ERROR opening https://cactus.nci.nih.gov/chemical/structure/CC%3D1C%3DCCC%28C%29%28C%29C%3D1C%3DO/file?format=sdf&get3d=True  -- CC%3D1C%3DCCC%28C%29%28C%29C%3D1C%3DO could not be loaded.