- Ionization of Porous Hypercrosslinked Polymers for Catalyzing Room-Temperature CO2 Reduction via Formamides Synthesis
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Porous materials with heterogeneous nature occupy a pivotal position in the chemical industry. This work described a facile pre- and post-synthetic approach to modify porous hypercrosslinked polymer with quaternary ammonium bromide, rendering it as efficient catalyst for CO2 conversion. The as-prepared porous ionic polymer (PiP@QA) displayed an improved specific surface area of 301 m2·g?1 with hierarchically porous structure, good selective adsorption of CO2, as well as high ion density. Accordingly, PiP@QA catalyst exhibited excellent catalytic performances for the solvent-free synthesis of various formamides from CO2, amines and phenylsilane under 35?°C and 0.5?MPa. We speculated that the superior catalytic efficiency and broad substrate scope of this catalyst could be resulted from the synergistic effect of flexible ionic sites with unique nanoporous channel that might increase the collision probability of reactants and active sites as well as enhance the diffusion of reactants and products during the reaction process. With the good reusability, PiP@QA was also available for the efficient conversion of simulated flue gas (15% CO2 in N2, v/v) into target formamides with quantitative selectivity at room temperature, which further highlighted its industrial application potential in chemical recycling the real-word CO2 to valuable products. Graphic Abstract: [Figure not available: see fulltext.].
- Ren, Qinggang,Chen, Yaju,Qiu, Yongjian,Tao, Leiming,Ji, Hongbing
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p. 2919 - 2927
(2021/02/01)
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- Design of Lewis base functionalized ionic liquids for the N-formylation of amines with CO2 and hydrosilane: The cation effects
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A series of functionalized ionic liquids (ILs) were developed for the reductive functionalization of CO2 with amine and hydrosilane to afford formamides under mild conditions. It was found that 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-based IL i.e. [DBUC12]Br showed high efficiency for the N-formylation reaction of amines without using any organic solvents or additives. Furthermore, control experiments suggested the cations with active hydrogen may weaken the nucleophilicity of anions through ion pairing interactions, thereby affecting the activation of hydrosilane. The reaction mechanism was then investigated by Density Functional Theory (DFT) calculations. This protocol represents a highly efficient and environmentally friendly example for catalytic conversion of CO2 into value-added chemicals such as formamide derivatives by employing DBU functionalized ILs.
- Li, Xiao-Ya,Fu, Hong-Chen,Liu, Xiao-Fang,Yang, Shu-Han,Chen, Kai-Hong,He, Liang-Nian
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p. 563 - 569
(2020/02/05)
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- Tetracoordinate borates as catalysts for reductive formylation of amines with carbon dioxide
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We report sodium trihydroxyaryl borates as the first robust tetracoordinate organoboron catalysts for reductive functionalization of CO2. These catalysts, easily synthesized from condensing boronic acids with metal hydroxides, activate main group element-hydrogen (E-H) bonds efficiently. In contrast to BX3 type boranes, boronic acids and metal-BAr4 salts, under transition metal-free conditions, sodium trihydroxyaryl borates exhibit high reactivity of reductive N-formylation toward a variety of amines (106 examples), including those with functional groups such as ester, olefin, hydroxyl, cyano, nitro, halogen, MeS-, ether groups, etc. The over-performance to catalyze formylation of challenging pyridyl amines affords a promising alternative method to the use of traditional formylation reagents. Mechanistic investigation supports electrostatic interactions as the key for Si/B-H activation, enabling alkali metal borates as versatile catalysts for hydroborylation, hydrosilylation, and reductive formylation/methylation of CO2.
- Du, Chen-Xia,Huang, Zijun,Jiang, Xiaolin,Li, Yuehui,Makha, Mohamed,Wang, Fang,Zhao, Dongmei
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supporting information
p. 5317 - 5324
(2020/09/17)
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- Selective: N-formylation/N-methylation of amines and N-formylation of amides and carbamates with carbon dioxide and hydrosilanes: Promotion of the basic counter anions of the zinc catalyst
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A catalyst composed of commercially available Zn(OAc)2 and 1,10-phenanthroline (phen) was effective in the N-formylation/N-methylation of amines using CO2 as the C1 source in the presence of hydrosilanes. An equimolar reaction of N-methylaniline with PhSiH3 under a CO2 atmosphere yielded the N-formylation product in 92% yield at 25 °C. Scale-up of the reaction using 10 mmol substrate was also successful in affording the desired product in 83% yield (1.1 g). This catalyst exhibits a high thermal stability and a turnover number (TON) of 385000 at 150 °C. In addition, the reaction of N-methylaniline in the presence of excess Ph2SiH2 produced N,N-dimethylaniline. Furthermore, our catalytic protocol was developed for the N-formylation of amides and carbamates, which have smaller pKa values and lower reactivities than the corresponding amines. The present Zn(OAc)2/phen catalyst was found to show versatility in the conversion of CO2 and amines into several functionalized organic chemicals under mild conditions. We propose that the basic counter anion (i.e., the acetate) of the catalyst activates both the Si-H and N-H bonds.
