Yumiko Nakajima
@aist.go.jp
National Institute of Advanced Industrial Science and Technology (AIST)
RESEARCH INTERESTS
organometallics coordination chemistry silicon chemistry
Scopus Publications
Scopus Publications
Yasunori Minami, Sae Imamura, Nao Matsuyama, Yumiko Nakajima, and Masaru Yoshida
Springer Science and Business Media LLC
AbstractAs the effective use of carbon resources has become a pressing societal issue, the importance of chemical recycling of plastics has increased. The catalytic chemical decomposition for plastics is a promising approach for creating valuable products under efficient and mild conditions. Although several commodity and engineering plastics have been applied, the decompositions of stable resins composed of strong main chains such as polyamides, thermoset resins, and super engineering plastics are underdeveloped. Especially, super engineering plastics that have high heat resistance, chemical resistance, and low solubility are nearly unexplored. In addition, many super engineering plastics are composed of robust aromatic ethers, which are difficult to cleave. Herein, we report the catalytic depolymerization-like chemical decomposition of oxyphenylene-based super engineering plastics such as polyetheretherketone and polysulfone using thiols via selective carbon–oxygen main chain cleavage to form electron-deficient arenes with sulfur functional groups and bisphenols. The catalyst combination of a bulky phosphazene base P4-tBu with inorganic bases such as tripotassium phosphate enabled smooth decomposition. This method could be utilized with carbon- or glass fiber-enforced polyetheretherketone materials and a consumer resin. The sulfur functional groups in one product could be transformed to amino and sulfonium groups and fluorine by using suitable catalysts.
Kosuke Iizuka, Yoshifumi Maegawa, Yoshihiro Shimoyama, Kei Sakamoto, Natsuko Kayakiri, Yasutomo Goto, Yuki Naganawa, Shinji Tanaka, Masaru Yoshida, Shinji Inagaki,et al.
Wiley
AbstractPhosphine periodic mesoporous organosilicas (R‐P‐PMO‐TMS: R=Ph, tBu), which possess electron‐donating alkyl substituents on the phosphorus atom, were synthesized using bifunctional compounds with alkoxysilyl‐ and phosphino groups, bis[3‐(triethoxysilyl)propyl]phenylphosphine borane (1 a) and bis[3‐(triethoxysilyl)propyl]‐tert‐butylphosphine borane (1 b). Immobilization of Pd(0) species was performed to give R‐P‐Pd‐PMO‐TMS: R=Ph (2 a), tBu (3 a), respectively. The Pd(0) immobilized 2 a and 3 a were applicable as catalysts for Suzuki‐Miyaura cross‐coupling reactions of aryl chlorides with phenylboronic acid. It was revealed that 3 a bearing more electron‐donating tBu groups exhibited higher catalytic activity. Various functional groups including both electron withdrawing and donating substituents were compatible in the system. The recyclability of 3 a was examined to support its moderate utility for the recycle use.
Yoshihiro Shimoyama and Yumiko Nakajima
Wiley
AbstractPoly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) is one of the most important engineering plastics commonly utilized in various fields. Herein, chemical recycling of PPO was performed via oxidative depolymerization to form 2,6‐diemthyl‐p‐benzoquionone (26DMBQ) as a sole aromatic product in 66 % yield using nitronium ions (NO2+) as a mild oxidant. Mechanistic studies revealed that PPO is oxidized by NO2+ generated from the combination of a silicotungstic acid and nitrate salts, and then subsequently attacked by H2O to achieve C−O bond cleavage, resulting in the formation of 26DMBQ, which was sublimed at the headspace of the reaction vessel in pure form. 26DMBQ was applied to polymerization with dianilines to form polyimides. Thus, an upgrade recycling process of PPO was demonstrated.
Heng Zhang, Yoshihiro Shimoyama, and Yumiko Nakajima
Royal Society of Chemistry (RSC)
Hydrogenolysis of benzyl benzoate derivatives via β-C–O cleavage was achieved with atmospheric pressure H2 using a Co(i) catalyst bearing a phenanthroline-based PNNP ligand (2,9-bis((diphenylphosphanyl)methyl)-1,10-phenanthroline).
