1 H NMR : ( 500 MHz , acetone - d 6 ) : δ ( ppm ) = 7 . 83 ( d , J = 8 . 2 Hz , 4 H ) , 7 . 71 ( d , J = 7 . 1 Hz , 4 H ) , 7 . 64 ( d , J = 8 . 3 Hz , 2 H ) , 7 . 45 ( d , J = 8 . 4 Hz , 2 H ) , 7 . 34 ( d , J = 7 . 2 Hz , 2 H ) , 7 . 09 ( m , 12 H ) , 6 . 72 ( t , J = 7 . 9 Hz , 2 H ) , 6 . 62 ( d , J = 8 . 4 Hz , 2 H ) , 6 . 45 ( d , J = 8 . 3 Hz , 4 H ) , 2 . 11 ( s , 12 H )