[{"from": "human", "value": "Synthesize a molecule that matches the given characteristics. The molecule appears as a clear colorless liquid. Less dense than water. Vapors heavier than air. Corrosive to tissue. May polymerize exothermically if heated or contaminated. If the polymerization takes place inside a container, the container may rupture violently. Used to make plastics."}, {"from": "gpt", "value": "[C][=C][C][=Branch1][C][=O][O][C][C][O]"}]