leaving group ability, steric hindrance, and temperature influence which mechanism occurs. It provides examples for primary, secondary, and tertiary haloalkanes, highlighting the role of nucleophilicity and basicity, and discusses solvent effects on nucleophile strength.

Which reaction mechanism is least likely to occur with a tertiary haloalkane due to steric hindrance?

• E1

• SN2

• SN1

• E2

What is the relationship between nucleophilicity and basicity?

• Nucleophilicity is the same as basicity.

• Nucleophilicity parallels basicity.

• Nucleophilicity is inversely related to basicity.

• Nucleophilicity is unrelated to basicity.

In a polar aprotic solvent, which halide ion is the strongest nucleophile?

• Iodide

• Bromide

• Chloride

• Fluoride

Why is hydroxide considered a poor leaving group?

• It is too large.

• It is very basic and unstable.

• It is not polarizable.

• It is too small.

What effect does increased steric hindrance have on a nucleophile's ability to substitute?

• Increases elimination likelihood

• Has no effect

• Decreases substitution likelihood

• Increases substitution likelihood

At high temperatures, which type of reaction is generally favored?

• Substitution

• Both equally

• Neither

• Elimination

What is the main reason elimination reactions are more entropically favorable than substitution reactions?

• They produce fewer molecules.

• They produce more molecules.

• They require less energy.

• They involve more complex molecules.

In a reaction with a primary haloalkane and a strong base, which mechanisms are most likely?

• SN1 and E1

• SN2 and E2

• SN1 and SN2

• E1 and E2

Why is tert-butoxide a classic E2 promoter?

• It is too sterically hindered for substitution.

• It is a small nucleophile.

• It is a poor nucleophile.

• It is a weak base.

What is the effect of a weak nucleophile like methanol on reaction mechanisms?

• Favors SN2

• Favors E2

• Favors SN1 and E1

• Favors no reaction