1 H NMR ( 400 MHz , DMSO - d 6 ) δ ppm = 3 . 35 - 3 . 45 ( m , 2 H ) , 3 . 68 ( s , 3 H ) , 3 . 85 ( s , 3 H ) , 3 . 99 - 4 . 05 ( m , 1 H ) , 7 . 24 - 7 . 30 ( m , 2 H ) , 7 . 36 ( t , 1 H ) , 7 . 75 ( d , 1 H ) , 7 . 94 - 8 . 03 ( m , 2 H ) , 8 . 08 ( s , 1 H ) .