Novel heterocyclic poly(arylene ether ketone)s: Synthesis and polymerization of 4-(4′-hydroxyaryl)(2H)phthalazin-1-ones with methyl groups

Phthalic anhydride (PA): a valuable substrate in organic transformations

This review has been centralized on applications of phthalic anhydride (PA) as a valuable and significant heterocyclic substrate in two- and multicomponent organic reactions. The article has been subdivided into the following parts: (i) PA introduction by focusing on its characterization, synthesizing procedure, and multiple-aspect applications. In addition, the previous review articles based on PA have also been indicated; (ii) the applications of PA as a substrate have been subdivided into parts with a glance on the reaction components numbers; (iii) the applications of PA in esterification reactions; and (iv) some examples of PA in multistep synthesis. The review covers the corresponding literature up to the end of 2022. According to the abovementioned classifications, PA is a potent substrate to design a wide range of heterocyclic compounds that possess various kinds of properties and applications in chemistry, industry, and pharmaceuticals.

Synthesis and characterization of poly(phthalazinone ether ketone ketone) copolymers with 4,4′-dihydroxybiphenyls

Meta-poly(phthalazinone ether ketone ketone) copolymers with 4,4′-dihydroxybiphenyls (meta-PPBEKK) was synthesized with 4,4′-dihydroxybiphenyls (BP), 1,3-bis(4-fluorobenzoyl)benzene (meta-DFKK) and 4-(4-hydroxyphenyl)-2,3-diazaphthalene-1-one (DHPZ). The copolymers are high-temperature resistant and have good solubility in many solvents. With increasing molar ratio of BP to meta-DFKK from 0 to 0.2, the addition of BP improves number-average molecular masses, intrinsic viscosity, mechanical properties and fluidity of meta-PPBEKKs. When the molar ratio of BP to meta-DFKK is 0.2, the intrinsic viscosity reaches 1.14 dL g−1, the number-average molecular mass reaches 44700 g mol−1, the maximum thermal elongation ratio reaches 14 with strength of 127.1 MPa and Young’s modulus of 2.4 GPa. With increasing molar ratio of BP to meta-DFKK from 0 to 0.2, meta-PPBEKKs have improved comprehensive properties, and make sense in many fields.

New poly(aryl ether ketone)s containing 2,6-diphenylpyridyl units and diphenylphosphinophenyl pendant groups

4-(4-Diphenylphosphino)phenyl-2,6-bis(4-hydroxyphenyl)pyridine, as a new bisphenol monomer, was prepared from 4-(diphenylphosphino)benzaldehyde and 4-hydroxyacetophenone and used in the preparation of several aromatic poly(ether ketone)s (PEKs) containing 2,6-diphenylpyridyl units and diphenylphosphinophenyl pendant groups via a nucleophilic aromatic substitution polycondensation with difluorinated aromatic ketones. The polycondensation proceeded quantitatively in tetramethylene sulfone in the presence of anhydrous potassium carbonate and afforded the polymers with high molecular weights. The resulting PEKs are amorphous and exhibit high glass transition temperatures of 209–255°C and 5% weight loss temperatures of 536–554°C with char yields of 57–62% at 800°C in nitrogen. Their high char yields and good limited oxygen index values ranging from 39 to 43 indicated these polymers exhibited good thermal stability and flame-retardant property. All new PEKs were soluble in common organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and chloroform and could form tough, flexible, and strong films with tensile strengths of 74.6–86.8 MPa, tensile moduli of 2.9–3.6 GPa, and elongations at break of 5–9%.

Phthalazinone Scaffold: Emerging Tool in the Development of Target Based Novel Anticancer Agents

Phthalazinones are important nitrogen-rich heterocyclic compounds which have been a topic of considerable medicinal interest because of their diversified pharmacological activities. This versatile scaffold forms a common structural feature for many bioactive compounds, which leads to the design and development of novel anticancer drugs with fruitful results. The current review article discusses the progressive development of novel phthalazinone analogues that are targets for various receptors such as PARP, EGFR, VEGFR-2, Aurora kinase, Proteasome, Hedgehog pathway, DNA topoisomerase and P-glycoprotein. It describes mechanistic insights into the anticancer properties of phthalazinone derivatives and also highlights various simple and economical techniques for the synthesis of phthalazinones.

