Vinyl chloride () is extremely unreactive towards nucleophilic substitution compared to ethyl chlori — Haloalkanes and Haloarenes Chemistry Question

💡 Solution & Explanation

The low reactivity of vinylic halides is due to electronic factors, not steric bulk. The $C-Cl$ bond has partial double bond character due to resonance ($CH_2=CH-Cl \leftrightarrow ^-CH_2-CH=Cl^+$). Furthermore, the $sp^2$ hybridized carbon is more electronegative, resulting in a tighter, stronger $C-X$ bond. Additionally, the high electron density of the pi-bond cloud repels incoming nucleophiles. However, vinyl chloride lacks bulky adjacent alkyl groups; therefore, classical steric hindrance (which blocks backside attack in tertiary halides) is NOT the primary cause of its unreactivity.