Question

The correct order of boiling point:
CH\(_3\)-CH\(_2\)-CH\(_2\)-CH\(_2\)-NH\(_2\), CH\(_3\)-CH\(_2\)-NH-CH\(_2\)-CH\(_3\), CH\(_3\)-CH\(_2\)-N(CH\(_3\))\(_2\)

• A. CH\(_3\)-CH\(_2\)-CH\(_2\)-CH\(_2\)-NH\(_2\) > CH\(_3\)-CH\(_2\)-NH-CH\(_2\)-CH\(_3\) > CH\(_3\)-CH\(_2\)-N(CH\(_3\))\(_2\)
• B. CH\(_3\)-CH\(_2\)-NH-CH\(_2\)-CH\(_3\) > CH\(_3\)-CH\(_2\)-CH\(_2\)-CH\(_2\)-NH\(_2\) > CH\(_3\)-CH\(_2\)-N(CH\(_3\))\(_2\)
• C. CH\(_3\)-CH\(_2\)-N(CH\(_3\))\(_2\) > CH\(_3\)-CH\(_2\)-CH\(_2\)-CH\(_2\)-NH\(_2\) > CH\(_3\)-CH\(_2\)-NH-CH\(_2\)-CH\(_3\)
• D. CH\(_3\)-CH\(_2\)-N(CH\(_3\))\(_2\) > CH\(_3\)-CH\(_2\)-NH-CH\(_2\)-CH\(_3\) > CH\(_3\)-CH\(_2\)-CH\(_2\)-CH\(_2\)-NH\(_2\)

Hint:

When comparing boiling points of organic compounds, look for hydrogen bonding and the nature of the functional group. Compounds with stronger hydrogen bonding (like primary amines) will have higher boiling points.

Answer 1

The Correct Option is A

Boiling points of organic compounds are affected by various factors such as molecular weight, intermolecular forces, and functional groups. The key factors here are: 1. Intermolecular hydrogen bonding: Compounds that can form hydrogen bonds generally have higher boiling points than those that cannot. 2. Electron-donating groups: Alkyl groups, which donate electron density, can slightly increase the boiling point. Let’s analyze the compounds: - CH\(_3\)-CH\(_2\)-CH\(_2\)-CH\(_2\)-NH\(_2\): This is an amine with a primary amine group (-NH\(_2\)). Primary amines can form strong hydrogen bonds, leading to a higher boiling point compared to the other compounds. - CH\(_3\)-CH\(_2\)-NH-CH\(_2\)-CH\(_3\): This is a secondary amine. Although secondary amines can also form hydrogen bonds, they are less effective than primary amines because the nitrogen atom is less available for bonding. This results in a lower boiling point than the primary amine compound. - CH\(_3\)-CH\(_2\)-N(CH\(_3\))\(_2\): This is a tertiary amine, which cannot form hydrogen bonds with itself (since the nitrogen atom is fully bonded to alkyl groups). Therefore, this compound will have the lowest boiling point among the three. Thus, the correct order of boiling points is: Primary amine > Secondary amine > Tertiary amine