19028-72-9Relevant articles and documents
Manganese(ii) Schiff-base-mediated reversible deactivation controlled radical polymerization of vinyl acetate
Hashimoto, Patricia K.,Oliveira, Larissa F.,Riga-Rocha, Beatriz A.,MacHado, Antonio E. H.,Santana, Vinicius T.,Nascimento, Otaciro R.,Carvalho-Jr, Valdemiro P.,Goi, Beatriz E.
, p. 10109 - 10117 (2021)
A series of new manganese(ii) complexes were prepared with three bidentate Schiff-base ligands derived by condensation of salicylaldehyde and different cycloalkylamines (cycloalkyl = cyclopentyl, cyclohexyl, and cycloheptyl): [Mn(CyPen-Salicyl)2] (1), [Mn(CyHex-Salicyl)2] (2), and [Mn(CyHep-Salicyl)2] (3). The complexes 1-3 were characterized by FTIR, UV-vis and EPR spectroscopy, elemental analysis, cyclic voltammetry, and computational methods. The manganese(ii) complexes (1-3) were used as controlling agents for the polymerization of vinyl acetate (VAc) initiated by AIBN according to an organometallic-mediated radical polymerization (OMRP) mechanism. The VAc polymerization mediated by the Mn complexes suggests that the control level can be slightly tuned through substitution of the cycloalkyl group on the Schiff-base ligand. Kinetics studies and computational investigations support an RT mechanism and a tailorable Mn complex reactivity mainly altered by steric factors of the Schiff-base ligands. The calculated thermodynamic parameters agree with the mediating ability of these complexes, since the degree of polymerization control decreases with increasing steric hindrance of the Schiff-base ligands, as well as with increasing ΔG values for the formation of dormant species.
Catalyst-free direct ring-opening of cyclic aldimines with aliphatic primary amines to construct o-hydroxy schiff bases
Cao, Zubin,Ding, Qiuyue,Han, Dongyun,Li, Feng,Wang, Jingjing,Wu, Ziyan,Zhai, Hanhui
supporting information, (2022/01/28)
We firstly describe a catalyst-free direct ring-opening of cyclic aldimines with abundant aliphatic primary amines to construct o-hydroxy schiff bases under mild reaction conditions. The corresponding products were generated in good to excellent yields (80–99%). In addition, a gram-scale reaction and further application of the reaction strategy were performed.
Hydrogen-Bond Catalysis of Imine Exchange in Dynamic Covalent Systems
Schaufelberger, Fredrik,Seigel, Karolina,Ramstr?m, Olof
supporting information, p. 15581 - 15588 (2020/10/02)
The reversibility of imine bonds has been exploited to great effect in the field of dynamic covalent chemistry, with applications such as preparation of functional systems, dynamic materials, molecular machines, and covalent organic frameworks. However, acid catalysis is commonly needed for efficient equilibration of imine mixtures. Herein, it is demonstrated that hydrogen bond donors such as thioureas and squaramides can catalyze the equilibration of dynamic imine systems under unprecedentedly mild conditions. Catalysis occurs in a range of solvents and in the presence of many sensitive additives, showing moderate to good rate accelerations for both imine metathesis and transimination with amines, hydrazines, and hydroxylamines. Furthermore, the catalyst proved simple to immobilize, introducing both reusability and extended control of the equilibration process.
