Combined CO<sub>2</sub> Capture and Hydrogenation to Methanol: Amine Immobilization Enables Easy Recycling of Active Elements

Kar, Sayan; Goeppert, Alain; Prakash, G. K. Surya

doi:10.1002/cssc.201900324

Cited by 63 publications

(42 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As a result of their efforts, a catalyst TON up to 9900 was reached employing [Ru-MACHO-BH] and pentaethylenehexamine (PEHA) in a biphasic system suitable to be reused four times. In addition, Prakash and co-workers developed a protocol where solid supported amines could be employed as reusable carbon capture systems 112 .…”

Section: Related Catalytic Hydrogenative Transformationsmentioning

confidence: 99%

Homogeneous and heterogeneous catalytic reduction of amides and related compounds using molecular hydrogen

et al. 2020

View full text Add to dashboard Cite

Catalytic hydrogenation of amides is of great interest for chemists working in organic synthesis, as the resulting amines are widely featured in natural products, drugs, agrochemicals, dyes, etc. Compared to traditional reduction of amides using (over)stoichiometric reductants, the direct hydrogenation of amides using molecular hydrogen represents a greener approach. Furthermore, amide hydrogenation is a highly versatile transformation, since not only higher amines (obtained by CO cleavage), but also lower amines and alcohols, or amino alcohols (obtained by C-N cleavage) can be selectively accessed by fine tuning of reaction conditions. This review describes the most recent advances in the area of amide hydrogenation using H 2 exclusively and molecularly defined homogeneous as well as nanostructured heterogeneous catalysts, with a special focus on catalyst development and synthetic applications. T he development of green and sustainable methods is a central focus of modern organic synthesis and its applications in various areas of the chemical industry. In this respect, many reduction reactions, traditionally employing stoichiometric amounts of metal hydrides with inherent low atom efficiency 1 , can be favorably replaced by catalytic hydrogenations. In fact, the combination of molecular hydrogen and catalysts does not only allow avoiding formation of waste products 2 , it also opens the door to clean transformations based on renewable energies as the conversion of solar or wind energy to "green" hydrogen is likely to be implemented in the coming years. Among the many reduction reactions known, amide hydrogenation can be encountered as one of the most desired considering the importance of the derived amines in several branches of chemical industry. In fact, since the start of the Green Chemistry Institute Pharmaceutical Roundtable in the United States in 2005, several projects aimed to the achievement of a practical amide hydrogenation methodology have been supported 3,4. The long-term interest of the pharmaceutical industry in this specific transformation is explained by the fact that it ideally affords structurally complex amines, present in many of the currently employed drugs. Furthermore, amines are also in bulk and fine chemicals used in the manufacture of plastics, textiles, surfactants, dyes, and many more 5. Amides play a central role in the chemistry of life, as they are the key elements to generate peptides and proteins from amino acid monomers. At the same time, they are present in artificial

show abstract

Section: Related Catalytic Hydrogenative Transformationsmentioning

confidence: 99%

Homogeneous and heterogeneous catalytic reduction of amides and related compounds using molecular hydrogen

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Utilizing this strategy, not only a higher yield of CH 3 OH (>90 %) was obtained but more efficient recycling of both amines and the catalyst was demonstrated with 95 % of the catalyst activity after four cycles. To further enhance the recyclability of amines, in 2019, Prakash employed amines that were immobilized onto a solid support [67] . A highly active ruthenium catalyst ( Ru‐7 , TON up to 8900, Figure 3) was reported by Everett and co‐workers for the hydrogenation of CO 2 to methanol via formamide in the presence of amines [68] .…”

Section: Carbon Dioxidementioning

confidence: 99%

Homogeneous (De)hydrogenative Catalysis for Circular Chemistry – Using Waste as a Resource

