Facile synthesis of N-doped graphene encapsulated Pd@N/C catalyst and its efficient application in cascade flow synthesis of amines

doi:10.21203/rs.3.rs-763165/v1

Download PDF

Article

Facile synthesis of N-doped graphene encapsulated Pd@N/C catalyst and its efficient application in cascade flow synthesis of amines

https://doi.org/10.21203/rs.3.rs-763165/v1

This work is licensed under a CC BY 4.0 License

Version 1

posted

You are reading this latest preprint version

N-methylamines, as an important class of chemicals, crucial building blocks, have been widely used in pharmaceutical companies and materials synthesis. Transition metal-catalyzed synthesis of N-methylamines, especially the heterogeneous catalyzed N-methylation of amines via different C1 sources has become the most promising methodology, due to the environmentally friendlier process and the recyclable and easily accessible catalysts. However, these reactions generally require activated toxic methyl iodide or dimethyl sulfoxide, and homogeneous catalysts or Raney nickel catalyst. The synthesis of amines still suffering from narrow scopes of amines, harsh reaction conditions, low selectivity of the desired products, and against the requirements of atomic economy and sustainable green environment. Herein, we developed a novel facile synthesis of nitrogen-doped graphene encapsulated Pd@NC nanocatalysts. The resulting heterogeneous catalyst was active for the synthesis of amines (more than 83 examples, yield up to 99%). The nitrogen-doped effect was unlike the previous report that poisoned the metal, it could increase the interaction with the active metal resulting in excellent stability. As far as we know, for the first time, the developed N-doped graphene encapsulated Pd@NC nanocatalyst showed excellent stability and activity of amines synthesis in the 20 times’ recycling test, industrially applicable flow reactor 2880 minutes’ test, and 99% purity of primary amine and tertiary amines product preparation test. Moreover, we have also shown the high atomic economy and environmentally friendlier tandem flow synthesis of N, N-dimethylamine products via the combination of reduction of nitrobenzene and N-methylation of amines, using the single one Pd@NC nanocatalyst with H₂O as the only by-product. Upon our knowledge, this is a novel example of primary amine and tertiary amine synthesis methodology with the combined cascade reaction and flow process of nitrobenzene reduction and primary amines N-methylation with a single heterogeneous catalyst.

Catalysis

Materials Chemistry

Nanoscience

Amines, as an important class of compounds that are classified as privileged, are not the only important component which widely present in the biological world, such as proteins, nucleic acids, but also widely applied in the pharmaceutical, fine, and bulk chemical industries, and materials synthesis^1-5. Most of the clinically used drugs are also amines or amine derivatives. Specifically, according to the reported top 200 pharmaceuticals by Retail Sales in 2020, among the showing chemical structure 120 pharmaceuticals, there are 110 drugs containing nitrogen and/or amino groups which are amine derivatives⁶. So far, a lot of researchers have developed many advanced methodologies for the synthesis of amines using alkyl halides benzenes⁷, formaldehyde⁸, paraformaldehyde⁹, methanol¹⁰, dimethyl sulfoxide¹¹, dimethyl carbonate¹², and CO₂²^,¹³as methylation agents. However, most of the traditional N-methylation synthesis methods of amines suffer from operationally problematic, narrow amines substrates scopes, toxic methylation reagents, and production of a large amount of waste, which is against the economic, atomic, and sustainable chemistry process requirements. To overcome the above-mentioned N-methylation process disadvantage, many pioneers’ researchers did a great contribution and improved it dramatically. Beller and his co-workers applied the RuCl₂(dmso)₄ complex and BuPAd₂ ligand in the synthesis of amines. The PhSiH₃ and CO₂ served as the hydrogen source and methylation reagent respectively¹⁴. A number of amines were synthesized via N-methylation in good to excellent yield. Klankermayer group¹⁵ later also developed a high efficient homogeneous catalyst system for the N-methylation of imines, using Ru (triphos)(tmm) complex and HNTf₂ acid. Up to now, there are many advanced N-methylation synthesis processes using not only homogeneous Ru-complex ([RuCpCl₂]₂/dpePhos¹⁰, [Ru(p-cymene)I₂]₂¹⁶) but also other homogeneous metal complex like Ir^17,18, Rh¹⁹, Cu²⁰, Fe^21,22, Co²³, and Mn²⁴. In the meantime, the heterogeneous catalyst systems have not only obtained the same rapid development but also attracted more and more attention. They not only have advantages in catalyst/product separation, no need for additives (acids, ligands, and salts), catalysts recyclability, reuse, etc., but also show comparable activity and product selectivity, which are very consistent with the goal of the atomic economy and sustainable development^25-28. Shi and his co-workers²⁹ prepared the heterogeneous catalysts Pd/CuZrO_x and investigated the N-methylation of amines and nitro compounds with CO₂ and H₂, high activity and excellent selectivity were obtained for most of the desired amines products. Later, the Zhang group developed the TiO₂ supported nano-Pd catalyst and successfully applied it in the synthesis of amines, starting from nitro compounds with MeOH under UV irradiation at room temperature³⁰. Until recently, heterogeneous transition metal-based catalyst systems Pt-MoOx/TiO₂ ³¹, Pd/TiO₂ ³², PdZn/TiO₂ ³³ have been reported. But for the increasing demand for amine synthesis, especially the requirements for sustainable environmental and economic performance in recent years, heterogeneous catalysts are remained poorly developed. At the same time, it is worth noting that the general preparation methods of metal-supported nanoparticles are thermal (pyrolysis or calcination) and chemical reduction, which involves the reduction of metal salts onto the nanomaterial supports^34-38. Generally speaking, the metal-based supported nanoparticles catalysts usually suffer from poor activity and selectivity in challenging reactions, active metal species aggregation, or poison during the harsh reaction conditions or poor stability in acids due to leaching^39-41. A possible effective method is making the active metal components “wear bulletproof vests” or “protective armor” ⁴² just like soldiers, so as to enhance the stability and anti-interference ability of the active metal components, thereby avoiding the aggregation, poisoning, and loss of the active metal components during the reaction process.

