cas 2785-87-7, DIHYDROEUGENOL | Articles data

Articles about 2785-87-7Total 94 be found

Article title
Article abstract
Author
Journal number and time
Download

Lignin depolymerization to monophenolic compounds in a flow-through system
A reductive lignocellulose fractionation in a flow-through system in which pulping and transfer hydrogenolysis steps were separated in time and space has been developed. Without the hydrogenolysis step or addition of trapping agents to the pulping, it is possible to obtain partially depolymerized lignin (21 wt% monophenolic compounds) that is prone to further processing. By applying a transfer hydrogenolysis step 37 wt% yield of lignin derived monophenolic compounds was obtained. Pulp generated in the process was enzymatically hydrolyzed to glucose in 87 wt% yield without prior purification.
Kumaniaev, Ivan,Subbotina, Elena,S?vmarker, Jonas,Larhed, Mats,Galkin, Maxim V.,Samec, Joseph S.M.
p. 5767 - 5771
(2017)
Read Online

Antioxidant activity of eugenol and related monomeric and dimeric compounds
Since the inhibitory effect of eugenol (a), which was isolated as an antioxidative component from plant, Caryopylli flos, on lipid peroxidation was less than that of α-tocopherol, we synthesized, the eugenol-related compounds dieugenol (b), tetrahydrodieugenol (c), and dihydroeugenol (d), to find new strong antioxidants and assessed them for their inhibitory effect on lipid peroxidation and scavenging ability for superoxide and hydroxyl radicals. The antioxidative activities were in the order: (b)>(c)>(d)>(a) for the thiobarbituric acid reactive substance (TBARS) formation. These results suggest that the dimerized compounds have higher antioxidant activities than that of the monomers. Electron spin resonance (ESR) spin trapping experiments revealed that eugenol and its dimer, having allyl groups in the structure, scavenged superoxide, and that only eugenol trapped hydroxyl radicals under the conditions used. These finding suggest that eugenol and dieugenol have a different mechanism of antioxidation, i.e. eugenol may inhibit lipid peroxidation at the level of initiation, however, the related dimeric compounds may inhibit lipid peroxidation at the level of propagation of free radical chain reaction like α-tocopherol.
Ogata, Masahiro,Hoshi, Midori,Urano, Shiro,Endo, Toyoshige
p. 1467 - 1469
(2000)
Read Online

Abundance and reactivity of dibenzodioxocins in softwood lignin.
To define the abundance and comprehend the reactivity of dibenzodioxocins in lignin, model compound studies, specific degradation experiments on milled wood lignin, and molecular modeling calculations have been performed. Quantitative (31)P NMR measurements of the increase of biphenolic hydroxyl groups formed after a series of alkaline degradations in the presence of hydrosulfide anions (kraft conditions) showed the presence of 3.7 dibenzodioxocin rings/100 C9 units in milled wood lignin. The DFRC degradation protocol (Derivatization Followed by Reductive Cleavage) was chosen as an independent means to estimate their abundance. Initial experiments with a dibenzodioxocin model compound, trans-6,7-dihydro-7-(4-hydroxy-3-methoxyphenyl)-4,9-dimethoxy-2,11-dipropyldibenzo[e,g][1,4]dioxocin-6-ylmethanol, showed that it is not cleaved under DFRC conditions, but rather it isomerizes into a cyclic oxepine structure. Steric effects precluded this isomerization from occurring when DFRC was applied to milled wood lignin. Instead, monoacetylated biphenolic moieties were released and quantified by (31)P NMR, at 4.3 dibenzodioxocin rings/100 C9 units. The dibenzodioxocin content in residual lignins isolated from kraft pulps delignified to various degrees showed that during pulp delignification, the initial rate of dibenzodioxocin removal was considerably greater than the cleavage rate of arylglycerol-beta-aryl ether bonds. The activation energy for the degradation of dibenzodioxocins under kraft conditions in milled wood lignin was 96 +/- 9 kJ/mol, similar to that of arylglycerol-beta-aryl ether bond cleavage.
Argyropoulos, Dimitris S,Jurasek, Lubo,Kristofova, Livia,Xia, Zhicheng,Sun, Yujun,Palus, Ernest
p. 658 - 666
(2002)
Read Online

Determination of the carbonyl groups in native lignin utilizing Fourier transform Raman spectroscopy
A near-infrared Fourier transform Raman (NIR-FTR) spectroscopic technique was utilized to determine the chemical structure of lignin in a woody matrix. In the NIR-FTR spectra of coniferaldehyde and coniferyl alcohol, the Raman bands for the carbonyl group and the α, β unsaturated bond were detected at 1620 and 1660 cm-1, respectively. These peaks were also found in the NIR-FTR spectra of chemically synthesized lignins, isolated lignin from conifer wood, and conifer wood meal. Upon the reduction of carbonyl groups in the lignin samples and wood meal, the band at 1620 cm-1 disappeared; on the other hand, the band at 1660 cm-1 remained unchanged. However, upon the oxidation of reduced lignin at the benzyl hydroxyl group using dicyanodichrolobenzoquinone, the band at 1620 cm-1 clearly appeared, strongly suggesting that the band at 1620 cm-1 can be assigned as a carbonyl marker band. The hydrogenation reaction optimized for the reduction of the unsaturated bond in lignin caused the disappearance of the band at 1660 cm-1, indicating that the band at 1660 cm-1 is an α, β unsaturated bond marker band. The change in carbonyl content during the wood decay process was also shown to be monitored using the Raman intensity of the carbonyl marker band. It was indicated that the NIR-FTR spectroscopic techniques were suitable analytical method for a rapid and nondestructive analysis of wood samples.
Kihara, Momoko,Takayama, Miyuki,Wariishi, Hiroyuki,Tanaka, Hiroo
p. 2213 - 2221
(2002)
Read Online

Catalytic Activation of Unstrained C(Aryl)-C(Alkyl) Bonds in 2,2′-Methylenediphenols
Catalytic activation of unstrained and nonpolar C-C bonds remains a largely unmet challenge. Here, we describe our detailed efforts in developing a rhodium-catalyzed hydrogenolysis of unstrained C(aryl)-C(alkyl) bonds in 2,2′-methylenediphenols aided by removable directing groups. Good yields of the monophenol products are obtained with tolerating a wide range of functional groups. In addition, the reaction is scalable, and the catalyst loading can be reduced to as low as 0.5 mol %. Moreover, this method proves to be effective to cleave C(aryl)-C(alkyl) linkages in both models of phenolic resins and commercial novolacs resins. Finally, detailed experimental and computational mechanistic studies show that with C-H activation being a competitive but reversible off-cycle reaction, this transformation goes through a directed C(aryl)-C(alkyl) oxidative addition pathway.
Dong, Guangbin,Ratchford, Benjamin L.,Xue, Yibin,Zhang, Rui,Zhu, Jun
supporting information
p. 3242 - 3249
(2022/02/23)

Enhancing lignin depolymerizationviaa dithionite-assisted organosolv fractionation of birch sawdust
Sodium dithionite is utilized as a reducing agent in the organosolv fractionation of lignocellulose to concomitantly produce cellulosic pulp and promote the reductive conversion of lignin into phenolic monomers. Reactions with model compounds highlight the role of sodium dithionite with respect to the reductive cleavage of β-O-4 bonds in lignin and the consequent formation of phenolic monomers.
Brienza, Filippo,Van Aelst, Korneel,Thielemans, Karel,Sels, Bert F.,Debecker, Damien P.,Cybulska, Iwona
supporting information
p. 3268 - 3276
(2021/05/21)

POLITAG-Pd(0) catalyzed continuous flow hydrogenation of lignin-derived phenolic compounds using sodium formate as a safe H-source
Phenols are aromatic biobased compounds and as they are accessible from lignin depolymerization, they can be a useful platform chemicals to produce value-added products. Herein we report our recent investigations on the definition of an approach to the efficient continuous flow selective hydrogenation of phenols in water. Our protocol is based on the use of sodium formate as a clean and safe hydrogen source in combination with our newly defined heterogeneous POLITAG-Pd(0) catalytic system. POLITAG is a polymeric heterogeneous support decorated with pincer-type ionic ligands proven to be highly efficient for the stabilization of Pd(0) nanoparticles. The results obtained are remarkable in comparison with other protocols that employ sodium formate as H-source. Indeed, our investigation has been extended to a variety of differently substituted phenolic compounds that have been hydrogenated with excellent to good selectivity in continuous flow conditions. Durability of the catalyst has been also tested with a representative continuous processing of over 100 mmol that showed no loss in efficiency and minimal metal leaching.
Campana, Filippo,Ferlin, Francesco,Silvetti, Matteo,Trombettoni, Valeria,Vaccaro, Luigi,Valentini, Federica
(2021/07/09)

