E1 reaction

An elimination reaction in which a leaving group departs first to form a carbocation, followed by loss of a proton to create a double bond.

Carbocation: A molecular ion in which a carbon atom bears a positive charge and has only six valence electrons. It forms in the rate-determining first step and governs which products can follow.
E2 reaction: A concerted elimination in which a base removes a proton as a leaving group departs. Unlike E1, E2 forms the alkene in one step without a carbocation intermediate.
Tertiary alkyl halide: An alkyl halide whose carbon–halogen bond is attached to a carbon bonded to three other carbons. Ionization can produce a relatively stable tertiary carbocation, making E1 more accessible.
Leaving group: An atom or group that departs from a molecule with the bonding electron pair. Its departure creates the carbocation in the first E1 step.
Rate-determining step: The slowest step in a multistep reaction, which limits the overall reaction rate. Leaving-group departure sets the E1 rate because it occurs before the proton is removed.
E1cB reaction: A two-step elimination that forms a carbanion before the leaving group departs. It reverses E1's order: proton removal precedes leaving-group departure.
Solvolysis: A reaction in which the solvent acts as a reactant, often replacing a leaving group. Polar protic solvents can promote ionization, so solvolysis conditions may yield E1 products.
Brønsted base: A species that accepts a proton in a Brønsted–Lowry acid–base reaction. It removes a beta proton from the carbocation to form the alkene.
Zaitsev's rule: A rule predicting that elimination reactions often favor the more substituted alkene product. The proton-loss step commonly favors the more substituted alkene when several beta positions are available.
SN1 reaction: A substitution reaction in which a leaving group departs before a nucleophile bonds to the carbocation. SN1 shares E1's ionization step, but captures the carbocation by substitution instead of elimination.

Linked from 9 pages