Graphene, as currently one of the thinnest, hardest, electrical and thermal conductivity materials, is expected to host interesting new physics properties, have desirable and available electronic and mechanical properties in the future^43-46. Specifically, the recent great discovery of superconductivity and correlated insulating phases in magic-angle twisted bilayer graphene, three-layer graphene, will open more novel great applications of graphene^47-49. The traditional synthesis of graphene normally consists of multilayer graphitic carbon or composites thereof, and in this case, the electronic transmission between multi-layer graphene is more difficult and the outermost carbon layer electronic structure is modulated by the electron which is transferred from the encapsulated metal core, it will reduce catalytic activity^50-52. Motivated by the superconductivity of the magic-angle twisted bilayer graphene this pioneering idea⁴⁸, herein, we developed a facile synthesis of thin layer graphene (less than five) encapsulate Pd@NC nanoalloy catalysts (Scheme S1). In this developed advanced synthesis process, more environmentally friendly solvent and fewer synthetic steps were used. Most of the exciting things are undoubtedly the thin-layer graphene structure regulation and the successful synthesis of the unique graphene encapsulate active metal species catalysts. We then applied the resulting thin layer graphene encapsulated metal nanoparticles to the challenging reductive hydrogenation of nitrobenzene and N-methylation of primary amines for the general synthesis of amines. Under quite mild reaction conditions (60 ºC, 1 MPa H₂, 4 h), with the single graphene encapsulated Pd@NC catalyst, more than 83 substrates were successfully transformed to the corresponding amines in excellent activity of 99% and 99% selectivity. Even in the gram-scale synthesis and cascade flow synthesis process of nitrobenzene reduction and N-methylation of amines, the catalyst still showed excellent reactivity and stability.

