SN1, SN2, E1, and E2 Reactions

Flashcards covering SN1, SN2, E1, and E2 reactions, including factors that influence each reaction type, nucleophile/base strength, and stereochemistry.

What determines the rate of an SN1 reaction?

Only the concentration of the substrate (1st order).

What determines the rate of an SN2 reaction?

Both the substrate and nucleophile concentrations (2nd order).

Does SN2 form a carbocation?

No, SN2 is a concerted reaction with no carbocation intermediate.

What kind of nucleophile favors SN2?

A strong nucleophile.

What solvent favors SN2?

Polar aprotic solvents (e.g., DMSO, acetone).

Which reaction type leads to racemization of stereochemistry?

SN1, due to carbocation formation.

Which reactions may undergo rearrangement?

SN1 and E1 (due to carbocation intermediates).

What favors E2 over SN2?

A strong, bulky base and higher temperatures.

What is the stereochemical requirement for E2?

Anti-coplanar geometry (leaving group and beta hydrogen must be opposite).

Which reactions are favored by tertiary substrates?

SN1 and E1 (due to carbocation stability).

Which reactions are concerted (1-step)?

SN2 and E2.

What reaction is favored by methyl or primary substrates?

SN2.

Which reaction is favored by heat and a weak base?

E1.

What is the difference between SN1 and E1?

SN1 uses a nucleophile; E1 uses a base. Both form a carbocation.

What charge do strong nucleophiles usually have?

They are usually negatively charged (e.g., OH⁻ , CN⁻ , Br⁻).

Is I⁻ a strong nucleophile or a strong base?

Strong nucleophile, weak base.

Is OH⁻ a strong or weak base?

Strong base and strong nucleophile.

Is CH₃CH₂O⁻ (ethoxide) a strong base?

Yes, it is a strong base and a strong nucleophile.

Is H₂O a strong or weak nucleophile?

Weak nucleophile; neutral and slow to react.

What kind of reaction does tert-butoxide favor?

E2, because it's a strong, bulky base and poor nucleophile.

Which is a better nucleophile in polar aprotic solvents: F⁻ or I⁻?

F⁻ is better in polar aprotic solvents.

What kind of reaction do weak bases and weak nucleophiles favor?

SN1 or E1, usually with tertiary substrates and heat.