Nucleophilic aromatic substitution reviews

The general approaches for the synthesis of poly(arylene ether)s include electrophilic aromatic substitution, nucleophilic aromatic substitution, and metal-catalyzed coupling reactions. Poly(arylene ether sulfone)s and poly(arylene ether ketone)s have quite similar structures and properties, and the synthesis approaches are quite similar in many respects. However, most of the poly(arylene ether sul-fone)s are amorphous while some of the poly(arylene ether)s are semicrystalline, which requires different reaction conditions and approaches to the synthesis of these two polymer families in many cases. In the following sections, the methods for the synthesis of these two families will be reviewed. 

Phase transfer was used to catalyze nucleophilic aromatic substitutions by Makosza et al. in 1974.201 202 Zoltewicz203 has given a good early review of various methods and has compared other techniques that make use of polar solvents, transition metals, and monoelectron transfers. 

Nucleophilic aromatic substitution (reaction 4 in Review Table 3t occurs by addition of a nucleophile to an electrophilic aromatic ring, followed by elimination of the leaving group. The ring is made electrophilic, and hence reactive, only when substituted by strong electron-withdrawing groups such a nitro, cyano, and carbonyl. 

Nucleophilic Aromatic Substitution Reactions (Section 16.8 Review Table 3, reaction 4)... 

Prof V. Charushin is author of over 380 publications in the fields of heterocyclic and medicinal chemistry, including the hoo Nucleophilic Aromatic Substitution of Hydrogen, (Academic Press, New York, 1994), several chapters in Advances in Heterocyclic Chemistry and Progress in NMR Spectroscopy, over 20 review articles, and a lot of papers in international journals. He is a member of the editorial boards for Mendeleev Communications, Russian Chemical Reviews, Russian Chemical Bulletin, and Russian Journal of Organic Chemistry. 

The classical nucleophilic aromatic substitution reactions proceed by the bimolecular mechanism (24) the leading arguments for this have been put forward by Bunnett and co-workers since the early fifties (see reviews of Bunnett and Zahler, 1951, Bunnett, 1958 and Sauer and Huisgen, 1960). 

A detailed study of the nucleophilic aromatic substitution of hydrogen has been initiated at the Urals State Technical University (Russia) in the 1970s. In the first review on this topic, it was suggested to use the symbol Sjj in order to distinguish these reactions from the classical nucleophilic ipso-substitution Ar [8]. Later, a number of special reviews [9-38] and also the book Nucleophilic Aromatic Substitution of Hydrogen [39], which accumulated a considerable body of data on conditions, kinetics, structure of intermediates, electrochemical and mathematic modeling, as well as plausible mechanisms and the general concept of the 5 -reactions, have also been published. 

When Bunnett and Zahler [1] published their landmark review in 1951, only two mechanisms of nucleophilic aromatic substitution were known. These were the unimolecular S l process, typically observed with arenediazonium salts, as in Scheme 6.1, and the bimolecular S,.jAr pathway, which is shown in Scheme 6.2 involving substitution of a halide ion by an anionic nucleophile and involving an anionic intermediate (1). As in aliphatic substitutions, both unimolecular and bimolecular pathways are possible. 

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