Catalysts Development and Characterization. The graphene encapsulated Pd catalysts (Pd@NC) were synthesized using the simple modified two-step procedure (Scheme S1). We used the solvent EtOH instead of H₂O for the catalyst precursors preparation, which has been shown a great effect in the controlling synthesis of graphene layers and catalyst physical properties previously⁵³. The catalyst precursors were obtained easily after stirring at 70 ºC for 4 hours, and then were dried, calcined to give the graphene layer encapsulated nanoparticles catalysts Pd@NC. All the prepared Pd@NC and commercially available Pd@NC catalysts were characterized by XRD, ICP, XPS, SEM, and TEM for the structural physical properties analysis. As shown in the SEM images, the two synthesized nitrogen-doping catalysts have uneven particles, while the commercially available Pd@NC catalyst have uniform nanoparticles (Figure 1a-1c). According to the high-resolution TEM analysis, the two novel prepared N-doping catalysts Pd@NC-2 and Pd@NC-9 which consisted of Pd nanoparticles that were completely encapsulated by thin graphene layers (Figure 1d, 1f), while the commercially available N-doping catalyst Pd@NC was not observed same the phenomenon. Based on the HRTEM statistical analysis, the optimized N-doping catalyst Pd@NC-2 has less than 5 graphene layers for the nanoparticle Pd species, and >90% of Pd metal species consisted of a few graphene layers. The Pd sources could affect the catalysts’ physical properties significantly. Based on the high-angle annular dark-field STEM analysis, the uniform Pd metal nanoparticles had been formed for the Pd@NC-2 catalyst (Figure 1j), while for the Pd@NC-9 catalyst, better dispersion was observed for the Pd metal nanoparticles. And the corresponding energy-dispersive X-ray (EDX) maps showed that the C, N, and O atoms were distributed homogeneously over all the Pd NPs (Figure 1g-n), which was further confirmation of the alloy structure of Pd@NC. This phenomenon could further be confirmed by the XRD, BET, and ICP analysis of the catalysts. As shown in the XRD images (Figure 2a), all the catalysts showed wide and broad peaks of C (002) between 20 and 30, which confirmed the successful formation of the thin graphene layers. Although the Pd@NC-2 and Pd@NC-9 showed no big difference in the XRD images, both of them showed the graphitic carbon shell and the Pd alloy of Pd (111), Pd (200), Pd (220) metal species on the catalyst surface, the purchased Pd@NC catalyst did not show any obvious peak for the Pd alloy species. This indicated that the Pd species were highly dispersed in the graphene support. Moreover, the optimized catalyst Pd@NC-2 maintained the structure even after the 20^th recycling catalytic test. The Pd@NC-9 has the lower metal loading of 0.9% compared with the Pd@NC-2 of 8.2% according to the ICP analysis (Table S1). The Pd@NC-2 had the smallest surface area (119 m²/g) and largest pore size (4.6 nm) among the three catalysts Pd@NC-2, Pd@NC-9 (173 m²/g, 3.1 nm) and purchased Pd@NC (632m²/g, 2.2 nm). Based on the catalysts’ analysis of XPS (Figure 2e-h), in the fresh prepared thin graphene N-doping catalysts Pd@NC-2, Pd@NC-9, two big intensity peaks of both metallic Pd⁰ and Pd²⁺ species were observed at the binding energy of 340 ev, 335 ev, and 343 ev, 337 ev separately. While for the purchased Pd@NC, it only shows one peak of Pd⁰ at the binding energy of 335 ev and two peaks of Pd²⁺at 343 ev, 337 ev. For the reused catalyst Pd@NC-2, it showed clearly the three peaks of Pd⁰ and Pd²⁺ species. Even some of the active species of Pd⁰ were transformed to a more stable state Pd²⁺, the Pd@NC-2 still has excellent stability and catalytic activity.

Catalytic Reaction of Amines Synthesis. All the prepared catalysts, as well as commercially available catalysts were investigated in the benchmark N-methylation of benzylamine. As shown in Table 1, when we investigated the catalyst reactivity under 90 ºC, a long reaction time of 12 hours and 20 bars of H₂, excellent catalytic activity, and product selectivity were obtained (entry 1). When the reaction temperature decreased from 80 to 40 ºC, the desired product yield dropped from 99% to 62% (entries 2-6). We were excited to find that the reaction could be carried out in a short time but still with excellent selectivity (entry 10). When H₂ pressure dropped from 20 to 10 bar, the yield of 1 decreased slowly from 99% to 91% (entries 10, 12, and 13). With the optimized reaction conditions (70 ºC, 2 h, 20 bar H₂), the graphene encapsulated catalyst Pd@N/C-9 prepared from different Pd sources and the commercially available N-doping catalyst Pd@NC showed lower target product yield of 39% and 56% respectively. Even under the reaction conditions of higher pressure and longer reaction time, the target product yields of the other two commonly used commercial catalysts Pd/C and Rh/C still cannot achieve very satisfactory results (entries 16, 17).

