[{"from": "human", "value": "Create a molecule that satisfies the conditions outlined in the description. The molecule appears as a colorless, crystalline solid. Denser than water. May combust in contact with organic materials. Contact may irritate skin, eyes and mucous membranes. May be toxic by ingestion. Used to make other chemicals."}, {"from": "gpt", "value": "[C][=Branch1][C][=O][Branch1][C][O-1][O-1].[C][=Branch1][C][=O][Branch1][C][O-1][O-1].[O][O].[O][O].[O][O].[Na+1].[Na+1].[Na+1].[Na+1]"}]