[{"from": "human", "value": "Based on the given information, design a molecule that meets the desired specifications. The molecule appears as a colorless liquid. Denser than water. Contact may slightly irritate skin, eyes and mucous membranes. May be slightly toxic by ingestion. Used to make other chemicals."}, {"from": "gpt", "value": "[C][Branch1][=Branch1][C][O][C][C][O][O]"}]