Reaction Intermediate
A species produced in one step of a mechanism and consumed in a later one, so it does not appear in the overall equation.
Unit
mol/L
In depth
Intermediates are genuine chemical species with finite lifetimes, occupying energy minima between transition states, and can sometimes be detected spectroscopically or trapped. They must be distinguished from transition states, which are energy maxima with no lifetime at all.
Examples in the real world
The tertiary carbocation in an SN1 reaction; the bromine radicals in the photochemical bromination of alkanes.