- Selective catalysis of the aerobic oxidation of cyclohexane in the liquid phase by carbon nanotubes
-
Putting the N in nanotube: Carbon nanotubes (CNTs) catalyze the aerobic oxidation of cyclohexane into cyclohexanol, cyclohexanone, and adipic acid with excellent activity and controllable selectivity. The catalytic activity is further enhanced by nitrogen dopants in the nanotube (see diagram; AC=activated carbon, MWCNT=multiwalled CNT, N-CNT=nitrogen-doped CNT).
- Yu, Hao,Peng, Feng,Tan, Jun,Hu, Xiaowei,Wang, Hongjuan,Yang, Jian,Zheng, Wenxu
-
-
Read Online
- Studies on -Catalysed Homogeneous Transfer Hydrogenation Reactions; X-Ray Structure of
-
Using (1) as the homogeneous precatalyst, transfer hydrogenations of cyclohex-2-en-1-one, benzylideneaniline, and carbon tetrahalides by donor alcohols, in particular propan-2-ol, have been studied.Conversion of cyclohex-2-en-1-one into cyclohexanol has been found to proceed via the intermediate formation of cyclohexanone.From the temperature dependence of the overall reaction rates, the precatalysts and are involved in processes with comparable activation energies.Two catalytically active cluster complexes, and , were isolated from the reaction of (1) with cyclohex-2-en-1-one.Hydrogenation of the tetranuclear cluster led to the formation of and .The reaction of the complex (1) with benzylideneaniline gave a catalytically active cluster .With (1) as the precatalyst, analogues of benzylideneaniline of general formula RC6H4CH=NPh can all be transfer hydrogenated, with the exception of the o-methoxy derivative.The complex was found to undergo reversible carbonylation.Rational syntheses for and were designed by treating (1) with the appropriate alcohol and carbon tetrahalide.The X-ray structure of has been determined.The halogenoalkoxo clusters are considered to be active intermediates in the overall catalytic cycle for the transfer hydrogenations of carbon tetrahalides.
- Bhaduri, Sumit,Sapre, Niteen,Sharma, Krishna,Jones, Peter G.,Carpenter, Gene
-
-
Read Online
- Hydration of cyclohexene in sub-critical water over WOx-ZrO 2 catalysts
-
WOx/ZrO2 catalyzed hydration of cyclohexene in sub-critical water was experimentally investigated. The migration of reaction zone into sub-critical water makes it possible to run the hydration in a single liquid phase, and the reaction is free from the limitation of liquid-liquid phase mass transfer to hydration kinetics. The severe hydrothermal environments favor the transformation of surface active sites on WOx-ZrO 2 catalysts to Br?nsted acid centers of stronger acidity, which are highly effective for the hydration of cyclohexene to the desired product cyclohexanol.
- Yuan, Pei-Qing,Liu, Ying,Bai, Fan,Xu, Liang,Cheng, Zhen-Min,Yuan, Wei-Kang
-
-
Read Online
- The effect of metal (Nb, Ru, Pd, Pt) supported on SBA-16 on the hydrodeoxygenation reaction of phenol
-
Ordered silica materials of SBA-16 type were synthesized, characterized as to their physicochemical properties and used as supports of the active phases which were niobium, ruthenium, palladium or platinum ions. Physicochemical properties of the systems o
- Feliczak-Guzik, Agnieszka,Szczyglewska, Paulina,Nowak, Izabela
-
-
Read Online
- Fe(TPA)-catalyzed alkane hydroxylation. Metal-based oxidation vs radical chain autoxidation
-
Catalytic alkane functionalization by the Fe(TPA)/(t)BuOOH system (with [Fe(TPA)Cl2]+ (1), [Fe(TPA)-Br2]+ (2), and [Fe2O(TPA)2(H2O)2]4+ (3) as catalysts; TPA = tris(2-pyridylmethyl)amine) has been investigated in further detail to clarify whether the reaction mechanism involves a metal- based oxidation or a radical chain autoxidation. These two mechanisms can be distinguished by the nature of the products formed, their dependence on O2 (determined from argon purge and 18O2 labeling experiments), and the kinetic isotope effects associated with the products. The metal-based oxidation mechanism is analogous to heme-catalyzed hydroxylations and would be expected to produce mostly alcohol with a large kinetic isotope effect. The radical chain autoxidation mechanism entails the trapping of substrate alkyl radicals by O2 to afford alkylperoxy radicals that decompose to alcohol and ketone products in a ratio 1:1 or smaller via Russell termination steps. Consistent with the latter mechanism, alcohol and ketone products were observed in a ratio of 1:1 or less, when catalysts 1, 2, or 3 were reacted with alkane and 150 equiv of (t)BuOOH; these product yields were diminished by argon purging, demonstrating the participation of O2 in the reaction. However, when the 3-catalyzed oxidation was carried out in the presence of a limited (20 equiv) amount of (t)BuOOH or CmOOH, the sole product observed was alcohol; k(H)/k(D) values of 10 were observed, consistent with a metal- based oxidation. To reconcile these apparently conflicting results, a mechanistic scheme is proposed involving the formation of an alkylperoxyiron(III) intermediate which can oxidize either the substrate (metal-based oxidation) or excess ROOH (to generate alkylperoxy radicals that initiate a radical chain autoxidation process), the relative importance of the two mechanisms being determined by the concentration of ROOH.
- Kim, Jinheung,Harrison, Roger G.,Kim, Cheal,Que Jr., Lawrence
-
-
Read Online
- Highly Active and Selective RuPd Bimetallic NPs for the Cleavage of the Diphenyl Ether C-O Bond
-
The cleavage of C-O linkages of aryl ethers into aromatic platform compounds is a challenging reaction but of great importance for the sustainable future. Herein, we reported the efficient H2-assisted C-O bond cleavage of diphenyl ether (DPE) in aqueous phase over ultrasmall RuPd bimetallic nanoparticles (NPs) supported on amine-rich silica hollow nanospheres (NH2-SiO2). RuPd5/NH2-SiO2 with TOF of 172 h-1 and C-O cleavage selectivity of 99% outperformed the corresponding monometallic counterparts and is among the most active solid catalysts for C-O bond cleavage of DPE. The control experiments and characterization results showed that the effective isolation of Ru sites and optimized H2 dissociation ability mainly contributed to the enhanced catalytic performance of RuPd bimetallic NPs, in which Ru and Pd worked cooperatively with Ru sites for DPE activation and Pd sites for H2 dissociation. The alloying of two or multiple metal atoms provides an efficient approach for designing high-performance catalysts for chemical transformations.
- Guo, Miao,Peng, Juan,Yang, Qihua,Li, Can
-
-
Read Online
- Oxidation of Cycloalkanes and Arylalkanes with Sodium Periodate Catalysed by Manganese Porphyrins
-
Cycloalkanes and arylalkanes are transformed into their related alcohols and ketones in moderate to high yields and selectivities at room temperature with sodium periodate in the presence of manganese(III tetraarylporphyrin complexes associated with imidazole and tetra-n-butylammonium bromide in CH2Cl2-H2O solution.
- Mohajer, Daryoush,Tayebee, Reza,Goudarziafshar, Hameed
-
-
Read Online
- Synthesis, characterization and heterogeneous catalytic application of copper integrated mesoporous matrices
-
Ordered copper integrated mesoporous silicate catalysts (CuMSC) have been synthesized by the utilization of the amphiphilic tri-block copolymer pluronic F127 as a structure directing agent (SDA) under acidic aqueous conditions. The mesophase of the materials was investigated using small-angle powder X-ray diffraction and transmission electron microscopic (TEM) image analysis. N 2 adsorption-desorption studies show that the BET surface area of CuMSC (214-407 m2 g-1) is lower than that of pure silica (611 m2 g-1) and has smaller average pore dimensions (4.0-5.0 nm), both prepared following the same synthetic route. The reduction of pore size and surface area points to incorporation of copper within the silicate network. FEG-SEM results suggest that the materials have a plate-like morphology and are composed of very tiny nanoparticles. EDS surface chemical analysis was utilized for the detection of the distribution of Si, O and Cu in the matrix. The FT IR spectral study suggests the complete removal of the surfactants from the calcined materials and the presence of Si-O-Cu bonds for high nominal contents. X-ray photoelectron spectroscopy (XPS) and UV-vis reflectance spectra show the oxidation state of copper and coordination mode, respectively. These mesoporous materials display a good catalytic activity in the oxidation of cyclohexane to cyclohexanone and cyclohexanol in the presence of the green oxidant hydrogen peroxide. The maximum yield (cyclohexanone and cyclohexanol) was ca. 29% and the TON (turnover number) was 276 under optimal reaction conditions. The good catalytic activity could be attributed to the large surface area and the presence of a high number of active sites located at the surface of the material, as well as to its stability. The catalysts showed negligible loss of activity after five cycles.
- Das, Swapan K.,Mukherjee, Sanghamitra,Lopes, Luis M. F.,Ilharco, Laura M.,Ferraria, Ana M.,Botelho Do Rego, Ana M.,Pombeiro, Armando J. L.
-
-
Read Online
- Photooxidation of Hydrocarbons on Porphyrin-modified Titanium Dioxide Powders
-
A composite catalyst consisting of an iron porphyrin covalently linked to TiO2 shows a new reactivity in the photochemical mono-oxygenation of hydrocarbons under mild conditions, with respect to the porphyrin and TiO2 used separately.
- Amadelli, R.,Bregola, M.,Polo, E.,Carassiti, V.,Maldotti, A.
-
-
Read Online
- Vapor-phase catalytic dehydration of terminal diols
-
Vapor-phase catalytic reactions of several terminal diols were investigated over several rare earth oxides, such as Sc2O3, Y 2O3, CeO2, Yb2O3, and Lu2O3. Sc2O3 showed selective catalytic activity in the dehydration of terminal diols with long carbon chain, such as 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol, to produce the corresponding unsaturated alcohols. In the dehydration of 1,6-hexanediol, 5-hexen-1-ol was produced with selectivity over 60 mol%, together with by-products such as ε-caprolactone and oxacycloheptane. In the dehydration of 1,10-decanediol, 9-decen-1-ol was produced with selectivity higher than 70 mol%. In addition to Sc 2O3, heavy rare earth oxides such as Lu2O 3 as well as monoclinic ZrO2 showed moderate selectivity in the dehydration of the terminal diols.