With the well-defined catalyst Pd@NC-2 and optimized reaction conditions in hand, we then investigate the substrate scope of N-methylation reaction for tertiary amines synthesis (Scheme 1). When the substituent group on the para position changed from H to Methyl, Ethyl, ^tButyl, excellent selectivity was obtained for all the phenylmethanamine substrates (1-4). The important building blocks halo-substituted aromatic amines, no matter where the halogen is located, were successfully transformed to the corresponding tertiary amines in excellent selectivity (5-8). The biomass platform derivatives amines compounds (9-13) were well tolerated under modified reaction conditions to give the N, N-di-methylamines products in good to excellent yield. Surprisingly, the high steric substrate diphenylmethanamine could also be converted to the N, N-dimethyldiphenylmethanamine in a 72% yield. Moreover, the linear branched and cyclic aliphatic amines, furan, thiophene, pyrazole, and pyridine heterocyclic amines, which were previously reported challenging substrates ^54-56, were successfully converted to the corresponding N, N-di-methylated products in good to excellent yield (15-28). The thin graphene layer encapsulated N-doping catalyst also showed very efficient reactivity and selectivity in the double dimethylation reaction of diamines (31).

After the successful synthesis of tertiary amines starting from primary amines and formaldehyde, we then investigated the N-methylation of secondary amines substrates. As illustrated in Scheme 2, no matter the alkyl substitute or the halogen substitute substrates, the aromatic secondary amines were well tolerated to give the excellent yield of the target product. The alkyl, aryl, cyclic and halo-substituted benzylic aromatic secondary amines could give the corresponding tertiary amines in good to excellent yield. The challenging aliphatic and hetero-cyclic secondary amines could also be carried out under standard reaction conditions smoothly.

As far as we know, there are few reports for the synthesis of tertiary amines using secondary amines and functional aldehydes via transition metal-catalyzed mono and di-N-methylation methods. Motivated by the successfully developed graphene encapsulated N-doping catalyst Pd@NC-2 catalyzed N-methylation of primary or secondary amines for the synthesis of tertiary amines, we further explored the Pd catalyzed N-methylation reaction of varied functional substituted aldehydes with primary, secondary amines. The functionally substituted aldehydes such as aromatic, aliphatic, and heterocyclic substrates reacted with primary benzenamine smoothly and gave the desired tertiary amines product with moderate to good yield (Scheme 3A, 61-65). As shown in Scheme 3B and 3C, all the tested aromatic, aliphatic, and furan substituted functional aldehydes were well tolerated, and good to excellent yields up to 93% were obtained under the optimized reaction conditions (20 bar H₂, 80 °C, 4 h) (66-75). We were very excited to represent that this Pd catalyzed N-methylation methodology could also be applied for the synthesis of tertiary amines from dimethylamine and aromatic, aliphatic aldehydes (Scheme 3D, 76-80).

Gram-scale reactions, reusability test of the catalyst, and its application in cascade and flow synthesis. To make the developed Pd catalyzed N-methylation of tertiary amines synthesis method applicable on an industrial scale in the future, we then investigated the laboratory gram-scale synthesis of five tertiary amines. As shown in Scheme 4A, excellent yields were obtained for all the tested substrates no matter the mono or di N-methylation products. The stability and recyclability of the catalyst are undoubtedly very important characteristics of any heterogeneous catalyst, and also an important reference factor for whether the catalyst can be applied to industrialization. Here, we evaluated the graphene thin layer encapsulated Pd@NC catalyst’s stability and recycle ability using the benchmark reaction. Surprisingly, compared with the commercially available catalysts Pd/C and Pd/NC, the thin layer graphene shell encapsulated N-doping Pd@/NC-2 catalyst keeps the excellent reactivity (99% con.), stability, and product selectivity (99% sel.) after 20^th recycling test, which showed great potential in the industrial application (Scheme 4B).

