SN1, SN2, E1, and E2 Reactions

E = high priority groups on ___

opposite sides

Z = high priority groups on ___

same side

SN1 Reaction

Substrate Preference

3 (fast) > 2 (slow)

SN1 Reaction

Reagent Required

Weak Nucleophile

Is a SN1 reaction stepwise or concerted?

stepwise

SN1 Reaction

Solvent

Protic

SN1 Reaction

Is it racemic?

Yes

SN1 Reaction

Mechanism

1) Leaving group leaves; carbocation is formed (rearrangements possible)

2) Nucleophilic attack

3) Proton transfer (if needed)

SN2 Reaction

Substrate Preference

methyl > 1 > 2

SN2 Reaction

Reagent Required

Strong Nucleophile

Is a SN2 reaction stepwise or concerted?

Concerted

SN2 Reaction

Solvent

Aprotic

Which type of reaction experiences an inversion?

SN2

Does a SN2 reaction have possible rearrangements?

No

SN2 Reaction

Mechanism

Backside attack + Leaving group leaves

E1 Reaction

Substrate Preference

3 (fast) > 2 (slow)

E1 Reaction

Reagent Required

Weak base

Is an E1 reaction stepwise or concerted?

stepwise

E1 Reaction

Solvent

Protic

E1 Reaction

Mechanism

1) Leaving group leaves; carbocation formed (rearrangements possible)

2) Base removes beta-H; alkene forms

What is the product of an E1 reaction?

Zaitsev product (more substituted)

E2 Reaction

Substrate Preference

3 > 2 > 1

E2 Reaction

Reagent Required

Strong Base

Is an E2 reaction stepwise or concerted?

concerted

E2 Reaction

Solvent

Aprotic

Which reaction requires anti-coplanar geometry?

E2

Does an E2 reaction have possible rearrangements?

No

Heat favors ___ reaction

E2

E2 Reaction

Mechanism

Base removes beta-H + Leaving group leaves

If you have a bulky base in an E2 reaction, what is the product?

Hofmann product (less substituted alkene)

If you have a small base in an E2 reaction, what is the product?

Zaitsev product (more substituted alkene)