A lignin model (3E) with a propanol group on the β-carbon has been heated In alkali with no additives and with NaSH and anthrahydroquinone (AHQ) additives. The β-aryl ether bond of the model is efficiently fragmented by AHQ, but not by NaSH or simple NaOH. A competing cyclization of the propanol group with the quinonemethide of the model interferes with NaOH and NaSH fragmentation reactions. The data suggest that AHQ reacts by way of a mechanism different from that of NaSH - the AHQ by an electron transfer mechanism and the NaSH by an adduct mechanism. The reactions of β-allyl (3D) and β-propyl trityloxy (3F) models were also performed. The fragmentation efficiencies In these cases ware: AHQ > NaSH > NaOH.