Domino or Cascade reactions are sequences of atom-economical chemical transformations avoiding time-consuming protection/deprotection steps and isolation of intermediates, which are recognized as processes with minimal waste generation, a means to achieve green sustainable chemistry and a way to develop pharmaceuticals and other fine chemicals economically, synthetically processes^57-59. Since recently the pharmaceutical manufacturing begun to require high quality of synthesis, environmentally benign methods and reproducibility of manufacturing, another advanced continuous flow technology has been developed more recently than batch systems methods, and widely applied in the synthesis of natural products, materials, and other interest molecules due to its key advantages of improving heat and mass transfer efficiency, handling of hazardous species, and faster achievement of scale-up and greater synthetic efficiency, extremely in terms of safety, yield, and reproducibility^60-63. Since both the whole society and chemists strive for evermore responsible and effective methods for the management of our planet’s precious resources, the combination using cascade reaction and flow chemistry synthesis will become increasingly important in the coming years⁵⁸. Here, we are very excited to show the successful combination utilization of cascade reaction and flow-synthesis technology together. As shown in Scheme 4C, the N-doping thin layer graphene encapsulated Pd@NC-2 catalyst could efficiently transform nitrobenzene to the corresponding N-methylation product in excellent yield without isolating the amine intermediate. It is also desired to mention, the Pd catalyzed reduction of 1-(nitromethyl)benzene and Pd catalyzed N-methylation of phenylmethanamine intermediate were carried out using one solvent MeOH and single heterogeneous catalyst Pd@NC-2 with H₂O as the only by-product, and primary amine phenylmethanamine and N-methylation product N, N-dimethyl(phenyl)methanamine could be obtained separately using the flow synthesis process. This developed advanced cascade flow synthesis of tertiary amines process, which has the obvious advantages of highly cost-efficient, easy separation, and high yielding of target product, less and green by-product generation, will open a great potential application in both academic and industry.

In conclusion, we have demonstrated a simple and environmentally friendly method for the preparation of N-doped thin graphene layers encapsulated Pd@NC catalysts. The prepared heterogeneous catalyst coupled easily with accessible primary, secondary amines with functional aldehydes under very mild industrially viable and scalable conditions. It also showed excellent reactivity for the gram-scale synthesis of five amines products (activity > 99 %; selectivity > 99 %) and extremely stability during the 20 times’ recycling test, industrially applicable flow reactor 2880 minutes’ test, without the significant loss of activity and selectivity. More importantly, as far as we know, we successfully combined the cascade nitrobenzene reduction, N-methylation of primary amine with flow synthesis methodology using single Pd@NC catalyst and single solvent. The aforementioned novel thin graphene layer encapsulated Pd catalyst and its application in the high atomic economy and environmentally friendlier cascade flow synthesis of primary amine and tertiary amine synthesis methodology open up a way for the industrial application of catalysts and their high-value chemical synthesis applications.

ACKNOWLEDGMENT

This work was supported by the National Key R&D Program of China (2018YFB1501500), National Natural Science Foundation of China (51976225) and Dalian National Laboratory Cooperation Foundation, Chinese Academy of Sciences (DNL201916).

AUTHOR CONTRIBUTIONS

J.G.L. and L.L.M supervised the research. J.G.L., J.M.S. and Y.P.S designed and performed most of the experiments and data analysis. J.M.S. and S.S.L. performed the cascade flow synthesis of amines. J.G.L. wrote the original paper. All authors discussed the results and assisted during manuscript preparation.

COMPETING INTERESTS

The authors declare no competing financial interests.

DATA AVAILABILITY

Data supporting the findings of this study are available from the corresponding authors upon reasonable request.

1 Oku, T., Arita, Y., Tsuneki, H. & Ikariya, T. Continuous chemoselective methylation of functionalized amines and diols with supercritical methanol over solid acid and acid-base bifunctional catalysts. J. Am. Chem. Soc. 126, 7368-7377 (2004).

2 Bobbink, F. D., Das, S. & Dyson, P. J. N-formylation and N-methylation of amines using metal-free N-heterocyclic carbene catalysts and CO₂ as carbon source. Nat. Protoc. 12, 417-428 (2017).

3 Jagadeesh, R. V. et al. MOF-derived cobalt nanoparticles catalyze a general synthesis of amines. Science 358, 326-331 (2017).

4 Afanasyev, O. I., Kuchuk, E., Usanov, D. L. & Chusov, D. Reductive Amination in the Synthesis of Pharmaceuticals. Chem. Rev. 119, 11857-11911 (2019).

5 Beydoun, K., vom Stein, T., Klankermayer, J. & Leitner, W. Ruthenium-Catalyzed Direct Methylation of Primary and Secondary Aromatic Amines Using Carbon Dioxide and Molecular Hydrogen. Angew. Chem. Int. Ed. 52, 9554-9557 (2013).

