Pincer-Ruthenium-Catalyzed Direct Formation of Fuel-Grade Alkanes via a Net-Decarboxylative Coupling of Alcohols DOI

Pran Gobinda Nandi,

Pabitra Maity,

Akshai Kumar

et al.

ACS Catalysis, Journal Year: 2024, Volume and Issue: 15(1), P. 543 - 556

Published: Dec. 20, 2024

The net-decarboxylative coupling of low-molecular weight alcohols to high-molecular alkanes has been investigated using a series NNN pincer-Ru catalysts based on bis(imino)pyridine and 2,6-bis(benzimidazole-2-yl)pyridine ligands. Notably, majority the considered complexes, including Ru precursors, were either not very active or unselective giving alkene/alkane mixtures. However, in presence 0.5 equiv NaOH toluene at 140 °C, complex (MeBim2NNN)RuCl2(PPh3)2 ligand demonstrated high activity up 91% yield with 100% selectivity toward alkane (1,3-diphenyl propane) starting from 2-phenyl ethanol after 24 h reaction. On other hand, (iPr2NNN)RuCl2(PPh3) was found be least gave 14% 1,3-diphenyl propane 25% selectivity. Experimental mechanistic studies point evolution hydrogen (detected by GC) formic acid 1H NMR) during reaction along involvement organic intermediates such as α,β-unsaturated aldehydes. [(MeBim2NNN)RuCl(PPh3)2]Cl catalyzed transformation first-order dependence initial rate concentration both catalyst base. While poisoning experiments Hg revealed homogeneous well-defined molecular nature catalyst, few these species, resting state (MeBim2NNN)RuHCl (experimentally trapped its PPh3 adduct), have identified HRMS analysis NMR studies. DFT complement experimental findings indicate that more favorable hydrogenolysis path, dehydrogenolysis step is rate-determining (ΔG140‡ = 22.81 kcal/mol), it leads formation acetaldehyde (MeBim2NNN)RuHCl. corresponding cycle involved insertion propene into Ru–H bond RDS had relatively unfavorable barrier 27.81 kcal/mol. This work provides direct access jet-fuel-grade single-step, one-pot strategy offers great promise open exciting opportunities this important field study.

Language: Английский

Recent advances on cross-coupling of alcohols via borrowing hydrogen catalysis DOI

Suteerna Mullick,

Adrija Ghosh, Debasis Banerjee

et al.

Chemical Communications, Journal Year: 2024, Volume and Issue: 60(30), P. 4002 - 4014

Published: Jan. 1, 2024

This article highlights the recent advances and significance of β-alkylation reactions towards synthesis higher order alcohols.

Language: Английский

Citations

14
Guerbet-type β-alkylation of secondary alcohols catalyzed by chromium chloride and its corresponding NNN pincer complex DOI

Himani Narjinari,

Niharika Tanwar,

Lakshay Kathuria

et al.

Catalysis Science & Technology, Journal Year: 2022, Volume and Issue: 12(15), P. 4753 - 4762

Published: Jan. 1, 2022

β-Alkylation of alcohols has been efficiently accomplished using readily available 3d metal Cr under microwave conditions in air. Well-defined molecular is involved with a KIE 7.33 and insertion α-alkylated ketone into Cr–H bond as the RDS.

Language: Английский

Citations

34
Pincer–Ruthenium-Catalyzed Reforming of Methanol─Selective High-Yield Production of Formic Acid and Hydrogen DOI
Vinay Arora, Eileen Yasmin,

Niharika Tanwar

et al.

