Cleavage of β-aryl ether bonds in lignin by trimethylsilyl iodide

Trimethylsilyl iodide (TMSil) is a novel reagent to cleave ether bonds selectively under very mild reaction conditions. The authors applied the reagent for the cleavage of the arylglycerol- 0 -aryl ether bond using a guaiacylglycerol- 0 -guaiacylether as a model compound. Under the optimum conditions, the above ether bond was cleaved almost quantitatively, and the reaction mechanism turned out not to be direct cleavage proposed by Jung et al., but to be the iodination of the benzyl carbon followed by the formation of a o - 0 double bond and the cleavage of the 0-aryl ether bond. It was also found that TMSil reagent is able to depolymerize a milled wood lignin very effectively to a range of Mw 400–800.