Substrate: Tertiary Alkyl Halide
Reaction Coordinate Diagram

Concept Quiz

The E1 Mechanism

The E1 (Elimination Unimolecular) reaction is a two-step process that competes with the SN1 mechanism. It proceeds via the exact same rate-determining step: the formation of a carbocation. However, instead of a nucleophile attacking the carbon, a weak base extracts a proton from an adjacent ($\beta$) carbon, resulting in a $\pi$ double bond.

Rate $= k [\text{Substrate}]$
(Independent of Base Concentration)
Zaitsev's Rule:
Because the intermediate is a freely rotating carbocation, the system will thermodynamically favor the removal of a proton that leads to the most substituted, most stable alkene. E1 reactions do not have a strict anti-periplanar geometrical requirement like E2 reactions.