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NMR of enaminones. part 6—17O and 13C NMR study of tautomerization in Schiff bases

✍ Scribed by Jin-Cong Zhuo

Publisher
John Wiley and Sons
Year
1999
Tongue
English
Weight
134 KB
Volume
37
Category
Article
ISSN
0749-1581

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✦ Synopsis

13C and 17O NMR spectra are reported for three series of Schi † bases : 2-(aminomethylene)cyclohexanones (1), salicylideneamines (2) and N-(2-hydroxy-1-naphthalenylmethylene)amines (3). The 13C and 17O NMR data show that Schi † bases 1 exist in ketoenamine form, 2 in enolimine form and 3 as an equilibrium mixture of both forms. The tautomeric composition of Schi † base 3 was estimated. Alkylamines slightly favoured the ketoenamine form ; aromatic amines favoured the enolimine form. The tautomeric equilibria are shifted towards the enolimine form in non-polar solvents and with increase in temperature.

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