Solvent Influence on the Reactivity of Ambident Anions

Ambident anions are mesomeric, nucleophilic anions which have at least two reactive centers with a substantial fraction of the negative charge distributed over these cen-ters ) ). Such ambident anions are capable of forming two types of products in nucleophilic substitution reactions with electrophilic reactants . Examples of this kind of anion are the enolates of 1,3-dicarbonyl compounds, phenolate, cyanide, thiocyanide, and nitrite ions, the anions of nitro compounds, oximes, amides, the anions of heterocyclic aromatic compounds e.g. pyrrole, hydroxypyridines, hydroxypyrimidines) and others cf. Fig. 5-17. 

1 Reaction of sodium phenolate with 3-chloropropene according to equation (5-132) 

Dialkylated products included. Reaction with 3-bromopropene. = At 43 C. 

Some representative data, taken from the extensive work of Komblum et al. concerning the alkylation of phenolates [cf. Eq. (5-132)] and y9-naphtholates, are collected in Table 5-22 [370, 371]. 

In protic solvents, the solvent effect on orientation has been interpreted in terms of preferential deactivation of the more electronegative atom by specific solvation through H-bonding f As shown in Table 5-22, carbon alkylation competes more sig- 

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Specific Solvation Effects on Reaction Rates 269 5.5.6 Solvent Influence on the Reactivity of Ambident Anions... 

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