Reactions of thioureylene antithyroid drugs (1-methyl-2-mercaptoimidazole and carbimazole) with hypochlorous acid (HOCl) and superoxide were followed optically and products were analyzed by mass spectrometry. 1-methyl-2-mercaptoimidazole (MMI) and carbimazole reacted rapidly with HOCl with a rate constant of 1 x 10(7) and 7 x 10(6) M(-1)s(-1), respectively. The characteristic spectrum assigned ...