(3,4-dihydroxyphenylamino)-2-imidazoline 1,2-Benzenediol, 4-((4,5-dihydro-1H-imidazol-2-yl)amino)- 2-(3,4-Dihydroxyphenylimino)imidazolidine 57101-49-2 75594-10-4 DPI