Birchall LT, Shehata S, Serpell CJ, Clark ER, Biagini SCG. Himic Anhydride: A Retro Diels-Alder Reaction for the Organic Laboratory and an Accompanying NMR Study.
JOURNAL OF CHEMICAL EDUCATION 2021;
98:4013-4016. [PMID:
34924600 PMCID:
PMC8675133 DOI:
10.1021/acs.jchemed.1c00661]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 09/24/2021] [Indexed: 06/14/2023]
Abstract
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.
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