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What are functional groups and why are they important?

The functional group is the agent providing a molecule its quintessential character and is responsible for molecular reactivity.

It is a group of two to four atoms that connects with the rest of the molecule with a single covalent bond. Its position in a molecule can be internal or terminal.

 

What are functional groups in organic chemistry?

A molecule's functional group helps identify and classify molecules and provides predictive outcomes in a chemical reaction. That is, molecules with the same functional group behave exactly under a similar reaction condition.

For example, all molecules with functional group acid will react with a base to give salt. Or all molecules with functional group alcohol will react with sodium (Na) metal and generate Hydrogen (H2) gas.

The functional groups also help to isolate or identify an unknown compound based on its chemical properties.

Suppose an oily, aromatic compound is isolated, and its functional groups must be identified. The aroma leads to the belief that it could be a benzene derivative. However, on reaction with bromine, the orange-red colour of bromine disappears, indicating a positive addition reaction. 

Only an alkene (C=C) functional group always undergoes an addition reaction with the Br2 molecule (bromination). In contrast, a benzene derivative will only undergo a substitution reaction and not an addition reaction with bromine. 

How to identify a functional group?

The oily, aromatic compound is menthene, a menthol derivative, though more tests are required to get the complete molecular structure.

On comparing menthene with ethylene, a plant hormone that causes the ripening of fruits, it also undergoes bromination. Both molecules have a common alkene (C=C) functional group. Therefore, regardless of molecular complexity, the functional group behaves similarly in both molecules.

Uses of functional group

The functional groups are responsible for molecular transformations by undergoing a set of reactions like - addition (connecting two molecules), rearrangement (rearranging atoms within a molecule), substitution (replacing a group of atoms with another), and elimination (removing a group of atoms).

In addition, functional groups also decide on a molecule's physical properties of boiling point, melting point, polarity, and solubility.

Therefore, the chemistry of an organic molecule, regardless of size and complexity, is determined by its functional groups.

Some of the most important functional groups in organic chemistry are-

most important functional groups organic chemistry

 

Related Chapter- Preview Functional Groups in Organic Chemistry (subscribers only premium tutorials) 

Related Podcast - Functional Group - What are Functional Groups? How are they important?  (free)

Related Reading- What does R stands for in organic chemistry?   (free)

Related Video on YouTube 

 

Functional Groups in Organic Chemistry

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Functional Groups in Organic Chemistry

  • What are functional groups?
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