6-Chloro-2-pyridone

Different tautomeric species (e.g., 6-chloro-2-pyridone/6-chloro-2-hydroxypyridine). 

Complexes of Ni(OAc)2 with 6-chloro-2-pyridonate (97) have been organized into an elegant M12 wheel, which has been investigated as a single-molecule magnet . With 3-methyl-3-pyrazol-5-one (98) the larger Ni24 wheel has been assembled. ... 

The continuum model has been applied to an experimental study of the solvent effect on the 6-chloro-2-hydroxypyridine/6-chloro-2-pyridone equilibrium in a variety of essentially non-hydrogen-bonding solvents (Beak et al., 1980). In this study, a plot of log A nh/oh) versus (e - 1)/ (2e + 1), the solvent dielectric term, yielded a linear least-squares fit with a slope of 2.5 0.2, an intercept of -1.71, and a correlation coefficient of 0.9944. This result was used to estimate the gas phase free-energy difference of 9.2 kJ mole-1, which compares favorably with the observed value of 8.8 kJ mole-1 for this system. The authors also reported that alcohol solvents are correlated fairly well in this study but that other solvents seem to be divided into two classes, those that are electron-pair donors and those that are electron-pair acceptors in a hydrogen bond. The hydrogen bonding effect is assumed to be independent from the reaction field effect and is included in the continuum model by means of the Kamlet and Taft (1976) empirical parameters. The interested reader is referred to the original paper for a detailed discussion of the method and its application. 

The concentration dependence of FTIR and UV spectra of 2-hydroxypyridine and its 6-chloro analog was measured in chloroform and CCI4 in order to elucidate their tautomeric equilibrium and determine the association constants (96MI1). For unsubstituted 2-hydroxypyridine, the hydroxy monomer or dimer was not detected in both solvents, and the equilibrium existed exclusively between oxo monomer and dimer. In contrast, for 6-chloro-2-pyridone both monomeric hydroxy (about 72%) and oxo (about 28%) forms were observed in chloroform. Increase in the substrate concentration led to decrease in the content of the monomeric species in favor of relevant dimers. In CC14, 6-chloro-2-hydroxypyridine was found to exist mainly in hydroxy monomer hydroxy dimer equilibrium. 

Photoreaction of 6-chloro-2-pyridone 7 in methanol is the unique example of an apparent six-electron electrocyclic rearrangement that produces an intermediate ketene/chloroimine 8 which undergoes loss of HCl and addition of methanol to yield a mixture of three isomeric unsaturated nitrile esters 9 and 10. °... 

For cocrystal systems containing phosphorous (triphenylphosphine oxide 6-chloro-2-pyridone), P MAS NMR at slow MAS rates offers a more rapid way to confirm H-bonding and cocrystal formation fitting the CSA profile of the P spectrum. The anisotropy of the CST of a phosphine oxide group is strongly related to the... 

Vogt et al. [Ill] apphed multinuclear ID and 2D SSNMR to study several cocrystals and complexes. The chosen compounds were cocrystals of palmitic acid nicotinamide, piroxicam saccharin, fluoxetine HCl succinic acid and triphenylphosphine oxide 6-chloro-2-pyridone. As an example of the results obtained, we mention what they found for palmitic acid nicotinamide. From the ID and SSNMR spectra, they could determine the cocrystal formation. The hydrogen bond between the carboxylic group and the pyridine group was indicated by the chemical shift of the proton involved. The association of nicotinamide and palmitic add at molecular level was also proved with the 2D HETCOR experiments and... 

Ketoesters and cyanoacetic acid in benzene containing ammonium acetate and acetic acid ve ethyl y-cyano-2-butenoates (XII-11, X = OC2 Hj), which are saponified to the corresponding acids (XI-11,X = OH) and then are converted to the acyl chlorides (XII-11, X = Cl) with phosphorus pentachloride. The acyl chlorides cyclize to 6-chloro-2-pyridones (W-12) in n-butyl ether containing hydrogen chloride. ... 

In solid 2-pyridone, hydrogen bonding is of the NH 0 type. " 6-Chloro-2-pyridinol exists as the pyridinol tautomer in the solid state and forms hydrogen bonded dimers of the OH-N type. Molecular weight determinations in chloroform show that concentrated solutions of 4-methyl-, 4-phenyl-, 3,4-trimethylene-, and 3,4-tetramethylene-6-chloro-2-pyridone contain mainly hydrogen bonded dimers. ... 

SCHEME 14 Photoisomerization of 6 chloro-2 pyridone and photohydration of N-alkenyi pyridones. > ... 

Kaneko, C., Fujii, H., and Kato, K., Photochemistry of 6-chloro-2-pyridones the first example for electrocyclic ring opening of the pyridone ring system. Heterocycles, 17, 395—400, 1982. 

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