Selective catalytic oxidation of sugar alcohols to lactic acid

Manas, Michael G.; Campos, Jesús; Sharninghausen, Liam S.; Lin, Elisa; Crabtree, Robert H.

doi:10.1039/c4gc01694g

Cited by 57 publications

(64 citation statements)

References 38 publications

(35 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In light of N‐heterocyclic carbene‐metal (NHC‐M) complexes can act as robust and viable catalysts in a broad range of reactions, various strategies have been developed for their immobilization . Among them, self‐supporting strategy may represent one of the most practical and efficient approaches .…”

Section: Fabrication Of Pomp‐nhc‐m By Direct Knitting With Different mentioning

confidence: 99%

“…In light of their robustness toward Friedel‐Crafts reaction conditions, bis‐chelating NHC‐M (Ir, Pd and Ru) complexes 4 , 5 and 6 , derived from corresponding benzimidazolium salts, were selected to fabricate POMPs via direct knitting with benzene (Figure a). Concerning the plausible impact of the ratio between the crosslinking reagent and the Lewis acid on the porous structure, surface area and catalytic activity, with bis‐NHC‐Ir complex 4a , the amounts of FeCl 3 , formaldehyde dimethyl acetal (FDA) and benzene in the knitting process were investigated for the generation of POMP‐NHC‐Ir 1a‐h ( Table 1 , entries 1–8).…”

Section: Fabrication Of Pomp‐nhc‐m By Direct Knitting With Different mentioning

confidence: 99%

“…The successful immobilization of bis‐chelating NHC‐M complexes within the polymer matrices was further confirmed by Fourier transform infrared (FT‐IR) spectroscopy, solid‐state 13 C NMR spectroscopy and XPS ( Figure a,b and Figure S45, Supporting Information). In the case of POMP‐NHC‐Ir 1d , the presence of the absorption band at 2088 cm −1 in its FT‐IR spectra, corresponding to the CO ligand attached to the iridium center, indicated the successful knitting of bis‐NHC‐Ir complex 4a (Figure S45, Supporting Information). In the solid‐state 13 C NMR spectra (Figure a, blue line, Figure S50, Supporting Information), peaks for C Ar (135 ppm, aromatic rings) and C Me (35 ppm, N‐methyl groups and bridging methylene) in the POMPs correspond well with those observed in bis‐NHC‐Ir 4a .…”

Section: Fabrication Of Pomp‐nhc‐m By Direct Knitting With Different mentioning

confidence: 99%

See 2 more Smart Citations

Hierarchical Porous Organometallic Polymers Fabricated by Direct Knitting: Recyclable Single‐Site Catalysts with Enhanced Activity

et al. 2019

View full text Add to dashboard Cite

supported catalysts by simply knitting rigid aromatic ligands via hypercross-linking (Friedel-Crafts reactions) has recently been proposed. [13] After further postmodification/activation, several MCPPs have been successfully developed. [14][15][16][17] However, with postmodification, avoiding the problems, like low density of catalytic sites due to incomplete modification and random/ nonselective metal anchoring, can be difficult. These issues may still lead to low catalytic activity and selectivity, especially in some challenging transformations. [18] In light of N-heterocyclic carbene-metal (NHC-M) complexes can act as robust and viable catalysts in a broad range of reactions, [19][20][21][22][23][24][25][26][27][28] various strategies have been developed for their immobilization. [29,30] Among them, selfsupporting strategy may represent one of the most practical and efficient approaches. [31][32][33][34] It has to be noted that NHC ligands still have to be carefully designed and modified before selfsupporting. Alternatively, the high catalytic activities and robustness of NHC-M complexes make them perfect candidates for direct knitting. To the best of our knowledge, there are only two reported examples on MCPPs in which the NHC ligands are firstly knitted and then coordinated to active metal ions (postmodification approach). [14,15] Direct knitting of NHC-M complexes to fabricate porous organometallic polymers (POMPs) that do not require postmodification/activation is still unknown.Herein, we have designed and prepared a series of unprecedented porous organometallic polymers POMPs-NHC-M 1-3 via direct knitting three types of bis-chelating NHC-M complexes (M = Ir, Pd, and Ru, Figure 1a). Using this facile strategy, which does not require postmodification/activation, 1) the metal active sites are atomically dispersed in the hierarchical porous matrix, and 2) the intrinsic well-defined bis-chelating mode and their molecular catalytic properties are maximally retained, which allows 3) the precise design and control of the immobilized catalysts at the molecular level. The advantages of direct knitting allow the resulting POMPs-NHC-M 1-3 to behave as recyclable solid single-site catalysts and exhibit extremely high catalytic activities in both hydrogenation and dehydrogenation reactions.In light of their robustness toward Friedel-Crafts reaction conditions, bis-chelating NHC-M (Ir, Pd and Ru) complexes 4, 5 and 6, derived from corresponding benzimidazolium salts, [24,25,27] were selected to fabricate POMPs via direct knitting with benzene ( Figure 1a). Concerning the plausible impact Porous organometallic polymers (POMPs) with hierarchical pore structures, high specific surface areas, and atomically dispersed metal (Ir, Pd, Ru) centers are successfully fabricated by a facile one-pot method through direct knitting of diverse N-heterocyclic carbene metal (NHC-M) complexes. These polymers can function as recyclable solid single-site catalysts and exhibit excellent catalytic activity and selectivity in both dehydrogenat...

