Two compounds, (chlorobenzene) and (cyclohexyl chloride), have significantly different experimentall — Haloalkanes and Haloarenes Chemistry Question
Question
Two compounds, $X$ (chlorobenzene) and $Y$ (cyclohexyl chloride), have significantly different experimentally measured dipole moments. Which of the following accurately describes the relationship and the primary reason for this observed difference?
💡 Solution & Explanation
The dipole moment of chlorobenzene ($1.69$ D) is lower than that of cyclohexyl chloride ($2.05$ D). This is primarily due to two factors: (1) The carbon atom in chlorobenzene is $sp^2$ hybridized (more electronegative) compared to the $sp^3$ hybridized carbon in cyclohexyl chloride, which reduces the effective electronegativity difference between C and Cl. (2) The lone pairs on the chlorine atom in chlorobenzene undergo delocalization into the benzene ring ($+R$ effect), pushing electron density in the opposite direction of the inductive dipole ($-I$ effect), leading to a reduced net dipole moment.