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Hard-Soft Acid-Base Theory and Nucleophilicity

Hard-Soft Acid-Base Theory and Nucleophilicity [Pg.505]

Pearson and Edwards noted that some substrates in Sn2 reactions seem more susceptible to the Bronsted basicity of a nucleophile, while other substrates seem more susceptible to its polarizability. Pearson proposed that bases be divided into two categories soft (polarizable) and hard (nonpolarizable). On the basis of equilibrium data, Pearson concluded that H, Li, Na, Mg, and Ca are hard acids, while Cu, Ag, Hg, I, Br, I2, and Br2 are soft. Pearson noted that hard acids show greater association with hard bases, while soft acids prefer soft bases. One explanation for this behavior is the ionic/covalent bond description, in which it is assumed that hard acids and hard bases are attracted primarily through ionic interactions, while soft acids and soft bases associate through covalent bonds. In addition, the two [Pg.505]

For the data plotted, the correlation coefficient is only 0.7, but a general trend is evident. [Pg.505]

Data are for reaction of the two ions with CH3I in methanol solution. See Pearson, R. G. Sobel, H. Songstad, J. /. Am. Chem. Soc. 1968, 90, 319. [Pg.505]

Pearson appbed the concept of hard and soft acids and bases to nucleo-philicity in the 2 reaction by using the concept of absolute hardness, rj  [Pg.506]




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Acid theory

Acid-base theory

Acids hard and soft

And hardness

Bases and Nucleophiles

Bases hard and soft

Bases theories

Hard acids

Hard acids and bases

Hard and Soft Acids-bases

Hard and soft

Hard and soft nucleophilicity

Hard bases

Hard nucleophile

Hard-soft acid-base theory

Hard-soft, acid-bases

Hardness acids and bases

Hardness and softness

Hardness, nucleophile

Nucleophiles bases

Nucleophiles hardness

Nucleophilic bases

Nucleophilic bases hardness

Nucleophilic bases softness

Nucleophilicity acids

Soft acids

Soft acids and bases

Soft acids/bases

Soft bases

Soft bases and

Soft nucleophile

Soft nucleophiles

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