[{"from": "human", "value": "Create a molecule that satisfies the conditions outlined in the description. The molecule is a 2-oxo monocarboxylic acid that is the 2-oxo derivative of butanoic acid. It is a 2-oxo monocarboxylic acid and a short-chain fatty acid. It is functionally related to a butyric acid. It is a conjugate acid of a 2-oxobutanoate."}, {"from": "gpt", "value": "[C][C][C][=Branch1][C][=O][C][=Branch1][C][=O][O]"}]