[{"from": "human", "value": "Synthesize a molecule that matches the given characteristics. The molecule appears as a crystalline solid. Denser than water and insoluble in water. Inhalation of dust or powder may cause adverse health reactions."}, {"from": "gpt", "value": "[C][Branch1][#Branch1][C][=Branch1][C][=O][C][Cl][Cl]"}]