- Abe, Katsutoshi,Ohishi, Yusuke,Okada, Takuto,Yamada, Yasuhiro,Sato, Satoshi
-
-
Read Online
- Supported nickel catalysts for anisole hydrodeoxygenation: Increase in the selectivity to cyclohexane
-
The hydrodeoxygenation (HDO) of anisole was performed with Ni catalysts supported on SBA-15 silica and protonated titanate nanotubes (PTN), in order to determine the effect of the support's nature and the method of incorporation of Ni species on the catalytic activity and selectivity in HDO. Catalysts with 10 wt.percent of Ni were prepared by two methods: deposition-precipitation with urea (DP) and the classical incipient wetness impregnation (IM). Characterization of the catalysts was performed by nitrogen physisorption, temperature programmed reduction, temperature programmed desorption of ammonia, high resolution transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, XPS and O2 chemisorption. The obtained results show that the support's nature and the preparation method had a strong influence on the dispersion of the supported Ni species and their HDO performance. Catalysts with larger metallic Ni particles showed higher ability for hydrogenation of anisole and higher intrinsic activity (TOF) than those with smaller Ni particles. On the other side, the use of the PTN support and the DP with urea preparation method resulted in catalysts with increased acidity and improved selectivity for the formation of deoxygenated products (cyclohexane).
- Vargas-Villagrán,Flores-Villeda,Puente-Lee,Solís-Casados,Gómez-Cortés,Díaz-Guerrero,Klimova
-
-
Read Online
- An efficient Pt nanoparticle-ionic liquid system for the hydrodeoxygenation of bio-derived phenols under mild conditions
-
Platinum nanoparticles (NPs) were synthesized in situ in the ionic liquid (IL) [Emim]NTf2 (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) as well as in mixtures of [Emim]NTf2 with a second IL, Lewis acid or Br?nsted acid, but in the absence of additional stabilizers. The resulting NP/IL systems catalyze the hydrodeoxygenation of a phenol under mild conditions (60 °C, 1.0 MPa H2), achieving full substrate conversion and a high deoxygenation rate (over 95%) to cyclohexane and cyclohexene. The combination of [Emim]NTf2 and [Bmim]PF6 results in the best catalytic performance. Also the transformation of other substituted phenols and dimers such as catechol, guaiacol and diphenyl ether was studied in the Pt NP/[Emim]NTf2-[Bmim]PF6 system and in most cases afforded cyclohexane in good yield.
- Chen, Lu,Fink, Cornel,Fei, Zhaofu,Dyson, Paul J.,Laurenczy, Gabor
-
-
Read Online
- The effect of oxalic acid and glyoxal on the VO(acac)2-catalyzed cyclohexane oxidation with H2O2
-
A new protocol for the effective oxidation of cyclohexane in acetonitrile at 40 °C and atmospheric pressure into cyclohexanol, cyclohexanone and cyclohexyl hydroperoxide using hydrogen peroxide as the oxidant, vanadyl(IV)-acetylacetonate as the catalyst, oxalic acid and glyoxal as additives is presented with some reaction mechanism proposals.
- Pokutsa, Alexander,Kubaj, Yulia,Zaborovskyi, Andriy,Maksym, Dariya,Muzart, Jacques,Sobkowiak, Andrzej
-
-
Read Online
- Highly selective cycloalkane oxidation in water with ruthenium nanoparticles
-
Ruthenium(0) nanospecies, with small sizes of approximately 1.75 nm, proved to be active, selective, and retrievable nanocatalysts for the oxidation of various cycloalkanes in neat water, using tert-butylhydroperoxide as an oxidant and at room temperature. Relevant conversions and selectivities (up to 97 %) were achieved towards the major formation of the ketone product, which constitutes a high-value-added intermediate for polymer or fine chemistry. The lifetime of the catalyst has been checked over several runs, with no significant loss of activity and selectivity. Kinetic and mechanistic investigations proved that radical species are involved in the oxidation process. A literature comparison showed the relevance and the usefulness of the present ruthenium nanocatalytic system in a benign reaction context. Active, selective, and retrievable! A sustainable oxidation process of cycloalkanes to the ketones with an easy-to-handle and reusable catalyst, in neat water, and under ambient conditions is described. The active catalyst is a ruthenium(0) nanospecies. t-BHP=tert-butylhydroperoxide.
- Denicourt-Nowicki, Audrey,Lebedeva, Anastasia,Bellini, Clément,Roucoux, Alain
-
-
Read Online
- Synthesis, characterization and catalytic performance in cyclohexane transformation by Bi2O3/MCM-41 nanocomposite materials
-
The nanoparticles of Bi2O3 supported on mesoporous MCM-41 were prepared in a simple way and were well characterized. The oxidation of cyclohexane to cyclohexanol and cyclohexanone under 1 atmospheric pressure of air in the absence of any solvent and reducing agents with Bi2O3/MCM-41 nanocomposites were considered. These nanoparticles of Bi2O3 supported on mesoporous MCM-41 were found to be the very effective catalysts for cyclohexane oxidation with air in a temperature range of 280–370 ?C. The influences of reaction temperature, the loading amount of Bi2O3 and space velocity on the oxidation of cyclohexane were also studied, and optimized conditions were investigated.
- Mozaffari, Majid,Ebadi, Amin
-
-
Read Online
- Light-triggered oxy-chlorination of cyclohexane by metal chlorides
-
This paper discloses that visible light can trigger efficiently the oxy-chlorination of cyclohexane by some metal chlorides at ambient temperature under N2 atmosphere. Among the metal chlorides examined, only a few metal chlorides with easily changeable valence such as VOCl3, CuCl2·2H2O and FeCl3·6H 2O were found to be efficient chlorinating agents for this photoreaction in acetonitrile or acetone, providing mono- and di-chlorinated cyclohexane as main products, with concomitant formation of a small amount of cyclohexene, cyclohexanol and cyclohexanone. CuCl2·2H 2O was the most active chlorinating agent for this photoreaction, but provided an appreciable amount of the non-chlorinated products. FeCl 3·6H2O possessed the best selectivity for the chlorinated products. In addition, it was found that a suitable amount of concentrated HCl was capable of realizing the visible light-driven CuCl 2·2H2O or the UV-driven FeCl3· 6H2O to catalyze photo-oxy-chlorination of cyclohexane under air, providing a high chlorination efficiency (turnover number (TON), 2.46 for CuCl2·2H2O and 4.66 for FeCl3· 6H2O). This is likely because the HCl can itself be used as a chlorinating agent; on the other hand, it also efficiently promotes the photoredox cycling of CuCl2 or FeCl3, as supported by UV-vis spectra. Based on these findings, a free radical mechanism for the present photo-oxy-chlorination system was proposed.
- Wu, Wenfeng,Fu, Zaihui,Wen, Xu,Wang, Yongjun,Zou, Shuai,Meng, Yue,Liu, Yachun,Kirk, Steven Robert,Yin, Dulin
-
-
Read Online
- Copper ion substituted hercynite (Cu0.03Fe0.97Al 2O4): A highly active catalyst for liquid phase oxidation of cyclohexane
-
Copper ion substituted MAl2O4 (M = Mg, Mn, Fe, Ni and Zn) spinels, CuxM1-xAl2O4 (x = 0.03 and 0.05), have been synthesized by a single step solution combustion method. Of the various compositions studied the 3 at.% copper ion substituted hercynite, Cu0.03Fe0.97Al2O4, reported here for the first time, is shown to be much more active (~92% conversion with ~99% selectivity) than other spinel analogues towards liquid phase oxidation of cyclohexane in acetonitrile with H2O2 as oxidant in air. Powder XRD analyses have revealed formation of pure hercynite phases. The least-square refined lattice parameters obtained from XRD data together with microstructural data by HRTEM have indicated copper ion substitution in the spinel lattice. The oxidation state of copper has been established as +2 from XPS analysis and it seem to be primarily substituted in the Fe-site of hercynite. Incorporation of the copper in the spinel structure of FeAl 2O4 leading to an ionic interaction is explained to be responsible for the higher oxidation activity observed over the combustion synthesized catalyst than the corresponding impregnated catalyst which contains finely dispersed CuO crystallites. Effect of recycling (repeated thrice) has shown almost no degradation of activity of the copper ion substituted hercynite. In contrast, the analogous impregnated catalyst has shown appreciable loss of activity in the consecutive cycles due to the presence of dispersed CuO crystallites which can agglomerate with ease and subsequently leach out.
- Mistri, Rajib,Maiti, Sayantani,Llorca, Jordi,Dominguez, Montserrat,Mandal, Tapas Kumar,Mohanty, Paritosh,Ray, Bidhan Chandra,Gayen, Arup
-
-
Read Online
- Organosilane-mediated free radical cyclization reactions employing carbonyl traps
-
Free-radical cyclization of halocarbonyl compounds can be achieved using the organosilane reagents phenylsilane and tristrimethylsilylsilane. Both 6- exo-trig and 5-exo-trig cyclizations can be accomplished using aldehydes or ketones as radical traps.
- Batey, Robert A.,MacKay, D. Bruce
-
-
Read Online
- Cyclohexane Functionalization Catalyzed by Octahedral Molecular Sieve (OMS-1) Materials
-
Both the abundance of alkanes and their extremely low activity have greatly interested several researchers. In this paper, different metal substituted 3×3 octahedral molecular sieves (OMS-1) materials were used to catalyze the functionalization of cyclohexane by using tert-butyl hydroperoxide as oxidant and tert-butyl alcohol as solvent at different temperatures (60, 80, and 100°C). [Fe]-OMS-1 at 80°C exhibits the best activity and selectivity. The solvent t-butyl alcohol (the reduced state of t-butyl hydroperoxide) was first introduced to the reaction system which makes the system simple to study. The effects of catalyst amount and ratio of tert-butyl alcohol to cyclohexane were examined. Variable speed stirring (200-800 rpm) experiments suggest that under conditions reported here that diffusion is not a problem. Studies of the liquid phase after separation from the solid OMS-1 catalysts have shown that metal does not leach into the solution and that heterogeneous catalysis occurs. At 80°C, the conversion of cyclohexane or the total yield of products can reach 13.1% in 40 h. The yields of cyclohexanone, cyclohexanol, and cyclohexyl hydroperoxide were 6.57,2.83, and 1.38%, respectively, and t-butyl cyclohexyl perether was 2.36%. The reaction conditions are mild, and the catalysts retain their crystallinity after reaction. Moreover, the catalyst can be easily separated from the reaction mixture and used catalysts retain similar catalytic activity over a 40-h time period.
