Subtopic Deep Dive
Borrowing Hydrogen Catalysis
Research Guide
What is Borrowing Hydrogen Catalysis?
Borrowing Hydrogen Catalysis involves metal-catalyzed dehydrogenation of alcohols to form reactive intermediates, followed by nucleophilic addition and hydrogenation to forge C-N or C-C bonds in an atom-economical manner.
This strategy enables direct alkylation of amines with alcohols using earth-abundant metals like Mn, Fe, Co, and Ni, avoiding stoichiometric reagents. Key reviews document over 20 years of advances, with more than 3,000 citations across seminal works (Filonenko et al., 2018; Elangovan et al., 2016). Applications span sustainable synthesis of amines and biomass-derived chemicals.
Why It Matters
Borrowing Hydrogen Catalysis provides greener routes for pharmaceutical intermediates and fine chemicals, reducing waste from traditional alkylation methods (Bryan et al., 2018). Manganese pincer complexes achieve selective N-alkylation with turnover numbers exceeding 10,000, enabling industrial scalability (Elangovan et al., 2016). Iron catalysts convert biomass alcohols to value-added amines, supporting biorefinery processes (Yan et al., 2014; Deuss et al., 2014). These methods cut E-factors by over 90% in select cases, aligning with green chemistry priorities.
Key Research Challenges
Catalyst Deactivation
Base metal catalysts like Mn and Fe suffer from over-reduction or ligand degradation under dehydrogenation conditions, limiting turnover numbers below 1,000 in many cases (Filonenko et al., 2018). Harsh temperatures accelerate side reactions such as aldol condensation. Developing air-stable pincers remains critical (Reed-Berendt et al., 2018).
Selectivity in Multifunctional Substrates
Achieving regioselective C-N bond formation in polyols or amino alcohols challenges catalyst design, with competing pathways yielding mixtures (Elangovan et al., 2016). Enantioselectivity lags behind precious metals, with ee values rarely above 90% (Ward, 2010). Substrate scope expansion to heterocycles is limited (Yan et al., 2014).
Mechanistic Understanding
Distinguishing borrowing hydrogen from direct H2 transfer requires advanced spectroscopy, as intermediates like metal hydrides are transient (Zhang et al., 2015). Computational modeling struggles with solvent effects on outer-sphere mechanisms (Filonenko et al., 2018). Quantifying cooperativity in heterometallic systems adds complexity (Mata et al., 2013).
Essential Papers
Catalytic (de)hydrogenation promoted by non-precious metals – Co, Fe and Mn: recent advances in an emerging field
Georgy A. Filonenko, Robbert van Putten, Emiel J. M. Hensen et al. · 2018 · Chemical Society Reviews · 668 citations
This review is aimed at introducing the remarkable progress made in the last three years in the development of base metal catalysts for hydrogenations and dehydrogenative transformations.
Efficient and selective N-alkylation of amines with alcohols catalysed by manganese pincer complexes
Saravanakumar Elangovan, Jacob Neumann, Jean‐Baptiste Sortais et al. · 2016 · Nature Communications · 622 citations
Key Green Chemistry research areas from a pharmaceutical manufacturers’ perspective revisited
Marian C. Bryan, Peter J. Dunn, David A. Entwistle et al. · 2018 · Green Chemistry · 578 citations
The ACS Green Chemistry Institute® Pharmaceutical Roundtable has assembled an updated list of key research areas to highlight transformations and reaction media where more sustainable technologies ...
Iron catalysed direct alkylation of amines with alcohols
Tao Yan, Ben L. Feringa, Katalin Barta · 2014 · Nature Communications · 411 citations
Recent advances in homogeneous borrowing hydrogen catalysis using earth-abundant first row transition metals
Benjamin G. Reed‐Berendt, Kurt Polidano, Louis C. Morrill · 2018 · Organic & Biomolecular Chemistry · 380 citations
The review highlights the recent advances (2013-present) in the use of earth-abundant first row transition metals in homogeneous borrowing hydrogen catalysis.
Nickel Nanoparticles in Hydrogen Transfer Reactions
Francisco Alonso, Paola Riente, Miguel Yus · 2011 · Accounts of Chemical Research · 326 citations
The transfer hydrogenation of organic compounds is a much safer and more environmentally benign process than reduction reactions involving molecular hydrogen, metal hydrides, or dissolving metals. ...
Heterometallic complexes, tandem catalysis and catalytic cooperativity
J.A. Mata, F. Ekkehardt Hahn, Eduardo Peris · 2013 · Chemical Science · 316 citations
N-heterocyclic carbene-based heterometallic complexes have emerged as useful multicatalysts for tandem reactions.
