Question

Primary amines have a higher boiling point than tertiary amines .justify the statement

Answer 1

Amines

• Amines are the organic compounds that are derived from ammonia by replacing one or more hydrogen atoms with organic groups.
• Amines are of different types, primary amines, secondary amines, and tertiary amines.
• In primary Amines, one of the Hydrogen atoms in the ammonia molecule has been replaced(${\mathrm{RNH}}_2$ where $\mathrm{R}$ is an alkyl group).
• In secondary Amines, two of the Hydrogens in the Ammonia molecule have been replaced by hydrocarbon groups.(${\left(\mathrm{R}\right)}_2\mathrm{NH}$ where $\mathrm{R}$ is an alkyl group).
• In tertiary Amines, all of the Hydrogens in the Ammonia molecule have been replaced by hydrocarbon groups.(${\left(\mathrm{R}\right)}_3\mathrm{N}$ where $\mathrm{R}$ is an alkyl group).

The difference in boiling points:

• Amines have a greater tendency to form Hydrogen bonding due to the presence of a polar covalent bond between hydrogen and nitrogen atoms.
• Primary amines have two replaceable hydrogen atoms which are available for hydrogen bonding.
• Tertiary amines have no replaceable hydrogen atoms for intermolecular hydrogen bonding.
• As the intermolecular Hydrogen bonding increases in primary amines, it requires more energy to break the attraction between two molecules.
• Since primary amines need more amount of heat to break these hydrogen bonds, it is having higher boiling points.
• Therefore, Primary amines have a higher boiling point than tertiary amines.