What is steric hinderance ? Explain in detail.
Each atom present in a molecule occupies certain amount of space. If in a molecule bulky groups such as -CH3, -C2H5, -C6H5 etc are present around the central atom then, these bulky groups crowd the central atom and provide hindrance to certain chemical reactions that are observed in related molecules with smaller groups. For example, neopentyl chloride does not follow SN2 mechanism like pentyl chloride due to steric hindrance provided by three bulky -CH3 groups present around the primary carbon where SN2attack occurs.