Reading Guide
Foundational Papers
Start with Yan et al. (2014, 411 cites) for Fe-catalyzed alkylation mechanism; Alonso et al. (2011, 326 cites) for Ni nanoparticle H-transfer basics; Mata et al. (2013, 316 cites) for tandem cooperativity principles.
Recent Advances
Filonenko et al. (2018, 668 cites) surveys Co/Fe/Mn advances; Elangovan et al. (2016, 622 cites) details Mn selectivity; Reed-Berendt et al. (2018, 380 cites) covers first-row metals post-2013.
Core Methods
Pincer ligands (PNP, PNN) enable bifunctional catalysis; dehydrogenation forms metal hydride/oxo pairs; key techniques include in situ IR for aldehydes, Hammett studies for outer-sphere reduction.
How PapersFlow Helps You Research Borrowing Hydrogen Catalysis
Discover & Search
Research Agent uses searchPapers('borrowing hydrogen catalysis manganese') to retrieve Elangovan et al. (2016, 622 citations), then citationGraph to map 150+ citing papers on Mn pincers, and findSimilarPapers to uncover Fe analogs by Yan et al. (2014). exaSearch semantic queries like 'earth-abundant metal borrowing hydrogen reviews' surface Filonenko et al. (2018) amid 250M+ OpenAlex papers.
Analyze & Verify
Analysis Agent applies readPaperContent on Elangovan et al. (2016) to extract TON=9900 data, verifyResponse with CoVe to cross-check mechanisms against Filonenko et al. (2018), and runPythonAnalysis to plot yield vs. temperature from supplementary tables using pandas/matplotlib. GRADE grading scores mechanistic claims A (high evidence) for Mn vs. C (low) for Ni systems.
Synthesize & Write
Synthesis Agent detects gaps like 'limited Co catalysts post-2015' via contradiction flagging across Reed-Berendt et al. (2018) and Zhang et al. (2015). Writing Agent uses latexEditText for reaction schemes, latexSyncCitations to integrate 20 refs, latexCompile for PDF, and exportMermaid to diagram borrowing hydrogen cycles.
Use Cases
"Plot TON vs metal for borrowing hydrogen amine alkylation catalysts from key papers"
Research Agent → searchPapers → Analysis Agent → runPythonAnalysis(pandas scrape TON/yield data from Elangovan 2016, Yan 2014, Zhang 2015) → matplotlib bar chart exported as PNG.
"Write LaTeX review section on Mn borrowing hydrogen with citations and mechanism figure"
Synthesis Agent → gap detection → Writing Agent → latexEditText('draft text') → latexSyncCitations(Elangovan 2016 et al.) → latexGenerateFigure(mechanism) → latexCompile → PDF output.
"Find open-source codes for DFT modeling of borrowing hydrogen mechanisms"
Research Agent → paperExtractUrls(Filonenko 2018) → Code Discovery → paperFindGithubRepo → githubRepoInspect → verified DFT input files for Mn pincer hydrides.
Automated Workflows
Deep Research workflow scans 50+ papers via searchPapers on 'borrowing hydrogen earth-abundant', structures report with sections on Mn/Fe/Co/Ni, and GRADE-scores claims (e.g., Elangovan TON verified). DeepScan's 7-step chain analyzes Yan et al. (2014) with CoVe checkpoints for mechanism fidelity. Theorizer generates hypotheses like 'heterometallic Fe-Ni boosts selectivity' from Mata et al. (2013) + Reed-Berendt (2018).
Frequently Asked Questions
What defines Borrowing Hydrogen Catalysis?
It is a sequence where catalysts dehydrogenate alcohols to aldehydes/ketones, enable nucleophilic attack by amines, then hydrogenate imines to alkylated products, all from alcohol-derived H2.
What are key methods and metals used?
Mn pincer complexes (Elangovan et al., 2016), Fe catalysts (Yan et al., 2014), and Co PNP systems (Zhang et al., 2015) dominate, often with tBuOK base at 120-150°C in toluene.
What are the most cited papers?
Filonenko et al. (2018, Chem. Soc. Rev., 668 cites) reviews base metals; Elangovan et al. (2016, Nat. Commun., 622 cites) reports Mn N-alkylation; Yan et al. (2014, Nat. Commun., 411 cites) discloses Fe catalysis.
What open problems persist?
Asymmetric variants with >95% ee, broader substrate scope for biomass polyols, and catalysts stable beyond 10,000 turnovers without precious metals remain unsolved (Reed-Berendt et al., 2018).
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