Direct Observation of Phenoxy as the Key and Common Intermediate for the Decomposition of Lignin Fragments Containing the β‑O‑4 Linkage

The decomposition of phenol, anisole, and 2-phenoxyethanol on Pt(111) in ultrahigh vacuum is studied as a model to understand the reactivity of the β-O-4 linkage in lignin. Desorption of the multilayer and monolayer is observed as well as the generation of decomposition products. Using RAIRS to monitor the vibrational signatures of all the species, we observed the appearance of the characteristic 1480 cm–1 vibration for the phenoxy group. This, in conjunction with changes in other bands, is used to identify the phenoxy species (as opposed to the oxocyclohexadienyl moiety) as the common key intermediate in the decomposition of the three molecules. The nature of the phenoxy species is discussed in comparison with previous literature and may lead to insight into the reaction–product selectivity of the decomposition.