1 H NMR ( 400 MHz , DMSO - d 6 ) δ [ ppm ] = 3 . 43 ( dd , 2 H ) , 3 . 69 ( s , 3 H ) , 3 . 85 ( s , 3 H ) , 4 . 02 - 4 . 08 ( m , 1 H ) , 7 . 11 ( t , 1 H ) , 7 . 68 ( d , 2 H ) , 7 . 76 ( s , 1 H ) , 8 . 06 ( d , 2 H ) , 8 . 09 ( s , 1 H ) .