show abstract

Section: Fabrication Of Pomp‐nhc‐m By Direct Knitting With Different mentioning

confidence: 99%

Section: Fabrication Of Pomp‐nhc‐m By Direct Knitting With Different mentioning

confidence: 99%

Section: Fabrication Of Pomp‐nhc‐m By Direct Knitting With Different mentioning

confidence: 99%

See 1 more Smart Citation

Hierarchical Porous Organometallic Polymers Fabricated by Direct Knitting: Recyclable Single‐Site Catalysts with Enhanced Activity

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Additionally, 4 is able to dehydrogenate crude glycerol directly obtained from the biodiesel industry in spite of its having a deep brown color due to numerous impurities . We were later able to extend DO catalysis with 4 to higher polyols, namely sugar alcohols with 4–6 carbons . The reaction again gives lactate as the major product albeit with lower selectivity, and a series of base‐catalyzed steps including a retro‐aldol reaction were proposed.…”

Section: Dehydrogenative Oxidationmentioning

confidence: 97%

Activation, Deactivation and Reversibility in a Series of Homogeneous Iridium Dehydrogenation Catalysts

Sharninghausen

Crabtree

2017

Israel Journal of Chemistry

Self Cite

View full text Add to dashboard Cite

Dehydrogenation is a sustainable form of oxidation catalysis, as it avoids any primary oxidant and the waste that would accompany it. Homogeneous catalyst design for this reaction is delicate: the catalyst must have a sufficient H2 affinity to abstract two hydrogen atoms from the substrate but not so much affinity as to fail to release them as free H2. N‐Heterocyclic carbene (NHC) ligands achieve this balancing act in a series of iridium catalysts based on the Ir(IMe)2 motif (IMe=N,N′‐dimethylimidazol‐2‐ylidene). Catalyst design also needs to account for mechanistic points outside of the catalytic cycle itself. To enter the cycle, there is often an initial precatalyst activation process, and elucidating this can lead to optimization of both precatalyst and reaction conditions. To leave the cycle, we can have reversible formation of off‐cycle species as well as an irreversible catalyst deactivation step. In our Cp*Ir(IMe)2Cl precatalyst for dehydrogenative oxidation, Cp* is lost in the activation step. This suggested moving to a catalyst precursor lacking the Cp*, [Ir(IMe)2(CO)2]+. Catalyst deactivation produces a series of unusual cluster cations such as [Ir6(IMe)8(CO)2H14]2+. Among applications, dehydrogenative oxidation can be useful in upgrading of biomass glycerol by conversion to lactate, as a part of hydrogen borrowing chemistry and in reversible hydrogenation/dehydrogenation for H2 storage.

show abstract

“…Despite the possible formation of several by-products, selectivity to lactic acid with the reported iridium complexes surpasses 95% in a broad range of experimental conditions. Remarkably, C4-C6 sugars can been converted to lactic acid and H 2 by complex 1, although catalyst deactivation prevents from obtaining very high LA yields [64]. A unique carbene-Ir 6 cluster was characterized and identified as major product of deactivation in glycerol dehydrogenation suggesting a minor role of other ancillary ligands in the iridium precatalyst [65].…”

Section: From Glycerol To Lactic Acidmentioning

confidence: 98%

Lactic acid and hydrogen from glycerol via acceptorless dehydrogenation using homogeneous catalysts

Bottari¹,

Barta²

2015

Recyclable Catalysis

View full text Add to dashboard Cite

Acceptorless dehydrogenation of alcohols has emerged as a powerful methodology for the valorization of biomass derived platform chemicals and building blocks. In this review we provide a short overview of the advantages and possible product outcomes of this method. The main focus will be devoted to the conversion of glycerol, which is the major waste product of biodiesel production, to lactic acid. While extensive research addresses the development of heterogeneous catalysts, recently new and highly active iridium and ruthenium complexes have also been reported. These novel homogeneous catalysts are even more active than the already reported heterogeneous systems and enable the direct conversion of glycerol into lactic acid and molecular hydrogen. While the product hydrogen might be used either as fuel or as reducing agent for other processes, lactic acid is a platform chemical widely employed by the polymer, pharmaceutical and food industries. The used catalytic methodology is atom-economic, waste-free and is uniquely suited for the efficient conversion of renewable resources.

show abstract

Selective catalytic oxidation of sugar alcohols to lactic acid

Abstract: Homogeneous iridium catalysts are reported for the highly efficient and selective conversion of polyols to hydrogen gas and lactic acid.

Cited by 57 publications

References 38 publications

Hierarchical Porous Organometallic Polymers Fabricated by Direct Knitting: Recyclable Single‐Site Catalysts with Enhanced Activity

Hierarchical Porous Organometallic Polymers Fabricated by Direct Knitting: Recyclable Single‐Site Catalysts with Enhanced Activity

Activation, Deactivation and Reversibility in a Series of Homogeneous Iridium Dehydrogenation Catalysts

Lactic acid and hydrogen from glycerol via acceptorless dehydrogenation using homogeneous catalysts

Contact Info

Product

Resources

About