Question

Which isomer of \(C_4H_9Cl\) has the lowest boiling point?

Hint:

Branched isomers generally have lower boiling points compared to their straight-chain counterparts due to weaker van der Waals forces arising from their reduced surface area.

Answer 1

The isomer of C₄H₉Cl exhibiting the lowest boiling point is tert-butyl chloride (C₄H₉Cl), systematically named 2-chloro-2-methylpropane (CH₃)₃C-Cl.

This characteristic is attributed to the significant branching within the tert-butyl chloride molecule, which diminishes the surface area available for intermolecular forces, specifically Van der Waals forces. Consequently, with fewer sites for these interactions, the molecule requires less energy to vaporize, resulting in a lower boiling point when contrasted with less branched isomers, such as n-butyl chloride or sec-butyl chloride.