Mixed Co–Mn Oxide‐Catalysed Selective Aerobic Oxidation of Vanillyl Alcohol to Vanillin in Base‐Free Conditions

Jha, Ajay; Patil, K.R.; Rode, Chandrashekhar V.

doi:10.1002/cplu.201300247

Cited by 68 publications

(49 citation statements)

References 43 publications

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“…68,86 The use of a manganese-doped cobalt mixed oxide catalyst prepared by a solvothermal method was proposed in the oxidation of vanillyl alcohol to vanillin without using a base. 87 Three different types of metal oxides were observed in the prepared catalysts, which could be identified as Co 3 O 4 , Mn 3 O 4 and CoMn 2 O 4 . Among these, the tetragonal phase of CoMn 2 O 4 was found to be the most active and selective for vanillyl alcohol oxidation.…”

Section: Oxidation Of Alcohols Using Single-metal and Alloy Catalystsmentioning

confidence: 99%

Homogeneous, Heterogeneous and Nanocatalysis

Albonetti

Mazzoni

Cavani

2014

Transition Metal Catalysis in Aerobic Alcohol Oxidation

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The past decade has seen ever-increasing interest in the catalytic aerobic oxidation of alcohols, which is one of the pivotal functional group transformations in organic chemistry. Nevertheless, most of the current methods for alcohol oxidation are not catalytic, hence the use of catalysts and green oxidants such as O2 or air, instead of stoichiometric quantities of inorganic oxidants, will provide a highly desirable approach to this reaction. This chapter summarizes the latest breakthroughs in the use of homogeneous and heterogeneous catalysts in aerobic alcohol oxidation in the liquid phase; the use of microwaves and photochemistry to assist and promote catalytic activities is also highlighted. Moreover, since nanoparticle systems may be considered an interesting compromise between heterogeneous and homogeneous catalytic systems, the recent development of soluble transition metal colloids as active nanocatalysts for aerobic alcohol oxidation is also presented.

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Section: Oxidation Of Alcohols Using Single-metal and Alloy Catalystsmentioning

confidence: 99%

Homogeneous, Heterogeneous and Nanocatalysis

Albonetti

Mazzoni

Cavani

2014

Transition Metal Catalysis in Aerobic Alcohol Oxidation

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“…Figure shows conversion/selectivity (%) values with respect to time obtained in the Ru/ n ‐HT catalyzed aerobic oxidation of cinnamyl, vanillyl and veratryl alcohols, we found that Ru/ n ‐HT provided turnover frequency (TOF; TOF=mol of product/mol of ruthenium×time and all TOF values given here are not corrected to for the number of exposed surface atoms; that is, the values given are lower limits) values of 13.2, 5.1 and 11.4 h −1 for the aerobic oxidation of cinnamyl, vanillyl and veratryl alcohols, respectively. These TOF values are notably higher than those of obtained by Bi−Pt/Al 2 O 3 (2.1 h −1 for (1)), Pd/SWCNT (0.7 h −1 for (1)), MnFe 1.5 Ru 0.35 Cu 0.15 O 4 (7.9 h −1 for (1)), Au/CeO 2 (1.2 h −1 for (1)), CoMn 2 O 4 (3.1 h −1 for (2)), Co 3 O 4 (2.8 h −1 for (2)), Ru/Al 2 O 3 (1.8 h −1 for (3)), Ru/SiO 2 (1.6 h −1 for (3)), and Ru/ZIF‐8 (1.9 h −1 for (3)) catalysts tested in the aerobic oxidation of same substrates.…”

Section: Resultsmentioning

confidence: 99%

“…In particular, cinnamyl, vanillyl and veratryl alcohols are most widely used lignin model compounds to mimic the propyl side‐chain (cinnamyl alcohol), phenolic (vanillyl alcohol) and non‐phenolic (veratryl alcohol) functional groups of lignin . Up to date, various enzymatic,, homogeneous, and heterogeneous catalytic systems have been developed and tested in the aerobic oxidation of these lignin model compounds. Despite the improvements made by the enzymatic catalysis, these systems usually suffer from low stability, pH adjustments and enzyme deactivation and these concerns limit their usability.…”

