Home › MHT-CET › Chemistry › Halogen Derivatives › Aryl halides are far **less reactive** than alky…
Aryl halides are far **less reactive** than alkyl halides toward nucleophilic substitution because:
AAryl halides are more polar
BC–X bond in aryl halide is shorter and stronger (sp² C, partial double-bond character from C–X conjugation with ring); also Ar⁺ would be very unstable
CHalogen is in different orbital
DAryl rings act as nucleophiles
Answer & Solution
Correct answer: B. C–X bond in aryl halide is shorter and stronger (sp² C, partial double-bond character from C–X conjugation with ring); also Ar⁺ would be very unstable
Aryl C-X has partial double-bond character (lone-pair conjugation from X into ring) ⇒ shorter, stronger bond. Plus, breaking it would form an aryl cation (very unstable) for S$_N$1, and aromatic π-system blocks backside S$_N$2 attack. Hence aryl halides need harsh conditions (e.g., NaOH at 350°C) or electron-withdrawing groups (NO₂) ortho/para to activate.
Related questions
When (R)-2-bromobutane reacts with NaOH via the **S$_N$2** mechanism, the product is:**Grignard reagent** R-Mg-X is formed by reacting:Among para-, meta-, ortho-dichlorobenzene, the **melting point** is highest for:**Sandmeyer's reaction** prepares aryl halides from:**Aryl halides are prepared** by direct halogenation of arenes with which catalyst?The **IUPAC name** of (CH₃)₃C-Br (tert-butyl bromide) is:Addition of HBr to propene **without peroxide** gives mainly:**Swartz reaction** prepares: