tautomer


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tautomer

(tô`təmər), one of two or more structural isomersisomer
, in chemistry, one of two or more compounds having the same molecular formula but different structures (arrangements of atoms in the molecule). Isomerism is the occurrence of such compounds. Isomerism was first recognized by J. J. Berzelius in 1827.
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 that exist in equilibrium and are readily converted from one isomeric form to another. Of the various types of tautomerism that are possible, two are commonly observed. In keto-enol tautomerism a simultaneous shift of electrons and a hydrogen atom occurs; it was first observed by K. Meyer in the ethyl ester of 3-oxobutanoic acid (ethyl acetoacetate), which occurs naturally as a mixture of the two forms. Ring-chain tautomerism, first recognized by Emil Fischer, is exhibited by glucose. It arises as a result of the aldehyde group (-CHO) in a sugar chain molecule reacting with one of the hydroxy groups (-OH) in the same molecule to give it a cyclic (ring-shaped) form.
References in periodicals archive ?
The compound also exists as a keto-enol tautomer in aqueous solution that can form stable complexes stoichiometrically with transition metals including copper (II) (Kanhathaisong et al.
Furthermore, we investigated the relaxation process of keto tautomer in the irradiated film, by monitoring the changes of absorbance specific to the enol-imine isomer (342 nm).
THEORETICAL STUDY OF TWO TAUTOMERS OF LOSARTAN IN GAS PHASE AND AQUEOUS SOLUTION.
ion does not exist for DiMMA can be explained by the fact that the a carbon in the DiMMA molecule does not have an active hydrogen that would allow tautomer formation.
In general the Schiff bases that are derived from salicylaldehyde exist mainly as the enol-tautomer with a variable contribution from the keto-tautomer (depending on the substituents) while those derived from 2- hydroxynaphthaldehyde are dominated by the keto- tautomer structure [5].
It is available as freeware, with tools for tautomer prediction, 2-D structure cleaning, 3-D optimization and viewing, drawing of polymers, organometallics and Markush structures.
39] hydroxy group with the lactone function, producing another ring tautomer very similar to the one described for iso-FK-506 [18, 19] and decreasing the binding affinity of this rapamycin metabolite for its pharmacological receptor FKBP-12.