MolView is unable to generate correct 3D structure for hydroxypropadiene MolView is unable to generate the correct structure of hydroxypropadiene. It instead generates the structure of acrolein (which has the same molecular formula). Why is this so? Is it because hydroxypropadiene is so unstable that the calculations done while generating the structure degenerate it to acrolein?



MolView is using the default GLMol renderer. Switching to JMol or ChemDoodle does not change the structure.

EDIT: The exact workflow I used was open MolView, delete the caffiene molecule, draw this molecule and click the 2D to 3D button. The generated URL is http://molview.org/?cid=7847, which, when pasted in a browser, interestingly redirects to Acrolein and not the compound that was drawn.
I suspect MolView simply fails to parse the compound's name you are trying to input. "Hydroxypropadiene" isn't the proper name, at least not by IUPAC standards. According to Google services, this name doesn't appear in any textbooks and is mentioned only in three research articles from 1980s.

The PIN propa‐1,2‐dien‐1‐ol appears to work correctly with MolView:



When you are trying to get a 3D image from the 2D drawing, there is the following issue which MolView usually reports (not sure why you haven't received the message): 


  Failed to load structure from sketcher. This structure may contain allenes, which cannot be represented in the SMILES notation.


MolView relies on SMILES in order to fetch the 3D structure.
The problem is likely that Ketcher generates wrong SMILES because PubChem indeed receives C=CC=O instead of the proper one, C=C=CO.