Question

What are aprotic solvents?

Answer 1

Hint: A substance that forms a solution upon dissolving a solute is known as a solvent. Even though solvents are usually liquid, they can sometimes also be gas, solid, or supercritical fluid. The ability of a solute to dissolve in a solvent and form a solution is known as solubility.

Complete answer:
To understand aprotic solvents, we first need to know what are polar protic solvents.
When there is a hydrogen atom bonded to either a
- Nitrogen atom as amine group ($-N{{R}_{3}}$),
- Oxygen atom as hydroxyl group (-OH), or
- Fluoride atom as hydrogen fluoride group (HF)
in a solvent, it is known as a polar protic solvent.
In these solvents, the hydrogen atom is a liable ${{H}^{+}}$ ion. Solutes can easily gain protons (${{H}^{+}}$) from the molecules of these solvents through hydrogen bonding.
One of the most common examples of polar protic solvents is water.
Now, solvents that do not donate ${{H}^{+}}$ or accept protons to the solute are known as polar aprotic solvents.
Even though polar aprotic solvents cannot donate or accept protons, they can still dissolve various salts.
Polar aprotic solvents are hence chemically inert. They do not have any charges and are neutral.
Some polar aprotic solvents usually have huge dipole moments and low dielectric constant.
The ${{S}_{N}}2$ reaction mechanism is followed in chemical reactions when polar aprotic solvents are used.
Some examples of polar aprotic solvents are carbon tetrachloride ($CC{{l}_{4}}$), acetone, carbon disulfide, dichloromethane, etc.

Note: It should be noted that a common distinguishing factor between polar protic solvents and polar aprotic solvents is the bonding of hydrogen.
In polar protic solvents, an electronegative atom is directly attached to a hydrogen atom whereas in polar aprotic solvents there are no hydrogen atoms directly attached to an electronegative atom.