Efficient demethylation of aromatic methyl ethers with HCl in water
A green, efficient and cheap demethylation reaction of aromatic methyl ethers with mineral acid (HCl or H2SO4) as a catalyst in high temperature pressurized water provided the corresponding aromatic alcohols (phenols, catechols, pyrogallols) in high yield. 4-Propylguaiacol was chosen as a model, given the various applications of the 4-propylcatechol reaction product. This demethylation reaction could be easily scaled and biorenewable 4-propylguaiacol from wood and clove oil could also be applied as a feedstock. Greenness of the developed methodversusstate-of-the-art demethylation reactions was assessed by performing a quantitative and qualitative Green Metrics analysis. Versatility of the method was shown on a variety of aromatic methyl ethers containing (biorenewable) substrates, yielding up to 99% of the corresponding aromatic alcohols, in most cases just requiring simple extraction as work-up.
Bomon, Jeroen,Bal, Mathias,Achar, Tapas Kumar,Sergeyev, Sergey,Wu, Xian,Wambacq, Ben,Lemière, Filip,Sels, Bert F.,Maes, Bert U. W.
supporting information
p. 1995 - 2009
(2021/03/26)

Highly selective reductive catalytic fractionation at atmospheric pressure without hydrogen
Reductive catalytic fractionation (RCF) is an efficient and selective way to produce phenolic monomers from lignin. However, this strategy is difficult to scale up due to its high operating pressure. In this work, we investigated RCF reaction at or near atmospheric pressure and without the use of hydrogen. The atmospheric RCF (ARCF) was conducted in acidified ethylene glycol in glass vessels at 185-195 °C catalyzed by 5% Ru/C. The products mainly include propylguaiacol and propylsyringyl (up to 95.6% among the lignin monomers) and do not contain propanolguaiacol, propanolsyringyl, or H monomers. Although the total yield of lignin monomers in ARCF is about one-quarter less than that of RCF, the operation of ARCF is much easier, milder, safer, and cheaper due to the atmospheric condition and the feasibility of the semi-continuous operation.
Ren, Tianyu,You, Shengping,Zhang, Zhaofeng,Wang, Yuefei,Qi, Wei,Su, Rongxin,He, Zhimin
supporting information
p. 1648 - 1657
(2021/03/09)

Ambient Hydrogenation and Deuteration of Alkenes Using a Nanostructured Ni-Core–Shell Catalyst
A general protocol for the selective hydrogenation and deuteration of a variety of alkenes is presented. Key to success for these reactions is the use of a specific nickel-graphitic shell-based core–shell-structured catalyst, which is conveniently prepared by impregnation and subsequent calcination of nickel nitrate on carbon at 450 °C under argon. Applying this nanostructured catalyst, both terminal and internal alkenes, which are of industrial and commercial importance, were selectively hydrogenated and deuterated at ambient conditions (room temperature, using 1 bar hydrogen or 1 bar deuterium), giving access to the corresponding alkanes and deuterium-labeled alkanes in good to excellent yields. The synthetic utility and practicability of this Ni-based hydrogenation protocol is demonstrated by gram-scale reactions as well as efficient catalyst recycling experiments.
Beller, Matthias,Feng, Lu,Gao, Jie,Jackstell, Ralf,Jagadeesh, Rajenahally V.,Liu, Yuefeng,Ma, Rui
supporting information
p. 18591 - 18598
(2021/06/28)

Controlled lignosulfonate depolymerization: Via solvothermal fragmentation coupled with catalytic hydrogenolysis/hydrogenation in a continuous flow reactor
Sodium lignosulfonate (LS) was valorized to low molecular weight (Mw) fractions by combining solvothermal (SF) and catalytic hydrogenolysis/hydrogenation fragmentation (SHF) in a continuous flow system. This was achieved in either alcohol/H2O (EtOH/H2O or MeOH/H2O) or H2O as a solvent and Ni on nitrogen-doped carbon as a catalyst. The tunability according to the temperature of both SF and catalytic SHF of LS has been separately investigated at 150 °C, 200 °C, and 250 °C. In SF, the minimal Mw was 2994 g mol-1 at 250 °C with a dispersity (?) of 5.3 using MeOH/H2O. In catalytic SHF using MeOH/H2O, extremely low Mw was found (433 mg gLS-1) with a ? of 1.2 combined with 34 mg gLS-1. The monomer yield was improved to 42 mg gLS-1 using dual catalytic beds. These results provide direct evidence that lignin is an unstable polymer at elevated temperatures and could be efficiently deconstructed under hydrothermal conditions with and without a catalyst. This journal is
Al-Naji, Majd,Antonietti, Markus,Brandi, Francesco
supporting information
p. 9894 - 9905
(2021/12/24)

CATALYTIC FUNNELING OF PHENOLICS
In general, present invention concerns an integrated wood-to-xylochemicals biorefinery, enabling production of renewable phenol, phenolic oligomers, propylene, and carbohydrate pulp from lignocellulosic biomass.
-
Paragraph 0026; 0087-0088; 0146

(2021/04/30)

Scrap waste automotive converters as efficient catalysts for the continuous-flow hydrogenations of biomass derived chemicals
The catalytic activity of scrap ceramic-cores of automotive catalytic converters (SCATs) was investigated in the continuous-flow hydrogenation of different biomass-derived chemicals. The waste SCAT powders were deeply characterized by ICP-MS, TGA, MP-AES, XRD, N2 physisorption, TPR, HRTEM and EDS before and after utilization as a catalyst. The hydrogenation reactions of isopulegol to menthol, cinnamyl alcohol to hydrocinnamyl alcohol, isoeugenol to dihydroeugenol, vanillin to vanillyl alcohol and benzaldehyde to benzyl alcohol were performed studying the influence of various reaction parameters (temperature, pressure, flow rate and concentration of the starting material) on the final yields. The outstanding performance and stability obtained for the low metal content of waste-derived catalysts can be attributed to the co-presence of different noble metals as well as to the composite structure itself.
Cova, Camilla Maria,Zuliani, Alessio,Manno, Roberta,Sebastian, Victor,Luque, Rafael
p. 1414 - 1423
(2020/03/11)

Atomically Dispersed Co Catalyst for Efficient Hydrodeoxygenation of Lignin-Derived Species and Hydrogenation of Nitroaromatics
Single-atom catalysts (SACs) have attracted much attention due to their outstanding catalytic performance in heterogeneous catalysis. Here, we report a template sacrificial method to fabricate an atomically dispersed Co catalyst; three kinds of silica templates with different microstructures (MCM-41, SBA-15, and FDU-12) were employed and the effect of pore structure of the templates on the dispersity of Co was investigated. The catalysts fabricated with different templates presented different Co dispersities, leading to distinguishing catalytic performance. The optimized Co1?NC-(SBA) catalyst with atomically dispersed Co displayed outstanding catalytic activity for the hydrodeoxygenation (HDO) of lignin-derived species as well as the hydrogenation of various nitroaromatics. The reaction mechanism of the HDO of vanillin was investigated by using density functional theory calculations as well.
Du, Congcong,Gao, Shutao,Gao, Yongjun,Huang, Jianyu,Meng, Tao,Qiao, Yuqing,Shang, Ningzhao,Shen, Tongde,Wang, Chun,Wang, Haijun,Wang, Junmin,Wang, Zhi,Wu, Qiuhua,Zhang, Longkang
p. 8672 - 8682
(2020/09/18)

Monolithic Silica Support for Immobilized Catalysis in Continuous Flow
Monolithic and packed-bed reactors featuring immobilized catalysts are well-precedented in continuous flow synthesis but can suffer from adverse pressure drops during use due to their small pore sizes and/or structural changes. Herein, we overcome this challenge with the synthesis of a structurally robust silica-based monolith featuring pore sizes on the millimeter scale. The 3-dimensional solid support structure is constructed from a polystyrene foam-based template and features a functional group handle that can be modified to display a reactive catalyst. Here we functionalize the support with palladium(0) for hydrogenation reactions and a modified proline catalyst for the alpha functionalization of aldehydes. Both reactors showed good activity and excellent catalytic longevity when utilized under continuous flow conditions. (Figure presented.).
Russell, M. Grace,Veryser, Cedrick,Hunter, James F.,Beingessner, Rachel L.,Jamison, Timothy F.
supporting information
p. 314 - 319
(2019/12/24)