Section: Introductionmentioning

confidence: 99%

Nanohydrotalcite Supported Ruthenium Nanoparticles: Highly Efficient Heterogeneous Catalyst for the Oxidative Valorization of Lignin Model Compounds

et al. 2017

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The catalytic transformation of lignocellulosic biomass derived chemicals into value‐added chemicals under mild conditions remains a challenge in the fields of synthetic chemistry and catalysis. Herein, we describe a new heterogeneous catalyst system that efficiently works in the oxidative valorization of lignin model compounds. This new heterogeneous catalyst system comprised of nano‐sized hydrotalcite (n‐HT; Mg6Al2(CO3)(OH)16) supported ruthenium(0) nanoparticles (Ru/n‐HT) was prepared by ion‐exchange of [Ru(OH2)Cl5]2− anions with the extraframework CO32− anions of n‐HT followed by their borohydride reduction (NaBH4) in water at room temperature. The characterization of Ru/n‐HT was done by the combination of various spectroscopic and the sum of their results revealed that the formation of well‐dispersed ruthenium(0) nanoparticles with a mean diameter of 3.2 ± 0.9 nm on the surface of n‐HT structure. The catalytic performance of Ru/n‐HT in terms of activity, selectivity and stability was tested in the aerobic oxidation of cinnamyl, veratryl and vanillyl alcohols, which are important lignin model compounds used to mimic the propyl side chain, the phenolic and non‐phenolic, respectively functional groups of lignin. We found that Ru/n‐HT nanocatalyst displays remarkable activity at high selectivity and almost complete conversion in these catalytic transformations under mild reaction conditions (at 373 K under 3 bar initial O2 pressure).

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“…The oxygen concentration at the interface of the gas-liquid phase can be calculated by Henry's Law directly (Equation (15)). Thus, Equations (12)(13) were derived based on the assumptions above.…”

Section: Kinetic Parametersmentioning

confidence: 99%

“…During the reaction process, less than 0.5 g solvent was detected in gas absorption equipment 15 (Figure 1), demonstrating no reactant leakage. The intrinsic kinetic constants k 21 and k 22 were derived by nonlinear regression of Equations (12)(13). The Hatta numbers satisfied the pseudo-first order reactions well for both steps of the consecutive reactions (Tables 1 and 2).…”

Section: Kinetic Parametersmentioning

confidence: 99%

Kinetic studies on the liquid‐phase catalytic oxidation of 4‐methyl guaiacol to vanillin

Liu

Mao

et al. 2017

Can J Chem Eng

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Kinetic studies on the catalytic oxidation of 4‐methyl guaiacol using an ether intermediate towards vanillin in an agitator bubbling reactor were presented. The reaction was catalyzed by N,N′‐ethylenebis(acetylacetoniminato)‐cobalt(II) hexafluorophosphoric pyridinium (Co‐[Salen‐Py][PF6]2) under strong alkaline conditions with molecular oxygen as the terminal oxidant. The reaction scheme was demonstrated by a detailed analysis of the products distribution and control experiments. The intrinsic kinetics were explored based on our proposed p‐benzoquinone methide mechanism, which revealed that the oxidation rate was determined by the oxidation of phenoxyl anion to phenoxyl radical catalyzed by LCo3+(O2·) (L = [Salen‐Py][PF6]2). The kinetic experiments were performed under a mass transfer‐reaction condition due to the inevitable mass transfer resistance involved. Pseudo‐first order fast reactions were observed for both steps of the consecutive reactions based on the calculated physical and mass transfer parameters. The intrinsic kinetic equations for the first and second steps can be written as RA=5.98×105exp(−31950RT)CCcat.CO2A and RF=1.02×106exp(−29770RT)CCcat.CO2E, respectively, which are well in accordance with the mechanism. These conclusions are expected to give a clue for the mechanistic study, kinetic investigation, reaction optimization, and catalyst design for the oxidation of various p‐cresols.

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Mixed Co–Mn Oxide‐Catalysed Selective Aerobic Oxidation of Vanillyl Alcohol to Vanillin in Base‐Free Conditions

Cited by 68 publications

References 43 publications

Homogeneous, Heterogeneous and Nanocatalysis

Homogeneous, Heterogeneous and Nanocatalysis

Nanohydrotalcite Supported Ruthenium Nanoparticles: Highly Efficient Heterogeneous Catalyst for the Oxidative Valorization of Lignin Model Compounds

Kinetic studies on the liquid‐phase catalytic oxidation of 4‐methyl guaiacol to vanillin

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