Metal carbonyl 18-electron complexes is sometimes catalysed by catalytic amounts of oxidants, via electron-transfer. Metal carbonyls react with reducing agents such as metallic sodium or sodium amalgam to give carbonylmetalate (or carbonylate) anions: For iron pentacarbonyl, one obtains the tetracarbonylferrate with loss of CO: Mercury can insert into the metal-metal bonds of some polynuclear metal carbonyls: The CO ligand is often susceptible to attack by nucleophiles. For example, trimethylamine oxide and bistrimethylsilylamide convert CO ligands to CO and CN, respectively. In the "Hieber base reaction", hydroxide ion attacks the CO ligand to give a metallacarboxylic acid, followed by the release of carbon
Favorskii reaction Favorskii reaction The Favorskii reaction is the nucleophilic attack of an acetylide on a carbonyl group. The reaction was discovered in the early 1900s by the Russian chemist Alexei Yevgrafovich Favorskii. When catalyzed by acid, this reaction is called the Meyer–Schuster rearrangement. A metal acetylide is formed "in situ" when an alkyne is treated with a strong bases such as a hydroxide or an alkoxide: The metal acetylide then reacts with an aldehyde or ketone to form a propargyl alcohol. When an α-hydrogen is present (as is the case when the carbonyl is an aldehyde), it will tautomerize to the