- Zhang, Qiao,Lin, Xiao-Tao,Fukaya, Norihisa,Fujitani, Tadahiro,Sato, Kazuhiko,Choi, Jun-Chul
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supporting information
p. 8414 - 8422
(2020/12/29)
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- Zinc Powder Catalysed Formylation and Urealation of Amines Using CO2 as a C1 Building Block?
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Transformation of CO2 into valuable organic compounds catalysed by cheap and biocompatible metal catalysts is one of important topics of current organic synthesis and catalysis. Herein, we report the zinc powder catalysed formylation and urealation of amines with CO2 and (EtO)3SiH under solvent free condition. Using 2 molpercent zinc powder as the catalyst, a series of secondary amines, both the aromatic ones and the aliphatic ones, can be formylated into formamides. When primary aromatic amines were used as the substrates, the reactions produce urea derivatives. The electronic and steric effects from the substrates on the formylation and urealation reactions were observed and discussed. The recovery and reusability of zinc powder were investigated, showing the zinc powder can be reused in the formylation reaction without loss of catalytic activity. The analysis on the reactants/products mixture after filtering out the zinc powder showed the zinc concentration in the mixture is low to 1 ppm. The pathways for the formylation and urealation of amines with this catalytic system were also investigated, and related to the different substrates.
- Du, Chongyang,Chen, Yaofeng
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p. 1057 - 1064
(2020/06/30)
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- Catalyst-free selective: N -formylation and N -methylation of amines using CO2 as a sustainable C1 source
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We herein describe catalyst-free selective N-formylation and N-methylation of amines using CO2 as a sustainable C1 source. By tuning the reaction solvent and temperature, the selective synthesis of formamides and methylamines is achieved in good to excellent yields using sodium borohydride (NaBH4) as a sustainable reductant.
- Zou, Qizhuang,Long, Guangcai,Zhao, Tianxiang,Hu, Xingbang
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supporting information
p. 1134 - 1138
(2020/03/11)
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- Imidazolium-Salt-Functionalized Covalent Organic Frameworks for Highly Efficient Catalysis of CO2 Conversion
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The conversion of CO2 into valuable chemicals is an ideal pathway for CO2 utilization in industry, although the development of highly efficient catalysts remains a challenge. Herein, the design and synthesis of two covalent organic frameworks (COFs) functionalized with imidazolium salts were reported as catalysts for CO2 conversion. The resultant COFs possessed highly crystalline structures, showed high stability and surface area, and contained dense catalytic active sites on the pore walls. They exhibited outstanding catalytic performances for the reaction of CO2 with epoxides without any solvent or cocatalyst under mild conditions and afforded a record turnover number of 495 000. In addition, the COFs could serve as effective catalysts in the reductive reaction of CO2 with amines. The results presented here thus demonstrate the exceptional potential of the functionalized COFs for various challenging CO2 transformations.
- Qiu, Jikuan,Zhao, Yuling,Li, Zhiyong,Wang, Huiyong,Shi, Yunlei,Wang, Jianji
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p. 2421 - 2427
(2019/05/15)
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- Function-oriented ionic polymers having high-density active sites for sustainable carbon dioxide conversion
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On the basis of the development of function-oriented synthesis (FOS), we presented for the first time an efficient and one-pot construction of functional ionic polymers (FIPs) through the phenol-formaldehyde condensation process (pre-synthetic approach); FIPs had high density of Br?nsted acidic and ionic sites. Considering the electrophilic-nucleophilic dual activation of phenolic hydroxyl groups and bromide anions, the imidazolium-based FIP-Im exhibited high activity for metal-, solvent- and additive-free synthesis of cyclic carbonates from CO2 and epoxides under mild conditions. Then, to obtain higher ionic density and a more flexible skeleton, FIP-Im@QA was also prepared by implanting quaternary ammonium (QA) in the framework of FIP-IMvia the Williamson ether synthesis (post-synthetic modification), which demonstrated high efficiency in the N-formylation reaction of multitudinous secondary amines with CO2 and PhSiH3 at ambient temperature. More interestingly, these function-oriented catalysts were compatible with the target transformation under low CO2 concentration (15% in 85% N2, v/v) and were also reused for more than six times without a significant loss of activity and selectivity. Therefore, this study could not only facilitate the design and construction of FIPs, but also provide sustainable protocols for efficient production of value-added chemicals from CO2 under mild conditions.