- Wang, Jin-Yun,Xia, Guan-Guang,Yin, Yuan-Gen,Suib, Steven L.,O'Young
-
-
Read Online
- Improved Cyclohexane Oxidation Catalyzed by a Heterogenized Iron (II) Complex on Hierarchical Y Zeolite through Surfactant Mediated Technology
-
The hydrotris (pyrazol-1-yl) methane iron (II) complex [FeCl2(Tpm)] [Tpm=HC(C3N2H3)3] was successfully immobilized, by the incipient wetness impregnation method, in parent and hierarchical Y zeolite m
- Van-Dúnem, Vanmira,Carvalho, Ana P.,Martins, Luísa M. D. R. S.,Martins, Angela
-
-
Read Online
- Hydrocarbon Oxidations with Hydrogen Peroxide Catalyzed by a Soluble Polymer-Bound Manganese(IV) Complex with 1,4,7-Triazacyclononane
-
Soluble manganese(IV) complexes with polymer-bound 1,4,7-triazacyclononanes as ligands (compound 2) catalyze the oxidation of alkanes by hydrogen peroxide in acetonitrile at room and lower temperatures. The corresponding alkyl hydroperoxides are the main products. The presence of a relatively small amount of acetic acid is obligatory for this reaction. The oxidation of alkanes and olefins exhibits some features (kinetic isotope effect, bond selectivities) that distinguish this system from an analogous one based on the dinuclear Mn(IV) complex 1.
- Nizova, Galina V.,Bolm, Carsten,Ceccarelli, Simona,Pavan, Chiara,Shul'pin, Georgiy B.
-
-
Read Online
- Cyclohexane oxidation: Small organic molecules as catalysts
-
The catalytic activity of several small organic molecules including ketones, aldehydes, esters, alcohols and amines toward cyclohexane oxidation was investigated. The catalytic activity was found to be closely related to polarity, α-H activity, the strength of hydrogen bond formed with cyclohexane and the radical scavenging capability of these molecules. Based on the obtained results, the catalytic role of the organic solvent must be considered for cyclohexane oxidation. Tripropylamine has very high activity in cyclohexane oxidation and it might be further developed as a promising small-molecule organocatalyst for future application.
- Zhang, Yicheng,Dai, Weili,Wu, Guangjun,Guan, Naijia,Li, Landong
-
-
Read Online
- Generation and Chemistry of Cyclohexyloxy Radicals
-
In this paper we report our work on cyclohexyloxy radicals from dicyclohexyl hyponitrite (CyON2OCy) and the related CyO sources dicyclohexyl peroxydicarbonate and dicyclohexyl peroxide (CyO2Cy), including the 13C and 1H NMR spectra of the radical sources, the kinetics of the DCHN decomposition over a wide range of temperature (followed by both UV and chemiluminescence), ESR spin-trapping studies, the kinetics of hydrogen atom abstraction from a variety of substrates by CyO, and the effect of CyO radical source on product composition.We have also investigated the effects of dissolved O2 on DCHN decomposition in cyclohexane and comment on the source of the observed chemiluminescence.
- Druliner, J. D.,Krusic, P. J.,Lehr, G. F.,Tolman, C. A.
-
-
Read Online
- 2-Methylimidazole copper iminodiacetates for the adsorption of oxygen and catalytic oxidation of cyclohexane
-
The mixed-ligand copper(II) iminodiacetates [Cu(ida)(2-mim)(H2O)2]·H2O (1), [Cu(ida)(2-mim)2]·2H2O (2), [Cu(ida)(2-mim)(H2O)]n·4.5nH2O (3), and [Cu2(ida)su
- An, Dong-Li,Chen, Xi,Zhan, Xin-Qi,Zhou, Zhao-Hui
-
-
Read Online
- Morphology-Reserved Synthesis of Discrete Nanosheets of CuO?SAPO-34 and Pore Mouth Catalysis for One-Pot Oxidation of Cyclohexane
-
Discrete nanosheets of silicon-doped AlPO4 molecular sieves (SAPO-34) with a thickness of ≈7 nm have been prepared through morphology-reserved synthesis with a lamellar aluminum phosphate as precursor. Cages of the nanosheets are in situ incorporated with copper oxide clusters. The CuO?SAPO-34 nanosheets exhibit a large external surface area with a high number of (010) channel pores on the surface. Due to the thin morphology, copper oxide clusters occupy the outmost cages with a probability >50 %. The distinctive configuration facilitates a new concept of pore mouth catalysis, i.e., reactant molecules larger than the pores cannot enter the interior of the molecular sieves but can interact with the CuO clusters at “the mouth” of the pore. In heterogeneous catalysis, CuO?SAPO-34 nanosheets have shown top performance in one-pot oxidation of cyclohexane to adipic acid by O2, a key compound for the manufacture of nylon-66, which is so far produced using non-green nitric acid oxidation.
- Chen, Zhaoxu,Ding, Weiping,Guo, Xiangke,Guo, Xuefeng,Lin, Ming,Peng, Luming,She, Minyi,Shi, Taotao,Xu, Mengxia,Zhu, Yan
-
-
Read Online
- Reduced graphene oxide/iron oxide hybrid composite material as an efficient magnetically separable heterogeneous catalyst for transfer hydrogenation of ketones
-
Reduced graphene oxide was synthesized and functionalized with FeSO4?7H2O to form a reduced graphene oxide/iron oxide hybrid composite. The hybrid composite was extensively characterized using various techniques. Its application for transfer hydrogenation of various ketones was studied. The investigation showed that it serves as a good catalyst for transfer hydrogenation of aromatic and some aliphatic ketones resulting in excellent isolated yields (97–99%) of products. It is magnetically separable showing good reusability. The products were characterized and compared with authentic ones.
- Borah, Geetika,Bordoloi, Shreemoyee,Gogoi, Pradip K.,Konwer, Surajit,Sultana, Samim
-
-
Read Online
- Liquid-phase oxidation of cyclohexane to cyclohexanone over cobalt-doped SBA-3
-
Liquid-phase oxidation of cyclohexane was carried out under mild reaction conditions over mesoporous Co/SBA-3 catalyst using aqueous hydrogen peroxide (30%) as oxidant and acetic acid as solvent without adding any initiator. The catalyst exhibited high substrate conversion (91.6%) and reasonable product (cyclohexanone) selectivity (64.3%). Fast hot catalyst filtration experiment proved that the catalyst acted as a heterogeneous one and it can be reused two times without losing its activity to a greater extent.
- Liu, Xiaochen,He, Jiao,Yang, Lijun,Wang, Yunan,Zhang, Shihong,Wang, Wei,Wang, Jiaqiang
-
-
Read Online
- Efficient and recyclable multi-cationic polyoxometalate-based hybrid catalyst for heterogeneous cyclohexane oxidation with H2O2
-
A polyoxometalate-based organic-inorganic hybrid was prepared by ionic self-assembly of the ionic liquid precursor N,N′-bis-2-aminoethyl-4,4′-bipyridinium dibromide dihydrobromide ([DPyAM]Br2·2HBr) with the Keggin-structured V-substituted polyo
- Xue, Shuang,Chen, Guojian,Long, Zhouyang,Zhou, Yu,Wang, Jun
-
-
Read Online
- Continuous hydrogenation of hydroquinone to 1,4-cyclohexanediol over alkaline earth metal modified nickel-based catalysts
-
Effects of different alkaline earth metals (Mg, Ca, Sr) on the nickel-based catalysts for the continuous hydrogenation of hydroquinone were studied, and it was found that the by-products, characterized by GC-MS analysis, were mainly composed of phenol and cyclohexanol. The conversion of hydroquinone was 99.2% and the selectivity to 1,4-cyclohexanediol was above 96.7% over a Ni-Sr/γ-Al2O3 catalyst at 160°C and 2.0 MPa hydrogen pressure. The high selectivity of the Ni-Sr/γ-Al 2O3 catalyst was ascribed to its weak acidity due to the formation of SrCO3, confirmed from XRD and NH3-TPD characterizations. Moreover, it was proposed that SrCO3 can disperse and stabilize the active Ni species, making the catalyst stable during the 90 h service life test.
- Bai, Guoyi,Li, Fei,Fan, Xinxin,Wang, Yalong,Qiu, Mande,Ma, Zheng,Niu, Libo
-
-
Read Online
- New copper(II) salicylaldimine derivatives for mild oxidation of cyclohexane
-
Abstract: Two new salicylaldiminato-copper(II) complexes, [Cu(L1)2] (1) and [Cu(L2)2] (2) (where HL1= 4 -tert-Butyl-2-[(thiophen-2-ylmethylimino)-methyl]-phenol and HL2= 2 , 4 -Di-tert-butyl-6-[(thiophen-2-ylmethylimino)-methyl]-phen
- Busa, Asanda V,Lalancette, Roger,Nordlander, Ebbe,Onani, Martin
-
-
Read Online
- Metal chlorides-catalyzed selective oxidation of cyclohexane by molecular oxygen under visible light irradiation
-
The development of mild and efficient process for the selective oxidation of organic compounds with molecular oxygen can be one of the key technologies for synthesizing oxygenates. Here, a visible light-driven metal chloride to catalyze the selective oxidation of cyclohexane was carried out at ambient temperature under a pure O2 atmosphere. Among the metal salts examined, only a few metal chlorides, with easily changeable valence, such as CuCl2·2H2O, VOCl3, and FeCl 3·6H2O, were found to be active to this photo-oxidation reaction in acetonitrile or acetone, providing cyclohexanol, cyclohexanone, chlorocyclohexane, and cyclohexene as main products. This is likely because the weak coordination of these metal chlorides with solvent molecules plays key roles in absorbing visible light and realizing photoredox cycle, as supported by UV-Vis spectrum and cyclic voltammetry measurements. Among these active metal chlorides, CuCl2·2H2O showed a higher conversion and better selectivity for cyclohexanol and cyclohexanone (the oxygenated products) than the other two metal chlorides, and its activity and selectivity for chlorocyclohexane were significantly improved in the case of adding concentrated HCl, because HCl promotes the photocatalytic cycling, as supported by UV-Vis spectra. Notably, a high turnover frequency (TOF, 7.4 h-1) and an excellent selectivity for the oxygenated products (93%) were achieved upon a low concentration of CuCl 2·2H2O (0.002 mol L-1), 0.1 ml of concentrated HCl and 2 atm of O2 pressure. Based on these findings, a free radical mechanism for the present photocatalysis system was proposed.
