Aromatic nucleophilic displacement reaction

Polyetherification is similar to a polycondensation process formation of high molecular weight polymer requires precise adjustment of composition to approximately 1 1 ratio of bisphenol to dihalosulfone. Trace amounts of water gready reduce the molecular weight attainable owing to side reactions that unbalance the stoichiometry (76). The reactivity of the halosulfone is in the order expected for two-step nucleophilic aromatic displacement reactions ... 

Because of resonance stabilization of the anion, a tet-nazolyl moiety is often employed successfully as a bioisosteric replacement for a carboxy group. An example in this subclass is provided by azosemide (27). Benzonitrile analogue is prepared by phosphorus oxychloride dehydration of the corresponding benzamide. Next, a nucleophilic aromatic displacement reaction of the fluorine atom leads to The synthesis concludes with the 1,3-dipolar addition of azide to the nitrile liinction to produce the diuretic azosemi de (27). ... 

Norfloxacin (41), the substance which triggered this avalanche of activity, has recently been introduced into clinical practice in the United States. Its synthesis parallels closely that of its N-methyl analogue, pefloxacin, except that the nucleophilic aromatic displacement reaction of 32 is carried out with mono-N-carboethoxypiperazine instead and the final step encompasses deblocking of this carbamoyl ester moiety [8]. 

Table II. Phase Transfer Catalyzed Nucleophilic Aromatic Displacement Reactions ...

Compounds 19 and 20 have been obtained39 (equation 16) in less than 2 h synthesis time by Baeyer-Villiger oxidation of the corresponding 4-[18F]fluoro-2-alkoxybenzaldehydes 21 and 22 prepared through nucleophilic aromatic displacement reactions (equations 17a... 

The high performance characteristics of polyetherimide polymers and our desire to prepare them by an economically attractive scheme led us to explore several synthetic approaches. The key reaction in all of these was the formation of the diaryl ether linkage by a nucleophilic aromatic displacement reaction on suitably substituted (and activated) phthalic derivatives. Chloride displacement proceeded relatively slowly and gave polymers having only modestly high molecular weights. Fluoride displacement was quite facile, but processes based on the fluoro-deriviatives were economically unattractive. The synthetic and economic accessibility of appropriate nitro-substituted phthalic... 

A wide variety of photo-responsive aromatic polyethers containing azo linkages in the main chain were prepared by nucleophilic aromatic displacement reactions. These polymers undergo cis-trans isomerism in solution when exposed to ultraviolet light. This photo induced isomerization was found to have a profound affect on solution viscosity of the polymers. The polymers were amorphous in nature and undergo crosslinking reactions at elevated temperatures. 

This chapter will be concerned only with this last class of reactions. Nucleophilic aromatic displacement reactions have been extensively reviewed. One of the earliest and still most comprehensive articles... 

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