ERROR opening https://cactus.nci.nih.gov/chemical/structure/InChI=1/C6H8O2/c1-3-4-5-8-6(2)7/h3-5H,1H2,2H3/file?format=sdf&get3d=True  -- InChI=1/C6H8O2/c1-3-4-5-8-6(2)7/h3-5H,1H2,2H3 could not be loaded.