Fittig Reaction — the NEET Chemistry reaction: mechanism, reagents, conditions, structures and exam traps.
Fittig Reaction The Fittig reaction is a coupling reaction in organic chemistry where two aryl halides react with sodium metal in the presence of a dry ether solvent to form a biaryl compound. It is analogous to the Wurtz reaction, which couples two alkyl halides. The reaction mixture typically requires heating (often refluxing in ether). Sodium metal, initially silvery, will gradually disappear as it reacts. A white precipitate of sodium halide (e.g., NaBr or NaCl) will form. The reaction is generally exothermic due to the formation of strong C-C bonds and the high reactivity of sodium metal. Step 1: An aryl halide reacts with two atoms of sodium to form an aryl sodium intermediate and sodium halide. Ar-X + 2Na Ar-Na + NaX Step 2: The aryl sodium intermediate then acts as a nucleophile, attacking another molecule of aryl halide to form the biaryl compound and regenerate sodium halide. Ar-Na + Ar-X Ar-Ar + NaX Confusing Fittig reaction (aryl-aryl coupling) with Wurtz reaction (alkyl-alkyl coupling). Confusing with Wurtz-Fittig reaction (aryl-alkyl coupling). Attempting to perform the reaction with alkyl halides instead of aryl halides. Not using an anhydrous, inert solvent (e.g., dry ether or THF), which can lead to side reactions with sodium metal. Expecting a high yield of a single unsymmetrical biaryl product when two different aryl halides are used; this typically results in a mixture of three different biaryl products (Ar1-Ar1, Ar2-Ar2, Ar1-Ar2).