Yasunori Minami, Nao Matsuyama, Yasuo Takeichi, Ryota Watanabe, Siby Mathew, and Yumiko Nakajima
Springer Science and Business Media LLC
AbstractSuper engineering plastics, high-performance thermoplastic resins such as polyetheretherketone, and polyphenylene sulfide have been utilized in industries, owing to their high thermal stability and mechanical strength. However, their robustness hinders their depolymerization to produce monomers and low-weight molecules. Presently, chemical recycling for most super engineering plastics remains relatively unexplored. Herein, we report the depolymerization of insoluble polyetheretherketone using sulfur nucleophiles via carbon–oxygen bond cleavages to form benzophenone dithiolate and hydroquinone. Treatment with organic halides converted only the former products to afford various dithiofunctionalized benzophenones. The depolymerization proceeded as a solid–liquid reaction in the initial phase. Therefore, this method was not affected by the shape of polyetheretherketone, e.g., pellets or films. Moreover, this depolymerization method was applicable to carbon- or glass fiber-enforced polyetheretherketone material. The depolymerized product, dithiofunctionalized benzophenones, could be converted into diiodobenzophenone, which was applicable to the polymerization.
Yasunori Minami, Yuuki Inagaki, Tomoo Tsuyuki, Kazuhiko Sato, and Yumiko Nakajima
American Chemical Society (ACS)
Super engineering plastics, high-performance thermoplastic resins, show high thermal stability and mechanical strength as well as chemical resistance. On the other hand, chemical recycling for these plastics has not been developed due to their stability. This study describes depolymerization of oxyphenylene super engineering plastics via carbon–oxygen main chain cleaving hydroxylation reaction with an alkali hydroxide nucleophile. This method is conducted with cesium hydroxide as a hydroxy source and calcium hydride as a dehydration agent in 1,3-dimethyl-2-imidazolidinone, which provides hydroxylated monomers effectively. In the case of polysulfone, both 4,4′-sulfonyldiphenol (bisphenol S) and 4,4′-(propane-2,2-diyl)diphenol (bisphenol A) were obtained in high yields. Other super engineering plastics such as polyethersulfone, polyphenylsulfone, and polyetheretherketone were also applicable to this depolymerization.
Hajime Kameo, Yudai Tanaka, Yoshihiro Shimoyama, Daisuke Izumi, Hiroyuki Matsuzaka, Yumiko Nakajima, Pierre Lavedan, Arnaud Le Gac, and Didier Bourissou
Wiley
A T-shaped Pt(0) complex with a diphosphine-borane (DPB) ligand was prepared. The Pt→B interaction enhances the electrophilicity of the metal and triggers the addition of Lewis bases to give the corresponding tetracoordinate complexes. For the first time, anionic Pt(0) complexes are isolated and structurally authenticated. X-ray diffraction analyses show the anionic complexes [(DPB)PtX]- (X = CN, Cl, Br, I) to be square-planar. The d10 configuration and Pt(0) oxidation state of the metal were unambiguously established by X-ray photoelectron spectroscopy and DFT calculations. The coordination of Lewis acids as Z-type ligands is a powerful mean to stabilize elusive electron-rich metal complexes and achieve uncommon geometry.
Siby Mathew, Yuki Naganawa, Fan Jiang, Raphael Wischert, Stephane Streiff, Pascal Metivier, and Yumiko Nakajima
Wiley
Placement of phosphorus in the polymer main chain leads to organophosphorus polymers with potentially unique chemical and physical properties. Here, we demonstrate that the Abramov phosphonylation reaction can be extended to the synthesis of such polymers, by reacting di- or tricarbaldehydes with phosphinic acid (PA) in the presence of N,O-bis(trimethylsilyl)acetamide (BSA). This technique affords polymers with main chain PࣿC bonds, wherein phosphorus(V), aromatic rings, and hydroxymethylene moieties are linked by bis(α-hydroxymethylene)phosphinic acid (BHMPA) units. The resulting polymers are water soluble, display resilience against acid- and base- catalyzed hydrolysis, and exhibit superior thermal stability with high char yield in air (∼83%) and nitrogen (∼76%) atmosphere. This article is protected by copyright. All rights reserved.
Yuki Naganawa, Akira Fujita, Kei Sakamoto, Shinji Tanaka, Kazuhiko Sato, and Yumiko Nakajima
American Chemical Society (ACS)
Shinji Tanaka, Maito Koga, Takashi Kuragano, Atsuko Ogawa, Hibiki Ogiwara, Kazuhiko Sato, and Yumiko Nakajima
American Chemical Society (ACS)
Yuki Naganawa, Hajime Kameo, and Yumiko Nakajima
The Society of Synthetic Organic Chemistry, Japan
Takashi Komuro, Yumiko Nakajima, Jun Takaya, and Hisako Hashimoto
Elsevier BV
Kosuke Iizuka, Yumiko Nakajima, and Kazuhiko Sato
Royal Society of Chemistry (RSC)
Heterolytic cleavage of a Si–H bond was achieved mediated by a metal–ligand cooperation of a cationic iridium amido complex. The reaction was applied to the catalytic hydrosilylation of benzaldehyde and its derivatives.
