Question

Write the reaction: (i) Wurtz-fitting reaction (ii) Ullmann reaction (iii) Gattermann reaction (iv) Hunsdiecker reaction (v) Balz-Schiemann reaction

Hint:

Name reactions are high-yield questions. Create a chart: Reactant $\to$ Reagent $\to$ Product for each.

Answer 1

(i) Wurtz-Fittig Reaction: Reaction of an aryl halide with an alkyl halide and sodium metal to form substituted benzene.
C$_6$H$_5$X + 2Na + R-X $\xrightarrow{\text{Dry Ether}}$ C$_6$H$_5$-R + 2NaX
(ii) Ullmann Reaction: Heating an aryl iodide with copper powder to form biaryl.
2 C$_6$H$_5$I + 2Cu $\xrightarrow{\Delta}$ C$_6$H$_5$-C$_6$H$_5$ (Biphenyl) + 2CuI
(iii) Gattermann Reaction: Modification of Sandmeyer reaction using Copper powder instead of CuCl.
C$_6$H$_5$N$_2^+$Cl$^-$ $\xrightarrow{\text{Cu/HCl}}$ C$_6$H$_5$Cl + N$_2$
(iv) Hunsdiecker Reaction: Reaction of silver salt of carboxylic acid with Bromine to form alkyl bromide (Decarboxylation).
R-COOAg + Br$_2$ $\xrightarrow{\text{CCl}_4, \Delta}$ R-Br + CO$_2$ + AgBr
(v) Balz-Schiemann Reaction: Preparation of fluorobenzene from diazonium salt using HBF$_4$.
C$_6$H$_5$N$_2^+$Cl$^-$ + HBF$_4$ $\to$ C$_6$H$_5$N$_2^+$BF$_4^-$ $\xrightarrow{\Delta}$ C$_6$H$_5$F + N$_2$ + BF$_3$