A laboratory experiment emphasizing the structural elucidation of organic compounds has been developed. The “unknown” compounds are the products of the pH-controlled oxidation of 4'-methoxyacetophenone with bleach. The chemoselectivity of this reaction is highly dependent on the pH of the reaction media: under acidic conditions electrophilic aromatic substitution of the aromatic ring occurred to generate 3'-chloro-4'-methoxyacetophenone, but under basic conditions the haloform reaction oxidatively cleaved the methyl ketone to generate 4-methoxybenzoic acid. Each product was characterized by physical methods including melting point determination and IR, proton, and carbon NMR spectroscopy. Students analyzed the experimental data to determine the structures of the “unknowns.” In addition, since the reactions were conducted without organic solvent, principles of green chemistry and sustainable development could be introduced.