Efficient preparation and application of monodisperse palladium loaded graphene oxide as a reusable and effective heterogeneous catalyst for suzuki cross-coupling reaction
A homogeneously dispersed graphene oxide supported palladium nanomaterial (Pd?GO) has been successfully synthesized and used as a catalyst in cross-coupling reactions at room temperature. Various analytical techniques such as X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) were used to characterize the monodisperse Pd?GO. Monodisperse Pd?GO nanomaterials were used for the cross-coupling reactions which brought together organic molecules with functional significance. This catalyst showed superior catalytic activity and stability for these coupling reactions. High product yields, short reaction times and mild reaction conditions, obtained by the using of developed catalysts. Importantly, the catalyst can be used at least five experiments successfully without losing its efficiency.
Diler, Fatma,Burhan, Hakan,Genc, Hayriye,Kuyuldar, Esra,Zengin, Mustafa,Cellat, Kemal,Sen, Fatih
(2019/11/29)

Synthesis of bisphenol neolignans inspired by honokiol as antiproliferative agents
Honokiol (2) is a natural bisphenol neolignan showing a variety of biological properties, including antitumor activity. Some studies pointed out 2 as a potential anticancer agent in view of its antiproliferative and pro-apoptotic activity towards tumor cells. As a further contribution to these studies, we report here the synthesis of a small library of bisphenol neolignans inspired by honokiol and the evaluation of their antiproliferative activity. The natural lead was hence subjected to simple chemical modifications to obtain the derivatives 3–9; further neolignans (12a-c, 13a-c, 14a-c, and 15a) were synthesized employing the Suzuki–Miyaura reaction, thus obtaining bisphenols with a substitution pattern different from honokiol. These compounds and the natural lead were subjected to antiproliferative assay towards HCT-116, HT-29, and PC3 tumor cell lines. Six of the neolignans show GI50 values lower than those of 2 towards all cell lines. Compounds 14a, 14c, and 15a are the most effective antiproliferative agents, with GI50 in the range of 3.6–19.1 μM, in some cases it is lower than those of the anticancer drug 5-fluorouracil. Flow cytometry experiments performed on these neolignans showed that the inhibition of proliferation is mainly due to an apoptotic process. These results indicate that the structural modification of honokiol may open the way to obtaining antitumor neolignans more potent than the natural lead.
Cardullo, Nunzio,Barresi, Vincenza,Muccilli, Vera,Spampinato, Giorgia,D’Amico, Morgana,Condorelli, Daniele Filippo,Tringali, Corrado
(2020/02/18)

Rhodium porphyrin molecule-based catalysts for the hydrogenation of biomass derived levulinic acid to biofuel additive γ-valerolactone
Rhodium-meso-tetraphenylporphyrin (RhTPP) and rhodium-meso-tetrakis(4-carboxyphenyl)porphyrin (RhTCPP) complexes were synthesized and surface grafted on amine-functional mesoporous molecular sieves. The formation of ligands (TPP and TCPP) and their rhodium complexes (RhTPP and RhTCPP) was evident with the help of 1H NMR, 13C NMR, mass spectral and elemental (CHN) analysis. The absence of the pyrrole proton of the porphyrin units on RhTPP and RhTCPP confirmed the successful formation of metallo-macro-molecules. Further, RhTPP and RhTCPP were fixed on the surface of SBA-15 through amino-silane as the linker. The rhodium containing homogeneous (RhTPP and RhTCPP) and heterogeneous catalysts (RhTPP-SBA-AM and RhTCPP-SBA-AM) were used for biomass-derived levulinic acid hydrogenation. Further, the synthesized catalysts were utilized for the hydrogenation of various organic molecules having arene, carbonyl, and alkene functionality under moderate reaction conditions. Both homogeneous and heterogeneous catalysts showed more than 95% levulinic acid conversion even after four cycles. The homogeneous RhTPP and RhTCPP yielded γ-valerolactone (GVL) as a major product, whereas heterogeneous catalysts showed only comparable γ-valerolactone (GVL) selectivity, with improved reusability and recylability in the presence of relatively lower amounts of rhodium complexes. Among RhTPP and RhTCPP, RhTPP showed better selectivity for γ-valerolactone (GVL) compared to RhTCPP. Further, as the number of catalytic runs increased, there was a gradual increase in diol selectivity, which was predominant in the case of RhTCPP, possibly due to the presence of the hydrophilic carboxylate ion which facilitates the interaction of water by-products with γ-valerolactone and favours diol formation. The hydrophobic environment of the RhTPP catalyst facilitated the formation of γ-valerolactone as the major product even in the fifth run. This journal is
Anjali, Kaiprathu,Christopher, Jayaraj,Sakthivel, Ayyamperumal,Venkatesha, Naragalu J.
supporting information
p. 11064 - 11075
(2020/07/15)

Biphasic hydrogenation of eugenol with ruthenium and rhodium nanoparticles stabilized in ionic liquids
The purpose of this study was to evaluate on the catalytic activity nanostructured systems of ruthenium and rhodium stabilized in ionic liquids derived from imidazole: IL1= butylmethyllimidazole tetrafluoroborate [BMIM][BF4] and IL2= butylmethylimidazole hexafluorophosphate [BMIM][PF6] in the biphasic hydrogenation of eugenol under mild reaction conditions T= 80°C, P= 100psi during 4 hours. The metallic nanoparticles (NPs-M) were synthesized using the ligand hydrogenation displacement reaction for the ruthenium III tris(acetylacetonate), [Ru(acac)3], and bis-μ-cloro-di(1,5-ciclooctadieno) dirhodium(I), [Rh(COD)Cl]2, showing a mean particle size between (2.0±0.2) nm and (4.0±0.2) nm. The nanostructured systems Rh/IL2, Ru/IL2 and Ru/IL1 show similar activities and different from the Rh/IL1 system. On the other hand, the systems stabilized in the IL1 were more selective towards the formation of the 2-methoxy-4-propylphenol than the systems stabilized in the IL2. Nevertheless, in general, the catalysts were good for hydrogenating eugenol, resulting in Rh/IL1 nanoparticles less reactive than Rh/IL2, Ru/IL1 and Ru/IL2.
Baricelli, Pablo,Borusiak, Margarita,Castro, William,Crespo, Isis,Dominguez, Olgioly,Oma?a, Ofelia,Rosales, Merlin
p. 4982 - 4987
(2020/12/28)

Photocatalytic transfer hydrogenolysis of aromatic ketones using alcohols
A mild method of photocatalytic deoxygenation of aromatic ketones to alkyl arenes was developed, which utilized alcohols as green hydrogen donors. No hydrogen evolution during this transformation suggested a mechanism of direct hydrogen transfer from alcohols. Control experiments with additives indicated the role of acid in transfer hydrogenolysis, and catalyst characterization confirmed a larger number of Lewis acidic sites on the optimal Pd/TiO2 photocatalyst. Hence, a combination of hydrogen transfer sites and acidic sites may be responsible for efficient deoxygenation without additives. The photocatalyst showed reusability and achieved selective reduction in a variety of aromatic ketones.
Gao, Zhuyan,Han, Jianyu,Hong, Feng,Lei, Lijun,Li, Hongji,Liu, Huifang,Luo, Nengchao,Wang, Feng
p. 3802 - 3808
(2020/07/09)

