steric hindrance

Steric hindrance refers to the hindrance of a chemical reaction due to the arrangement of atoms within a molecule. This spatial arrangement can affect how easily molecules can approach each other to react.1

When atoms or groups of atoms in a molecule are large or bulky, they can physically block or slow down a chemical reaction. This is because the transition state, which is the intermediate stage before a reaction is complete, becomes more crowded. Conversely, if the formation of the transition state reduces crowding, the reaction can be accelerated.2

Understanding steric hindrance is crucial in predicting and controlling chemical reactions, as it directly impacts reaction rates and pathways.2