What is steric hindrance?

Question

Answer

Steric hindrance is stopping of chemical reaction which is caused by bulky molecule

Answer

It is the problem created by atoms by crowding due to which the stability is reduced

Answer

Obstacle (u can say resistance) provided by presence of bulky group is called steric hinderence.
E.g tertiry alkyl halide provides more steric hinderence than primary alkyl halide in case of nucleophili substitution reactions.
CHEMISTRY BY KUNAL SIR

Answer

**Steric hindrance** refers to the phenomenon where the movement or reactivity of molecules is impeded due to the presence of bulky substituents or groups. It occurs when the size of these groups prevents other molecules or functional groups from approaching or reacting with the molecule.

**Causes of Steric Hindrance:**
Steric hindrance arises from the repulsion between electron clouds of atoms or groups within a molecule. It occurs due to the following reasons:

1. **Bulkiness of Substituents:** When a molecule contains large substituents or groups, they can occupy a significant amount of space, leading to steric hindrance. These bulky groups can hinder the movement of other molecules or prevent them from approaching the reactive site of the molecule.

2. **Steric Interactions:** Steric interactions occur when the electron clouds from different atoms or groups repel each other. These repulsive forces prevent the molecules from adopting certain conformations or hinder the approach of other molecules.

**Effects of Steric Hindrance:**
Steric hindrance has several effects on molecular behavior and reactivity:

1. **Spatial Constraints:** Steric hindrance limits the available space around a molecule, affecting its shape and overall conformation. It can restrict the rotation or movement of functional groups, leading to changes in the molecule's properties or reactivity.

2. **Reduced Reactivity:** Steric hindrance can hinder the approach of other molecules or functional groups, reducing the reactivity of the molecule. The bulky substituents can block the reactive sites, preventing interactions or reactions.

3. **Stability:** Steric hindrance can affect the stability of a molecule. In some cases, the presence of bulky groups can increase the stability by preventing unwanted interactions. However, in other cases, it can destabilize the molecule due to unfavorable steric interactions.

4. **Stereochemistry:** Steric hindrance plays a crucial role in determining the stereochemistry of a molecule. It can influence the arrangement of atoms or groups around a chiral center, affecting the molecule's optical activity or enantiomeric purity.

**Examples of Steric Hindrance:**
1. In organic chemistry, the presence of bulky groups in a molecule can hinder the approach of reagents during a chemical reaction, reducing the reaction rate or preventing the reaction altogether.

2. In biological systems, steric hindrance is important in protein folding and enzyme-substrate interactions. Bulky side chains in amino acids can restrict the folding of proteins and hinder the binding of substrates to the active site of enzymes.

In conclusion, steric hindrance refers to the obstruction or hindrance of molecular movement or reactivity due to the presence of bulky substituents or groups. It arises from repulsive interactions between electron clouds and can have various effects on molecular behavior, reactivity, stability, and stereochemistry. Understanding steric hindrance is crucial in fields such as organic chemistry and biochemistry to predict and explain molecular behavior and reactions.

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