2,2',4,4'-Tetrahydroxybenzophenone131-55-530 % similar 4-Isopropylresorcinol23504-03-230 % similar 4-Aminobenzene-1,3-diol hydrochloride34781-86-730 % similar 4-Hydroxy-2(1H)-pyridinone626-03-930 % similar