Radical copolymerization of N-alkylmaleimides with isobutene and the properties of the resulting alternating copolymers

Radical copolymerization of N-methylmaleimide (MeMI) as well as other N-alkylmaleimides (RMI) and isobutene (IB) was carried out with 2,2′-azobis(isobutyronitrile) as an initiator at 60°C. The initial rate of the copolymerization (R_p) was dependent on the monomer composition and was maximum at the 40 mol % of MeMI in the feed. A solvent effect on the R_p and the monomer reactivity ratio was observed in this copolymerization system, i.e., copolymerization in chloroform produced a higher R_p and an alternating tendency compared with those in dioxane (r_MeMI = 0.14, r_1B = 0 in chloroform and r_MeMI = 0.47, r_1B = 0 in dioxane). The alternating copolymer of RMI and IB shows a high glass transition temperature (T_g) and excellent thermal stability, e.g., the T_g and the thermal decomposition temperature (T_d) were 152 and 363°C, respectively, for the alternating copolymer of MeMI and IB. Both the T_g and T_d increased as the concentration of the MeMI unit in the copolymers increased. Colorless transparent sheets were obtained from press molding the alternating copolymers. They showed excellent mechanical and optical properties. © 1996 John Wiley & Sons, Inc.     

Detailed mechanism of radical high polymerization of sterically hindered dialkyl fumarates

The radical polymerization kinetics and mechanism of sterically hindered dialkyl fumarates (DRF) bearing various ester alkyl groups are described comprehensively. The overall polymerization reactivity of DRF, the initiation mechanism and the reactivity of the primary radicals in the polymerizations with azo initiators, the determination of the propagation and termination rate constants by means of electron spin resonance spectroscopy, the propagation mechanism and the microstructure of the polymers, and the chain rigidity of poly(DRF) and bimolecular termination process are discussed.     

O2/n2-separation by polymer-bound cobalt complexes

Facilitated or complexation-mediated transport of oxygen in the solid membrane containing a fixed carrier was described, by using the polymer-bound cobalt Schiff's base chelate (CoS) and cobaltporphyrin (CoP). α³ β-Substituted cobaltporphyrin derivatives were synthesized: The oxygen-binding reaction to cobalt was affected by the cavity structure on porphyrin, i.e., unbulky amido-substituted groups such as acetylamido- and acrylamido-substituents enhanced oxygen-binding and -dissociation rate constant or provided an oxygen-binding pathway. Oxygen transport through the membranes of these polymer-bound CoP derivatives was selectively augmented due to the rapid and reversible oxygen-binding. Diffusion constants via the fixed CoPs correlated to the characteristics of oxygen-binding reaction.     

Effects of Roxadustat on Erythropoietin Production in the Rat Body

Anemia is a major complication of chronic renal failure. To treat this anemia, prolylhydroxylase domain enzyme (PHD) inhibitors as well as erythropoiesis-stimulating agents (ESAs) have been used. Although PHD inhibitors rapidly stimulate erythropoietin (Epo) production, the precise sites of Epo production following the administration of these drugs have not been identified. We developed a novel method for the detection of the Epo protein that employs deglycosylation-coupled Western blotting. With protein deglycosylation, tissue Epo contents can be quantified over an extremely wide range. Using this method, we examined the effects of the PHD inhibitor, Roxadustat (ROX), and severe hypoxia on Epo production in various tissues in rats. We observed that ROX increased Epo mRNA expression in both the kidneys and liver. However, Epo protein was detected in the kidneys but not in the liver. Epo protein was also detected in the salivary glands, spleen, epididymis and ovaries. However, both PHD inhibitors (ROX) and severe hypoxia increased the Epo protein abundance only in the kidneys. These data show that, while Epo is produced in many tissues, PHD inhibitors as well as severe hypoxia regulate Epo production only in the kidneys.     

Ir(III)‐Catalyzed C7‐Position‐Selective Oxidative CH Alkenylation of Indolines with Alkenes in Air

An efficient method for C7‐position‐selective alkenylation of N‐substituted indolines with alkenes is reported. Various 7‐alkenylindolines were obtained in moderate to excellent yields in air in the presence of catalytic amounts of [Cp*IrCl₂]₂, AgOTf, and Cu(OAc)₂. The protocol relies on the use of a carbonyl or carbamoyl group on the nitrogen atom of indoline as a directing group and is potentially applicable to the synthesis of 7‐alkenylindoles and 7‐alkylindoles.