PFASを分解する新規触媒を開発（PFAS: A Novel Path to Breaking Down “Forever Chemicals”）

2025-06-13

2025-06-12 ゲーテ大学

New catalyst splits C-F bonds: Two boron atoms (green spheres) are embedded in a framework of carbon atoms (black). The electrons required for C-F cleaving currently still come from lithium (pink), in future from electric current. Image: Group of Matthias Wagner, Goethe University Frankfurt

フランクフルト大学のワグナー教授らの研究チームは、環境残留性が高いPFAS（フォーエバーケミカル）の強固なC–F結合を、室温かつ数秒で切断できる新しい触媒を開発しました。この触媒はプラチナやパラジウムといった高価・有害な重金属を使用せず、安価で環境に優しいのが特徴です。技術はPFAS汚染の浄化だけでなく、医薬品合成など多用途への応用が期待されています。

＜関連情報＞

平面性は平坦ではない構造的に拘束された二重還元アリールボランのフルオロベンゼンに対する閉殻反応性と開殻反応性 Planarity Is Not Plain: Closed- vs Open-Shell Reactivity of a Structurally Constrained, Doubly Reduced Arylborane toward Fluorobenzenes

Christoph D. Buch,Alexander Virovets,Eugenia Peresypkina,Burkhard Endeward,Hans-Wolfram Lerner,Felipe Fantuzzi,Shigehiro Yamaguchi,and Matthias Wagner
Journal of the American Chemical Society Published: May 29, 2025
DOI:https://doi.org/10.1021/jacs.5c05588

Abstract

The ability to activate small molecules is imparted to 9,10-dihydro-9,10-diboraanthracenes (DBAs) through the injection of two electrons. We report on the activation of fluorobenzenes C₆F_nH_6–n by the doubly reduced, structurally constrained DBA [1]^2– in THF (n: 1,3,4,5,6). Compound 1 is a 9,10-diphenyl DBA, forced into planarity by methylene bridges between the phenyl substituents and the DBA core. This rigidity results in enhanced stability under ambient conditions and an elevated planar-to-pyramidal reorganization energy upon boron tetracoordination, unlocking new reactivity. The dianion salts M₂[1] were synthesized in excellent yields by stirring neutral 1 with alkali metals M in THF (M: Li, Na, K); comproportionation of Li₂[1] with 1 generates the blue radical salt Li[1], characterized by EPR spectroscopy and X-ray diffraction. While Li₂[1] is inert toward C₆FH₅ up to 120 °C, it reacts with 1,3,5-C₆F₃H₃ at 100 °C to yield a B(sp²)/B(sp³) adduct with a difluorophenyl ligand (Li[2]). Treatment of Li₂[1] with 1 eq. of C₆F₅H or C₆F₆ induces selective monohydrodefluorination, occurring in parallel with the formation of a unique B(sp²)/B(sp³) tetrahydrofuran-2-yl adduct (Li[3]). The three isomers of C₆F₄H₂ represent intermediate cases, where the competition between trifluorophenyl- and tetrahydrofuran-2-yl-adduct formation is governed by the relative positions of the F substituents and the nature of the countercation (M⁺: Li⁺, K⁺). Through experimental and quantum-chemical studies, we unveil the underlying reaction mechanisms and show that Li₂[1] acts either as a B-centered nucleophile in an S_NAr-type conversion (low benzene fluorination) or as a reducing agent in a single-electron transfer/H atom abstraction sequence (high benzene fluorination).