| 释义 |
tautomerism Chem.|tɔːˈtɒmərɪz(ə)m|
[f. Gr. ταὐτο- tauto- + µέρος part, after isomerism; rendering Ger. tautomerie (Laar 1885).]
The property exhibited by certain organic compounds of behaving in different reactions as if they possessed two (or more) different constitutions, that is, as if the atoms of the same compound or group were arranged in two (or more) different ways, expressible by different structural formulæ (e.g. the group {b1}CH:C(OH){b1}, or {b1}CH2.CO{b1}, in ethyl aceto-acetate); esp. such a property due to the reversible migration of an atom (esp. of hydrogen) or group within a molecule (see also quots.).
[1885Conrad Laar in Ber. Dtsch. Chem. Ges. XVIII. 652 Um die gegenseitige Beziehung gleichberechtigter Formeln..kurz bezeichnen zu können, schlage ich hierfür den Ausdruck ‘Tautomerie’ vor.] 1890Nef in Jrnl. Chem. Soc. LVIII. 983 A discussion of the alleged cases of tautomerism in ethyl succinosuccinate and analogous compounds. 1901Dixon ibid. LXXIX. 543 Hitherto no isomerism (or tautomerism) has been established amongst mineral derivatives analogous to that subsisting between the normal and isothiocyanates of organic radicles. 1927T. M. Lowry in Chem. Rev. IV. 233 The necessity for a new definition of tautomerism arises from the fact that Laar embodied in his original definition a theory which is now universally recognized as being incorrect,..namely, that the various formulae which can be assigned to a tautomerism compound represent ‘not isomeric but identical substances’. The new definition has the advantage that there is no theory behind it, since it is limited to a mere statement of the fact of dual reactivity. 1927,1936[see keto-enol s.v. keto- b]. 1937H. B. Watson Mod. Theories Org. Chem. ix. 117 Until a relatively recent date..‘tautomerism’ was used exclusively to denote the migration of hydrogen. The similar migration of anionic atoms or groups is now recognized, however; this .. is included under .. ‘tautomerism’. 1964[see prototropy]. 1969C. K. Ingold Structure & Mechanism Org. Chem. (ed. 2) xi. 795 Laar's interpretation was that two such structures did not represent distinct and potentially separable species, but only the end-phases of an intramolecular oscillatory situation in a single chemical species. Ibid. 799 Since 1911 there has been no question but that the concept of tautomerism, in terms of which Conrad Laar had incorporated so many scattered observations into a phenomenon, has to be redefined..as meaning reversible isomeric change. Problems of isolation and proof of identity of tautomers are dependent simply on temperature and the available techniques.
So tautomer |ˈtɔːtəmə(r)|, any one of the forms of a tautomeric compound in relation to another; tautomeric |tɔːtəʊˈmɛrɪk| a., pertaining to or exhibiting tautomerism; tauˈtomerize v. intr., to change into another tautomeric form; tauˌtomeˈrizable a., capable of being changed into a tautomeric form; tauˌtomeriˈzation; tautomery |tɔːˈtəʊmərɪ| [ad. Ger. tautomerie], = tautomerism.
1886tr. Richter's Organic Chem. (1899) I. 55 Laar..assumes that such compounds consist of a mixture of structural isomerides, in that an easily mobile hydrogen atom oscillates between two positions in equilibrio, and thereby the entire complex becomes mobile. He designates the phenomenon as tautomery. 1890Goldschmidt & Meissler in Jrnl. Chem. Soc. LVIII. 499 Assuming that in the reactions of tautomeric compounds which take place under the influence of electrolytes, the intramolecular change is brought about by the free ions. 1903Amer. Chem. Jrnl. May XXIX. 406 It [thio-urea] may react with the metal [silver] to form a sulphide, or its tautomer may form an insoluble silver compound. 1904Ibid. Dec. 606 There are ten possible tautomeric formulas for this phenylacetylurazole, and four possible positions for the acetyl group. 1905Walker Chem. Soc. Annual Rep. 9 It is suggested that an absorption band appears wherever there is tautomeric change within the molecule. 1934Webster, Tautomerize... Tautomerizable... Tautomerization. 1938H. Adkins in H. Gilman Org. Chem. I. ix. 820 Unsaturated acids tautomerize in the absence of added reagents at temperatures near their boiling points. Ibid., There is little or no correlation between the rate of tautomerization (mobility) and the extent of the reaction. 1962Tautomerizable [see Raman]. 1972R. A. Jackson Mechanism iv. 60 This could plausibly lose carbon dioxide to give the carbanion 82 which would rapidly tautomerize to pyridine 83 by a proton shift. 1978Jrnl. Amer. Chem. Soc. C. 4627/2 Activation of the catalyst by tautomerization to a rhodium (I) complex. |