Microwave-Enhanced Organic Syntheses for the Undergraduate Laboratory:: Diels−Alder Cycloaddition, Wittig Reaction, and Williamson Ether Synthesis

• Marsha R. Baar ^[1] ; Danielle Falcone ^[1] ; Christopher Gordon ^[1]
  1. [1] Muhlenberg College

     Muhlenberg College

     City of Allentown, Estados Unidos

     
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 87, Nº 1 (January), 2010, págs. 84-86
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • Microwave heating enhanced the rate of three reactions typically performed in our undergraduate organic chemistry laboratory: a Diels−Alder cycloaddition, a Wittig salt formation, and a Williamson ether synthesis. Ninety-minute refluxes were shortened to 10 min using a laboratory-grade microwave oven. In addition, yields improved for the Wittig salt and ether preparations. The Diels-Alder cycloaddition of N-phenylmaleimide and 1,3-cyclohexadiene in absolute ethanol in a closed vessel and 130 °C gave 84−90% yields. Formation of the Wittig salt, benzyltriphenylphosphonium chloride, from triphenylphosphine and benzyl chloride gave yields greater than 90% when heated in acetonitrile at 200 °C Yields doubled in the Williamson ether synthesis of 2-ethoxynaphthalene, from 2-naphthol, methanolic potassium hydroxide, and iodoethane with microwave heating at 130 °C.