One-pot synthesis of aldoximes from alkenes: Via Rh-catalysed hydroformylation in an aqueous solvent system
Aldoxime synthesis directly starting from alkenes was successfully achieved through the combination of hydroformylation and subsequent condensation of the aldehyde intermediate with aqueous hydroxylamine in a one-pot process. The metal complex Rh(acac)(CO)2 and the water-soluble ligand sulfoxantphos were used as the catalyst system, providing high regioselectivities in the initial hydroformylation. A mixture of water and 1-butanol was used as an environmentally benign solvent system, ensuring sufficient contact of the aqueous catalyst phase and the organic substrate phase. The reaction conditions were systematically optimised by Design of Experiments (DoE) using 1-octene as a model substrate. A yield of 85% of the desired linear, terminal aldoxime ((E/Z)-nonanal oxime) at 95% regioselectivity was achieved. Other terminal alkenes were also converted successfully under the optimised conditions to the corresponding linear aldoximes, including renewable substrates. Differences of the reaction rate have been investigated by recording the gas consumption, whereby turnover frequencies (TOFs) >2000 h-1 were observed for 4-vinylcyclohexene and styrene, respectively. The high potential of aldoximes as platform intermediates was shown by their subsequent transformation into the corresponding linear nitriles using aldoxime dehydratases as biocatalysts. The overall reaction sequence thus allows for a straightforward synthesis of linear nitriles from alkenes with water being the only by-product, which formally represents an anti-Markovnikov hydrocyanation of readily available 1-alkenes.
Gr?ger, H.,Guntermann, A.,Hinzmann, A.,Jolmes, T.,Panke, D.,Plass, C.,R?sler, J.,Seidensticker, T.,Terhorst, M.,Vogt, D.,Vorholt, A. J.
supporting information
p. 7974 - 7982
(2020/11/30)

Structural features and antioxidant activities of Chinese quince (Chaenomeles sinensis) fruits lignin during auto-catalyzed ethanol organosolv pretreatment
Chinese quince fruits (Chaenomeles sinensis) have an abundance of lignins with antioxidant activities. To facilitate the utilization of Chinese quince fruits, lignin was isolated from it by auto-catalyzed ethanol organosolv pretreatment. The effects of three processing conditions (temperature, time, and ethanol concentration) on yield, structural features and antioxidant activities of the auto-catalyzed ethanol organosolv lignin samples were assessed individually. Results showed the pretreatment temperature was the most significant factor; it affected the molecular weight, S/G ratio, number of β-O-4′ linkages, thermal stability, and antioxidant activities of lignin samples. According to the GPC analyses, the molecular weight of lignin samples had a negative correlation with pretreatment temperature. 2D-HSQC NMR and Py-GC/MS results revealed that the S/G ratios of lignin samples increased with temperature, while total phenolic hydroxyl content of lignin samples decreased. The structural characterization clearly indicated that the various pretreatment conditions affected the structures of organosolv lignin, which further resulted in differences in the antioxidant activities of the lignin samples. These results can be helpful for controlling and optimizing delignification during auto-catalyzed ethanol organosolv pretreatment, and they provide theoretical support for the potential applications of Chinese quince fruits lignin as a natural antioxidant in the food industry.
Cheng, Xi-Chuang,Guo, Xin-Ran,Liu, Hua-Min,Liu, Yu-Lan,Qin, Zhao,Wang, Xue-De
p. 4348 - 4358
(2020/09/22)

Low-Temperature Catalytic Hydrogenolysis of Guaiacol to Phenol over Al-Doped SBA-15 Supported Ni Catalysts
Selective hydrogenolysis of aromatic carbon-oxygen (Caryl?O) bonds is a key strategy for the generation of aromatic chemicals from lignin. However, this process is usually operated at high temperatures and pressures over hydrogenation catalysts, resulting in a low selectivity for aromatics and an extra consumption of hydrogen. Here, a series of Al-doped SBA-15 mesoporous materials with different Si/Al molar ratios (Al-SBA-15) were prepared via a post-synthesis method using NaAlO2 as the Al source, and then Al-SBA-15 supported Ni catalysts (Ni/Al-SBA-15) were prepared by a deposition-precipitation method using urea as the hydrolysis reagent. The prepared supports and catalysts were extensively characterized using various techniques such as XRD, N2 adsorption/desorption, TEM, 27Al NMR, NH3-TPD, XPS, H2-TPR, and pyridine-FT-IR, and the catalysts were evaluated in the hydrogenolysis of the Caryl?O bond in guaiacol and lignin derived compounds under mild conditions. The effects of the Si/Al ratio in catalyst and reaction parameters on guaiacol conversion and product distribution were investigated in detail, associated with solvent effect. The incorporation of Al into the framework of SBA-15 can improve the Lewis acidity and the dispersion of the supported Ni particles and yet modulate the metal-support interactions, which are propitious to the hydrogenolysis of the Caryl?O bond in guaiacol. The catalyst Ni/Al-SBA-15 with a Si/Al molar ratio of 10 shows the best performance with a guaiacol conversion of 87.4 % and a phenol selectivity of 76.9 % under the mild conditions conducted, because of its proper acidity, suitable metal-support interactions, and high dispersion of the active species. The present study would stimulate research and development in multi-functional catalysts for the generation of valuable chemicals from biomass.
Wang, Qiuyue,Chen, Yufang,Yang, Guanheng,Deng, Ping,Lu, Xinqing,Ma, Rui,Fu, Yanghe,Zhu, Weidong
p. 4930 - 4938
(2020/08/26)

Effect of organic template removal approaches on physiochemical characterization of Ni/Al-SBA-15 and eugenol hydrodeoxygenation
Template removing approaches can significantly impact the physiochemical properties of mesoporous molecular sieve materials. In order to better understand the relationship between template removing approaches and the properties of Ni/Al-SBA-15, four kinds of template removing approaches were introduced to remove the organic template from Al-SBA-15, respectively. The structural characteristics of these materials were analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray fluorescence (XRF), powder X-ray diffraction (XRD), N2-sorption, Fourier transform infrared spectra (FT-IR), infrared spectra of pyridine adsorption (Py-FTIR), magic angle spinning-nuclear magnetic resonance (MAS-NMR), X-ray photoelectron spectroscopy (XPS) and gas chromatography-mass spectrometry (GC-MS). Ni/Al-SBA-15 of which the organic template was removed by two-step calcination method had the maximum specific surface area (619 ?m2/g). In contrast, Ni/Al-SBA-15 of which the organic template was removed using solvent extraction approaches had the lowest specific surface area (555 ?m2/g). The mesopore diameter of Ni/Al-SBA-15, using electric heating digestion method to remove the template, was significantly increased and the wall thickness was significantly decreased to 11.62 ?nm in comparison with the other samples. The selectivity of products during the process of eugenol hydrodeoxygenation was investigated. High hydrocarbons were obtained during catalytic hydrodeoxygenation over Ni/Al-SBA-15 of which the organic template was removed by using solvent extraction approaches. Compared with direct calcination process, two-step calcination was more effective in removing template and the corresponding catalyst was much more suitable for the hydrodeoxygenation process.
Li, Xiangping,Yin, Han,Zhang, Jianguang,Liu, Juping,Chen, Guanyi
(2019/12/23)

Selective Preparation of 4-Alkylphenol from Lignin-Derived Phenols and Raw Biomass over Magnetic Co–Fe?N-Doped Carbon Catalysts
Lignin valorization to produce high-value chemicals selectively is an enormous challenge in biorefinery. In this study, 4-alkylphenol, formed by breaking the robust Caryl?OCH3 bonds solely with the retention of other structures in lignin-derived methoxylalkylphenols, was produced selectively over a Co1–Fe0.1?NC catalyst from real lignin oil as feedstock, which was obtained by a “lignin-first” strategy from either birch or cornstalk. A yield of 64.7 or 88.3 mol % of 4-propylphenol was obtained if birch lignin oil or eugenol was used as the substrate, respectively. The catalysts were characterized by using methods that include Brunauer–Emmett–Teller measurements, XRD, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, high-angle annular dark-field scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy, and temperature-programmed desorption with synchrotron vacuum ultraviolet photoionization mass spectrometry. The results of catalyst characterization and comparison experiments indicated that CoNx was the main active phase for demethoxylation and hydrogenation, and the incorporation of Fe weakens the adsorption of 4-propylphenol to the catalyst, which inhibits the excessive hydrogenation of 4-propylphenol. This work shows the potential to produce high-value-added 4-alkylphenol from renewable raw biomass.
Liu, Xiaohao,Wang, Chenguang,Zhang, Ying,Qiao, Yan,Pan, Yang,Ma, Longlong
p. 4791 - 4798
(2019/11/03)