Kumar

Gao

2020

ChemCatChem

View full text Add to dashboard Cite

Increasing production and usage of several consumer products and energy sources have resulted in the accumulation of a substantial amount of waste products that are toxic and/or difficult to biodegrade, thus creating a severe threat to our planet. With the recently advocated concepts of circular chemistry, an attractive approach to tackle the challenge of chemical waste reduction is to utilize these waste products as feedstocks for the production of useful chemicals. Catalytic (de)hydrogenation is an atom‐economic, green and sustainable approach in organic synthesis, and several new environmentally benign transformations have been reported using this strategy in the past decade, especially using well‐defined transition metal complexes as catalysts. These discoveries have demonstrated the impact and untapped potential of homogeneous (de)hydrogenative catalysis for the purpose of converting chemical wastes into useful resources. Four types of chemical waste that have been (extensively) studied in recent years for their chemical transformations using homogeneous catalytic (de)hydrogenation are CO2, N2O, plastics, and glycerol. This review article highlights how these chemical wastes can be converted to useful feedstocks using (de)hydrogenative catalysis mediated by well‐defined transition metal complexes and summarizes various types of homogeneous catalysts discovered for this purpose in recent years. Moreover, with examples of hydrogenative depolymerization of plastic waste and the production of virgin plastic via dehydrogenative pathways, we emphasize the potential applications of (de)hydrogenation reactions to facilitate closed‐loop production cycles enabling a circular economy.

show abstract

“…[53] When amines were immobilized onto solid supports, after the reaction, the immobilized amines can be easily filtered, recovered, and reused. [54] Branched and linear poly(ethyleneimine)s (PEIs) can form formamide units easily under CO 2 hydrogenation conditions with a series of PNHPpincer Ru complexes at 100°C in tetrahydrofuran (THF). [55] After reducing formamide units on the polymer, methanol was released so that the starting polymer can be separated from the reaction mixture in the liquid phase.…”

Section: Ru-based Catalystsmentioning

confidence: 99%

“…[33] As the Ru-based complexes have been widely used as the homogeneous catalysts in the condensed-phase CO 2 hydrogenation processes, the challenges of recycling such catalysts need to be addressed ( Figure 4). [53,54,57] The catalyst, RuÀ MACHO-BH, was recovered from the organic layer in a unique biphasic process and reused for successive hydrogenation cycles ( Figure 4A). Over four cycles, the catalyst was relatively stable.…”

Section: Ru-based Catalystsmentioning

confidence: 99%

CO₂ Reduction to Methanol in the Liquid Phase: A Review

et al. 2020

View full text Add to dashboard Cite

Excessive carbon dioxide (CO2) emissions have been subject to extensive attention globally, since an enhanced greenhouse effect (global warming) owing to a high CO2 concentration in the atmosphere could lead to severe climate change. The use of solar energy and other renewable energy to produce low‐cost hydrogen, which is used to reduce CO2 to produce bulk chemicals such as methanol, is a sustainable strategy for reducing carbon dioxide emissions and carbon resources. CO2 conversion into methanol is exothermic, so that low temperature and high pressure are favorable for methanol formation. CO2 is usually captured and recovered in the liquid phase. Herein, the emerging technologies for the hydrogenation of CO2 to methanol in the condensed phase are reviewed. The development of homogeneous and heterogeneous catalysts for this important hydrogenation reaction is summarized. Finally, mechanistic insight on CO2’s conversion into methanol over different catalysts is discussed by taking the available reaction pathways into account.

show abstract

Combined CO₂ Capture and Hydrogenation to Methanol: Amine Immobilization Enables Easy Recycling of Active Elements

Cited by 63 publications

References 56 publications

Homogeneous and heterogeneous catalytic reduction of amides and related compounds using molecular hydrogen

Homogeneous and heterogeneous catalytic reduction of amides and related compounds using molecular hydrogen

Homogeneous (De)hydrogenative Catalysis for Circular Chemistry – Using Waste as a Resource

CO₂ Reduction to Methanol in the Liquid Phase: A Review

Contact Info

Product

Resources

About

Combined CO2 Capture and Hydrogenation to Methanol: Amine Immobilization Enables Easy Recycling of Active Elements

Cited by 63 publications

References 56 publications

Homogeneous and heterogeneous catalytic reduction of amides and related compounds using molecular hydrogen

Homogeneous and heterogeneous catalytic reduction of amides and related compounds using molecular hydrogen

Homogeneous (De)hydrogenative Catalysis for Circular Chemistry – Using Waste as a Resource

CO2 Reduction to Methanol in the Liquid Phase: A Review

Contact Info

Product

Resources

About

Combined CO₂ Capture and Hydrogenation to Methanol: Amine Immobilization Enables Easy Recycling of Active Elements

CO₂ Reduction to Methanol in the Liquid Phase: A Review