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2- Methoxypyridine tautomers

The PE spectra of hydroxy- and mercapto-pyridines have been examined, together with the model iV-alkyl and S- or O-alkyl compounds, to elucidate the tautomeric equilibria in the vapor phase (77JCS(P2)1652) (Section 2.04.4.2). Figure 21 and Table 13 show details of the PE spectra of l-methylpyridin-2-one, 2-methoxypyridine and the tautomeric mixture at equilibrium of pyridin-2-one and 2-hydroxypyridine. This indicates that there is approximately 25% of oxo form present once adjustment has been made for the expected influence of methylation, similar measurements reveal ca. 10% of the thione form in the mercapto-thione equilibrium. Other spectra indicate that 3- and 4-hydroxy- and 3- and 4-mercapto-pyridine exist in the vapor phase with less than 5% of the alternative tautomer present. [Pg.140]

Books sometimes disagree on the preferred tautomer of guanine—6.f versus 6.g. A parallel can be found in 2-pyridone, which also has two likely tautomeric forms, 6.h and 6.i. To determine which form of 2-pyridone predominates, the ultraviolet spectra of two isomers, l-methyl-2-pyridone (6.j) and 2-methoxypyridine (6.k), were obtained with the observed Amax wavelengths shown. The Amax of 2-pyridone is at 229 nm. Does 2-pyridone likely favor tautomer 6.h or 6.i Which tautomer of guanine is likely favored, 6.f or 6.g (Elguero, J., Marzin, C., Katritzky, A. R., Linda, P. The Tautomer-ization of Heterocycles. Adv. Heterocycl. Chem., Suppl. 1 New York Academic Press, 1976.)... [Pg.147]

Pyridone likewise reacts mainly as the neutral pyridone tautomer at pH <6 and via the conjugate anion at pH > 6, 4-methoxypyridine being unreactive by comparison over the whole pH range. Facile dibromination of 4-pyridone occurs because at most pH values the lower pKa of the monobromo derivative more than compensates for its intrinsically lower reactivity (83CJC2556). [Pg.307]


See other pages where 2- Methoxypyridine tautomers is mentioned: [Pg.347]    [Pg.60]    [Pg.283]    [Pg.358]    [Pg.121]    [Pg.10]    [Pg.421]    [Pg.66]   
See also in sourсe #XX -- [ Pg.121 ]




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