ACS Catalysis, Journal Year: 2023, Volume and Issue: 13(6), P. 3605 - 3617

Published: Feb. 27, 2023

A series of NNN pincer–ruthenium complexes the type (R2NNN)RuCl2(CH3CN) based on bis(imino)pyridine ligands were synthesized and characterized. These pincer ruthenium acetonitrile complexes, along with their phosphine carbonyl counterparts, tested for reforming methanol in water presence a base. The catalyst (Cy2NNN)RuCl2(PPh3) was found to be most efficient comparison other considered catalysts. Among bases screened, KOtBu (1.5 equiv respect water) give best results at temperatures as low 100 °C. Under these conditions, while (0.2 mol %) mixture 2:1 ratio gave yield up 81% each hydrogen formic acid (FA) 100% selectivity, corresponding reaction 2 % 90% 73% FA 80% selectivity. On hand, (0.8 catalyzed 3:1 methanol/water good yields (84%) 95% cross-verified by using it reduce unsaturated compounds determining reduced product, which consistent. Isotope-labeling studies suggest involvement C–H activation part catalytic cycle not rate-determining step (RDS) an average secondary KIE 1.96. observed have first-order dependence rate concentration both methanol. DFT are agreement this, σ-bond metathesis leading elimination first molecule is computed RDS either moles or that carbon dioxide 3 hydrogen. Ru–H species (Cy2NNN)RuCl(H) plays decisive role unprecedented selectivity toward FA. In its choice undergo O–H (that completes cycle) leads dioxide, chooses former kinetically more favored 4.58 kcal/mol. current system comprising pincer-ruthenium phosphines gives high H2 operating temperature offers immense promise transformation clean-burning high-value

Language: Английский

Citations

18
Pincer-Cobalt-Catalyzed Guerbet-Type β-Alkylation of Alcohols in Air under Microwave Conditions DOI

Pran Gobinda Nandi,

Prasad Thombare,

Siriyara Jagannatha Prathapa

et al.

Organometallics, Journal Year: 2022, Volume and Issue: 41(22), P. 3387 - 3398

Published: Aug. 5, 2022

Pincer complexes of the type (R2NNN)CoCl2 (R = iPr, tBu, Cy, Ph, p-F-C6H4) derived from environmentally benign, earth-abundant, and inexpensive base metal cobalt have been synthesized that exist in equilibrium with [(R2NNN)2Co]CoCl4. Among these complexes, (iPr2NNN)CoCl2 has found to be highly efficient for catalytic β-alkylation alcohols air at 140 °C. While pincer-Co (0.0025 mol %)-catalyzed presence NaOtBu (2.5 %) took 24 h (85%, 34000 TON 1417 TO/h) under conventional heating (140 °C), corresponding reaction microwave conditions °C 75 W) was complete only 2 comparable yields (83%, 33200 TON), albeit a better TOF (16600 TO/h). In contrast, CoCl2 otherwise identical leads lower both (66%, 26400 1100 (61%, 24400 12200 The system successfully implemented (39 examples) accomplish secondary several primary alcohols. Well-defined molecular Co(II) species are involved during catalysis, as inferred HRMS hot-filtration experiments. EPR studies magnetic moment measurements using Evans method demonstrate Co remains its +2 state an octahedral geometry throughout reaction. Pivotal evidence involvement β-hydride elimination leading acetophenone RDS catalyzed is obtained competitive deuterium labeling experiments, which indicative KIE 6.14. current report on base-metal catalysis high unprecedented turnovers (33200 16600 very short time (2 h) offers exciting atom-economical greener possibilities class synthetically valuable Guerbet-type reactions.

Language: Английский

Citations

23
Microwave-assisted pincer-ruthenium catalyzed Guerbet reaction for the upgradation of bio-ethanol to bio-butanol DOI
Kanu Das, Lakshay Kathuria, Raksh V. Jasra

et al.

Catalysis Science & Technology, Journal Year: 2023, Volume and Issue: 13(6), P. 1763 - 1776

Published: Jan. 1, 2023

Bis(benzimidazole-2-yl)pyridine based pincer-ruthenium (immobilized or otherwise) catalyzes the upgradation of feed agnostic bio-ethanol to fuel grade n -butanol at unprecedented turnovers under microwave conditions within two hours reaction.

Language: Английский

Citations

12
NNN Pincer-Manganese-Catalyzed Guerbet-Type β-Alkylation of Alcohols under Microwave Irradiation DOI

Akshara Bisarya,

Raksh V. Jasra, Akshai Kumar

et al.

