Palladium-Catalysed Reactions in Water Using Catalysts Covalently Tethered on a Thermo-responsive Polymer Noriyuki Suzuki,* Nozomu Ebara, Rikito Arai, Chirika Takahashi, Tsai-Yu Hung, Yuko Takeoka, Masahiro Rikukawa, Yukie Yokota, Fu-Yu Tsai,* Catalysis Science & Technology, 2025, in press. DOI: 10.1039/D4CY01108B |
Abstract: Bidentate N,N-ligand moieties were covalently tethered on a RAFT agent by H?isgen cycloaddition, and poly(N-isopropylacrylamide) (PNIPAAm) bearing the ligand moiety was obtained by living-radical polymerization using these RAFT agents. The polymer formed a palladium complex covalently immobilized at the terminus of each polymer chain. Palladium-catalysed Mizoroki-Heck and Suzuki-Miyaura cross coupling reactions proceeded in water with these polymer-immobilized Pd catalysts. The products were obtained in good yields and the aqueous layer containing the polymer catalysts could be reused. Electron microscopic analysis suggested that palladium nanoparticles formed during the reaction were responsible for the catalytic activity. Using an NNC-pincer Pd complex tethered on the polymer, the catalytic reaction was completed with 0.01 mol% of Pd loading. The aqueous solution could be reused 8 times, and a turnover number (TON) of up to 82,800 was achieved. |
![]() ![]() |
温度応答性ポリマーに固定化した触媒を用いる水中でのパラジウムによる触媒反応 Noriyuki Suzuki,* Nozomu Ebara, Rikito Arai, Chirika Takahashi, Tsai-Yu Hung, Yuko Takeoka, Masahiro Rikukawa, Yukie Yokota, Fu-Yu Tsai,* Catalysis Science & Technology, 2025, in press. DOI: 10.1039/D4CY01108B |
N,N-二座配位子部位をRAFT剤上に固定化することにより、配位子を有するポリ(N-イソプロピルアクリルアミド) (PNIPAAm)を得た。このポリマー鎖の末端にパラジウム錯体を形成し、これらのポリマー固定化Pd触媒を用いて溝呂木-Heck反応および鈴木-宮浦クロスカップリング反応を水中でおこなった。生成物が良好な収率で得られ、ポリマー触媒を含む水層を再利用することができた。電子顕微鏡分析等により、反応中に形成されたパラジウムナノ粒子が触媒活性を担っていることが示唆された。NNC-ピンサーPd錯体をポリマー上に固定した系では、0.01 mol%のPd触媒により反応が進行し触媒水溶液の再利用により82,800の回転数(TON)を達成した。 |