[{"from": "human", "value": "Generate a molecule based on this description. The molecule is a synthetic carcinogenic compound found in a variety of smokes and industrial products, N-butyl-N-4-hydroxybutyl nitrosamine is used in biomedical research to induce transitional and squamous cell urinary bladder cancers and to promote experimental hepatocarcinogenesis, probably through abnormal DNA methylation. (NCI04)"}, {"from": "gpt", "value": "[C][C][C][C][N][Branch1][=Branch1][C][C][C][C][O][N][=O]"}]