- Kinetics and products of reactions of pyridine N-oxides with alkyl halides
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The kinetics of formation of alkoxypyridinium salts [R1C5H4NOCH2R2] +·Hlg- (R1 = H, Me, MeO, Me2N; R2 = H, Me, Ph, PhCO; Hlg = Br, I) in acetonitrile at 25°C have been studied. The stability of these salts depends on the substituents R1 and R2. O- and N-Nucleophiles exhibit different sensitivities to steric structure of the alkylating agent. 1996 MAEe Cyrillic signΚ Hayκa/Interperiodica Publishing.
- Popov,Matveev,Koblik,Savelova,Matvienko
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p. 587 - 590
(2007/10/03)
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- Collisionally Activated Dissociation of 1-Benzyloxypyridinium Cations.
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Eighteen pyridine-ring substituted N-benzyloxypyridinium cations all dissociate by two alternative pathways to give (A) a cation C7H7+ and the substituted pyridine 1-oxide, and (B) a cation C7H7O+ and the substituted pyridine.Appearance potentials (Eapp) have been measured for both pathways; they are higher by 3-17 kcal mol-1 for the dominant pathway (A) than for (B).The Eapp values are compared with the ΔHf values calculated by the AM1 method for reactants and products demonstrating extensive rearrangement in a product-like transition state (TS) for pathway (A) but not for (B).Both sets of Eapp correlate roughly with Σ? for the pyridine ring substituents.For the 4-dimethylamino derivatives, two additional homolytic pathways are found to give (C) a cation Me2NC5H4NO+* and (D) the 4-dimethylaminopyridine radical cation.
- Katritzky, Alan R.,Dega-Szafran, Zofia,Watson, Clifford H.,Eyler, John R.
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p. 1051 - 1057
(2007/10/02)
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