Aggregation-induced Substrate Specificity in Aerobic Reduction of Olefins with Ultrasound Gel Catalyst of Synthetic Flavin
A riboflavin derivative bearing octadecanoyl functionalities 1 a gelatinizes a variety of organic solvents upon brief ultrasonication in an organic fluid. The rate of gelation with 1 a can be externally and precisely controlled by tuning the sonication time and type of solvent. The present ultrasound gel exhibits unprecedented substrate specificity for the catalytic aerobic reduction of olefins, which can be performed with hydrazine at ambient temperature and atmospheric pressure in air. The reaction rates of 1-dodecene (2), allylbenzene (3), and o-allylphenol (4) with the ultrasound gel 1 a catalyst is in the order of 2?3>4, the substrate specificity of which is in contrast to the almost non-specificity with the non-gelled catalyst 1 b bearing butanoyl functionalities, and entirely inverse specificity with a flavin-dendrimer association catalyst (234). Based on kinetic studies, the aggregation effects on the substrate specificity have been ascribed to the specific inclusion of aliphatic olefins into the enzyme-like artificial cavities of the gel catalysts.
Kawamorita, Soichiro,Fujiki, Misa,Li, Zimeng,Kitagawa, Takahiro,Imada, Yasushi,Naota, Takeshi
p. 878 - 884
(2019/01/14)

Degradation of lignin with aqueous ammonium-based ionic liquid solutions under milder conditions
This study investigates the performance of two aqueous ionic liquids (ILs), dimethylbutylammonium acetate ([DMBA][Ac]) and dimethylbutylammonium butanoate ([DMBA][B]), solutions for depolymerizing alkali lignin into valuable phenolic compounds. The favorable operation conditions, including reaction temperature and reaction time, are explored. The extent of depolymerization of the lignin is evaluated by analysis with gel permeation chromatography (GPC). The results show that the average molecular weights of the depolymerized lignin samples can be reduced by as high as 93.8% and 86.8% after treating with the aqueous [DMBA][Ac] and [DMBA][B], respectively. Moreover, the aromatic chemical species in the depolymerized solutions are identified by using gas chromatography?mass spectrophotometry (GC-MS). The confirmation of the chemical species is further made by using a series of spectroscopic techniques, such as FT-IR, and 1H NMR and 13C NMR spectroscopy. Promising results have been achieved for the depolymerization of the lignin into valuable chemicals by using the proposed green media, aqueous solutions of ionic liquids [DMBA][Ac] and [DMBA][B], under milder conditions.
Gupta, Bhupender S.,Lee, Ming-Jer,Tolesa, Leta Deressa
p. 3357 - 3365
(2019/02/25)

CALCIUM SALTS-SUPPORTED METAL CATALYST, METHOD FOR PREPARING THE SAME, AND METHOD FOR HYDRODEOXYGENATION REACTION OF OXYGENATES USING THE SAME
Disclosed herein are a calcium salts-supported metal catalyst, a method for preparing the same, and a method for the hydrodeoxygenation reaction of oxygenates using the same. The catalyst, in which a metal catalyst is supported on a carrier of a calcium salt, for example, calcium carbonate, has the effect of increasing the efficiency of hydrodeoxygenation reaction of oxygenates.
-
Paragraph 0072; 0073

(2020/01/04)

One-pot Cu/TiO2 nanoparticles synthesis for trans-ferulic acid conversion into vanillin
In this study, the co-synthesis of TiO2 and Cu metallic nanoparticles obtained via one-pot cost-efficient hydrothermal process has been addressed. Different nanocatalysts with Cu contents were characterized by X-ray diffraction, nitrogen porosimetry, scanning electron microscopy, and transmission electron microscopy. The TiO2 and Cu metallic nanoparticles were synthesized with copper loading up to one (Cu/Ti atomic ratio). Synthesized catalysts exhibited pore sizes in the mesoporous range and high surface areas above 150 m2/g. The particle size for TiO2 presented a homogeneous distribution of approximately 8 nm, moreover, Cu nanoparticles varied from 12 to >100 nm depending on the metal loading. The nanostructured materials were successfully tested in the conversion of trans-ferulic acid into vanillin under sustainable conditions, achieving the best performance for 0.3 Cu/Ti atomic ratio (70% vanillin yield).
Gómez-López, Paulette,Lázaro, Noelia,Alvarado-Beltrán, Clemente G.,Pineda, Antonio,Balu, Alina M.,Luque, Rafael
(2019/11/19)

Chemodivergent hydrogenolysis of eucalyptus lignin with Ni@ZIF-8 catalyst
Reductive catalytic fractionation (RCF) of lignocellulosic biomass, that is depolymerization of the native lignin component into well-defined monomeric phenols in the first step, offers an opportunity to utilize entire biomass components. Herein, we report that Ni@ZIF-8 can serve as a chemodivergent catalyst in RCF of eucalyptus sawdust, thus selectively producing phenolic compounds having either a propyl or propanol end-chain under different reaction conditions. In both cases, high yields of lignin monomers and a high degree of delignification were achieved, next to well-preserved carbohydrate pulp suitable for further processing. A mechanistic study using model compounds indicated that the dehydroxylation at the γ-position of the β-O-4 structure may be involved in the selectivity-controlling step.
Liu, Xue,Li, Helong,Xiao, Ling-Ping,Sun, Run-Cang,Song, Guoyong
supporting information
p. 1498 - 1504
(2019/03/26)

Catalytic Hydrogenolysis of Substituted Diaryl Ethers by Using Ruthenium Nanoparticles on an Acidic Supported Ionic Liquid Phase (Ru@SILP-SO3H)
Catalytic hydrogenolysis of diaryl ethers is achieved by using ruthenium nanoparticles immobilized on an acidic supported ionic liquid phase (Ru@SILP-SO 3 H) as a multifunctional catalyst. The catalyst components are assembled through a molecular approach ensuring synergistic action of the metal and acid functions. The resulting catalyst is highly active for the hydrogenolysis of various diaryl ethers. For symmetric substrates such as diphenyl ether, hydrogenolysis is followed by full hydrodeoxygenation producing the corresponding cycloalkanes as the main products. For unsymmetric substrates, the cleavage of the C-O bond is regioselective and occurs adjacent to the unsubstituted phenyl ring. As hydrogenation of benzene is faster than hydrodeoxygenation over the Ru@SILP-SO 3 H catalyst, controlled mixtures of cyclohexane and substituted phenols are accessible with good selectivity. Application of Ru@SILP-SO 3 H catalyst in continuous-flow hydrogenolysis of 2-methoxy-4-methylphenoxybenzene is demonstrated with use of commercial equipment.
Rengshausen, Simon,Etscheidt, Fabian,Gro?kurth, Johannes,Luska, Kylie L.,Bordet, Alexis,Leitner, Walter
p. 405 - 412
(2019/02/26)

Lignin Valorization by Cobalt-Catalyzed Fractionation of Lignocellulose to Yield Monophenolic Compounds
Herein, a catalytic reductive fractionation of lignocellulose is presented using a heterogeneous cobalt catalyst and formic acid or formate as a hydrogen donor. The catalytic reductive fractionation of untreated birch wood yields monophenolic compounds in up to 34 wt % yield of total lignin, which corresponds to 76 % of the theoretical maximum yield. Model compound studies revealed that the main role of the cobalt catalyst is to stabilize the reactive intermediates formed during the organosolv pulping by transfer hydrogenation and hydrogenolysis reactions. Additionally, the cobalt catalyst is responsible for depolymerization reactions of lignin fragments through transfer hydrogenolysis reactions, which target the β-O-4′ bond. The catalyst could be recycled three times with only negligible decrease in efficiency, showing the robustness of the system.
Rautiainen, Sari,Di Francesco, Davide,Katea, Sarmad Naim,Westin, Gunnar,Tungasmita, Duangamol N.,Samec, Joseph S. M.
p. 404 - 408
(2019/01/04)

Catalytic activation of unstrained C(aryl)–C(aryl) bonds in 2,2′-biphenols
Transition metal catalysis has emerged as an important means for C–C activation that allows mild and selective transformations. However, the current scope of C–C bonds that can be activated is primarily restricted to either highly strained systems or more polarized C–C bonds. In contrast, the catalytic activation of non-polar and unstrained C–C moieties remains an unmet challenge. Here we report a general approach for the catalytic activation of the unstrained C(aryl)–C(aryl) bonds in 2,2′-biphenols. The key is to utilize the phenol moiety as a handle to install phosphinites as a recyclable directing group. Using hydrogen gas as the reductant, monophenols are obtained with a low catalyst loading and high functional group tolerance. This approach is also applied to the synthesis of 2,3,4-trisubstituted phenols. A further mechanistic study suggests that the C–C activation step is mediated by a rhodium(i) monohydride species. Finally, a preliminary study on breaking the inert biphenolic moieties in lignin models is illustrated.
Zhu, Jun,Wang, Jianchun,Dong, Guangbin
p. 45 - 51
(2018/11/23)

