A new monomer, bis[4-(p-phenoxybenzoyl)-1,2-benzenedioyl]-N,N,N′,N′-4,4′-diaminodiphenyl sulfone (BPBDADPS), was prepared by the Friedel–Crafts reaction of bis(4-chloroformyl-1,2-benzenedioyl)-N,N,N′,N′-4,4′-diaminodiphenyl sulfone (BCBDADPS) with diphenyl ether (DPE). Novel poly(aryl ether ketone)s containing sulfone and imide linkages in the main chains (PAEKSI) were synthesized by electrophilic solution polycondensation of terephthaloyl chloride (TPC) with a mixture of DPE and BPBDADPS under mild conditions. The copolymers obtained were characterized by different physico-chemical techniques. The copolymers with 10–30 mol% BPBDADPS are semi-crystalline and had remarkably increased Tg values over commercially available PEEK and PEKK due to the incorporation of sulfone and imide linkages in the main chains. The copolymers III and IV with 20–30 mol% BPBDADPS had not only high Tg values of 180–187 °C, but also moderate Tm values of 338–341 °C, having good potential for the melt processing. The copolymers III and IV had tensile strengths of 100.7–104.2 MPa, Young’s moduli of 2.31–2.44 GPa, and elongations at break of 12.2–14.7% and exhibited high thermal stability and good resistance to organic solvents.
In this work, a density functional theory (DFT) study was performed to identify the catalytically active species in the copper-catalyzed three-component reductive hydroxymethylation of styrene with CO2 and hydrosilane. The calculations reveal that the dimeric copper(I) hydride species, formed in a mixture of the bisphosphine ligand, Cu(OAc)2, and hydrosilane, probably acts as the catalyst precursor. In the beginning, this species is catalytically competent to trigger the hydrocupration of styrene, along with the formation of the dimeric copper(I) alkyl intermediate. Subsequently, CO2 insertion into the dimeric copper(I) alkyl intermediate occurs, which is accompanied by the cleavage of the Cu–Cu bond and the generation of the monomeric copper(I) carboxylate intermediate. In the end, the sequential reduction of the monomeric copper(I) carboxylate intermediate with the hydrosilane produces the monomeric copper(I) hydride species as the actual catalyst and turns on the catalytic cycle. On the other hand, the monomeric copper(II) hydride species, yielded as the kinetic product in the initial reaction of the bisphosphine ligand, Cu(OAc)2, and hydrosilane, is also reactive for the hydrocupration of styrene. However, the resulting monomeric copper(II) alkyl intermediate is found to be the catalyst resting state, because of the much higher energy barrier demanded for the subsequent nucleophilic attack toward CO2. On the basis of the results of an activation-strain model (ASM) analysis and charge decomposition analysis (CDA), the low activity of the monomeric copper(II) alkyl intermediate can be ascribed to the more crowded environment around the central copper(II) ion and the weaker nucleophilicity of the alkyl moiety. Furthermore, all of the possible CuH species generated in the system are competent to promote the two-component hydrosilylation of CO2 with hydrosilane, which is an inevitable side reaction along with the reductive hydroxymethylation of styrene with CO2 and hydrosilane.
A new monomer containing naphthalene, 2,6-bis( β -naphthoxy)benzonitrile (BNOBN) was synthesized by reaction of β -naphthol with 2,6-difluorobenzonitrile in N-methyl-2-pyrrolidone (NMP) in the presence of KOH and K 2 CO 3 . Novel copolymers of poly(ether ketone ketone) and poly(ether ether ketone ketone) containing naphthalene moieties and pendant cyano groups were prepared by electrophilic Friedel—Crafts solution copolycondensation of terephthaloyl chloride (TPC) with varying mole proportions of diphenyl ether and 2,6-bis( β -naphthoxy)benzonitrile (BNOBN) using 1,2-dichloroethane as solvent and NMP as Lewis base in the presence of anhydrous AlCl 3 . The crystallinity and melting temperatures of the polymers were found to decrease as the concentration of BNOBN in the polymer increased, whereas the glass transition temperatures of the polymers increased as the concentration of BNOBN in the polymer increased. The copolymers with 20—25 mol% BNOBN had high T g values of 182—184 ° C; moderate T m values of 324—335 ° C; tensile strengths of 101.8—103.2 MPa, Young’s moduli of 3.14—3.23 GPa, and elongations at break of 15—18%. The copolymers exhibited outstanding thermal stability and good resistance to organic solvents, acidity and alkali.
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