1 H NMR ( 300 MHz , DMSO - d 6 ) δ 1 . 70 - 1 . 81 ( 3 H , m ) , 1 . 85 - 2 . 09 ( 4 H , m ) , 3 . 24 - 3 . 29 ( 2 H , m ) , 3 . 43 - 3 . 55 ( 2 H , m ) , 3 . 72 - 3 . 91 ( 3 H , m ) , 7 . 32 ( 2 H , d , J = 7 . 6 Hz ) , 7 . 50 ( 2 H , d , J = 7 . 6 Hz ) .