ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI%3DInChI%3D1S/C4H4O2/c1-3-2-4%285%296-3/h1-2H2/file?format=sdf&get3d=True  -- InChI%3DInChI%3D1S/C4H4O2/c1-3-2-4%285%296-3/h1-2H2 could not be loaded.