- Wu, Wenfeng,He, Xiangling,Fu, Zaihui,Liu, Yachun,Wang, Yanlong,Gong, Xinglang,Deng, Xiaolin,Wu, Haitao,Zou, Yanhong,Yu, Ningya,Yin, Dulin
-
-
Read Online
- Enhanced stability and activity for solvent-free selective oxidation of cyclohexane over Cu2O/CuO fabricated by facile alkali etching method
-
The easy deactivation of cuprous oxide (Cu2O) have significantly limited their practical applications in catalysis. Formation of composites with other semiconductors including CuO is an crucial strategy for stability improvement of Cu2O. However, this strategy developed so far has often focused on only Cu2O thin film systems. Herein, Cu2O/CuO composites were fabricated via a simple alkali etching method, for the first time, to stabilize the powdered Cu2O in liquid-phase selective oxidation of cyclohexane under solvent-free conditions. The etching method presented remarkable high dispersion of copper species and an appropriate Cu+/Cu2+ ratio on catalyst surface, which leads to superior catalytic activity and stability. Hot filtration experiment confirmed that Cu2O/CuO composite was a heterogeneous catalyst which could be reused at least five times without considerable loss of catalytic activity, whereas the pure Cu2O suffered from severe deactivation caused by oxidative decomposition of Cu2O and copper leaching. Moreover, the amount of Cu+ and Cu2+ sites on catalyst surface are dramatically affected by the amount of alkali during etching process and the catalytic performance can be further tuned by regulating the Cu+/Cu2+ ratio. The Cu2O/CuO with a molar ratio of NaOH/Cu2O = 1:1 exhibited the highest catalytic activity with a cyclohexane conversion of 84.3 percent and cyclohexanone selectivity of 77.0 percent. The present work provides a promising strategy to stabilize Cu2O catalysts in catalytic oxidation systems.
- Chen, Yongjuan,He, Jiao,Jiang, Liang,Wang, Jiaqiang,Wang, Wei,Xie, Congjia,Yang, Yepeng
-
-
Read Online
- Ordered macroporous Co3O4-supported Ru nanoparticles: A robust catalyst for efficient hydrodeoxygenation of anisole
-
A three-dimensional ordered macroporous Co3O4 (OM-Co3O4) supported Ru catalyst was developed for the efficient hydrodeoxygenation (HDO) of anisole. It is revealed that small-sized Ru nanoparticles evenly distributed over the surface of OM-Co3O4 with large quantities of oxygen vacancies could strongly capture Ru0 species, thereby resulting in strong Ru-Co3O4 interactions. Compared with commercial Co3O4 supported Ru catalyst, Ru/OM-Co3O4 displays a better catalytic HDO performance, with a high cyclohexane yield of 92.4% at 250 °C and 0.5 MPa hydrogen pressure after 5 h on stream. Such a significant efficiency of Ru/OM-Co3O4 is mainly attributed to both high dispersion of Ru0 species and an enhanced formation of surface defects, as well as the unique macroporous framework of OM-Co3O4 support.
- Wang, An,Shi, Yisheng,Yang, Lan,Fan, Guoli,Li, Feng
-
-
Read Online
- Synthesis, structural characterization, catalytic, thermal and electrochemical investigations of bidentate Schiff base ligand and its metal complexes
-
In this study, we prepared the Schiff base ligand (L) and its Cu(II), Co(II) and Ni(II) complexes. The compounds were characterized by the analytical and spectroscopic methods. The ligand (L) behaves as a bidentate ligand and coordinates to the metal ions via the nitrogen atoms. The complexes have the mononuclear structures. The analytical and spectroscopic results indicated that the chloride ions coordinate to the metal ions. The complexes have the general formulae [M(L)(Cl)2] (M: Cu(II), Co(II) and Ni(II) metal ions). Electrochemical properties were investigated as ligand and metal centres in the different solvents and at the scan rates, respectively. The thermal properties of the metal complexes were studied in the N2 atmosphere. We investigated the improved catalytic activity of the Cu(II), Co(II) and Ni(II) complexes on the cyclohexane as a substrate. Obtained data showed that the best catalyst is the Cu(II) complex. The single crystal of the ligand (L) was obtained from CH3CN solution. There is a C-H...N H-bond linking the molecules into chains (C6)...N(2) 3.4415(18) ? under symmetry operation (x + 1,y,z) as well as π-π stacking on the outside of the "V" shape - nothing on the inside.
- Dolaz, Mustafa,McKee, Vickie,Uru?, Serhan,Demir, Necmettin,Sabik, Ali E.,G?lcü, Ay?egül,Tümer, Mehmet
-
-
Read Online
- Pd@MIL-101 as an efficient bifunctional catalyst for hydrodeoxygenation of anisole
-
A series of highly porous acidic metal-organic framework MIL-101 supported Pd nanoparticles materials with different Pd contents were prepared through a simple sol-gel method. The obtained heterogeneous catalytic material Pd@MIL-101 was comprehensively characterized by powder X-ray diffraction (PXRD), N2 adsorption, FTIR spectroscopy of pyridine adsorption (Py-IR) and transmission electron microscopy (TEM). The intact crystallinity of MIL-101 was found before and after the Pd loading process, and Pd nanoparticles with diameter of 2-3.5 nm were found homogeneously dispersed in MIL-101. The bifunctional Pd@MIL-101 catalyst exhibits good activity in hydrodeoxygenation (HDO) of anisole. It has been shown that the reaction temperature and the Pd content play important roles in the activity toward oxygen-removal. The catalyst after reaction at a high temperature of 240 °C revealed that the Pd nanoparticles tended to migrate to the external surface of the MOF materials and form larger aggregates.
- Ren, Hangxing,Li, Chuang,Yin, Dongdong,Liu, Jinxuan,Liang, Changhai
-
-
Read Online
- Isolation and X-ray structure determination of Ru4(CO)12(C6H6O), a precatalyst for the transfer hydrogenation of cyclohex-1-en-2-one
-
Ru4(CO)12(C6H6O) (1) and Ru3(CO)10(C6H8O) (2) have been obtained from the reaction of Ru3(CO)12 with cyclohex-1-en-2-one; 1 has been characterized by an X-ray structure determination.Both 1 and 2 have been found to be active precatalysts for the transfer hydrogenation of cyclohex-1-en-2-one.
- Basu, Amithaba,Bhaduri, Sumit,Sharma, Krishna
-
-
Read Online
- Catalytic hydroxylation in biphasic systems using CYP102A1 mutants
-
Cytochrome P450 monooxygenases are biocatalysts that hydroxylate or epoxidise a wide range of hydrophobic organic substrates. Their technical application is, however, limited to a small number of whole-cell processes. The use of the isolated P450 enzymes is believed to be impractical due to their low stability, stoichiometric need of the expensive cofactor NAD(P)H and low solubility of most substrates in aqueous media. We investigated the behaviour of an isolated bacterial monooxygenase (mutants of CYP102A1) in a biphasic reaction system supported by cofactor recycling with the NADP +-dependent formate dehydrogenase from Pseudomonas sp 101. Using this experimental set-up cyclohexane, octane and myristic acid were hydroxylated. To reduce the process costs a novel NADH-dependent mutant of CYP102A1 was designed. For recycling of NADH an NAD+-dependent FDH was used. The stability of the monooxygenase mutants under the reaction conditions in the biphasic system was quite high as revealed by total turnover numbers of up to 12,850 in the NADPH-dependent cyclohexane hydroxylation and up to 30,000 in the NADH-dependent myristic acid oxidation.
- Maurer, Steffen C.,Kuehnel, Katja,Kaysser, Leonard A.,Eiben, Sabine,Schmid, Rolf D.,Urlacher, Vlada B.
-
-
Read Online
- Regioselective Dye-Induced Photocleavage of Epoxides as an Alternative Mild Synthetic Route to a Targeted Alcohol Functionality
-
The regioselective cleavage of epoxides using visible light and a catalytic dye is reported in this study as an alternative mild synthetic approach. The epoxide radical anion is generated via visible light in an electron transfer reaction, induced by non-toxic dyes, leading to ring opening and formation of the corresponding alcohol with the hydroxyl group on the less substituted carbon in excellent yields.
- Provatas, Anthony A.,Epling, Gary A.,Stuart, James D.,Yeudakimau, Aliaksandr
-
-
Read Online
- Different crystal form titania supported ruthenium nanoparticles for liquid phase hydrodeoxygenation of guaiacol
-
Titania supported Ruthenium-based catalysts were prepared for liquid phase hydrodeoxygenation of guaiacol to cyclohexanol. The catalytic performance is affected by the different crystal forms of titania supports. Anatase and rutile titania supported catalyst 5%Ru/a-r-TiO2 presents higher BET surface area, better dispersion of Ru particles with smaller particle size of 3-4 nm, more acidic centers, and more Ruδ+ located at the boundary between anatase titania and rutile titania. Hence, 5%Ru/a-r-TiO2 gives the best catalytic performance of 95.33% conversion of guaiacol and 79.23% selectivity to cyclohexanol, other products mainly include cyclohexane, benzene, cyclohexanone and 1,2-cyclohexanediol. Based on the results of this work, the possible reaction path for guaiacol hydrodeoxygenation was proposed.
