tautomerismn.
/tɔːˈtɒmərɪz(ə)m/, U.S. /tɔˈtɑməˌrɪzəm/, /tɑˈtɑməˌrɪzəm/ Chemistry.
The property exhibited by certain (organic) compounds of behaving in different reactions as if they possessed different constitutions; (in later use) spec. the phenomenon of the existence of two (or more) structural isomers in equilibrium, these isomers being readily interconvertible by migration of an atom or group within the molecule.A common example is the existence of keto (—CH2C(=O)—) and enol (—CH=C(OH)—) forms of a molecule (e.g. as in ethyl acetoacetate).
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the world > matter > chemistry > isomerism > [noun] > structural isomerism > tautomerism
tautomerism1888
tautomery1896
ionotropy1928
1888 Jrnl. Chem. Soc. 54 944 (title) Tautomerism of thiocarbamides. By F. Foerster.
1901 Jrnl. Chem. Soc. 79 543 Hitherto no isomerism (or tautomerism) has been established amongst mineral derivatives analogous to that subsisting between the normal and isothiocyanates of organic radicles.
1916 M. W. Onslow Anthocyanin Pigments Plants v. 75 Under certain conditions..a change readily takes place by tautomerism to a colourless isomer: [formula] which is really a flavone with an extra hydroxyl in position 2.
1927 Jrnl. Amer. Chem. Soc. 49 849 Acetylacetone may undergo keto-enol tautomerism in the following way. CH3COCH2COCH3 ⇌ CH3COCH:C(OH)CH3.
1983 J. R. S. Fincham Genetics xii. 317 They [sc. Watson and Crick] invoked the known tautomerism of the DNA bases, in which each base can exist in two alternative forms interconvertible by the shifting of a double bond and a redistribution of hydrogen atoms.
2012 J. Clayden et al. Org. Chem. (ed. 2) xx. 453 The tautomerism that interconverts the keto and enol forms of a carbonyl compound..is a real equilibrium between two different structures.
This entry has been updated (OED Third Edition, June 2014; most recently modified version published online March 2022).
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