tautomerism


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tautomerism

 [taw-tom´er-izm]
stereoisomerism in which the compounds are mutually interconvertible, under normal conditions, forming a mixture that is in dynamic equilibration. adj., adj tautomer´ic.

tau·tom·er·ism

(taw-tom'ĕr-izm),
A phenomenon in which a chemical compound exists in two forms of different structure (isomers) in equilibrium, the two forms differing, usually, in the position of a hydrogen atom; for example, keto-enol tautomerism, R-CH2-C(O)-R' ⇄ R-CH=C(OH)-R'.
[G. tautos, the same, + meros, part]

tautomerism

/tau·tom·er·ism/ (-izm) the relationship that exists between two constitutional isomers (those having the same atoms linked in different structures) that are in chemical equilibrium and freely change from one to the other.tautomer´ic

tau·tom·er·ism

(taw-tom'ĕr-izm)
A phenomenon in which a chemical compound exists in two forms of different structure (isomers) in equilibrium, the two forms differing, usually, in the position of a hydrogen atom.
[G. tautos, the same, + meros, part]

tautomerism

stereoisomerism in which the compounds are mutually interconvertible, under normal conditions, forming a mixture that is in dynamic equilibration.
References in periodicals archive ?
1976) Tautomerism of isoguanosine and solvent-induced keto-enol equilibrium.
Thus, it is reasonable to prefer the MNDO/d method for further investigation of phosphorus-carbon diad tautomerism, provided that no hypervalent sulphur atoms are present.
The in vitro immunosuppressive activity of the C15-demethylated metabolite of FK-506 is governed by ring- and open-chain tautomerism effects.
2003) Reversible valence tautomerism induced by a single-shot laser pulse in a cobalt-iron Prussian blue analog.
The reason might be that the tautomerism of the keto form to enol form increased the extent of [pi]-delocalization on the conjugated polymer chain, and more work should be done to investigate it in detail in our future work.
Electronic delocalization and tautomerism are responsible for color change in these dyes on changing pH of medium.
Abdallah, Synthesis, Azohydrazone Tautomerism and Antitumor Screening of N-(3-ethoxycarbonyl-4,5,6,7tetrahydro-benzo[b]thien-2-yl)-2-arylhydrazono3-oxobutanamide Derivatives, Arkivoc, 17, 295 (2008).
In addition to the O/H-N1 H-bond the study provides evidence on the involvement of the H-N1 proton in a second H-bond (N2/H-N1) and that it leads to substantial diverse effects on the structures the NMR chemical shifts the atomic charges the orbitals interaction the tautomerism energies and the band gaps.
While the peak of hydrazide -NH remains unaltered, and the peak of non coordinated carbonyl diminishes due to amide-imidic acid type tautomerism, it can be proposed that the carbonyl peak diminishes due to hydrogen bond formation with free non-coordinated amine group [25].
Existence of tautomerism has also been observed from 1H-NMR spectral data of synthesized carboxamides (3a-e).
This may be attributed to the contribution of NH group in the formation of a hydrogen chelate ring with the participation of the azohydrazone tautomerism [30].
Keywords: 7-chloro-1-phenylpyrimido [4,5-e] [1,3,4] thiadiazines, 7-hydrazinyl-1-phenylpyrimido [4,5-e] [1,3,4]thiadiazin, 5H-tetrazolo[1',5':1,2]pyrimido[4,5-e][1,3,4]thiadiazine, 9H-tetrazolo[5',1':2,3]pyrimido[4,5- e][1,3,4]thiadiazine, 1H-NMR study, diazotization, tetrazole-azide tautomerism.