A Nitration Reaction Puzzle for the Organic Chemistry Laboratory.

• Autores: Milton J. Wieder, Russell D. Barrows
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 85, Nº 4, 2008, págs. 549-551
• Idioma: inglés
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• Resumen

  • Treatment of phenylacetic acid with 90% HNO3 yields a product, I, whose observed melting point is 175�179 °C and whose equivalent weight is approximately 226 grams. Treatment of phenylacetic acid with 70% HNO3 yields a product, II, whose observed melting point is 106�111 °C and whose equivalent weight is approximately 181 grams. Based on these data and 1H NMR and infrared spectral data, students are asked to deduce the structures of nitration products I and II. The above nitration experiment illustrates fundamental electrophilic aromatic substitution concepts while posing an interesting structure elucidation puzzle for organic chemistry students. The nitration of phenylacetic acid requires students to ponder the directing ability of the carboxymethyl group. Given that nitric acid is a powerful oxidizing agent, students must also ponder whether the carboxymethyl group is subject to oxidation under the reaction conditions employed. Lastly, students must determine what impact, if any, the concentration of the nitric acid used will have on the structures of the nitration products obtained.