6 Njarðarson, J. Top 200 Brand Name Drugs by Retail Sales in 2020, <https://njardarson.lab.arizona.edu/sites/njardarson.lab.arizona.edu/files/Top%20200%20Pharmaceuticals%20By%20Retail%20Sales%202020V3.pdf> (2021).

7 Fatemeh, N. H., Farasat, Z., Nabavizadeh, S. M., Wu, G. & Abu-Omar, M. M. N-methylation versus oxidative addition using MeI in the reaction of organoplatinum(II) complexes containing pyrazine ligand. J. Organomet. Chem. 880, 232-240 (2019).

8 Men, N. Y. T., Li, W. F., Stewart, S. G. & Wu, X. F. Transition Metal-free Methylation of Amines with Formaldehyde as the Reductant and Methyl Source. Chimia 69, 345-347 (2015).

9 Wang, H. L., Huang, Y. J., Dai, X. C. & Shi, F. N-Monomethylation of amines using paraformaldehyde and H-2. Chem. Commun. 53, 5542-5545 (2017).

10 Dang, T. T., Ramalingam, B. & Seayad, A. M. Efficient Ruthenium-Catalyzed N-Methylation of Amines Using Methanol. ACS Catal. 5, 4082-4088 (2015).

11 Jiang, X. et al. A General Method for N-Methylation of Amines and Nitro Compounds with Dimethylsulfoxide. Chem. Eur. J. 20, 58-63 (2014).

12 Tundo, P. & Selva, M. The chemistry of dimethyl carbonate. Accounts. Chem. Res. 35, 706-716 (2002).

13 Tlili, A., Frogneux, X., Blondiaux, E. & Cantat, T. Creating Added Value with a Waste: Methylation of Amines with CO₂ and H-2. Angew. Chem. Int. Ed. 53, 2543-2545 (2014).

14 Li, Y. H., Sorribes, I., Yan, T., Junge, K. & Beller, M. Selective Methylation of Amines with Carbon Dioxide and H-2. Angew. Chem. Int. Ed. 52, 12156-12160 (2013).

15 Beydoun, K., Ghattas, G., Thenert, K., Klankermayer, J. & Leitner, W. Ruthenium-Catalyzed Reductive Methylation of Imines Using Carbon Dioxide and Molecular Hydrogen. Angew. Chem. Int. Ed. 53, 11010-11014 (2014).

16 van der Waals, D. et al. Ruthenium-Catalyzed Methylation of Amines with Paraformaldehyde in Water under Mild Conditions. Chemsuschem 9, 2343-2347 (2016).

17 Huang, S. et al. N-Methylation of ortho-substituted aromatic amines with methanol catalyzed by 2-arylbenzo[d]oxazole NHC-Ir(iii) complexes. Dalton Trans. 48, 5072-5082 (2019).

18 Gonzalez-Lainez, M., Jimenez, M. V., Passarelli, V. & Perez-Torrente, J. J. Effective N-methylation of nitroarenes with methanol catalyzed by a functionalized NHC-based iridium catalyst: a green approach to N-methyl amines. Catal. Sci. Technol. 10, 3458-3467 (2020).

19 Lam, R. H. et al. Selective formylation or methylation of amines using carbon dioxide catalysed by a rhodium perimidine-based NHC complex. Green Chem. 21, 538-549 (2019).

20 Qiao, C., Liu, X. F., Liu, X. & He, L. N. Copper(II)-Catalyzed Selective Reductive Methylation of Amines with Formic Acid: An Option for Indirect Utilization of CO₂. Org. Lett. 19, 1490-1493 (2017).

21 Zheng, J. X., Darcel, C. & Sortais, J. B. Methylation of secondary amines with dialkyl carbonates and hydrosilanes catalysed by iron complexes. Chem. Commun. 50, 14229-14232 (2014).

22 Li, W. D., Zhu, D. Y., Li, G., Chen, J. & Xia, J. B. Iron-Catalyzed Selective N-Methylation and N-Formylation of Amines with CO₂. Adv. Synth. Catal. 361, 5098-5104 (2019).

23 Liu, Z. H. et al. Efficient Cobalt-Catalyzed Methylation of Amines Using Methanol. Adv. Synth. Catal. 359, 4278-4283 (2017).

