Activating-deactivating effects

Activating/Deactivating Effects on Electrophilic Aromatic Substitution. 190... 

The electrophilicity index also accounts for the electrophilic activation/deactivation effects promoted by EW and electron-releasing substituents even beyond the case of cycloaddition processes. These effects are assessed as responses at the active site of the molecules. The empirical Hammett-like relationships found between the global and local electrophilicity indexes and the reaction rate coefficients correctly account for the substrate selectivity in Friedel-Crafts reactions, the reactivity of carbenium ions, the hydrolysis of esters, the reactivity at the carbon-carbon double bonds in conjugated Michael additions, the philicity pattern of carbenes and the superelectrophilicity of nitronium, oxonium and carboxonium ions. This last application is a very promising area of application. The enhanced electrophilicity pattern in these series results from... 

Table 9.1 lists the directing and activating-deactivating effects for the major functional groups with which we are concerned in this text. 

We account for the activating-deactivating effects of substituent groups by a combination of resonance and inductive effects ... 

Listed in Table 22.2 are the directing and activating-deactivating effects for the major functional groups with which we are concerned in this text. If we compare these ortho-para and meta directors for stmctural similarities and differences, we can make the following generalizations. 

Orientation and activating/deactivating effects have a large practical significance, because in synthesizing polysubstituted aromatics, the order of addition of the substituents must be taken into account. 

Substituent directing and activation/deactivation effects are the result of two types of interactions operating on the cation intermediate ... 

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