Elimination reactions are endothermic organic reactions that are used to prepare alkenes from alkyl halides and alcohols.
Strong nucleophiles act as better reagents for elimination reactions. Now we have to find the strong nucleophiles among the given ones. \(\overline{\mathrm{O}} \mathrm{Et}\) and \(\mathrm{OH}^{-}\)are strong bases and strong nucleophiles and in the presence of strong bases like ethanol, they promote elimination reaction. The base abstracts \(\beta\) hydrogen from the alkyl halide.
lodide ion, \(I^{-}\), is a weak base and therefore a weak nucleophile. Therefore, if we use Nal, a substitution reaction takes place (\(S N_2\)). In \(S N_2\) mechanism, the incoming nucleophile (\(I^{-}\)) approaches in a direction opposite to the leaving group (\(\mathrm{Br}^{-}\)) and a bond is made and broken simultaneously involving a fivemembered transition state. This mechanism occurs in substitution reactions in primary alkyl halides. The bromide in bromopropane will be replaced by iodide ion. We get iodopropane as a product instead of an alkene. It does not favour elimination reactions. The reaction is as follows:
The right option is (1) Nal.
.
The right option is (1) Nal.
.