Nitrosoanisoles. Sensitive indicators of dimerisation criteria for C-nitrosoarenes
| Autor: | John R. Roberts, Keith G. Orrell, Mark J. Maidment, Ivan Proke, Brian G. Gowenlock |
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| Rok vydání: | 2001 |
| Předmět: | |
| Zdroj: | Journal of the Chemical Society, Perkin Transactions 2. :1904-1911 |
| ISSN: | 1364-5471 1472-779X |
| Popis: | A series of mono- and di-methyl substituted p-nitrosoanisoles was synthesised either by direct nitrosation of the anisoles with NO+HSO4− or by mild oxidation (H2O2–Mo catalyst) of the appropriate amines. The nature of these compounds in solution was established by 1H and 13C NMR spectroscopy. Variable temperature 1H dynamic NMR studies provided thermodynamic data for the cases of dimer–monomer solution equilibria, and ΔG‡ data for the restricted rotation of the NO group in the monomers. Magnitudes of ΔG‡ were in the range 28–41 kJ mol−1 and were shown to be sensitive predictors of self-dimerisation tendencies of these compounds. This activation parameter, together with the 14,15N and 17O chemical shifts of the NO group, was shown to be a reliable predictor of self-dimerisation of nitroso compounds in general. The NO bond length and the wavenumber of the IR-active NO stretching mode were found to be somewhat less reliable predictors of this behaviour. |
| Databáze: | OpenAIRE |
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