Kinetic and Thermodynamic Control
The distinction between a reaction giving the product that forms fastest and one giving the product that is most stable.
Unit
Dimensionless
In depth
At low temperature and short reaction times the kinetic product dominates, since it has the lower activation barrier and the reaction is irreversible. At higher temperature and longer times, equilibrium is established and the thermodynamically more stable product prevails.
Examples in the real world
The addition of HBr to buta-1,3-diene gives the 1,2-adduct at −80 °C but the more stable 1,4-adduct at 40 °C.