- Long, Wei,Lv, Yang,Liu, Pingle,Hao, Fang,Xiong, Wei,Li, Xie,Cui, Haishuai,Luo, He'an
-
-
Read Online
- An eco-friendly approach to the cyclohexane oxidation catalyzed by manganese porphyrins: Green and solvent-free systems
-
The selective cyclohexane oxidation to cyclohexanone and cyclohexanol based on a green strategy has been a challenge. A new manganese porphyrin [MnIII(T2,4,5TMPP)Cl] was prepared and its activity and selectivity as a catalyst were studied toget
- Guimar?es, Adriano Silva,Schmitberger, Bernardo,Meireles, Alexandre Moreira,Martins, Dayse Carvalho da Silva,DeFreitas-Silva, Gilson
-
-
Read Online
- Demethoxylation of hydrogenated derivatives of guaiacol without external hydrogen over platinum catalyst
-
Selective deoxygenation of 2-methoxycyclohexanone, one of the hydrogenated by-products in guaiacol hydrodeoxygenation, to phenol, cyclohexanone and cyclohexanol was investigated over carbon supported noble metal catalysts without external H2. Pt/C exhibited the best performance and the yield of target products reached 48% in water solvent at 493 K. This system can be applied to demethoxylation of 2-methoxycyclohexanol (49% yield). Demethoxylation of guaiacol is also possible under 0.1 MPa of H2 (46% yield). The yield of the target demethoxylation products was strongly dependent on the catalyst amount; too much catalyst decreased the yield due to the over-reaction, while the reaction stopped before total conversion of intermediates when the catalyst amount was too small. Fresh Pt/C catalyst has activity in hydrodeoxygenation of the target products and the reusability test showed deactivation of Pt/C during reaction, suggesting that deactivation at appropriate reaction progress controlled by catalyst amount is a key to good yield of the target products. In contrast to other noble metal catalysts, Pt/C has activity in both dehydrogenation of cyclohexane ring and hydrogenolysis of C–O bond, both of which contributed to the conversion of 2-methoxycyclohexanone to target demethoxylation products, according to the reactions of cyclohexanone and cyclohexanol as model substrates.
- Miyagawa, Akari,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
-
-
Read Online
- ACID-CATALYZED DECOMPOSITIONS OF HYDROPEROXIDES IN THE PRESENCE OF KETONES
-
Ketones and aldehydes accelerate decomposition of hydroperoxides in acetonitrile solution in the presence of strong acids.An explanation of the effect, due to the formation of semiperketals (semiperacetals) which undergo rapid acid-catalytic decomposition, is proposed.The macrostage character of the reaction of acid-catalyzed decomposition of cyclohexyl hydroperoxide was demonstrated for the first time.The initially slow decomposition takes place homolytically and yields the product cyclohexanone, which accelerates decomposition.
- Petrov, L. V.,Drozdova, T. I.,Lyuta, L. Ya.,Solyanikov, V. M.
-
-
Read Online
- Mechanistic study of decomposition of cyclohexyl hydroperoxide catalysed by manganese(III) tetraarylporphyrins
-
The reaction between manganese(III) tetraarylporhyrins and cyclohexyl hydroperoxide has been investigated.Since pyridine increases the decomposition rate of cyclohexyl hydroperoxide, all experiments were performed in the presence of pyridine.Experiments with 2,6-di-tert-butylpyridine showed that pyridine increases the reaction rate by ligation to the manganese porphyrin as well as by acting as a base.Cyclohexyl hydroperoxide is decomposed into cyclohexanol and cyclohexanone.Since neither 3,3,5,5-tetramethylcyclohexanol nor cyclohexanol-d12 are oxidized under these reaction conditions, cyclohexanone is formed directly from the peroxide and not by oxidation of the alcohol.During the reaction, a manganese(V)oxo porphyrin complex is formed.This complex may react with (i) the peroxide under formation of cyclohexanol and molecular oxygen, (ii) the solvent cyclohexane, or (iii) manganese(III) porphyrin.The latter reaction leads to destruction of the catalyst.This destruction is prevented by introduction of bulky groups on the ortho positions of the phenyl.The scission of the hydroperoxide is suggested to be heterolytic.It is also base-catalysed.The rate-determining step in the decomposition of cyclohexyl hydroperoxide is scission of the oxygen-oxygen bond of the manganese peroxyl porphyrin complex.A mechanism in line with the kinetic data is proposed.
- Hansen, Carola B.,Mul, Guido,Tabor, Roland B. J.,Drenth, Wiendelt
-
-
Read Online
- Experimental and computational investigation of the electrocatalytic hydrogenation of phenol in an electrochemical cell
-
The electrocatalytic hydrogenation (ECH) of phenol was carried out in aqueous media with a commercial Pd/Al2O3 (5% w/w) catalyst. A porous matrix of reticulated vitreous carbon (RVC) was used to study the porosity - stirring speed co
- Chagnes,Laplante,Kerdouss,Proulx,Menard
-
-
Read Online
- INFLUENCE OF CYCLODEXTRINS ON THE SODIUM BOROHYDRIDE REDUCTION OF CYCLOHEXENONES
-
The sodium borohydride reduction of cyclohexenones in aqueous medium is changed in the presence of cyclodextrins. β-cyclodextrin favours the 1,4-reduction over the 1,2-reduction whereas α-cyclodextrin favours the 1,2-reduction.
- Chenevert, Robert,Chamberland, Daniel
-
-
Read Online
- Mn2+ -Exchanged Clay-catalysed Oxidation of Alkanes with tert-Butyl Hydroperoxide
-
Oxidation of alkanes such as cyclohexane, cyclooctane, adamantane and octane with 70percent aqueous tert-butyl hydroperoxide in benzene in the presence of Mn2+ -exchanged clay catalyst and molecular sieves 4 Angstroem produces mainly the corresponding ketones with high turnover numbers.
- Tateiwa, Jun-ichi,Horiuchi, Hiroki,Uemura, Sakae
-
-
Read Online
- Efficient and selective oxidation of hydrocarbons with tert-butyl hydroperoxide catalyzed by oxidovanadium(IV) unsymmetrical Schiff base complex supported on γ-Fe2O3 magnetic nanoparticles
-
The catalytic activity of an oxidovanadium(IV) unsymmetrical Schiff base complex supported on γ-Fe2O3 magnetic nanoparticles, γ-Fe2O3@[VO(salenac-OH)] in which salenac-OH = [9-(2′,4′-dihydroxyphenyl)-5,8-diaza-4
- Ardakani, Mehdi Hatefi,Sabet, Mohammad,Samani, Mahnaz
-
-
- Rational synthesis of palladium nanoparticles modified by phosphorous for the conversion of diphenyl ether to KA oil
-
Conversion of lignin-derived molecules into value-added chemicals is critical for sustainable chemistry but still challenging. Herein, phosphorus-modified palladium catalyzed the degradation of lignin-derived 4-O-5 linkage to produce KA oil (cyclohexanone-cyclohexanol oil) was reported. The reaction proceeds via a restricted partial hydrogenation-hydrolysis pathway. Phosphorus-modified palladium catalyst suppressed the full hydrogenation of diary ether, which was the key point to produce KA oil selectively. Under the optimized conditions, the 4.5 nm Pd-P NPs could catalyze the conversion of 4-O-5 linkage into KA oil in 83% selectivity with a high production rate of 32.5 mmol·g?1Pd·min?1. This study represented an original method for KA oil production.
- Bai, Hong-Cun,Cao, Jing-Pei,Jiang, Wei,Wei, Yu-Lei,Xie, Jin-Xuan,Zhang, Chuang,Zhao, Liang,Zhao, Ming,Zhao, Xiao-Yan
-
-
- Synergies of surface-interface multiple active sites over Al-Zr oxide solid solution supported nickel catalysts for enhancing the hydrodeoxygenation of anisole
-
Currently, the catalytic hydrodeoxygenation (HDO) of oxygen-containing compounds derived from biomass to highly valuable chemicals or hydrocarbon bio-fuels is attracting more and more attention. Concerning the design and synthesis of high-performance supported metal catalysts for HDO, the efficient deposition/immobilization of active metal species on supports, as well as the construction of the favorable properties of supports, is quite necessary. In this work, we fabricated series of aluminum-zirconium oxide solid solution supported Ni-based catalysts by a simple surfactant-assisted homogeneous coprecipitation and applied them in the HDO of anisole. Various structural characterizations showed that surface-interface properties of Ni-based catalysts (i.e., surface acidity, defective structures, and metal-support interactions) could be finely tuned by adjusting the amount of Al introduced into Al-Zr oxide solid solutions, thus profoundly governing their catalytic HDO activities. It was demonstrated that the introduction of an appropriate amount of Al could not only enhance surface acidity and promote the formation of defective Zr-Ov-Al structures (Ov: oxygen vacancy) but also facilitate the generation of interfacial Niδ+ species bound to the support. Over the Ni-based catalyst bearing an Al2O3:ZrO2 mass ratio of 5:2, a high cyclohexane yield of ~77.4% was attained at 230 °C and 1.0 MPa initial hydrogen pressure. The high catalytic HDO efficiency was revealed to be correlated with the catalytic synergy between Ni0 and adjacent interfacial Niδ+ species, together with the promotion of neighboring defective oxygen vacancies and acidic sites, which contributed to the enhanced activation of the methoxy group in anisole and reaction intermediate and thus greatly improved HDO activity. The present findings offer a new and promising guidance for constructing high-performance metal-based catalysts via a rational surface-interface engineering.
