Competing processes for poly(aryl ether‐ketone) synthesis, 3. Polymerization reactions of 1,3‐bis(4‐chlorobenzoyl)benzene and 1,3‐bis(4‐fluorobenzoyl)benzene in N‐methyl‐2‐pyrrolidinone

Abstract

The effects of N-methyl-2-pyrrolidinone (NMP) as solvent on the polymerizaton reactions of 1,3-bis(4-chlorobenzoyl)benzene (1,3-CBB) and 1,3-bis(4-fluorobenzoyl)benzene (1,3-FBB) with 4,4'-isopropylidenediphenol (bisphenol-A) were examined. The failure of these reactions to produce high molecular weight polymers in the presence of anhydrous potassium carbonate is due to dehalogenation of 1,3-CBB via substitution radical-nucleophilic unimolecular (SRNl) processes. On the other hand, 1,3-FBB undergoes nucleophilic aromatic substitution reactions (SNAR) with the carbonate anion at elevated temperatures. However, it is possible to synthesize high molecular weight polymers from 1,3-FBB and bisphenol-A in NMP either by first forming the bisphenoxide with stoichiometric amounts of aqueous sodium hydroxide or in the presence of anhydrous potassium carbonate at a lower reaction temperature.

Synthesis of poly(aryl ether phenylquinoxaline) via Ullmann ether condensation of chlorine-substituted A-B quinoxaline monomers

“…A polymerization in diphenylsulfone (DPC) containing potassium carbonate at 320°C was also unsuccessful. It is well-known that the polymerization of activated aryl chlorides via aromatic nucleophilic substitution reactions is difficult, particularly when the chloro groups are activated by relatively weak withdrawing groups, such as the pyrazine ring [13][14][15]. Hence, it was decided to attempt the polymerization using Ullman ether coupling reactions.…”

Poly(ether sulfone)s using a rigid dibenzothiophene dioxide heterocycle

“…Polymerization at longer times and higher temperatures were not found to increase the molecular weight. Aryl chlorides are also known to undergo possible side reactions during S N Ar polymerizations that could offset the stoichiometry . The polymerization results indicate that while monomer 1b is activated toward S N Ar, aryl fluorides are required to sufficiently activate the electrophilic monomer and avoid side reactions to achieve high molecular weight under the employed reaction conditions.…”

Synthesis of polyphenylquinoxaline copolymers via aromatic nucleophilic substitution reactions of an A‐B quinoxaline monomer

“…One problem with the use of chlorine‐containing monomers as compared with fluorine‐containing monomers in S N Ar reactions is the greater likelihood of single‐electron transfer (SET) side reactions that limit the molecular weight 15–20. Percec and coworkers15–20 determined that SET side reactions could be minimized through polymerization in NMP at temperatures less than 160 °C and at longer polymerization times.…”