Question

Write notes on the following:
(I) Wurtz–Fittig reaction
(II) Sandmeyer reaction

Hint:

- Wurtz–Fittig = Aryl halide + Alkyl halide → Alkylbenzene.
- Sandmeyer = Diazonium salt → Aryl halide or cyanide (with Cu(I) salts).

Answer 1

(I) Wurtz–Fittig Reaction:
Definition: The Wurtz–Fittig reaction involves the reaction of an aryl halide with an alkyl halide in the presence of sodium metal in dry ether to give alkyl-substituted aromatic hydrocarbons.
Equation:
\[ C_6H_5Cl + CH_3Cl + 2Na \xrightarrow{dry\ ether} C_6H_5CH_3 + 2NaCl \] Conclusion: It is used to prepare alkylbenzenes (like toluene).
(II) Sandmeyer Reaction:
Definition: The Sandmeyer reaction involves the replacement of the diazonium group (-N$_2^+$) in an aromatic diazonium salt with a halogen (Cl, Br, CN) using copper(I) salts as catalysts.
Equation:
\[ C_6H_5N_2^+Cl^- + CuCl \rightarrow C_6H_5Cl + N_2 \uparrow \] Conclusion: It is an important method for the preparation of aryl halides and aryl cyanides.