Himic Anhydride: A Retro Diels–Alder Reaction for the Organic Laboratory and an Accompanying NMR Study

• Published in: Journal of chemical education Vol. 98; no. 12; pp. 4013 - 4016
• Main Authors: Birchall, Lee T, Shehata, Sara, Serpell, Christopher J, Clark, Ewan R, Biagini, Stefano C. G
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society and Division of Chemical Education, Inc 14-12-2021; Division of Chemical Education, Inc; American Chemical Society
• Subjects: Acidic oxides; Chromatography; Coupling (molecular); Dicarboxylic acids; Dicarboxylic anhydride; Diels-Alder reactions; Heat conductivity; Laboratory Equipment; Laboratory Experiment; Laboratory Experiments; Molecules; NMR; Nuclear magnetic resonance; Organic Chemistry; Recrystallization; Scientific Concepts; Undergraduate Students; NMR Spectroscopy; Hands-On Learning/Manipulatives; Upper-Division Undergraduate; Synthesis; Laboratory Instruction; Reactions; Second-Year Undergraduate; Stereochemistry; Equilibrium; Organic Chemistry
• ISSN: 0021-9584; 1938-1328
• DOI: 10.1021/acs.jchemed.1c00661

The thermal equilibration of himic anhydride [IUPAC (2-endo,3-endo)-bicyclo­[2.2.1]­hept-5-ene-2,3-dicarboxylic acid anhydride] to (2-exo,3-exo)-bicyclo­[2.2.1]­hept-5-ene-2,3-dicarboxylic acid anhydride and subsequent recrystallization of the exo-product can be performed as a standard undergraduate laboratory experiment requiring minimal equipment. The interpretation of the 1H NMR spectra for these norbornene carboxylic anhydride molecules promotes an appreciation of constrained ring systems and factors that affect chemical shifts and coupling constants.