24 Huang, Z. J. et al. Mn-Catalyzed Selective Double and Mono-N-Formylation and N-Methylation of Amines by using CO₂. Chemsuschem 12, 3054-3059 (2019).

25 Mizuno, N. & Misono, M. Heterogenous catalysis. Chem. Rev. 98, 199-217 (1998).

26 Astruc, D., Lu, F. & Aranzaes, J. R. Nanoparticles as recyclable catalysts: The frontier between homogeneous and heterogeneous catalysis. Angew. Chem. Int. Ed. 44, 7852-7872 (2005).

27 Yang, X. F. et al. Single-Atom Catalysts: A New Frontier in Heterogeneous Catalysis. Accounts. Chem. Res. 46, 1740-1748 (2013).

28 Dai, Y. H. et al. Recent progress in heterogeneous metal and metal oxide catalysts for direct dehydrogenation of ethane and propane. Chem. Soc. Rev. 50, 5590-5630 (2021).

29 Cui, X. J., Zhang, Y., Deng, Y. Q. & Shi, F. N-Methylation of amine and nitro compounds with CO₂/H-2 catalyzed by Pd/CuZrOx under mild reaction conditions. Chem. Commun. 50, 13521-13524 (2014).

30 Zhang, L. N., Zhang, Y., Deng, Y. Q. & Shi, F. Light-promoted N,N-dimethylation of amine and nitro compound with methanol catalyzed by Pd/TiO₂ at room temperature. RSC Adv. 5, 14514-14521 (2015).

31 Kon, K., Siddiki, S. M. A. H., Onodera, W. & Shimizu, K. Sustainable Heterogeneous Platinum Catalyst for Direct Methylation of Secondary Amines by Carbon Dioxide and Hydrogen. Chem.-Eur. J. 20, 6264-6267 (2014).

32 Wang, L. M. et al. Photocatalytic N-Methylation of Amines over Pd/TiO₂ for the Functionalization of Heterocycles and Pharmaceutical Intermediates. ACS Sustain. Chem. Eng. 6, 15419-15424 (2018).

33 Lin, W. W. et al. Selective N-Methylation of N-Methylaniline with CO₂ and H-2 over TiO₂-Supported PdZn Catalyst. ACS Catal. 10, 3285-3296 (2020).

34 Zecevic, J., Vanbutsele, G., de Jong, K. P. & Martens, J. A. Nanoscale intimacy in bifunctional catalysts for selective conversion of hydrocarbons. Nature 528, 245-253 (2015).

35 Sankar, M. et al. Designing bimetallic catalysts for a green and sustainable future. Chem. Soc. Rev. 41, 8099-8139 (2012).

36 Munnik, P., de Jongh, P. E. & de Jong, K. P. Recent Developments in the Synthesis of Supported Catalysts. Chem. Rev. 115, 6687-6718 (2015).

37 Galvis, H. M. T. et al. Supported Iron Nanoparticles as Catalysts for Sustainable Production of Lower Olefins. Science 335, 835-838 (2012).

38 Corma, A. & Serna, P. Chemoselective hydrogenation of nitro compounds with supported gold catalysts. Science 313, 332-334 (2006).

39 Lefevre, M., Proietti, E., Jaouen, F. & Dodelet, J. P. Iron-Based Catalysts with Improved Oxygen Reduction Activity in Polymer Electrolyte Fuel Cells. Science 324, 71-74 (2009).

40 Haslam, G. E., Chin, X. Y. & Burstein, G. T. Passivity and electrocatalysis of nanostructured nickel encapsulated in carbon. Phys. Chem. Chem. Phys. 13, 12968-12974 (2011).

41 Deng, D. H. et al. Iron Encapsulated within Pod-like Carbon Nanotubes for Oxygen Reduction Reaction. Angew. Chem. Int. Ed. 52, 371-375 (2013).

42 Huang, J. H., Durden, H. & Chowdhury, M. Bio-inspired armor protective material systems for ballistic shock mitigation. Mater. Design. 32, 3702-3710 (2011).

43 Kolmer, M. et al. Rational synthesis of atomically precise graphene nanoribbons directly on metal oxide surfaces. Science 369, 571-575 (2020).

