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Electromeric effect refers to a molecular polarizability effect occurring by an intramolecular electron displacement (sometimes called the ‘conjugative mechanism’ and, previously, the ‘tautomeric mechanism’) characterized by the substitution of one electron pair for another within the same atomic octet of electrons.〔(). IUPAC GoldBook〕 However, this term is now considered and this effect is considered along with the inductive effect. This effect is shown by those compounds containing multiple bonds. When a double bond or triple bond is exposed to an attack by a reagent, a pair of bonding electrons involved in the pi bond is transferred completely from one atom to another. This effect will remain as long as the attacking reagent is present. As soon as the reagent is removed, the polarized molecule will come back to the original state. ==+E and -E groups== Electromeric effect can be classified into +E and -E effects based on the direction of transfer of the electron pair. When the electron pair moves towards the attacking reagent, it is termed as the +E effect. The addition of acids to alkenes is an example of the +E effect. After the transfer takes place, the reagent gets attached to the atom where the electrons have been transferred to. The -E effect can be found in reactions such as addition of cyanide ion to carbonyl compounds. In these reactions, the electron pair moves away from the attacking reagent. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Electromeric effect」の詳細全文を読む スポンサード リンク
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