ERROR opening https://cactus.nci.nih.gov/chemical/structure/C%3DCCNCCC1%3DCNC2%3DC1C%28%3DCC%3DC2%29O/file?format=sdf&get3d=True  -- C%3DCCNCCC1%3DCNC2%3DC1C%28%3DCC%3DC2%29O could not be loaded.