1 H NMR : ( 500 MHz , acetone - d 6 ) : δ ( ppm ) = 7 . 82 ( m , 14 H ) , 7 . 72 ( d , J = 8 . 7 Hz , 4 H ) , 7 . 45 ( m , 8 H ) , 7 . 35 ( m , 10 H ) , 7 . 26 ( t , J = 8 . 6 Hz , 4 H ) , 7 . 16 ( t , J = 8 . 3 Hz , 4 H ) , 7 . 10 ( t , J = 7 . 9 Hz , 4 H ) , 6 . 98 ( d , J = 8 . 6 Hz , 4 H ) , 6 . 75 ( m , 4 H )