- Fan, Guoli,Li, Feng,Lin, Yanjun,Yang, Lan,Zhang, Yaowen
-
-
- An efficient method for the catalytic aerobic oxidation of cycloalkanes using 3,4,5,6-Tetrafluoro-N-Hydroxyphthalimide (F4-NHPI)
-
N-Hydroxyphthalimide (NHPI) is known to be an effective catalyst for the oxidation of hydrocarbons. The catalytic activity of NHPI derivatives is generally increased by introducing an electron-withdrawing group on the benzene ring. In a previous report, two NHPI derivatives containing fluorinated alkyl chain were prepared and their catalytic activity was investigated in the oxidation of cycloalkanes. It was found that the fluorinated NHPI derivatives showed better yields for the oxidation reaction. As a continuation of our work with fluorinated NHPI derivatives, our next aim was to investigate the catalytic activity of the NHPI derivatives by introducing fluorine atoms in the benzene ring of NHPI. In the present research, 3,4,5,6-Tetrafluoro-N-Hydroxyphthalimide (F4-NHPI) is prepared and its catalytic activity has been investigated in the oxidation of two different cycloalkanes for the first time. It has been found that F4-NHPI showed higher catalytic efficiency compared with that of the parent NHPI catalyst in the present reactions. The presence of a fluorinated solvent and an additive was also found to accelerate the oxidation.
- Guha, Samar K.,Ishii, Yasutaka
-
p. 327 - 335
(2021/12/13)
-
- Selective hydrogenation of substituted styrene to alkylbenzene catalyzed by Al2O3 nanoparticles
-
A straightforward and suitable protocol is described for the conversion of substituted styrene to alkylbenzenes in the presence of Al2O3 nanoparticles (nano-Al2O3) as heterogeneous solid catalysts using N2H4·H2O as a hydrogen source under mild reaction conditions. A complete conversion of styrene is obtained using nano-Al2O3 as a heterogeneous catalyst. Besides, this catalyst system is also successfully applied to promote the broad range of styrene substituted derivatives to their respective alkylbenzene compounds in moderate to higher conversions. The reaction is discovered to be heterogeneous in nature and nano-Al2O3 can be reused for three runs with no diminish in its performance. Besides, the analyses of the fresh and three times reused nano-Al2O3 solid by various analytical techniques. Transmission electron microscope indicates that the structural features, surface morphology, and particle size endure unchanged throughout the reaction. Some of the significant features of this procedure are mild reaction conditions, price effectiveness of the catalyst (Pd or Pt free catalyst), high conversion, functional group endurance, absence of noble metals/additives, and reusability of the catalyst. The scope of the reaction procedure can be extended to various linear and cyclic alkenes. Graphical abstract: [Figure not available: see fulltext.]
- Kaleeswari, Kalairajan,Tamil Selvi, Arunachalam
-
-
- MOF-derived Ru@ZIF-8 catalyst with the extremely low metal Ru loading for selective hydrogenolysis of C–O bonds in lignin model compounds under mild conditions
-
Lignin hydrogenolysis to produce chemicals and biofuels is a challenge due to the stable C–O ether bond structure. Metal–organic framework (MOF) materials with excellent structural and chemical versatility have received widespread attention. Herein, a highly dispersed Ru metal anchored in functionalised ZIF-8 was fabricated by a general host–guest and reduction strategy. The Ru@ZIF-8 catalyst with a high specific surface area could efficiently promote the C–O bond cleavage of a variety of lignin model compounds under mild conditions. Compared with previous studies, the extremely low metal Ru loading in the Ru@ZIF-8 catalyst achieved a relatively higher activity. The introduction of Ru metal not only improved the dispersion of Zn metal, but also enhanced the electron density on the Zn surface, suggesting a high catalytic performance. It was more conducive for the Ru@ZIF-8 catalyst to exhibit the C–O bond cleavage activity when in the presence of both H2 and isopropanol. An investigation of the mechanism revealed that the direct hydrogenolysis of benzyl phenyl ether was the main reaction pathway.
- Cao, Jing-Pei,Jiang, Wei,Xie, Jin-Xuan,Zhang, Chuang,Zhang, Jian-Li,Zhao, Liang,Zhao, Xiao-Yan,Zhao, Yun-Peng,Zhu, Chen
-
p. 488 - 496
(2022/02/07)
-
- Highly Selective Hydrodeoxygenation of Lignin to Naphthenes over Three-Dimensional Flower-like Ni2P Derived from Hydrotalcite
-
A strategy for low-temperature synthesis of hydrotalcite-based nickel phosphide catalysts (Ni2P-Al2O3) with flower-like porous structures was proposed. The in situ reduction of red phosphorus at 500 °C enables Ni2P catalysts with small particle size and abundant active and acidic sites, which facilitate the activation of substrates and H2. In the hydrodeoxygenation of guaiacol, a 100% conversion and 94.5% yield of cyclohexane were obtained over the Ni2P-Al2O3 catalyst under 5 MPa H2 at 250 °C for 3 h. Other lignin-derived phenolic compounds could also afford the corresponding alkanes with yields higher than 85%. Moreover, Ni2P-Al2O3 exhibited high hydrodeoxygenation activity in the deconstruction of more complex wood structures, including lignin oil and real lignin. Among the two different types of Ni sites of Ni(1) and Ni(2) in Ni2P, density functional theory (DFT) calculations showed that the Ni(2) site, highly exposed on the Ni2P-Al2O3 surface, possesses a stronger ability to break C-OH bonds during the hydrodeoxygenation of guaiacol in comparison with the Ni(1) site.
- Chen, Guanyi,Diao, Xinyong,Ji, Na,Jia, Zhichao,Li, Changzhi,Li, Xinxin,Liu, Caixia,Liu, Qingling,Lu, Xuebin,Ma, Longlong,Song, Chunfeng,Wang, Shurong,Zhao, Yujun
-
p. 1338 - 1356
(2022/02/07)
-
- Fabricating nickel phyllosilicate-like nanosheets to prepare a defect-rich catalyst for the one-pot conversion of lignin into hydrocarbons under mild conditions
-
The one-pot conversion of lignin biomass into high-grade hydrocarbon biofuels via catalytic hydrodeoxygenation (HDO) holds significant promise for renewable energy. A great challenge for this route involves developing efficient non-noble metal catalysts to obtain a high yield of hydrocarbons under relatively mild conditions. Herein, a high-performance catalyst has been prepared via the in situ reduction of Ni phyllosilicate-like nanosheets (Ni-PS) synthesized by a reduction-oxidation strategy at room temperature. The Ni-PS precursors are partly converted into Ni0 nanoparticles by in situ reduction and the rest remain as supports. The Si-containing supports are found to have strong interactions with the nickel species, hindering the aggregation of Ni0 particles and minimizing the Ni0 particle size. The catalyst contains abundant surface defects, weak Lewis acid sites and highly dispersed Ni0 particles. The catalyst exhibits excellent catalytic activity towards the depolymerization and HDO of the lignin model compound, 2-phenylethyl phenyl ether (PPE), and the enzymatic hydrolysis of lignin under mild conditions, with 98.3% cycloalkane yield for the HDO of PPE under 3 MPa H2 pressure at 160 °C and 40.4% hydrocarbon yield for that of lignin under 3 MPa H2 pressure at 240 °C, and its catalytic activity can compete with reported noble metal catalysts.
- Cao, Meifang,Chen, Bo,He, Chengzhi,Ouyang, Xinping,Qian, Yong,Qiu, Xueqing
-
supporting information
p. 846 - 857
(2022/02/09)
-
- Titania-supported molybdenum oxide combined with Au nanoparticles as a hydrogen-driven deoxydehydration catalyst of diol compounds
-
A heterogenous catalyst for the deoxydehydration (DODH) reaction was developed using less expensive Mo than Re as the active center. The combination of Mo with anatase-rich TiO2 and Au as the support and promoter for H2 activation, respectively, can selectively convert 1,4-anhydroerythritol to 2,5-dihydrofuran, which is a typical DODH model reaction, with H2 as a reducing agent. Loading of Au on TiO2 by the deposition-precipitation method gave the more active MoOx-Au/TiO2 catalyst (MoOx-dpAu/TiO2) than that obtained by the impregnation method (MoOx-impAu/TiO2), and the activity difference is derived from the smaller size of Au particles in MoOx-dpAu/TiO2 (3-5 nm) than that in MoOx-impAu/TiO2 (>25 nm). The MoOx-dpAu/TiO2 catalyst could be applied to the DODH reaction of linear alkyl vicinal diols and cis-1,2-cyclohexanediol. The characterization with XRD, STEM, H2-TPR, XAFS and XPS revealed that the MoIV oxide cluster species on the surface of anatase TiO2 particles are responsible for the DODH reaction.
- Cao, Ji,Gan, Jianxing,Hacatrjan, Schanth,Liu, Lujie,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi,Yabushita, Mizuho
-
p. 2146 - 2161
(2022/04/28)
-
- Rh-PVP Catalyzed Reductive Amination of Phenols by Ammonia or Amines to Cyclohexylamines under Solvent-free Conditions
-
Colloidal metal nanoparticles were examined for reductive amination of phenol by ammonia under mild reaction conditions. The results showed that Rh-PVP was the most active catalyst for reductive amination reaction. Linear, cyclic, and amino alcohols were used as nucleophiles and converted to primary/secondary/tertiary amines. Using this strategy, the synthesis of an industrially important chemical, N-cyclohexyl- 2-pyrrolidone was explored.
- Chaudhari, Chandan,Nagaoka, Katsutoshi,Nishida, Yoshihide,Rumi, Saeki,Sato, Katsutoshi,Shiraishi, Masaya
-
supporting information
p. 81 - 84
(2022/01/12)
-
- Reduction of α,β-unsaturated carbonyl compounds and 1,3-diketones in aqueous media, using a raney ni-al alloy
-
The treatment of α,β-unsaturated carbonyl compounds and 1,3-diketones with Raney Ni-Al alloy in aqueous media yielded as major reaction products the corresponding saturated alcohols and/or the corresponding hydrocarbons, in a complete transformation of the starting material.