Cleavage of lignin C-O bonds over a heterogeneous rhenium catalyst through hydrogen transfer reactions
Hydrogenolysis is one of the most popular strategies applied in the depolymerization of lignin for the production of aromatic chemicals. Currently, this strategy is mainly conducted under high hydrogen pressure, which can pose safety risks and is not sustainable and economical. Herein, we reported that heterogeneous rhenium oxide supported on active carbon (ReOx/AC) exhibited excellent activity in the selective cleavage of lignin C-O bonds in isopropanol. High yields of monophenols (up to 99.0%) from various lignin model compounds and aromatic liquid oils (>50%) from lignin feedstock were obtained under mild conditions in the absence of H2. The characterization of the catalyst by X-ray absorption fine structure, X-ray photoelectron spectroscopy and H2-temperature-programed reduction suggested that the activity of ReOx/AC could be attributed to the presence of ReIV-VI. The interaction between the surface oxygen groups of the active carbon and rhenium oxide could also play an important role in the cleavage of the C-O bonds. Notably, an ReOx/AC-catalyzed C-O bond cleavage pathway beyond a typical deoxydehydration mechanism was disclosed. More importantly, 2D-HSQC-NMR and GPC characterizations showed that ReOx/AC exhibited high activity not only in β-O-4 cleavage, but also in the deconstruction of more resistant β-5 and β-β linkages in lignin without destroying the aromatic ring. This study paves the way for the development of rhenium-based catalysts for the controlled reductive valorization of realistic lignin materials through a hydrogen transfer pathway.
Zhang, Bo,Qi, Zaojuan,Li, Xinxin,Ji, Jianwei,Zhang, Leilei,Wang, Hua,Liu, Xiaoyan,Li, Changzhi
supporting information
p. 5556 - 5564
(2019/10/28)

Recyclable cobalt(0) nanoparticle catalysts for hydrogenations
The search for new hydrogenation catalysts that replace noble metals is largely driven by sustainability concerns and the distinct mechanistic features of 3d transition metals. Several combinations of cobalt precursors and specific ligands in the presence of reductants or under high-thermal conditions were reported to provide active hydrogenation catalysts. This study reports a new method of preparation of small, monodisperse Co(0) nanoparticles (3-4 nm) from the reduction of commercial CoCl2 in the absence of ligands or surfactants. High catalytic activity was observed in hydrogenations of alkenes, alkynes, imines, and heteroarenes (2-20 bar H2). The magnetic properties enabled catalyst separation and multiple recyclings.
Büschelberger, Philipp,Reyes-Rodriguez, Efrain,Sch?ttle, Christian,Treptow, Jens,Feldmann, Claus,Jacobi Von Wangelin, Axel,Wolf, Robert
p. 2648 - 2653
(2018/05/30)

Production of Cycloalkanes in Hydrodeoxygenation of Isoeugenol Over Pt- and Ir-Modified Bifunctional Catalysts
Hydrodeoxygenation of isoeugenol was investigated at 200 °C under 3 MPa total pressure in dodecane as a solvent, in hydrogen, over bifunctional Pt- and Ir-modified Beta zeolites and mesoporous materials. As a comparison, Pt and Ir supported on Al2O3, SiO2 and mesoporous MCM-41 were also tested. The catalysts were characterized by XRD, CO pulse chemisorption, transmission electron microscopy, scanning electron microscopy, nitrogen adsorption and FTIR pyridine adsorption desorption. The results revealed that the most active and selective catalyst was Pt-H-Beta-300, which exhibits the lowest acidity and largest crystal size of Beta zeolite among the studied Pt- and Ir-modified Beta zeolites. Complete conversion of isoeugenol and 89 % selectivity to propylcyclohexane was obtained with this catalyst in 240 min. The overall deoxygenation selectivity was 100 %, giving dialkylated cyclohexanes as the second major product. The catalyst was regenerated, reduced and reused in the hydrodeoxygenation of isoeugenol with almost the same performance as the fresh catalyst. Thermodynamic analyses and kinetic modelling of the data were also performed.
Bomont, Louis,Alda-Onggar, Moldir,Fedorov, Vyacheslav,Aho, Atte,Peltonen, Janne,Er?nen, Kari,Peurla, Markus,Kumar, Narendra,W?rn?, Johan,Russo, Vincenzo,M?ki-Arvela, P?ivi,Grénman, Henrik,Lindblad, Marina,Murzin, Dmitry Yu.
p. 2841 - 2854
(2018/07/06)

Efficient hydro-deoxygenation of lignin derived phenolic compounds over bifunctional catalysts with optimized acid/metal interactions
Efficient hydro-deoxygenation (HDO) of lignin derived phenolic compounds was a challenging task due to the incompatibility of the phenolic feedstock and the current hydro-processing catalysts. In this paper, hydro-deoxygenation of lignin derived phenolic compounds over a series of bifunctional catalysts with different metal/acid interactions was firstly carried out. It was found that the distance between the acidic site and noble metal played an important role in the catalytic performance of phenolic hydro-deoxygenation. A highly stable bifunctional catalyst for hydro-deoxygenation of lignin derived phenolic compounds was obtained through simple selective deposition of Pt on alumina in a commonly used Al2O3-ZSM-5 nanocomposite. The bifunctional catalyst retained its complete deoxygenation capacity for more than 500 h. The catalyst can also be used for the HDO of various phenolic model compounds and real bio-oil derived from lignin. A correction of the generally accepted the closer the better criterion in metal/acid bifunctional catalysts when used in bio-oxygenate HDO was also discussed.
Ju, Chao,Li, Mingrui,Fang, Yunming,Tan, Tianwei
supporting information
p. 4492 - 4499
(2018/10/24)

A High Mobility Reactor Unit for R&D Continuous Flow Transfer Hydrogenations
A suitcase sized mobile reactor unit (MRU) weighing in at less than 10 kg was designed for laboratory scale transfer hydrogenations in continuous flow. Simple cyclohexene and a cosolvent in combination with a palladium-on-charcoal packed bed reactor provided a setup with isolation of nearly all products without the need for further purification. Several functional groups including olefins, triple bonds, nitro-groups, carbonyls, and so forth were effectively reduced with retention times as low as 2 min. Additionally, standard protection groups such as Cbz, benzyl, and allyl ether or esters were removed in high yields. To prove the flexibility of the setup an example of the Mizoroki-Heck reaction was also performed on the MRU. Finally, two scale-up transfer hydrogenation experiments were performed affording isolation of the desired target compounds in 0.5 and 0.8 mol scales with less than 4 h of continuous operation on the MRU.
Jensen, Rasmus K.,Thykier, Nikolaj,Enevoldsen, Martin V.,Lindhardt, Anders T.
supporting information
p. 370 - 376
(2017/03/24)

Amphipathic monolith-supported palladium catalysts for chemoselective hydrogenation and cross-coupling reactions
A palladium catalyst immobilized on an amphipathic and monolithic polystyrene-divinylbenzene polymer bearing strongly acidic cation exchange functions (sulfonic acid moieties) (Pd/CM) was developed. It was used as a catalyst for hydrogenation and ligand-free cross-coupling reactions, such as the Suzuki-Miyaura, Mizoroki-Heck, and copper- and amine-free Sonogashira-type reactions, together with a palladium catalyst supported on monolithic polymer (Pd/AM) bearing basic anion exchange functions (ammonium salt moieties), which has been in practical use for the decomposition of hydrogen peroxide produced as a byproduct during the manufacture of ultrapure water. While the Pd/CM was highly active as a catalyst for the hydrogenation and a variety of reducible functional groups could be reduced, the use of Pd/AM led to a unique chemoselective hydrogenation. Aromatic carbonyl groups were tolerant under the Pd/AM-catalyzed hydrogenation conditions, although benzyl esters, benzyl ethers, and N-Cbz groups could be smoothly hydrocracked. The cross-coupling reactions readily proceeded using either catalyst. The palladium leaching from the Pd/CM into the reaction media was never observed during the Sonogashira-type reaction, which was hardly achieved by other palladium-supported heterogeneous catalysts due to the good affinity of the palladium species with alkynes.
Monguchi, Yasunari,Wakayama, Fumika,Ueda, Shun,Ito, Ryo,Takada, Hitoshi,Inoue, Hiroshi,Nakamura, Akira,Sawama, Yoshinari,Sajiki, Hironao
p. 1833 - 1840
(2017/01/21)