- Chen, Yaju,Luo, Rongchang,Bao, Junhui,Xu, Qihang,Jiang, Jun,Zhou, Xiantai,Ji, Hongbing
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supporting information
p. 9172 - 9182
(2018/05/28)
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- Tungstate catalysis: Pressure-switched 2- and 6-electron reductive functionalization of CO2 with amines and phenylsilane
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An efficient and environmentally benign tungstate catalyst for reductive functionalization of CO2 with amines and phenylsilane was developed. By simply varying the pressure, 2-electron or 6-electron reduction of CO2 was successfully achieved with simultaneous C-N bond formation, thus leading to the formation of formamides and methylamines, respectively. That is, secondary and primary amines furnished the corresponding methylamines or dimethylamines in excellent yields under atmospheric pressure of CO2, while various formamides were formed in yields ranging from 52% to 98% when increasing the CO2 pressure to 2 MPa. 1H NMR studies and control experiments demonstrate that N-formylation proceeds through the formation of silyl formate, while N-methylation proceeds through an aminal intermediate generated by 4-electron reduction of CO2.
- Wang, Mei-Yan,Wang, Ning,Liu, Xiao-Fang,Qiao, Chang,He, Liang-Nian
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supporting information
p. 1564 - 1570
(2018/04/12)
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- Catalyst-free: N -formylation of amines using BH3NH3 and CO2 under mild conditions
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The catalyst-free N-formylation of amines using CO2 as the C1 source and BH3NH3 as the reductant has been developed for the first time. The corresponding formylated products of both primary and secondary amines are obtained in good to excellent yields (up to 96% of isolated yield) under mild conditions.
- Zhao, Tian-Xiang,Zhai, Gao-Wen,Liang, Jian,Li, Ping,Hu, Xing-Bang,Wu, You-Ting
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supporting information
p. 8046 - 8049
(2017/07/22)
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- Cooperative Catalytic Activation of Si?H Bonds: CO2-Based Synthesis of Formamides from Amines and Hydrosilanes under Mild Conditions
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A simple cooperative catalytic system was successfully developed for the solvent-free N-formylation of amines with CO2 and hydrosilanes under ambient conditions, which was composed of a Zn(salen) catalyst and quaternary ammonium salt. These commercially available binary components activated the Si?H bonds effectively, owing to the intermolecular synergistic effect between Lewis base and transition metal center (LB–TM), and subsequently facilitated the insertion of CO2 to form the active silyl formats, thereby leading to excellent catalytic performance at a low catalyst loading. Furthermore, the bifunctional Zn(salen) complexes, with two imidazolium-based ionic-liquid (IL) units at the 3,3′-position of salen ligand, acted as intramolecularly cooperative catalysts, and the solvent-regulated separation resulted in facile catalyst recycling and reuse.
- Luo, Rongchang,Lin, Xiaowei,Chen, Yaju,Zhang, Wuying,Zhou, Xiantai,Ji, Hongbing
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p. 1224 - 1232
(2017/03/29)
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- Direct and efficient synthesis of pyrrole-3-carbaldehydes by Vilsmeier-Haack formylation of pyrroles with sterically crowded amides
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A simple and convenient synthetic method to prepare N-substituted pyrrole-3-carbaldehydes by Vilsmeier-Haack formylation of pyrroles using sterically crowded formamides was developed. The dependence of the formylation regioselectivity on steric features of substrates and reagents is discussed. Georg Thieme Verlag Stuttgart · New York.
- Ilyin, Petrv.,Pankova, Alenas.,Kuznetsov, Mikhail A.
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experimental part
p. 1353 - 1358
(2012/07/03)
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- Oxoiminium Ions for N-Demethylation: 1-Oxo-2,2,6,6,-tetramethylpiperidinium Chloride
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In an attempt to assess the synthetic utylity of oxoiminium ions as oxidizing agents and to delineate their reaction mechanisms, we reacted 1-oxo-2,2,6,6-tetramethylpiperidinium chloride (1) with several N,N-dialkylanilines.With N,N-dimethylaniline the only basic product was N-nethylaniline while N- methylformanilide was the only neutral product.The relative amounts of base and neutral product proved to be sensitive to the amount of water present in the reaction medium.With N-alkyl-N-methylanilines, the basic products were N-alkylanilines from exlusive loss of the N-methyl group.The neutral products were the N-alkylformanilides.The alkyl groups studied were ethyl, n-butyl, isopropyl, and benzyl.With N-tert-butyl-N-methylaniline, there was no observed reaction, and N,N-diethylaniline was found to be significantly less reactive than N,N-dimethylaniline.This study has shown that 1 is selective in N-demethylation of anilines in the presence of other alkyl groups either on the same nitrogen or on separate nitrogens.These results have been interpreted in terms of important steric interactions resulting from formation of an adduct en route to an intermediate iminium ion.
- Hunter, Duncan H.,Racok, Julie S.,Rey, Allan W.,Ponce, Yolanda Zea
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p. 1278 - 1281
(2007/10/02)
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