4714-63-0Relevant articles and documents
A highly efficient Co-based catalyst fabricated by coordination-assisted impregnation strategy towards tandem catalytic functionalization of nitroarenes with various alcohols
Li, Guangming,Li, Jingfang,Li, Weizuo,Li, Xuewei,Li, Zhibin,Mao, Guijie,She, Wei,Wang, Jing
, p. 462 - 474 (2021/11/11)
A well-defined hexamethylenetetramine (abbreviated as HMTA) based two-dimensional (2D) MOFs metalloligand (termed Zn-HMTA), with free uncoordinated tertiary amine groups, has been synthesized via solution diffusion method for the first time. The crystal structure of 2D Zn-HMTA metalloligand was determined by the single crystal X-ray diffraction (SCXRD). The SCXRD and X-ray photoelectron spectroscopy (XPS) analyses have revealed that the 2D Zn-HMTA metalloligand is rich in- free tertiary amine groups, which are of strong coordination ability to transition metal ions (e.g. Ni2+, Co2+, Zn2+, Cu2+). As a result, a 2D bimetallic Co@Zn-HMTA MOFs was synthesized via coordination-assisted impregnation (CAI) strategy attributed to the unique feature of strong coordinated ability of free tertiary amine groups. Furthermore, a series of self-supported Co-ZnO-CN nanocatalysts were afforded upon the as-synthesized Co@Zn-HMTA MOFs served as a self-sacrificial template for pyrolysis at different temperatures. The optimized catalyst (termed as Co-ZnO@CN-CAI) demonstrated the excellent catalytic performance for hydrogenation-alkylation tandem reaction in comparison with the classic ZnO@CN composite (derived from Zn-HMTA MOFs) supported metallic Co catalyst (Co-ZnO@CN-IWI) prepared by incipient wetness impregnation method. Moreover, the kinetic study was also performed to confirm that the alkylation is the rate-determining step in the hydrogenation-alkylation tandem reaction. The origin of enhanced catalytic performance of Co-ZnO@CN-CAI and the role of Co@Zn-HMTA MOFs precursor have been explored by way of various characterizations, e.g. HADDF-STEM-EDS, SEM-EDS, 13C MAS NMR, XRD, Raman and XPS, etc. It is anticipated that the prepared low-cost and easily prepared 2D Zn-HMTA metalloligand will become a general template for synthesis of highly self-supported catalysts with coordination-assisted impregnation strategy (CAI) for various catalytic reactions.
A strategy of two-step tandem catalysis towards direct N-alkylation of nitroarenes with ethanol via facile fabricated novel Co-based catalysts derived from coordination polymers
Wang, Jing,Qi, Tianqinji,Li, Zhibin,She, Wei,Li, Xuewei,Li, Jingfang,Yan, Pengfei,Li, Weizuo,Li, Guangming
, p. 106 - 118 (2019/07/19)
Three novel N-doped carbon supported Co/Co3O4 catalysts, namely, Co@CN-hmta, Co@CN-larg and Co-Co3O4@CN-bipy, with sheet-, worm-, honeycomb-like morphologies respectively, have been fabricated by the pyrolysis of well-defined coordination polymers (CPs). Upon the as-prepared catalysts were applied for the reaction of N-alkylation of nitroarenes with ethanol, a direct two-step tandem reaction is realized, in which the Co@CN-hmta delivers 100% conversion/selectivity of N-ethylaniline/N,N-diethylaniline from the direct N-alkylation of nitroarenes with ethanol. The kinetic studies were conducted to confirm that the N-alkylation of aniline with ethanol is the rate-determining step in the two-step tandem reaction. The SEM/EDX, XRD, Raman, TEM, XPS, and CO2-TPD characterization results have revealed that sizes and dispersion of metallic Co, amount of structural defects and surface Lewis basicity towards three catalysts can be tuned by changing the structures of Co-based CPs designed by different organic linkers, which may also help to understand the preparation of industrial catalysts on a molecular level. The optimized Co@CN-hmta catalyst is easily recycled by using the external magnet for successive reuses without any loss in both activity and selectivity. To the best of our knowledge, this is the first carbon-nitrogen species supported Co/Co3O4 catalysts derived from the CPs, which could effectively catalyzed the N-alkylation of nitroarenes with ethanol to produce the secondary amines and/or tertiary amines. This low-cost, recyclable and easy scale-up N-doped carbon supported catalyst may be of potential application in various heterogeneous catalytic reactions.
Selective Synthesis of Secondary and Tertiary Amines by Reductive N-Alkylation of Nitriles and N-Alkylation of Amines and Ammonium Formate Catalyzed by Ruthenium Complex
Alshakova, Iryna D.,Nikonov, Georgii I.
, p. 5370 - 5378 (2019/06/14)
A new ruthenium catalytic system for the syntheses of secondary and tertiary amines via reductive N-alkylation of nitriles and N-alkylation of primary amines is proposed. Isomeric complexes 8 catalyze transfer hydrogenation and N-alkylation of nitriles in ethanol to give secondary amines. Unsymmetrical secondary amines can be produced by N-alkylation of primary amines with alcohols via the borrowing hydrogen methodology. Aliphatic amines were obtained with excellent yields, while only moderate conversions were observed for anilines. Based on kinetic and mechanistic studies, it is suggested that the rate determining step is the hydrogenation of intermediate imine to amine. Finally, ammonium formate was applied as the amination reagent for alcohols in the presence of ruthenium catalyst 8. Secondary amines were obtained from primary alcohols within 24 hours at 100 °C, and tertiary amines can be produced after prolonged heating. Secondary alcohols can only be converted to secondary amines with moderate yield. Based on mechanistic studies, the process is suggested to proceed through an ammonium alkoxy carbonate intermediate, where carbonate acts as an efficient leaving group.
