Sn1 + Elimination

for an Sn1 reaction…

• occurs in “two” steps

• formation of carbocation intermediate is rate-determining and involves only the haloalkane and not the nucleophile

• first-order reaction

Sn1

• relative stabilities of carbocation intermediates

• governed by electronic factors

β-elimination

a chemical reaction in which atoms or groups (one of which is usually, but not always, a hydrogen) are lost from adjacent atoms, resulting in a new pi bond

regioselectivity

preference of one direction of bond-making or breaking of over other possible directions

Zaitsev’s rule

the major product of a β-elimination is the more stable (more highly substituted) alkene

E1 mechanism

at one extreme, breaking of the R-Lv bond to give a carbocation is complete before reaction with base to break the C-H bond

• unimoIecular: only R-Lv is involved in the rate-determining step

E2 mechanism

at the other extreme, breaking of the R-Lv and C-H bonds is concerted (simultaneous)

• bimolecular: both R-Lv and base are involved in the rate-determining step