Direct Hydrogenation of Biobased Carboxylic Acids Mediated by a Nitrogen‐centered Tridentate Phosphine Ligand

Deng, Li; Kang, Bin; Englert, Ulli; Klankermayer, Jürgen; Palkovits, Regina

doi:10.1002/cssc.201501461

Cited by 31 publications

(31 citation statements)

References 47 publications

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“…Catalysts comprised of platinum-group-metal complexes have played a leading role in carrying out selective hydrogenations. [15][16][17][18][19][20][21][22][23][24][25][26][27][28] However, the chemical and thermal stabilities of these catalysts are typically poor, and separation of catalysts from products is relatively difficult.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic study of the selective hydrogenation of carboxylic acid derivatives over supported rhenium catalysts

Toyao

Wei

Siddiki

et al. 2019

Catal. Sci. Technol.

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Section: Introductionmentioning

confidence: 99%

Mechanistic study of the selective hydrogenation of carboxylic acid derivatives over supported rhenium catalysts

Toyao

Wei

Siddiki

et al. 2019

Catal. Sci. Technol.

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“…After the reaction is complete, airfree aqueous workup to remove any residual sodium and borane salts is performed to isolate the ligands in fair to good yields (56−84%) and high purity. resonance in their 31 P{ 1 H} spectrum around −20 ppm corresponding to the phenyl substituted arm and a second resonance ranging from 1.8 (R = i Pr) to −41 ppm (R = i Bu, oTol). Symmetrical NP 3 tetradentate ligands can also be synthesized using ammonium salts as the lone nitrogen source.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…30 An unsymmetrical NP 2 P ligand with two chains linked by methylene spacers and one chain linked with an ethylene spacer has been reported with ruthenium for the hydrogenation of biobased carboxylic acids. 31 Increased flexibility can be achieved by lengthening the ethylene spacers to propylene in order to accommodate larger atoms like Mo(0). 32 Unsymmetrical tetradentate ligands have also been reported where one phosphorus donor is substituted for an additional nitrogen donor, resulting in an open-chain P 2 N 2 framework if the nitrogen donors are geometrically equivalent, or a P 2 NN′ framework if they are not.…”

Section: ■ Introductionmentioning

confidence: 99%

A One-Step Preparation of Tetradentate Ligands with Nitrogen and Phosphorus Donors by Reductive Amination and Representative Iron Complexes

et al. 2020

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The synthesis and use of the first examples of unsymmetrical, mixed phosphine donor tripodal NPP 2 ′ ligands N-(CH 2 CH 2 PR 2 ) 2 (CH 2 CH 2 PPh 2 ) are presented. The ligands are synthesized via a convenient, one pot reductive amination using 2-(diphenylphosphino)ethylamine and various substituted phosphonium dimers in order to introduce mixed phosphine donors substituted with P/ P′, those being Ph/Cy (2), Ph/ i Pr (3), Ph/ i Bu (4), Ph/o-Tol (5), and Ph/p-Tol (6). Additionally, we have developed the first known synthesis of a symmetrical tripodal NP 3 ligand N(CH 2 CH 2 PiBu 2 ) 3 using bench safe ammonium acetate as the lone nitrogen source (7). This new protocol eliminates the use of extremely dangerous nitrogen mustard reagents typically required to synthesize NP 3 ligands. Some of these tetradentate ligands and also P 2 NN′ ligands N(CH 2 -o-C 5 H 4 N)(CH 2 CH 2 PR 2 ) 2 (P 2 NN′-Cy, R = Cy; P 2 NN′-Ph, R = Ph) prepared by reductive amination using 2-picolylamine are used in the synthesis and reactions of iron complexes. FeCl 2 (P 2 NN′-Cy) (8) undergoes single halide abstraction with NaBPh 4 to give the trigonal bipyramidal complex [FeCl(P 2 NN′-Cy)][BPh 4 ] (9). Upon exposure to CO(g), complex 9 readily coordinates CO giving [FeCl(P 2 NN′-Cy)(CO)][BPh 4 ] (10), and further treatment with an excess of NaBH 4 results in formation of the hydride complex [Fe(H)(P 2 NN′-Cy)(CO)][BPh 4 ] (11). Our previously reported complex FeCl 2 (P 2 NN′-Ph) undergoes double halide abstraction with NaBPh 4 in the presence of the coordinating solvent to give [Fe(NCMe) 2 (P 2 NN′-Ph)][BPh 4 ] 2 (12). Ligand 3 can be coordinated to FeCl 2 , and upon sequential halide abstraction, treatment with NaBH 4 , and exposure to an atmosphere of dinitrogen, the dinitrogen hydride complex [Fe(H)(NPP 2 ′-i Pr)(N 2 )][BPh 4 ] (13) is isolated. Our symmetrical NP 3 ligand 7 can also be coordinated to FeCl 2 and, upon exposure to an atmosphere of CO(g), selectively forms [FeCl(NP 3 )(CO)][BPh 4 ] (14) after salt metathesis with NaBPh 4 . Complex 14 can be treated with an excess of NaBH 4 to give the hydride complex [Fe(H)(NP 3 )(CO)][BPh 4 ] (15), which can further be deprotonated/reduced to the Fe(0) complex Fe(NP 3 )(CO) (16) upon treatment with an excess of KH.

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“…Surprisingly, both [Ru(acac)3] and RuH2(PPh3)4 produced 99% and 95% yield in GVL respectively, when no ligand was added to the reaction mixture, while in the presence of the ethylated N-Triphos ligand, RuH2(PPh3)4 afforded 98% yield in PDO. With different The year after, Deng and Palkovits showed the same transformations using Ru precursors and a modified version of N-Triphos, where an ethylene linker was substituted in one of the arms [783]. The reactions were performed in THF, with 1.5 equivalents of the novel ligand, 70 bar H 2 , 160 • C, for 18 h. The selectivity was found to be highly dependent on the ruthenium precursor used (0.2 mol% Ru loading); when using [Ru(acac) 3 ] as in the previous study by Miller, the reaction afforded 33% yield of GVL and 66% yield of PDO.…”

Section: Valorization Of Biomass-derived Compoundsmentioning

confidence: 93%

Recent Progress with Pincer Transition Metal Catalysts for Sustainability

2020

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Our planet urgently needs sustainable solutions to alleviate the anthropogenic global warming and climate change. Homogeneous catalysis has the potential to play a fundamental role in this process, providing novel, efficient, and at the same time eco-friendly routes for both chemicals and energy production. In particular, pincer-type ligation shows promising properties in terms of long-term stability and selectivity, as well as allowing for mild reaction conditions and low catalyst loading. Indeed, pincer complexes have been applied to a plethora of sustainable chemical processes, such as hydrogen release, CO2 capture and conversion, N2 fixation, and biomass valorization for the synthesis of high-value chemicals and fuels. In this work, we show the main advances of the last five years in the use of pincer transition metal complexes in key catalytic processes aiming for a more sustainable chemical and energy production.

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Direct Hydrogenation of Biobased Carboxylic Acids Mediated by a Nitrogen‐centered Tridentate Phosphine Ligand

Cited by 31 publications

References 47 publications

Mechanistic study of the selective hydrogenation of carboxylic acid derivatives over supported rhenium catalysts

Mechanistic study of the selective hydrogenation of carboxylic acid derivatives over supported rhenium catalysts

A One-Step Preparation of Tetradentate Ligands with Nitrogen and Phosphorus Donors by Reductive Amination and Representative Iron Complexes

Recent Progress with Pincer Transition Metal Catalysts for Sustainability

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