ERROR opening https://cactus.nci.nih.gov/chemical/structure/CC%28CC1%3DCC2%3DC%28C%3DC1%29OCO2%29C%3DO/file?format=sdf&get3d=True -- CC%28CC1%3DCC2%3DC%28C%3DC1%29OCO2%29C%3DO could not be loaded.