Synthesis and Properties of Polymers Containing 2H-Benzimidazol-2-one Moieties: Polymerization via N-C Coupling Reactions

Synthesis of thermally robust benzimidazolone-based wholly aromatic polyketones

A series of wholly aromatic polyketones bearing benzimidazolone moieties (PK-BI) were synthesized via N-C coupling polycondensation. Calcium carbonate coupled with potassium carbonate was used for the first time to achieve a high molecular weight, with T g of the polymer as high as 299 °C. The polymer structure was confirmed by solid state 13C NMR and FT-IR. The thermal stability of wholly aromatic polyketones with a benzimidazolone unit in the main chain was significantly improved, being higher than those of PEEKs and other amorphous PAEKs, proved by thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) analysis. The degradation activation energy (E k) values estimated by Flynn-Wall-Ozawa (FWO) and Kissinger methods were 260.33 kJ mol-1 and 282.57 kJ mol-1, respectively, which are higher than those of PEEKs.

Synthesis of Multisubstituted Benzimidazolones via Copper-Catalyzed Oxidative Tandem C-H Aminations and Alkyl Deconstructive Carbofunctionalization

Benzimidazolone constitutes the core structure of numerous pharmaceuticals, agrochemicals, inhibitors, pigments, herbicides, and fine chemicals. Amination of hydrocarbons is an attractive tool for the creation of nitrogen-containing products. However, the multiple steps, harsh conditions, and low atom efficiencies often present in these reactions remain challenging. We present a multicomponent synthesis of functional benzimidazolones from arylamines, dialkylamines, and alcohols, acting via the sequence of copper-catalyzed oxidative tandem C-H aminations and alkyl deconstructive carbofunctionalization. The catalytic transformation forms multiple bonds in one single operation, uses readily available feedstocks and a naturally abundant Cu/O2 catalyst system, has broad substrate scope, avoids pre-installation of aminating agents and directing groups, and provides high chemo- and regioselectivity, resulting in direct functionalization of inert C-H and C-C bonds via single-electron oxidation-induced activation mode. This platform can be expected to provide structurally diverse products with interesting biological, chemical, and physical properties.

I2-Mediated transition-metal-free aromatic C–H amination for the synthesis of benzimidazol-2-ones and related heterocycles

A practical I₂-mediated aromatic C–H amination reaction was established for benzimidazol-2-one synthesis under transition-metal-free conditions. The present reaction can be performed directly from disubstituted amines and isocyanates without the purification of the urea intermediates in a scalable fashion.

Facile synthesis of novel poly(arylene ether)s containing N-arylenebenzimidazolyl groups via C–N/C–O coupling reaction

This article presents a convenient polymerization route to synthesize poly(arylene ether)s containing N-arylenebenzimidazolyl groups. The novel polymers were prepared by a catalyst-free nucleophilic substitution reaction, in which the N–H and O–H sites were removed from 2-(2-hydroxyphenyl)-1H-benzimidazole with different activated difluorides containing carbonyl groups in sulfolane. The reaction was carried out in the presence of anhydrous potassium carbonate at 210°C. The structures of the polymers were characterized using Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and elemental analysis. The results show good agreement with the proposed structure. All resulting polymers show essentially amorphous patterns. Moreover, differential scanning calorimetry and thermogravimetric measurements show that the polymers have high glass transition temperatures (>209°C), good thermostability, and high decomposition temperatures (>425°C). Furthermore, the polymers also exhibit excellent solubility in common organic solvents.

Synthesis of N-substituted poly(benzimidazole ketone ketone)s containing pyridine rings

Poly( N-arylenebenzimidazole ketone ketone pyridine)s have been prepared via N–C coupling reaction that removed the N–H sites from the novel bis(benzimidazoyl) derivatives with activated aromatic difluorides in sulfolane. The reaction was carried out at 210°C in the presence of anhydrous potassium carbonate. The structures of the polymers were characterized by means of Fourier transform infrared and proton nuclear magnetic resonance spectroscopies and elemental analysis. All resulting polymers showed essentially amorphous patterns. Differential scanning calorimetry and thermogravimetric measurements showed that the polymers had high glass transition temperatures (>179°C), good thermostability, and high decomposition temperatures (>401°C). These novel polymers also showed easy solubility.