PAB is a multi-purpose photocatalyst, recently used for the photoinduced stepgrowth polymerization of a variety of aromatic monomers through the abstraction of radical by photochemically generated bromine radical. However, best to our knowledge, the efficiency of PAB in cleavage/depolymerization reactions has not been previously investigated. Light-mediated cleavage of β-O-4 linkages using PAB was first investigated on lignin model compound 2-PAP, due its purity and much its simpler structure compared to that of SL. At ambient conditions (room temperature and air atmosphere), reacting 2-PAP in the presence of 1.1 equiv. of PAB in aqueous acetonitrile (ACN) solvent led to a color change from yellow to orange after 4 h of UV-A irradiation (~355 nm) inside photoreactor (Figure ). The choice of aqueous ACN is due to its relatively safe nature, SL's moderate solubility in this solvent and water being an important component of paper-matrix. H NMR spectra taken in CDCl3, showing the complete disappearance of -CH2 peak of 2-PAP (5.28 ppm) can be found in the supporting information (Figure ). In order to gain insight into the reaction mechanism, real-time 1 H NMR of the photocatalytic reaction between 2-PAP and PAB inside an NMR tube was employed (Figure ). Taking into consideration NMR and LC-HRMS (Figure ) data obtained, we propose the following reaction mechanism which is depicted in Scheme 3. Scheme 3. Proposed reaction pathways for the PAB catalyzed photocleavage reaction of 2-PAP.