44 Geim, A. K. & Novoselov, K. S. The rise of graphene. Nat. Mater. 6, 183-191 (2007).

45 Geim, A. K. Graphene: Status and Prospects. Science 324, 1530-1534 (2009).

46 Castro Neto, A. H., Guinea, F., Peres, N. M. R., Novoselov, K. S. & Geim, A. K. The electronic properties of graphene. Rev. Mod. Phys. 81, 109-162 (2009).

47 Wong, D. L. et al. Cascade of electronic transitions in magic-angle twisted bilayer graphene. Nature 582, 198-202 (2020).

48 Cao, Y. et al. Tunable correlated states and spin-polarized phases in twisted bilayer-bilayer graphene. Nature 583, 215-220 (2020).

49 Park, J. M., Cao, Y., Watanabe, K., Taniguchi, T. & Jarillo-Herrero, P. Tunable strongly coupled superconductivity in magic-angle twisted trilayer graphene. Nature 590, 249-255(2021).

50 Stauber, T., Peres, N. M. R. & Guinea, F. Electronic transport in graphene: A semiclassical approach including midgap states. Phys. Rev. B 76 (2007).

51 Guinea, F. Charge distribution and screening in layered graphene systems. Phys. Rev. B 75 (2007).

52 Deng, J., Ren, P. J., Deng, D. H. & Bao, X. H. Enhanced Electron Penetration through an Ultrathin Graphene Layer for Highly Efficient Catalysis of the Hydrogen Evolution Reaction. Angew. Chem. Int. Ed. 54, 2100-2104 (2015).

53 Liu, J. G. et al. Facile synthesis of controllable graphene-co-shelled reusable Ni/NiO nanoparticles and their application in the synthesis of amines under mild conditions. Green Chem. 22, 7387-7397 (2020).

54 Du, X. L. et al. Direct Methylation of Amines with Carbon Dioxide and Molecular Hydrogen using Supported Gold Catalysts. Chemsuschem 8, 3489-3496 (2015).

55 Cui, X. J., Dai, X. C., Zhang, Y., Deng, Y. Q. & Shi, F. Methylation of amines, nitrobenzenes and aromatic nitriles with carbon dioxide and molecular hydrogen. Chem. Sci. 5, 649-655 (2014).

56 Cabrero-Antonino, J. R., Alberico, E., Junge, K., Junge, H. & Beller, M. Towards a general ruthenium-catalyzed hydrogenation of secondary and tertiary amides to amines. Chem. Sci. 7, 3432-3442 (2016).

57 Volla, C. M., Atodiresei, I. & Rueping, M. Catalytic C-C bond-forming multi-component cascade or domino reactions: pushing the boundaries of complexity in asymmetric organocatalysis. Chem. Rev. 114, 2390-2431 (2014).

58 Nicolaou, K. C., Edmonds, D. J. & Bulger, P. G. Cascade reactions in total synthesis. Angew. Chem. Int. Ed. 45, 7134-7186 (2006).

59 Nicolaou, K. C. & Chen, J. S. The art of total synthesis through cascade reactions. Chem. Soc. Rev. 38, 2993-3009 (2009).

60 Tsubogo, T., Oyamada, H. & Kobayashi, S. Multistep continuous-flow synthesis of (R)- and (S)-rolipram using heterogeneous catalysts. Nature 520, 329-332 (2015).

61 Britton, J. & Jamison, T. F. The assembly and use of continuous flow systems for chemical synthesis. Nat. Protoc. 12, 2423-2446 (2017).

62 Robertson, J. C., Coote, M. L. & Bissember, A. C. Synthetic applications of light, electricity, mechanical force and flow. Nat. Rev. Chem. 3, 290-304 (2019).

63 Seo, H., Nguyen, L. V. & Jamison, T. F. Using Carbon Dioxide as a Building Block in Continuous Flow Synthesis. Adv. Synth. Catal. 361, 247-264 (2019).

Due to technical limitations, Table 1 and all schemes are only available as a download in the supplementary files.

There is NO Competing Interest.

Download PDF

Version 1

posted

You are reading this latest preprint version

Facile synthesis of N-doped graphene encapsulated Pd@N/C catalyst and its efficient application in cascade flow synthesis of amines

Status:

Version 1

Abstract

Figures

Introduction

Results and Discussion

Conclusions

Declarations

References

Tables and Schemes

Additional Declarations

Supplementary Files

Status:

Version 1