- Simion, Cristian,Mitoma, Yoshiharu,Katayama, Yumi,Simion, Alina Marieta
-
-
- Deep eutectic solvents as H2-sources for Ru(II)-catalyzed transfer hydrogenation of carbonyl compounds under mild conditions
-
The employment of easily affordable ruthenium(II)-complexes as pre-catalysts in the transfer hydrogenation of carbonyl compounds in deep eutectic media is described for the first time. The eutectic mixture tetrabutylammonium bromide/formic acid = 1/1 (TBABr/HCOOH = 1/1) acts both as reaction medium and hydrogen source. The addition of a base is required for the process to occur. An extensive optimization of the reaction conditions has been carried out, in terms of catalyst loading, type of complexes, H2-donors, reaction temperature and time. The combination of the dimeric complex [RuCl(p-cymene)-μ-Cl]2 (0.01–0.05 eq.) and the ligand dppf (1,1′-ferrocenediyl-bis(diphenylphosphine)ferrocene) in 1/1 molar ratio has proven to be a suitable catalytic system for the reduction of several and diverse aldehydes and ketones to their corresponding alcohols under mild conditions (40–60 °C) in air, showing from moderate to excellent tolerability towards different functional groups (halogen, cyano, nitro, phenol). The reduction of imine compounds to their corresponding amine derivatives was also studied. In addition, the comparison between the results obtained in TBABr/HCOOH and in organic solvents suggests a non-innocent effect of the DES medium during the process.
- Cavallo, Marzia,Arnodo, Davide,Mannu, Alberto,Blangetti, Marco,Prandi, Cristina,Baratta, Walter,Baldino, Salvatore
-
supporting information
(2021/02/22)
-
- Manganese-Catalyzed Hydrogenation of Ketones under Mild and Base-free Conditions
-
In this paper, several Mn(I) complexes were applied as catalysts for the homogeneous hydrogenation of ketones. The most active precatalyst is the bench-stable alkyl bisphosphine Mn(I) complex fac-[Mn(dippe) (CO)3(CH2CH2CH3)]. The reaction proceeds at room temperature under base-free conditions with a catalyst loading of 3 mol % and a hydrogen pressure of 10 bar. A temperature-dependent selectivity for the reduction of α,β-unsaturated carbonyls was observed. At room temperature, the carbonyl group was selectively hydrogenated, while the C=C bond stayed intact. At 60 °C, fully saturated systems were obtained. A plausible mechanism based on DFT calculations which involves an inner-sphere hydride transfer is proposed.
- Brünig, Julian,Kirchner, Karl,Veiros, Luis F.,Weber, Stefan
-
supporting information
p. 1388 - 1394
(2021/05/31)
-
- MATERIALS COMPRISING CARBON-EMBEDDED COBALT NANOPARTICLES, PROCESSES FOR THEIR MANUFACTURE, AND USE AS HETEROGENEOUS CATALYSTS
-
The present invention relates to catalytically active material, comprising grains of non-graphitizing carbon with cobalt nanoparticles dispersed therein, wherein dP, the average diameter of cobalt nanoparticles in the non-graphitizing carbon grains, is in the range of 1 nm to 20 nm, D, the average distance between cobalt nanoparticles in the non-graphitizing carbon grains, is in the range of 2 nm to 150 nm, and ω, the combined total mass fraction of metal in the non-graphitizing carbon grains, is in the range of 30 wt% to 70 wt% of the total mass of the non-graphitizing carbon grains, and wherein dP, D and ω conform to the following relation: 4.5 dP / ω > D ≥ 0.25 dP / ω. The present invention, further, relates to a process for the manufacture of material according to the invention, as well as its use as a catalyst.
- -
-
Page/Page column 17; 19-20
(2021/03/13)
-
- Bimetallic RuPd nanoparticles in ionic liquids: Selective catalysts for the hydrogenation of aromatic compounds
-
Bimetallic RuPd nanoparticles (NPs) immobilized in ionic liquids (ILs) were shown to be a highly active medium for the selective hydrogenation of benzene and phenol under mild conditions (4 bar H2, 60 °C) in a biphasic system (n-heptane/IL). The equimolar combination of Ru and Pd into a bimetallic particle generated a synergistic catalyst that allowed the selective production of cyclohexane (>99% selectivity, 94% conversion) and cyclohexanol (99% selectivity, >98% conversion) from the reduction of benzene and phenol, respectively. Moreover, the catalytic results revealed that the activity and selectivity are dependent on the Ru?:?Pd ratio into the bimetallic NPs.
- Abarca, Gabriel,Goncalves, Wellington D. G.,Albuquerque, Brunno L.,Dupont, Jairton,Prechtl, Martin H. G.,Scholten, Jackson D.
-
supporting information
p. 98 - 103
(2021/01/11)
-
- Tunable selectivity of phenol hydrogenation to cyclohexane or cyclohexanol by a solvent-driven effect over a bifunctional Pd/NaY catalyst
-
Hydrogenation of phenol is an important strategy to produce cyclohexane or cyclohexanol as both of them are raw materials for the synthesis of nylon-6 and nylon-66. Herein, we report a novel method for the selective hydrogenation of phenol to cyclohexane or cyclohexanol over a bifunctional Pd/NaY catalyst by regulating the solvent polarity. It was found that solvent polarity has a strong influence on the hydrogenation reaction mechanism. Under the identical conditions, 100% selectivity to cyclohexane could be obtained when reacting inn-octane (nonpolar solvent), while 92.3% selectivity to cyclohexanol was achieved in EtOH (polar solvent). The polarity of the solvent not only affects the competitive adsorption capacity but also the adsorption manner of phenol over the acid sites and the Pd nanoparticles in the Pd/NaY catalyst. DFT calculations show that different solvents have an almost negligible effect on the reaction energy barriers but highly affect the hydration reaction of cyclohexanol if the trace amount of water formed could not be timely removed from the catalytic system. This solvent-driven catalysis exhibits good recyclability, showing great promise for industrial applications. These findings not only provide new insights into the hydrogenation mechanism of phenolics, but also might help to develop facile strategies for the selective conversion of other phenolics into desired products.
- Xia, Heng,Tan, Hongzi,Cui, Hongyou,Song, Feng,Zhang, Yuan,Zhao, Rongrong,Chen, Zhe-Ning,Yi, Weiming,Li, Zhihe
-
p. 1881 - 1887
(2021/03/29)
-
- Pt and Ru Catalysts Based on Porous Aromatic Frameworks for Hydrogenation of Lignin Biofuel Components
-
Abstract: A platinum catalyst and a ruthenium catalyst were synthesized from a porousaromatic framework, namely PAF-30. The catalyst properties were examined inhydrogenation of phenol and guaiacol at 80–250°C and at a hydrogen pressure of30 atm in the presence of various solvents. Significant effects of the reactionmedium, process conditions, and catalyst morphology on the reaction mechanismwere demonstrated. Reaction conditions optimal for complete conversion of phenoland guaiacol to hydrogenation products were selected for both catalysts. [Figure not available: see fulltext.]
- Cherednichenko, K. A.,Kalinina, M. A.,Karakhanov, E. A.,Kulikov, L. A.,Makeeva, D. A.,Maximov, A. L.
-
p. 711 - 720
(2021/08/03)
-
- Hydroboration of Nitriles, Esters, and Carbonates Catalyzed by Simple Earth-Abundant Metal Triflate Salts
-
During the past decade earth-abundant metals have become increasingly important in homogeneous catalysis. One of the reactions in which earth-abundant metals have found important applications is the hydroboration of unsaturated C?C and C?X bonds (X=O or N). Within these set of transformations, the hydroboration of challenging substrates such as nitriles, carbonates and esters still remain difficult and often relies on elaborate ligand designs and highly reactive catalysts (e. g., metal alkyls/hydrides). Here we report an effective methodology for the hydroboration of challenging C≡N and C=O bonds that is simple and applicable to a wide set of substrates. The methodology is based on using a manganese(II) triflate salt that, in combination with commercially available potassium tert-butoxide and pinacolborane, catalyzes the hydroboration of nitriles, carbonates, and esters at room temperature and with near quantitative yields in less than three hours. Additional studies demonstrated that other earth-abundant metal triflate salts can facilitate this reaction as well, which is further discussed in this report.
- Thenarukandiyil, Ranjeesh,Satheesh, Vanaparthi,Shimon, Linda J. W.,de Ruiter, Graham
-
p. 999 - 1006
(2021/03/30)
-
- Honeycomb-structured solid acid catalysts fabricated via the swelling-induced self-assembly of acidic poly(ionic liquid)s for highly efficient hydrolysis reactions
-
The development of heterogeneous acid catalysts with higher activity than homogeneous acid catalysts is critical and still challenging. In this study, acidic poly(ionic liquid)s with swelling ability (SAPILs) were designed and synthesized via the free radical copolymerization of ionic liquid monomers, sodium p-styrenesulfonate, and crosslinkers, followed by acidification. The 31P nuclear magnetic resonance chemical shifts of adsorbed trimethylphosphine oxide indicated that the synthesized SAPILs presented moderate and single acid strength. The thermogravimetric analysis results in the temperature range of 300–345 °C revealed that the synthesized SAPILs were more stable than the commercial resin Amberlite IR-120(H) (245 °C). Cryogenic scanning electron microscopy testing demonstrated that SAPILs presented unique three-dimensional (3D) honeycomb structure in water, which was ascribed to the swelling-induced self-assembly of the molecules. Moreover, we used SAPILs with micron-sized honeycomb structure in water as catalysts for the hydrolysis of cyclohexyl acetate to cyclohexanol, and determined that their catalytic activity was much higher than that of homogeneous acid catalysts. The equilibrium concentrations of all reaction components inside and outside the synthesized SAPILs were quantitatively analyzed using a series of simulated reaction mixtures. Depending on the reaction mixture, the concentration of cyclohexyl acetate inside SAPIL-1 was 7.5–23.3 times higher than that outside of it, which suggested the high enrichment ability of SAPILs for cyclohexyl acetate. The excellent catalytic performance of SAPILs was attributed to their 3D honeycomb structure in water and high enrichment ability for cyclohexyl acetate, which opened up new avenues for designing highly efficient heterogeneous acid catalysts that could eventually replace conventional homogeneous acid catalysts.