Development of a Unique Heterogeneous Palladium Catalyst for the Suzuki–Miyaura Reaction using (Hetero)aryl Chlorides and Chemoselective Hydrogenation
A unique heterogeneous palladium catalyst (7% Pd/WA30) supported on an anion exchange resin, which contains N,N-dimethylaminoalkyl functionalities on the polymer backbone, was developed. 7% Pd/WA30 could smoothly catalyze Suzuki–Miyaura reactions of even less reactive heteroaryl chlorides and heteroarylboronic acids to afford various (hetero)biaryls due to the electron-donating effect of the tert-amines on WA30 to Pd species. It was also applicable as a chemoselective hydrogenation catalyst, showing inactivity for the hydrogenolysis of tert-butyldimethylsilyl (TBS) ethers, alkyl benzyl ethers, and benzyl alcohols. The tert-amines on WA30 acted as moderate catalyst poisons for Pd, resulting in chemoselective hydrogenation. 7% Pd/WA30 was reused for at least five times without any loss of the hydrogenation catalytic activity. (Figure presented.).
Ichikawa, Tomohiro,Netsu, Moeko,Mizuno, Masahiro,Mizusaki, Tomoteru,Takagi, Yukio,Sawama, Yoshinari,Monguchi, Yasunari,Sajiki, Hironao
supporting information
p. 2269 - 2279
(2017/07/07)

Tunable Photocatalytic Activity of Palladium-Decorated TiO2: Non-Hydrogen-Mediated Hydrogenation or Isomerization of Benzyl-Substituted Alkenes
Palladium-decorated TiO2 is a moisture- and air-tolerant versatile catalyst. Its photocatalytic activity can be tuned in favor of hydrogenation or isomerization of benzyl-substituted alkenes simply by changing the irradiation wavelength. Benzyl-substituted alkenes are selectively isomerized to phenyl-substituted alkenes (E-isomer) with complete conversion over Pd@TiO2 under H2-free conditions. The reaction can be thermally induced under air or driven by visible-light irradiation at room temperature under Ar. UV irradiation in methanol solvent leads to efficient hydrogenation. The fine-tunability of the catalyst can also be used for selective deuterium incorporation using deuterated solvents; here H/D exchange is used as a mechanistic tool but with clear potential for isotope substitution applications.
Elhage, Ayda,Lanterna, Anabel E.,Scaiano, Juan C.
p. 250 - 255
(2017/05/31)

Phosphate modified ceria as a Br?nsted acidic/redox multifunctional catalyst
Deposition of trimethylphosphate onto ceria followed by thermal treatment resulted in the formation of surface phosphates with retention of the ceria fluorite structure. The structural and chemical properties of the phosphate-functionalized ceria were studied using 31P solid-state NMR, XPS, zeta titration, ammonia thermal desorption, pyridine adsorption, and model reactions. The introduction of phosphates generated Br?nsted acid sites and decreased the number of Lewis acid sites on the surface. The relative amount of Lewis and Br?nsted acids can be controlled by the amount of trimethylphosphate used in the synthesis. Upon deposition of Pd, the multifunctional material showed enhanced activity for the hydrogenolysis of eugenol and guaiacol compared to Pd on the unmodified ceria support. This was attributed to the cooperativity between the Lewis acid sites, which activate the substrate for dearomatization, and the redox/Br?nsted acid properties, which catalyze hydrogenolysis.
Nelson, Nicholas C.,Wang, Zhuoran,Naik, Pranjali,Manzano, J. Sebastián,Pruski, Marek,Slowing, Igor I.
supporting information
p. 4455 - 4466
(2017/03/09)

Selective Hydrodeoxygenation of Lignin-Derived Phenols to Cyclohexanols or Cyclohexanes over Magnetic CoNx@NC Catalysts under Mild Conditions
The hydrodeoxygenation (HDO) of lignin-derived phenols is important to produce the renewable biofuels. Herein, we reported a simple method to prepare magnetic nitrogen-doped carbon supported cobalt nitride catalysts (CoNx@NC) by copyrolysis of cellulose and cobalt nitrate under ammonia atmosphere. The catalysts were prepared at different temperatures and characterized by elemental analysis, atomic absorption spectroscopy (AAS), Brunauer-Emmett-Teller (BET) surface area analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and temperature-programmed reduction (TPR). The CoNx@NC-650 (pyrolyzed at 650°C) exhibited the best HDO activity for eugenol conversion among a series of Co-based catalysts. The yield of propylcyclohexanol from eugenol was >99.9% under 2 MPa H2 at 200°C for 2 h. Moreover, a high yield of propylcyclohexane (99.1%) could be achieved when the solid acid HZSM-5 was added to the reaction system. Other lignin-derived phenolic compounds were also investigated and the yield of alkanes was >90%. Based on the mechanism investigation, the catalyst demonstrated a high selectivity to cleave the Caryl-OR bond under mild conditions. (Chemical Equation Presented).
Liu, Xiaohao,Xu, Lujiang,Xu, Guangyue,Jia, Wenda,Ma, Yanfu,Zhang, Ying
p. 7611 - 7620
(2016/11/17)

Highly selective hydrogenation and hydrogenolysis using a copper-doped porous metal oxide catalyst
A copper-doped porous metal oxide catalyst in combination with hydrogen shows selective and quantitative hydrogenolysis of benzyl ketones and aldehydes, and hydrogenation of alkenes. The approach provides an alternative to noble-metal catalysed reductions and stoichiometric Wolff-Kishner and Clemmensen methods.
Petitjean, Laurene,Gagne, Raphael,Beach, Evan S.,Xiao, Dequan,Anastas, Paul T.
p. 150 - 156
(2015/12/31)

Generation of Hydrogen from Water: A Pd-Catalyzed Reduction of Water Using Diboron Reagent at Ambient Conditions
Production of hydrogen from renewable sources, particularly from water, is an intensive area of research, which has far-reaching relevance in hydrogen economy. A homogeneous catalytic method is presented for producing clean hydrogen gas from water, in a reaction of water with a diboron compound as the reductant, under ambient reaction conditions. The Pd-catalytic system is stable in water and displays excellent recyclability. Hydroxy analogues such as alcohols are compatible with the Pd/B2Pin2 system and generate hydrogen gas efficiently. The B2Pin2-H2O system, in the presence of palladium, is an excellent catalytic system for selective hydrogenation of olefins.
Ojha, Devi Prasan,Gadde, Karthik,Prabhu, Kandikere Ramaiah
supporting information
p. 5062 - 5065
(2016/10/14)

Immobilized ruthenium metal-containing ionic liquid-catalyzed dehydrogenation of dimethylamine borane complex for the reduction of olefins and nitroarenes
An efficient immobilized ruthenium metal containing ionic liquid (ImmRu-IL) catalyst has been developed for the transfer hydrogenation of olefins and nitroarenes. Various olefins and nitroarenes were reduced in excellent yields within 2-6 h at room temperature. This methodology uses eco-friendly dimethylamine borane as a reducing agent which is nontoxic, water soluble, highly stable and easy to handle. The reactions take place through tandem dehydrogenation and hydrogenation of dimethylamine borane complex in the presence of ImmRu-IL catalyst. The catalyst was reused in up to four consecutive cycles without any significance loss in its activity. The fresh and reused catalysts have been studied by XPS analysis.
Patil, Nilesh M.,Sasaki, Takehiko,Bhanage, Bhalchandra M.
supporting information
p. 52347 - 52352
(2016/06/13)

