SN1 Reaction
A two-step nucleophilic substitution proceeding through a carbocation intermediate.
Formula / equation
rate = k[substrate]
Unit
s⁻¹
In depth
The slow first step is ionisation of the C–X bond, so the rate is independent of nucleophile concentration and the reaction is first order. The planar carbocation can be attacked from either face, giving racemisation, and it may rearrange to a more stable cation before capture.
Examples in the real world
Hydrolysis of 2-bromo-2-methylpropane, which proceeds rapidly in aqueous ethanol and gives a racemic product.