| 单词 |
mesomerism |
| 释义 |
mesomerism Chem.|mɛˈsɒmərɪz(ə)m|
[(in sense a) ad. F. mésomérie (A. Cornillot 1927, in Ann. de Chim. VIII. 267), f. meso- meso- after tautomérie tautomerism.]
†a. A kind of tautomerism (see quot.). Obs.
1928Chem. Abstr. XXII. 2155 The term mesomerism is proposed to designate affinitive tautomerism and distinguish it from structural tautomerism (or desmotropism) and activation tautomerism (or tautomerism proper).
b. The property exhibited by certain molecules of having a structure which cannot adequately be represented by a single structural formula but can only be said to be intermediate between two or more graphical structures which differ in the distribution of electrons; resonance.
1934Nature 23 June 947/1 Mesomerism and tautomerism are different concepts. 1951I. L. Finar Org. Chem. I. ii. 15 Heisenberg (1926), from quantum mechanics, supplied a theoretical background for mesomerism; he called it resonance, and this is the name which is widely used. 1973B. J. Hazzard tr. Organicum iii. iv. 147 The capacity of a substituent for entering into mesomerism with a neighbouring double bond is defined as the mesomeric effect, and its sign is determined..by the polarization of the substituent accompanying the mesomerism.
So mesoˈmeric a., exhibiting or arising from mesomerism (sense b).
1933C. K. Ingold in Jrnl. Chem. Soc. 1124 The permanent polarisation associated with the tautomeric effect was originally distinguished by the name ‘electronic strain’, but this term has not proved convenient and, on account of considerations indicated later, the designation mesomeric effect is now substituted. 1956E. de B. Barnett Mechanism Org. Chem. Reactions i. 5 Neither the double-bonded formula nor the dipolar formula is a true representation of the molecule, which must be regarded as a mesomeric hybrid to which both structures contribute. 1973B. J. Hazzard tr. Organicum iii. iv. 146 A mesomeric system may involve not only double and triple bonds between the various bond partners but also free electron pairs conjugated with them. |
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