Synthesis and characterization of soluble copoly(arylene ether ketone sulfone)s bearing xanthene moiety in the main chain

Several new poly(arylene ether ketone sulfone) (PEKS) copolymers containing xanthene moiety in the main chain were prepared by direct solution polycondensation reaction of 1,4-bis(4-fluorobenzoyl)benzene with varying mole ratios of 9,9-bis(4-hydroxyphenyl)xanthene and 4,4′-sulfonyldiphenol using sulfolane as solvent in the presence of anhydrous potassium carbonate. The introduction of xanthene and sulfone groups into the polymer chain resulted in an improvement in solubility of the polymers in common organic solvents such as N-methyl-2-pyrrolidone, N, N-dimethyl acetamide, sulfolane, pyridine, chloroform, and tetrahydrofuran. Thermal analysis revealed that the copolymers exhibited high glass transition temperatures ( Tgs) of 208–221°C and excellent thermal stability associated with 5% weight loss temperatures ranging from 490°C to 521°C and 62–66% residual weight at 650°C under nitrogen atmosphere. All copolymers were amorphous and their solubility increased with an increase of sulfone content in the polymer backbone, while the Tgs and overall thermal stability appeared to decrease slightly. This new kind of xanthene-containing PEKS copolymers may be considered a good candidate for using as high-performance structural materials.

Synthesis and properties of novel 9,9-diphenyl xanthene-based poly(aryl ether ketone)s with methyl substituents

A new bisphenol, 9,9-bis(4-hydroxy-3-methylphenyl)xanthene, was synthesized via a one-pot, two-step synthetic procedure in good yield and used for polymerization with difluorinated aromatic ketones in tetramethylene sulfone in the presence of anhydrous potassium carbonate to form several aromatic poly(ether ketone)s (PEKs) with 9,9-diphenylxanthene moieties and methyl substituents. The newly synthesized high-molecular-weight PEKs having number-average molecular weights in the range of 20,500–25,600 g mol−1 with the polydispersity index ranging from 1.9 to 2.1 were all amorphous and showed high glass transition temperatures in the range of 194–229.8°C, and the temperatures at the 5% weight loss were in the range of 420–445°C with char yields above 60% at 600°C under nitrogen atmosphere. All new PEKs are soluble in polar aprotic solvents, such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, chloroform, pyridine, m-cresol, and tetrahydrofuran, and could form transparent, strong, and flexible films with tensile strengths of 66–74 MPa, Young’s moduli of 2.47–2.77 GPa, and elongations at break of 8–14%. In addition, these polymers had high transparency with an ultraviolet–visible absorption cutoff wavelength in the 352–356 nm range and low moisture absorption in the range of 0.41–0.56%.

Synthesis and characterization of new poly(aryl ether ketone)s bearing (4-phenoxyphenyl)triphenylmethane moieties

1,1-Bis(4-hydroxyphenyl)-1-(4-phenoxyphenyl)-1-phenylmethane (BHPPPPM), a new bisphenol monomer, was synthesized with 65% yield from 4-benzoyl diphenyl ether in a one-pot, two-step synthetic procedure. Four new poly(aryl ether ketone)s (PAEKs) bearing (4-phenoxyphenyl)triphenylmethane moieties were prepared from BHPPPPM with four difluorinated aromatic ketones via a nucleophilic substitution reaction. The polycondensation proceeded in tetramethylene sulfone in the presence of anhydrous potassium carbonate and afforded the new PAEKs in nearly quantitative yields with inherent viscosities of 0.60–0.78 dL g−1. The resulting PAEKs having number-average molecular weights in the range of 29,500–34,200 g mol−1 with the polydispersity index ranged from 1.94 to 2.01 are all amorphous and show high glass transition temperatures ranging from 174°C to 196°C, excellent thermal stability, and the temperatures at the 5% weight loss are over 500°C with char yields above 60% at 700°C under nitrogen atmosphere. These new PAEKs are all soluble in polar aprotic solvents such as N-methyl-2-pyrrolidone and N,N′-dimethylacetamide and could also be dissolved in chloroform and tetrahydrofuran. All the polymers formed transparent, strong, and flexible films with tensile strengths of 78–85 MPa, tensile moduli of 1.9–2.4 GPa, and elongations at break of 7–10%.