Organometallics, Journal Year: 2023, Volume and Issue: 42(14), P. 1818 - 1831

Published: June 24, 2023

A series of manganese carbonyl complexes based on bis(imino)pyridine ligands the type R2NNN (R = Cy, iPr, Ph, p-FC6H4) were synthesized. While complex appears to be an NN bidentate-Mn(I) triscarbonyl species in solid state, solution, there is a gradual loss carbon monoxide leading first NNN pincer-Mn(I) biscarbonyl complex, which finally disproportionates pincer-Mn(II) dibromide and pincer-Mn(0) complex. Evidence for this transformation has been obtained from single-crystal X-ray diffraction, IR, EPR, HRMS analysis. The apparently faster with cyclohexyl-substituted than others. considered (0.05 mol %) utilized catalyzing β-alkylation secondary alcohols at 140 °C air under conventional heating (12 h), as well microwave (2 h) presence 2.5 % NaOtBu. Among complexes, catalyst (p-FC6H4NNN)Mn(CO)2Br was found highly efficient. heating, maximum 92% (1840 TON 153 TOs/h) β-alkylated product obtained; provided 85% yield (1700 850 just 2 h. catalytic system successfully implemented alkylate several other alcohols, (35 examples). analyses indicate intermediates cycle both pincer-Mn(II)/Mn(0) couple. Deuterium labeling studies point involvement C–H bond activation rate-determining step (RDS) kinetic isotope effect (KIE) 9.0.

Language: Английский

Citations

12
Highly Efficient Base Catalyzed N‐alkylation of Amines with Alcohols and β‐Alkylation of Secondary Alcohols with Primary Alcohols DOI Creative Commons
Nitish K. Garg, Mattias Tan, Magnus T. Johnson

et al.

ChemCatChem, Journal Year: 2023, Volume and Issue: 15(20)

Published: Aug. 8, 2023

Abstract Borrowing hydrogen (BH) reactions are very useful for the sustainable synthesis of C−C and C−N bonds. They generally operate with transition metal‐based catalysts along stoichiometric/catalytic amounts added base. Here we report that two catalytic transformations, carried out BH methodology, i. e. N ‐alkylation amines alcohols β‐alkylation secondary primary alcohols, can be performed effectively just base under air without using any catalyst. The mechanism is proposed to based on oxidation alcohol aldehyde followed by condensation an unsaturated intermediate which undergoes transfer hydrogenation product.

Language: Английский

Citations

11
Ruthenium-catalyzed β-alkylation of secondary alcohols with primary alcohols: Protic N-heterocyclic carbene's promotional influence DOI
Jing Shi,

Lizhu Zhang,

Panpan Li

et al.

Journal of Molecular Structure, Journal Year: 2024, Volume and Issue: 1305, P. 137815 - 137815

Published: Feb. 17, 2024

Language: Английский

Citations

3
Acceptorless or Transfer Dehydrogenation of Glycerol Catalyzed by Base Metal Salt Cobaltous Chloride – Facile Access to Lactic Acid and Hydrogen or Isopropanol DOI

Himani Narjinari,

Sunil Dhole,

Akshai Kumar

et al.

Chemistry - A European Journal, Journal Year: 2023, Volume and Issue: 30(1)

Published: Oct. 9, 2023

The dehydrogenation of glycerol to lactic acid (LA) under both acceptorless and transfer conditions using readily available, inexpensive, environmentally benign earth-abundant base metal salt CoCl

Language: Английский

Citations

9
Pincer–Ruthenium-Catalyzed β-Methylation of Alcohols DOI

Pran Gobinda Nandi,

Raksh V. Jasra, Akshai Kumar

et al.

Organometallics, Journal Year: 2023, Volume and Issue: 42(21), P. 3138 - 3152

Published: Oct. 30, 2023

The synthesis and characterization of three NNN pincer–Ru complexes based on bis(imino)pyridine ligands have been reported. These along with other previously reported catalysts 2,6-bis(benzimidazol-2-yl)pyridine employed to accomplish the β-methylation 2-phenylethanol selective β-dimethylation 1-phenylethanol using methanol as an alkylating agent. In general, pincer–ruthenium complex [(MeBim2NNN)RuCl(PPh3)2]Cl dimethyl-substituted ligand was found be most efficient among considered catalysts. Under best conditions, in (0.5 mol %)-catalyzed reactions presence 0.75 equiv KOH 7.5 methanol, up 92% yield β-methylated obtained at 140 °C. On hand, could achieved 2 Na 24.8 methanol. developed synthetic protocol is generic nature applied about 35 substrates. reaction has also probed from a mechanistic point view. While mercury poisoning experiments revealed catalyzed by well-defined molecular catalysts, kinetic indicated that rate product formation linear dependence concentrations both catalyst 2-phenylethanol. DFT studies complement observed secondary isotope effect (KIE) 1.56 suggest dehydrogenolysis involving σ-bond metathesis Ru–H species leading evolution hydrogen rate-determining step barrier 24.06 kcal/mol. Ru–OMe species, being lowest-energy intermediates catalytic cycle, are likely resting state cycle detected NMR HRMS analysis.

Language: Английский

Citations

9