Nucleophilic aromatic substitution polymerization

The reaction is fundamentally a Friedel-Crafts reaction utilizing thi-onyl chloride followed by the reduction of the sulfoxide to the sulfide with oxaloyl chloride. The sulfide group activates the fluorine atom for the nucleophilic aromatic substitution polymerization. Thus, the ether linkage in the backbone of the polymer can be readily produced by a nucleophilic aromatic substitution. The reaction with bisphenol A proceeds at 150 C. 

D. M. Knauss and J. B. Edson. Poly(aryl ether sulfide)s by sulfide-activated nucleophilic aromatic substitution polymerization. Polymer, 47(11) 3996-4003, May 2006. 

A new double adamantyl-substituted aromatic bisphenol monomer, 4,8-bis (l-adamantly)-l,5-dihydroxynaphthalene (AdNp) was successfully S5mthesized via the Friedel-Crafts reaction as depicted Scheme 10.11, and two new PAEKs containing adamantly groups (Ad-PAENKs) were synthesized based on the new monomer of AdNp, (3-trifluoromethyl)phenyl hydroquinone (3FHQ) and 4,4 -difluorobenzophenone (D ) via the nucleophilic aromatic substitution polymerization as depicted Scheme 10.12. 

The polymerizations require the use of dipolar aprotic solvents such as N-methylpyrrolidone (NMP), dimethyl acetamide (DMAC), dimethyl sulfoxide (DMSO) or N,N -dimethylpropylene urea (DMPU). Nucleophilic aromatic substitution polymerizations are t q>ically performed in a high boiling aprotic polar solvent with the monomer(s) reacted in the presence of a base, potassium carbonate, at elevated temperatures (ca. 180 C). Potassium carbonate is used to convert the phenol into the potassium phenolate and since K2CO3 is a weak base, no hydrolytic side reactions are observed. Dipolar aprotic solvents are used in these poly(aryl ether) syntheses, since they effectively dissolve the monomers and solvate the polar intermediates and the final polymer. DMPU has been shown to be an excellent solvent for poly(ether) syntheses, particularly for those polymers which are only marginally soluble in other dipolar aprotic solvents (22). Furthermore, DMPU allows higher reaction temperatures (260 C). We have observed that DMPU, when used in conjunction with toluene as a dehydrating agent, accelerates many nucleophilic substitution reactions. 

The use of NMR spectroscopy to evaluate potential aryl fluoride monomers as candidates for nucleophilic aromatic substitution polymerization has shown to be an accurate and time saving technique. Since the shift is controlled by the electron density of the carbon to which it is attached, the magnitude of the F chemical shift can... 

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