Shinji Tanaka, Shingo Takada, Tohru Suzuki, Yumiko Nakajima, and Kazuhiko Sato
American Chemical Society (ACS)
Nai-Yuan Jheng, Yusuke Ishizaka, Yuki Naganawa, Yasunori Minami, Akira Sekiguchi, Kosuke Iizuka, and Yumiko Nakajima
American Chemical Society (ACS)
Yuki Naganawa, Yumiko Nakajima, Shigeyoshi Sakaki, and Hajime Kameo
Wiley
Shinji Tanaka, Yumiko Nakajima, Atsuko Ogawa, Takashi Kuragano, Yoshihiro Kon, Masanori Tamura, Kazuhiko Sato, and Christophe Copéret
Royal Society of Chemistry (RSC)
We demonstrated that DNP-enhanced NMR spectroscopy enables the direct and detailed characterization of polymer-supported alkylammonium catalysts.
Shinji Tanaka, Junichi Sato, and Yumiko Nakajima
Royal Society of Chemistry (RSC)
A strategy of capturing ethylene glycol with dimethyl carbonate in the catalytic methanolysis of polyethylene terephthalate enabled depolymerization at ambient temperature.
Koya Inomata, Yuki Naganawa, Zhi An Wang, Kei Sakamoto, Kazuhiro Matsumoto, Kazuhiko Sato, and Yumiko Nakajima
Springer Science and Business Media LLC
AbstractThe transition-metal-catalysed hydrosilylation reaction of alkenes is one of the most important catalytic reactions in the silicon industry. In this field, intensive studies have been thus far performed in the development of base-metal catalysts due to increased emphasis on environmental sustainability. However, one big drawback remains to be overcome in this field: the limited functional group compatibility of the currently available Pt hydrosilylation catalysts in the silicon industry. This is a serious issue in the production of trichloro(3-chloropropyl)silane, which is industrially synthesized on the order of several thousand tons per year as a key intermediate to access various silane coupling agents. In the present study, an efficient hydrosilylation reaction of allyl chloride with trichlorosilane is achieved using the Rh(I) catalyst [RhCl(dppbzF)]2 (dppbzF = 1,2-bis(diphenylphosphino)-3,4,5,6-tetrafluorobenzene) to selectively form trichloro(3-chloropropyl)silane. The catalyst enables drastically improved efficiency (turnover number, TON, 140,000) and selectivity (>99%) to be achieved compared to conventional Pt catalysts.
Monika Gautam, Shinji Tanaka, Akira Sekiguchi, and Yumiko Nakajima
American Chemical Society (ACS)
Yasunori Minami, Yumiko Nakajima, Nao Matsuyama, Yasuaki Matsuo, Masanori Tamura, and Kazuhiko Sato
Georg Thieme Verlag KG
AbstractThe solvent-insoluble poly(phenylene sulfide) main chain was reductively cleaved by using triethylsilane as a hydrogen source under palladium/IcHex catalytic conditions. After the reaction, benzene and bis(triethylsilyl) sulfide as a sulfide source were formed efficiently. This method could be operated on a gram scale.
Yumiko Nakajima, Tomohiro Takeshita, and Nai-Yuan Jheng
Royal Society of Chemistry (RSC)
A metal–ligand cooperation (MLC) behavior was investigated using Iron and cobalt complexes bearing a phenanthroline-based meridional PNNP ligand, demonstrating a unique long-range MLC, where the phenanthroline backbone behaves as a H2 reservoir.
Yasunori Minami, Hitomi Miyamoto, and Yumiko Nakajima
Wiley
Furfural and its derivatives underwent alkenylation with alkynes via α‐C−H activation in the presence of a palladium/carboxylic acid catalyst to give the corresponding single and double alkenylated products. The reactive aldehyde group remained intact during this reaction. This catalytic system allowed selective alkenylation of furan substrates having electron‐withdrawing substituents.
Yuki Naganawa, Kei Sakamoto, and Yumiko Nakajima
American Chemical Society (ACS)
Direct catalytic transformation of chlorosilanes into organosilicon compounds remains challenging due to difficulty in cleaving the strong Si-Cl bond(s). We herein report the palladium-catalyzed cross-coupling reaction of chlorosilanes with organoaluminum reagents. A combination of [Pd(C3H5)Cl]2 and DavePhos ligand catalyzed the selective methylation of various dichlorosilanes 1, trichlorosilanes 5, and tetrachlorosilane 6 to give the corresponding monochlorosilanes.
Nai-Yuan Jheng, Yusuke Ishizaka, Yuki Naganawa, Akira Sekiguchi, and Yumiko Nakajima
Royal Society of Chemistry (RSC)
A cobalt(i) alkyl complex bearing a tetradentate phenanthroline-based PNNP ligand undergoes dearomatization of the ligand backbone skeleton upon heating and furthermore achieves H–H bond cleavage.