Determining SN1, SN2, E1, and E2 Reactions: Crash Course Organic Chemistry #23

How are alkyl halide substrates classified based on the number of carbon substituents attached to the carbon bearing the leaving group?

• Methyl, Primary, Secondary, Tertiary

• Alkane, Alkene, Alkyne

• Polar, Nonpolar

• Strong, Weak

Which type of reaction is exclusively observed for methyl substrates, regardless of the nucleophile encountered?

• SN1

• E1

• SN2

• E2

What type of reaction is favored when a primary substrate encounters a strong, bulky base?

• SN1 substitution

• E1 elimination

• SN2 substitution

• E2 elimination

Why are secondary substrates considered to have the most competing reaction mechanisms (SN1, SN2, E1, E2)?

• They lack beta-hydrogens, limiting elimination reactions.

• They are resistant to carbocation formation, favoring only concerted reactions.

• They possess branching that allows for more stable carbocations and are susceptible to both substitution and elimination pathways.

• They only react with poor nucleophiles, simplifying reaction outcomes.

What type of solvent conditions are generally preferred for an SN2 reaction?

• Polar protic solvents, which stabilize the nucleophile.

• Nonpolar solvents, which increase steric hindrance.

• Polar aprotic solvents, which enhance nucleophile reactivity.

• Highly acidic solvents, which protonate the nucleophile.

When a secondary substrate reacts with a strong base and heat, which type of reaction is typically favored, and what is the characteristic of the major product?

• SN1 reaction, forming a racemic mixture.

• E1 reaction, forming the least substituted alkene.

• SN2 reaction, resulting in inversion of stereochemistry.

• E2 reaction, forming the most substituted alkene.

How does increasing the temperature generally affect the spontaneity of elimination reactions compared to substitution reactions?

• Increasing temperature makes elimination reactions less spontaneous because it decreases entropy.

• Increasing temperature makes elimination reactions more spontaneous because it increases the significance of the entropy factor.

• Increasing temperature has no significant effect on the spontaneity of elimination reactions.

• Increasing temperature favors substitution reactions by decreasing the activation energy.

What is the effect of using a very bulky base, such as sodium tert-butoxide (NaOtBu), in an E2 elimination reaction?

• It favors the formation of the most substituted alkene, following Zaitsev's rule.

• It leads to a slower reaction rate due to increased steric hindrance, favoring substitution.

• It favors the formation of the least substituted alkene, deviating from Zaitsev's rule.

• It promotes SN1 reactions by stabilizing the carbocation intermediate.