1 H - NMR ( 500 MHz , CDCl 3 , δ ) : 7 . 80 ( d , J = 1 . 5 Hz , 2 H ) , 7 . 73 - 7 . 68 ( m , 4 H ) , 7 . 59 - 7 . 57 ( m , 2 H ) , 7 . 52 ( dd , J = 8 . 0 Hz , J = 1 . 5 Hz , 4 H ) , 7 . 42 ( t , J = 8 . 0 Hz , 4 H ) , 7 . 33 - 7 . 22 ( m , 6 H ) , 7 . 19 ( dd , J = 8 . 0 Hz , J = 1 . 5 Hz , 2 H ) , 7 . 14 - 6 . 92 ( m , 16 H ) , 6 . 74 ( dd , J = 8 . 0 Hz , J = 1 . 5 Hz , 2 H ) , 6 . 55 ( t , J = 8 . 0 Hz , 1 H ) , 6 . 48 ( t , J = 8 . 0 Hz , 2 H )