Poly(aryl ether ketone/sulfone)s containing ortho-methyl and pendant trifluoromethyl-substituted phenyl groups: Synthesis and properties

Two novel bisphenols, 1,1-bis(4′-hydroxy-3′,5′-dimethylphenyl)-1-(3′′-trifluoromethylphenyl)-2,2,2-trifluoroethane (4M6FDO) and 1,1-bis(4′-hydroxy-3′,5′-dimethylphenyl)-1-[3′′,5′′-bis(trifluoromethyl)phenyl]-2,2,2-trifluoroethane (4M9FDO), with methyl groups ortho-substituted to the phenol groups, bulky trifluoromethyl-substituted phenyl groups and trifluoromethyl groups in the structure, were synthesized and characterized. The bisphenols were polymerized with 4,4′-difluorobenzophenone and bis(4-fluorophenyl) sulfone, respectively, via a aromatic nucleophilic substitution polycondensation to afford four poly(aryl ether ketone/sulfone)s (PAEKs/PAESs) with the inherent viscosities of 0.32–0.52 dL g−1. The ortho-methyl and pendant trifluoromethyl-substituted phenyl groups endow the polymers with good solubility, the rigidity of the polymer chains increase the glass transition ( Tg) of the polymers to 197–235 °C. Flexible and tough films cast from N,N-dimethylacetamide showed good thermal stability, low dielectric constants of 2.67–2.73 and low water uptakes of 0.21–0.40%. Moreover, the polymers showed good transparency with light transmittance at 450 nm as high as 96% and cutoff wavelength as low as 285 nm. The PAEKs also exhibited low light-absorption at the optocommunication wavelengths of 1310 and 1550 nm.

Synthesis and characterization of poly(ether ether ketone)s and poly(ether ether ketone ketone)s containing pendant biphenyl and naphthyl groups

New poly(ether ether ketone)s (PEEKs) and poly(ether ether ketone ketone)s (PEEKKs) containing pendant biphenyl and naphthyl groups were synthesized by nucleophilic substitution reaction of each of the four bisphenols viz., 1-(4-biphenylyl)-1,1-bis(4-hydroxyphenyl) ethane, 1-(4-biphenylyl)-1,1-bis(3-methyl,4-hydroxyphenyl) ethane, 4,4’-[1-(2-naphthalenyl)ethylidene] bis-phenol and 4,4’-[1-(2-naphthalenyl) ethylidene] bis-3-methylphenol with 4,4’-difluorobenzophenone and 1,3-bis(4–fluorobenzoyl)benzene in a solvent mixture of N,N-dimethylacetamide and toluene in the presence of anhydrous potassium carbonate. Inherent viscosities and number-average molecular weights of polymers were in the range of 0.42–0.86 dl/g and 2.40–7.55 × 104, respectively. PEEKs and PEEKKs were amorphous in nature and were readily soluble in a wide range of organic solvents and could be cast into flexible and tough films from chloroform solution. Glass transition temperature of PEEKs and PEEKKs were in the range of 180°C –200°C. T10 values of PEEKs and PEEKKs were in the range of 424°C–512°C in nitrogen atmosphere, indicating their good thermal stability.

Synthesis, characterization and thermal degradation of phosphorus–nitrogen containing poly(aryl ether ketone)s

A series of high-molecular-weight poly(aryl ether ketone)s with phosphorus and nitrogen on their side and main chains was synthesized by a nucleophilic substitution polycondensation of 6-(4-hydroxyphenyl)pyridazin-3(2 H)-one (HPZ) with 1,1′-bis(4-hydroxyphenyl)-metheylene-bispheny-1-oxophosphine oxide (DOPO-PhOH) and 4, 4′-difluorobenzophenone (DFBP) at various molar ratios. The structures of the poly(aryl ether ketone)s were characterized by means of Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (1H NMR, 31P NMR) and elemental analysis. The influence of the nitrogen- and phosphorus-containing monomer ratio on their thermal stability was investigated by adjusting the proportion of the HPZ and DOPO–PhOH from 0:10 to 8:2. The polymers were readily soluble in polar organic solvents, such as N-methylpyrrolidone (NMP), N, N-dimethylacetamide (DMAc), N, N-dimethylformamide (DMF) and chloroform. Differential scanning calorimetry (DSC) demonstrated that these polymers have an amorphous morphology.