Theoretical calculations of minimum energy structures and thermodynamics for the formation of cyclic amidines and imidates by intramolecular nucleophilic addition/elimination reactions
- 1 January 1998
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 3,p. 635-638
- https://doi.org/10.1039/a707169h
Abstract
Theoretical calculations of minimum energy structures and thermodynamic terms using SCF theory with thermodynamic and solvation corrections have been made of the cyclisation of 1-amino-8-(acetylamino)naphthalene to give 2-methylperimidine with the liberation of water and of the related reaction of 1-hydroxy-8-(acetylamino)naphthalene to 2-methylnaphtho[1,8-d,e][1,3]oxazine. The calculations predict that in the gas phase the former reaction is strongly thermodynamically favourable (ΔG = –37.9 kJ mol–1, ΔH = –0.6 kJ mol–1 and TΔS = +37.3 kJ mol–1 at 298.2 K) whereas the latter is much less favourable (ΔG = –2.0 kJ mol–1, ΔH = +31.1 kJ mol–1 and TΔS = +33.1 kJ mol–1 at 298.2 K). The results are in qualitative agreement with experimental observations for the reactions in solution. Reasons for the different behaviour of the two reactions are discussed.Keywords
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