1 H - NMR ( 500 MHz , CDCl 3 , δ ) : 8 . 19 ( d , J = 7 . 5 Hz , 2 H ) , 8 . 15 ( d , J = 7 . 5 Hz , 2 H ) , 7 . 69 - 7 . 67 ( m , 2 H ) , 7 . 54 ( dt , J = 7 . 5 , 1 . 0 Hz , 4 H ) , 7 . 44 ( dt , J = 7 . 5 , 1 . 5 Hz , 4 H ) , 7 . 30 ( d , J = 8 . 0 Hz , 2 H )