Nuclear magnetic resonance studies of methyl-5, 6-dicarboxy-2-norbornene derivatives

✍ Scribed by Norimasa Kamezawa; Toyoichi Ueda

• Publisher: John Wiley and Sons
• Year: 1971
• Tongue: English
• Weight: 407 KB
• Volume: 3
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1270030510

✦ Synopsis

A simple procedure is provided for the quantitative analysis of Diels-Alder adduct prepared from commercial methylcyclopentadiene and maleic anhydride by N M R spectra without further separation of its components. The adduct is considered as a mixture of endo norbornene derivatives (C,), (Dn), (E) and (Fn) which are obtained from 1-, 2-and 5-methylcyclopentadiene and cyclopentadiene, respectively.

The quantitative analysis of the adduct can be made on a basis of the ratio of the signal intensities of the olefinic protons in the adduct. The result shows that the adduct prepared under mild conditions mainly consists of three norbornene derivatives (Cn), (Dn) and (Fn), with a negligibly small amount of (E). When the adduct prepared under mild conditions is heated, it contains the exo isomers (Cx), (Dx) and (Fx). The ratio of the endo and the exo norbornene derivatives, i.e. ((C,) + (D,) + (Fn)):((Cx) + (Dx) + (Fx)), may be estimated from the signal intensities of the 5-and 6-protons.