Scientists in the UK have shed light on the mechanism of an industrially-important process. 

Stuart Macgregor and colleagues at Heriot-Watt University, the University of St Andrews and Lucite International have used computational chemistry to investigate the methanolysis of palladium-acyl bonds. 

Methanolysis is an important process as it is a key step in the metal-mediated synthesis of esters and it is used in a number of industrial processes. Despite this, little is known about the details of the reaction. 

This prompted Macgregor and colleagues to explore the characteristics of the methanolysis reaction by comparing two previously suggested mechanisms - either the intermolecular or the intramolecular attack of methanol at Pd-acyl bonds. 

Using density functional theory, they determined that the mechanism is likely to involve the intermolecular attack of methanol and that the metal coordination sphere plays a key role in controlling the reaction. 'The presence of strong pi-accepting ligands or the dissociation of the phosphine ligand at a trans position to the acyl bond were found to promote methanolysis,' explained Macgregor. 'The latter aspect may be key to the efficient methanolysis that underpins efficient methyl propanoate production.' 

Macgregor admits that further work is required before the process can be fully understood. 'The steric bulk and donor characteristics of the phosphine ligands must also be incorporated, as well as the role of specific salvation in promoting the reaction.'  

Alison Stoddart