{"knowledge_schema": {"broad_category": "Chemistry \u2192 Spectroscopy \u2192 NMR Spectroscopy", "refinement": "This problem involves interpreting 13C NMR data to identify an organic compound based on its chemical shifts.", "specific_scope": "The task is to analyze the provided chemical shifts and match them with known compounds to determine the identity of the unknown compound.", "goal": "Identify the unknown organic compound from the given options based on the 13C NMR data."}, "summary": "This problem requires the application of NMR spectroscopy principles to identify an unknown organic compound by analyzing its 13C NMR data. The chemical shifts provided (170.0, 135.0, 128.0, 20.0 ppm) correspond to specific functional groups and structural features of the candidate compounds. By comparing these shifts with the known chemical environments in the options given (Methyl acrylate, Ethyl acetate, Methyl methacrylate, Ethyl acrylate), the correct identification of the compound can be made. In this case, the unknown compound is identified as Methyl acrylate."}