“…291–293°C. [ 35 ] IR (KBr) ʋ max : 3402, 3,244, 3,158, 1,645, 1,616, 1,508, 1,265 cm −1 . 1 H NMR (600 MHz, DMSO‐d 6 ) δ : 9.02 (s, 1H), 8.98 (s, 1H), 8.07 (s, 1H), 7.61 (d, 1H, J = 6.6 Hz), 7.23 (d, 1H, J = 6.6 Hz), 6.92 (s, 2H), 6.724 (s,), 6.66 (d, 3H, J = 6 Hz), 5.58 (s, 1H) ppm.…”