High Yield Production of Natural Phenolic Alcohols from Woody Biomass Using a Nickel-Based Catalyst
Efficient depolymerization of woody biomass to produce natural phenolic alcohols not only preserves the original structure of lignin, but also makes the depolymerization process atom-efficient. Here, high yield production of natural phenolic alcohols (38.7 wt %) from woody biomass has been achieved using a Ni/C catalyst in a methanol–water co-solvent. The Ni-based catalyst can efficiently etherify the Cα?OH group in lignin β-O-4 motifs under hydrogen atmosphere, which can break the hydrogen bond between the Cβ?O oxygen and the Cα?OH proton to facilitate the Cβ?O cleavage. It was reported that water can also accelerate the etherification of raw lignin with methanol through in situ formation of acid. Our results suggest that breaking the intramolecular hydrogen bonds can accelerate the Cβ?O cleavage, keeping the original structure of lignin unchanged. This work highlights the significance of structure modification in lignin depolymerization and displays a clear potential for the valorization of whole biomass.
Chen, Jiazhi,Lu, Fang,Si, Xiaoqin,Nie, Xin,Chen, Junsheng,Lu, Rui,Xu, Jie
p. 3353 - 3360
(2016/12/16)

Mechanistic investigation of the Zn/Pd/C catalyzed cleavage and hydrodeoxygenation of lignin
While current biorefinery processes use lignin only for its heat value, the conversion of lignin to high value chemicals is an area of increasing interest. Herein we present a detailed mechanistic study of the hydrodeoxygenation (HDO) of lignin by using a synergistic Pd/C and ZnII catalyst through use of both lignin model compounds and lignocellulosic biomass. Spectroscopic data coupled with the study of lignin model compounds suggest that ZnII activates and facilitates removal of the hydroxyl group at the Cγ position of the β-O-4 ether linkage. Activation is proposed to occur through formation of a six-membered ring complex of ZnII coordinated to the oxygen atoms at Cα and Cγ of the lignin model compound guaiacylglycerol-β-guaiacyl.
Klein, Ian,Marcum, Christopher,Kentt?maa, Hilkka,Abu-Omar, Mahdi M.
p. 2399 - 2405
(2016/05/19)

Chemo- and Regioselective Hydrogenolysis of Diaryl Ether C-O Bonds by a Robust Heterogeneous Ni/C Catalyst: Applications to the Cleavage of Complex Lignin-Related Fragments
We report the chemo- and regioselective hydrogenolysis of the C-O bonds in di-ortho-substituted diaryl ethers under the catalysis of a supported nickel catalyst. The catalyst comprises heterogeneous nickel particles supported on activated carbon and furnishes arenes and phenols in high yields without hydrogenation. The high thermal stability of the embedded metal particles allows C-O bond cleavage to occur in highly substituted diaryl ether units akin to those in lignin. Preliminary mechanistic experiments show that this catalyst undergoes sintering less readily than previously reported catalyst particles that form from a solution of [Ni(cod)2].
Gao, Fang,Webb, Jonathan D.,Hartwig, John F.
p. 1474 - 1478
(2016/02/12)

Selective cleavage of aryl ether bonds in dimeric lignin model compounds
Lignin is an abundant renewable feedstock with a complicated and ill-defined structure. As β-O-4 aryl ether bonds are dominant among all the linkages in lignin, it is important to explore lignin depolymerization targeting the cleavage of the β-O-4 aryl ether bond for efficiently utilizing this biomass. Selective cleavage of chemical bonds in β-O-4 lignin model compounds was investigated by using Fe2(SO4)3, HZSM-5 and Pd/C as catalysts under microwave irradiation. When Fe2(SO4)3 or HZSM-5 was used as a catalyst, the Cα-Cβ bond of the C3 side chain in the model compound was broken to form aldehyde, secondary alcohol or ketone compounds. When Pd/C and formate were used as the catalyst, the β-O-4 aryl bond of the non-phenolic model compound was selectively cleaved and hydrogenation of C=C on the side chain occurred at the same time. However, the hydrogenation reaction of C=C on the side chain was faster than that of cleavage of the ether bond. Increasing Pd content favored the selective cleavage of the β-O-4 bond, and microwave irradiation accelerated the cleavage of the β-O-4 bond dramatically. At a high dosage of formate or high temperature, the condensation reaction among phenolic products was promoted due to the presence of an active phenolic hydroxyl group. The β-O-4 bond of the phenolic model compound was also selectively cleaved with Pd/C as the catalyst, and the reaction temperatures of cleaving about one half β-O-4 bonds of the non-phenolic and phenolic model compounds were 120 and 100°C, respectively.
Zhu, Guodian,Ouyang, Xinping,Yang, Yun,Ruan, Tao,Qiu, Xueqing
p. 17880 - 17887
(2016/02/27)

Hydrogenation of lignin-derived phenolic compounds over step by step precipitated Ni/SiO2
The harsh reaction conditions for the valorization of lignin-derived phenolic compounds considerably limit the efficient utilization of the lignin derivatives. Here, we put forward a high efficient and selective hydrogenation process for phenolic compounds at a mild condition over step by step precipitated Ni/SiO2 catalyst. The properties of the Ni/SiO2 catalysts by different preparation methods were detailedly compared using various characterization measurements. Catalytic activity of the catalysts was tested by the hydrogenation of guaiacol, and the results showed that guaiacol could be completely converted into cyclohexanol with 99.9% selectivity at 120 °C, 2 MPa H2 atmosphere for 2 h. Other typical lignin-derived phenolic compounds also had excellent hydrogenation performance and great energy efficiency. Catalyst characterization results demonstrated that the high catalytic activity of the step by step precipitated Ni/SiO2 was mainly ascribed to its polyporous spherical structure, which led to the large specific surface area and high nickel dispersion. The appropriate acidity of the catalyst also promoted the catalytic performance significantly. Furthermore, the catalyst exhibited an excellent recyclability, where no significant loss of the catalytic activity was showed out after 3 runs.
Shu, Riyang,Zhang, Qi,Xu, Ying,Long, Jinxing,Ma, Longlong,Wang, Tiejun,Chen, Pengru,Wu, Qingyun
p. 5214 - 5222
(2016/02/05)

Ruthenium nanoparticle-intercalated montmorillonite clay for solvent-free alkene hydrogenation reaction
Well-characterized, ruthenium nanoparticle-intercalated montmorillonite clay was used as a catalyst in solvent-free alkene hydrogenation reactions and the corresponding products were obtained in good yields. The catalytic activity of ruthenium nanoparticle-intercalated montmorillonite clay was successfully tested with 16 different functionalized and non-functionalized alkenes. Apart from alkene reduction, the ruthenium nanoparticle-intercalated montmorillonite clay was also tested in Wittig-type reactions for obtaining dehydrobrittonin A, an important intermediate for the synthesis of brittonin A. Ruthenium nanoparticle-intercalated montmorillonite clay was found to be active in the synthesis of dehydrobrittonin A and brittonin A. The ability to recycle the catalyst nine times, together with low catalyst loading, high catalytic activity and catalytic selectivity were noteworthy advantages of the proposed protocol.
Upadhyay, Praveenkumar,Srivastava, Vivek
p. 740 - 745
(2015/02/05)

Flavin-functionalized gold nanoparticles as an efficient catalyst for aerobic organic transformations
Monolayer-protected gold clusters functionalized with synthetic flavins were synthesized and their catalytic activity in aerobic organic transformations investigated. Gold nanoparticles with 5-ethyl-3-(8-thiooctyl)lumiflavinium perchlorate acts as an efficient catalyst for the aerobic oxidation of organic sulfides to the corresponding sulfoxides upon treatment with hydrazine at room temperature and under atmospheric pressure in oxygen. With a catalytic amount of gold nanoparticles with 3-(8-thiooctyl)lumiflavin, diimide reduction of various olefins can be performed with hydrazine at room temperature under atmospheric pressure in air with greater yields of product alkanes than with non-supported 3-methyllumiflavin catalyst under the same conditions. Kinetic studies revealed that the mono-layer-protected gold cluster-catalyzed reactions proceeded faster than those with non-supported catalysts over the full substrate concentration range for the hydrogenation of olefins and at lower substrate concentrations for sulfoxidation. This positive effect was rationalized by assuming a Michaelis-Menten-type mechanism in which the specific inclusion of substrates into the enzyme-like reaction cavities was a key factor in the high efficiency of the supported flavin catalysts.
Imada, Yasushi,Osaki, Motonari,Noguchi, Mikiko,Maeda, Takatoshi,Fujiki, Misa,Kawamorita, Soichiro,Komiya, Naruyoshi,Naota, Takeshi
p. 99 - 106
(2015/03/04)