General procedure for the synthesis of 1,2,4,5-benzenetetrol from 2,5-dihydroxy-1,4-benzoquinone: To a solution of 2,5-dihydroxy-1,4-benzoquinone (2.0 g, 1.0 eq.) in hydrochloric acid (110 mL) was slowly added tin particles (2.068 g, 1.2 eq.). The reaction mixture was heated to 110 °C and maintained for 1 hour. When the temperature of the reaction solution was reduced to 50-60 °C, thermal filtration was carried out and the filtrate was subsequently cooled to 0 °C to promote crystallization, resulting in colorless crystals of 1,2,4,5-benzenetetrol (1.450 g, 74%). The product was characterized by 1H NMR (MeOD, 300 MHz): δ 5.0 (broad peak, 4H), 5.90 (single peak, 2H).ESI-MS showed molecular ion peak m/z 145.03 [M+].
