1 H - NMR ( 500 MHz , CDCl 3 , δ ) : 8 . 38 ( s , 1 H ) , 7 . 83 - 7 . 79 ( m , 4 H ) , 7 . 75 - 7 . 72 ( m , 2 H ) , 7 . 58 ( d , J = 4 . 0 Hz , 2 H ) , 7 . 43 - 7 . 33 ( m , 4 H ) , 7 . 30 - 7 . 11 ( m , 12 H ) , 7 . 10 - 7 . 03 ( m , 4 H ) , 7 . 00 - 6 . 93 ( m , 2 H ) , 2 . 41 ( s , 3 H ) , 2 . 39 ( s , 3 H )