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Insertion reactions are reversible

المؤلف:  Jonathan Clayden , Nick Greeves , Stuart Warren

المصدر:  ORGANIC CHEMISTRY

الجزء والصفحة:  ص1077-1078

2025-08-07

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Insertion reactions are reversible

The reverse process, decarbonylation, is also fast but can be arrested by maintaining a pressure of carbon monoxide above the reaction mixture. The reverse of hydrometallation involves the elimination of a hydride from the adjacent carbon of a metal alkyl to form an alkene complex.

This process is known as β hydride elimination or simply β elimination. It requires a vacant site on the metal as the number of ligands increases in the process and so is favoured by the shortage of ligands in 16-electron complexes. In more complex structures, the metal and the hydride must be syn to each other on the carbon chain for the elimination to be possible. The product is an alkene complex that can lose the neutral alkene simply by ligand exchange. β elimination is an important final step in a number of transition-metal catalysed processes, but it can be a nuisance because Pd–Et (and other similar Pd–alkyl) complexes cannot be used as β elimination is too fast.