Halogenoalkanes
The C–X bond is polar (C δ+), so halogenoalkanes are attacked by nucleophiles. Nucleophilic substitution: aqueous NaOH, heat under reflux → alcohol; KCN in ethanol → nitrile (chain lengthened by one carbon); excess NH₃ in ethanol, heat in a sealed tube → amine. SN2 (one step, transition state) for primary; SN1 (via carbocation) for tertiary. With ethanolic NaOH (hot), elimination gives an alkene. Reactivity: C–I > C–Br > C–Cl, because the C–I bond is weakest (bond enthalpy matters more than polarity). Hydrolysis rate can be compared with aqueous AgNO₃ in ethanol: AgI (yellow) forms fastest.
≈ 50 min