Polymeric materials is a steadily growing industry that has increased demand for scientists knowledgeable in polymer chemistry. For this reason, chemistry curricula in undergraduate programs need to incorporate instruction on polymers and better prepare students for a variety of professional fields. This capstone laboratory experience introduces a novel application of polymer chemistry in the organic chemistry undergraduate laboratory, resulting in the synthesis of both poly-β-nitrostyrene and polystyrene. The first synthetic step yields β-nitrostyrene from benzaldehyde and nitromethane in a Henry Reaction, which extends the application of enolate chemistry and allows students to learn a novel reaction mechanism based on a variation of the traditional aldol condensation. The second synthetic step introduces anionic polymerization to produce poly-β-nitrostyrene and emphasizes the importance of resonance stabilization of reactive intermediates when determining mechanisms of reactions. This anionic polymerization is done in parallel with free-radical polymerization of styrene. Students are able to revisit radicals and compare two distinct mechanisms of polymerization. The analysis of products with infrared spectroscopy allows students to confirm the formation of polymeric products. Polystyrene NMR analysis allows for the determination of polymer chain length using integral ratios, expanding the standard approach of NMR application in organic chemistry. This experiment reemphasizes fundamental organic chemistry principles and introduces new concepts in order to advance the knowledge and practical skills of undergraduate chemistry students. This protocol will first be implemented in a second-semester organic chemistry laboratory course in spring of 2019.

Using resonance to teach novel enolate chemistry and polymerization reaction mechanisms: A capstone organic laboratory experiment

2019 Spring National Meeting

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