Question

Write short notes on the following:
i) Wurtz reaction
ii) Wurtz-Fittig reaction
iii) Fittig reaction

Hint:

Wurtz → alkane synthesis, Wurtz-Fittig → alkylbenzene synthesis, Fittig → biaryl synthesis. All involve sodium metal in dry ether as the reagent.

Answer 1

i) Wurtz Reaction:
- The Wurtz reaction is used for the synthesis of higher alkanes from alkyl halides.
- In this reaction, two molecules of alkyl halide react with sodium metal in dry ether to give a higher alkane.
\[ 2R{-}X + 2Na \;\xrightarrow[\text{dry ether}]{}\; R{-}R + 2NaX \]
Example:
\[ 2CH_3Cl + 2Na \;\xrightarrow[\text{dry ether}]{}\; C_2H_6 + 2NaCl \]
ii) Wurtz-Fittig Reaction:
- This reaction is used to prepare alkyl-substituted aromatic hydrocarbons.
- An alkyl halide reacts with an aryl halide in the presence of sodium metal and dry ether to form an alkyl-substituted benzene.
\[ Ar{-}X + R{-}X + 2Na \;\xrightarrow[\text{dry ether}]{}\; Ar{-}R + 2NaX \]
Example:
\[ C_6H_5Br + CH_3Cl + 2Na \;\xrightarrow[\text{dry ether}]{}\; C_6H_5CH_3 + 2NaCl \]
iii) Fittig Reaction:
- The Fittig reaction is used for the synthesis of biaryl compounds (diphenyl and its derivatives).
- In this reaction, two aryl halide molecules react with sodium metal in dry ether to form a biaryl.
\[ 2Ar{-}X + 2Na \;\xrightarrow[\text{dry ether}]{}\; Ar{-}Ar + 2NaX \]
Example:
\[ 2C_6H_5Cl + 2Na \;\xrightarrow[\text{dry ether}]{}\; C_6H_5{-}C_6H_5 + 2NaCl \]
Thus, these three reactions (Wurtz, Wurtz-Fittig, and Fittig) are important methods for carbon-carbon bond formation in organic chemistry.