“…For the Piancatelli rearrangement, the presence of liquid water plays ac rucial role in the reaction. Several studies reported successfule xamples of HAA in systems comprising acetaldehyde/ p-cresol, [36] acetaldehyde/phenol, [37] formaldehyde/guaiacol, [38] acetaldehyde/o-xylene, [39] aldehyde/benzene derivatives, [40,41] acetone/p henol, [42] benzaldehyde/benzened erivatives, [43] paraformaldehyde/anisole, [44] formaldehyde/benzene, [45] and formaldehyde/phenol [46] over acid-functionalized solids, such as Amberlyst acidic resins and acidic zeolites, to produce crucial platformsf or the chemical industry.F or example, Garade et al [47] reported 80-95% yields of coupling products from the reaction of acetaldehyde/p-cresolo ver Hb and bentonite clay catalysts impregnated with dodecatungstophosphoric acid. [29] Components that are naturally present in biomass-derived streams, that is, aqueous solutions with high acidity,f avor the occurrence of this reaction.…”