- Chen, Bihua,Deng, Xi,Ding, Tong,Gao, Guohua,Ma, Sanguan,Ni, Bing,Wang, Xin,Zhang, Dawei,Zhang, Yongya
-
p. 297 - 309
(2020/07/25)
-
- Facile Peroxidation of Cyclohexane Catalysed by In Situ Generated Triazole-Functionalised Schiff Base Copper Complexes
-
A set of facile room temperature catalytic systems for the oxidation of cyclohexane C–H bonds was developed from in situ generated triazole-functionalised Schiff base copper complexes. The combination of a new triazolium-functionalised Schiff base, [(E)-3-methyl-1-propyl-4-(2-(((2-(pyridin-2-yl)ethyl)imino)methyl)phenyl)-1H-1,2,3-triazol-3-ium hexafluorophosphate(V), 2] with a range of bench-top Cu(I) and Cu(II) salts (Cu2O, CuO, Cu(CH3CN)4PF6, CuSO4·5H2O, Cu2(OAc)4·2H2O, CuCl2, Cu(NO3)2·3H2O) as catalysts were screened under varying reaction conditions for the peroxidation of cyclohexane using hydrogen peroxide as a green source of oxygen. High conversions to oxidised products were obtained with up to 80% in 6?h for the 2/CuSO4·5H2O system at 1?mol% catalyst concentration under optimised reaction conditions. All the copper salts yielded the ketone–alcohol (K–A) oil containing varying ratios of cyclohexanol and cyclohexanone. The results also showed that at room temperature, the various in situ generated copper catalysts exclusively yielded only the K–A oil. Furthermore, by changing the reaction temperature to reflux in acetonitrile and depending on the starting substrate (cyclohexane, cyclohexanol or cyclohexanone), 23–100% of adipic acid was also obtained. The kinetics study for the peroxidation reaction reveals activation energy of 12.29 ± 2?kJ/mol following a copper initiated radical mechanism. Graphic Abstract: [Figure not available: see fulltext.]
- Bala, Muhammad D.,Ibrahim, Halliru,Lawal, Nasir S.
-
-
- Efficient oxidation of cycloalkanes with simultaneously increased conversion and selectivity using O2 catalyzed by metalloporphyrins and boosted by Zn(AcO)2: A practical strategy to inhibit the formation of aliphatic diacids
-
The direct sources of aliphatic acids in cycloalkanes oxidation were investigated, and a strategy to suppress the formation of aliphatic acids was adopted through enhancing the catalytic transformation of oxidation intermediates cycloalkyl hydroperoxides to cycloalkanols by Zn(II) and delaying the emergence of cycloalkanones. Benefitted from the delayed formation of cycloalkanones and suppressed non-selective thermal decomposition of cycloalkyl hydroperoxides, the conversion of cycloalkanes and selectivity towards cycloalkanols and cycloalkanones were increased simultaneously with satisfying tolerance to both of metalloporphyrins and substrates. For cyclohexane, the selectivity towards KA-oil was increased from 80.1% to 96.9% meanwhile the conversion was increased from 3.83 % to 6.53 %, a very competitive conversion level with higher selectivity compared with current industrial process. This protocol is not only a valuable strategy to overcome the problems of low conversion and low selectivity lying in front of current cyclohexane oxidation in industry, but also an important reference to other alkanes oxidation.
- Shen, Hai-Min,Wang, Xiong,Ning, Lei,Guo, A-Bing,Deng, Jin-Hui,She, Yuan-Bin
-
-
- Tailoring the electron density of cobalt oxide clusters to provide highly selective superoxide and peroxide species for aerobic cyclohexane oxidation
-
The catalytic aerobic cyclohexane oxidation to cyclohexanol and cyclohexanone (KA oil) is an industrially relevant reaction. This work is focused on the synthesis of tailor-made catalysts based on the well-known Co4O4 core in order to successfully deal with cyclohexane oxidation reaction. The catalytic activity and selectivity of the synthesized catalysts can be correlated with the electronic density of the cluster, modulated by changing the organic ligands. This is not trivial in cyclohexane oxidation. Furthermore, the reaction mechanism is discussed on the basis of kinetics and spin trapping experiments, confirming that the electronic density of the catalyst has a clear influence on the distribution of the reaction products. In addition, in situ Raman spectroscopy was used to characterize the oxygen species formed on the cobalt cluster during the oxidation reaction. Altogether, it can be concluded that the catalyst with the highest oxidation potential promotes the formation of peroxide and superoxide species, which is the best way to oxidize inactivated CH bonds in alkanes. Finally, based on the results of the mechanistic studies, the contribution of these cobalt oxide clusters in each single reaction step of the whole process has been proposed.
- Gaona-Miguélez, José,Gutiérrez-Tarri?o, Silvia,O?a-Burgos, Pascual
-
supporting information
p. 15370 - 15379
(2021/11/17)
-
- Enthalpy-Entropy Compensation Effect in Oxidation Reactions by Manganese(IV)-Oxo Porphyrins and Nonheme Iron(IV)-Oxo Models
-
"Enthalpy-Entropy Compensation Effect"(EECE) is ubiquitous in chemical reactions; however, such an EECE has been rarely explored in biomimetic oxidation reactions. In this study, six manganese(IV)-oxo complexes bearing electron-rich and -deficient porphyrins are synthesized and investigated in various oxidation reactions, such as hydrogen atom transfer (HAT), oxygen atom transfer (OAT), and electron-transfer (ET) reactions. First, all of the six Mn(IV)-oxo porphyrins are highly reactive in the HAT, OAT, and ET reactions. Interestingly, we have observed a reversed reactivity in the HAT and OAT reactions by the electron-rich and -deficient Mn(IV)-oxo porphyrins, depending on reaction temperatures, but not in the ET reactions; the electron-rich Mn(IV)-oxo porphyrins are more reactive than the electron-deficient Mn(IV)-oxo porphyrins at high temperature (e.g., 0 °C), whereas at low temperature (e.g., -60 °C), the electron-deficient Mn(IV)-oxo porphyrins are more reactive than the electron-rich Mn(IV)-oxo porphyrins. Such a reversed reactivity between the electron-rich and -deficient Mn(IV)-oxo porphyrins depending on reaction temperatures is rationalized with EECE; that is, the lower is the activation enthalpy, the more negative is the activation entropy, and vice versa. Interestingly, a unified linear correlation between the activation enthalpies and the activation entropies is observed in the HAT and OAT reactions of the Mn(IV)-oxo porphyrins. Moreover, from the previously reported HAT reactions of nonheme Fe(IV)-oxo complexes, a linear correlation between the activation enthalpies and the activation entropies is also observed. To the best of our knowledge, we report the first detailed mechanistic study of EECE in the oxidation reactions by synthetic high-valent metal-oxo complexes.
- Guo, Mian,Zhang, Jisheng,Zhang, Lina,Lee, Yong-Min,Fukuzumi, Shunichi,Nam, Wonwoo
-
supporting information
p. 18559 - 18570
(2021/11/22)
-
- Direct synthesis of a high-density aviation fuel using a polycarbonate
-
High-density cyclic hydrocarbons were first synthesized with high carbon yields by a one-pot transfer hydrodeoxygenation of a polycarbonate (PC) using isopropanol as the solvent and hydrogen donor at the same time. RANEY nickel was found to be an effective catalyst for the conversion of the PC in isopropanol. Over it, the pure PC pellet was completely converted to a mixture of C6-C15oxygenates, aromatics and cycloalkanes after the reaction was carried out at 463 K for 1 h. The catalytic performance of RANEY Ni was further improved after the introduction of solid acids as co-catalysts. Among the investigated solid acids, ultrastable Y (USY), a commercial acidic zeolite, demonstrated the best promotion effect, which can be explained by its larger pore size and suitable acidity. Under the optimized conditions, an ~75% carbon yield of C6-C15cyclic hydrocarbons was achieved from the one-pot transfer hydrodeoxygenation of a chopped DVD disk under the co-catalysis of RANEY Ni and USY. According to our measurement, the C6-C15cyclic hydrocarbon mixture as obtained has a high density (0.94 g mL?1), good volumetric net heat of combustion (NHOC) (41.5 MJ L?1) and low freezing point (202 K-188 K). In real applications, it can be used as a potential substitute for currently used high-density aviation fuels.
- Wang, Lulin,Han, Fengan,Li, Guangyi,Zheng, Min,Wang, Aiqin,Wang, Xiaodong,Zhang, Tao,Cong, Yu,Li, Ning
-
supporting information
p. 912 - 919
(2021/02/09)
-
- Aromatic compound hydrogenation and hydrodeoxygenation method and application thereof
-
The invention belongs to the technical field of medicines, and discloses an aromatic compound hydrogenation and hydrodeoxygenation method under mild conditions and application of the method in hydrogenation and hydrodeoxygenation reactions of the aromatic compounds and related mixtures. Specifically, the method comprises the following steps: contacting the aromatic compound or a mixture containing the aromatic compound with a catalyst and hydrogen with proper pressure in a solvent under a proper temperature condition, and reacting the hydrogen, the solvent and the aromatic compound under the action of the catalyst to obtain a corresponding hydrogenation product or/and a hydrodeoxygenation product without an oxygen-containing substituent group. The invention also discloses specific implementation conditions of the method and an aromatic compound structure type applicable to the method. The hydrogenation and hydrodeoxygenation reaction method used in the invention has the advantages of mild reaction conditions, high hydrodeoxygenation efficiency, wide substrate applicability, convenient post-treatment, and good laboratory and industrial application prospects.
- -
-
Paragraph 0094-0097; 0100-0104
(2021/05/29)
-
- Improved Hydrodeoxygenation of Phenol to Cyclohexane on NiFe Alloy Catalysts Derived from Phyllosilicates
-
A phyllosilicate-derived NiFe/SiO2 catalyst (NiFe/SiO2?AE) was successfully prepared by the ammonia evaporation method and applied in the hydrodeoxygenation of phenol to cyclohexane. Another two catalysts were also prepared for a comparison by impregnation (NiFe/SiO2?IM) and deposition-precipitation (NiFe/SiO2?DP) methods, respectively. It was found that Ni?Fe alloy, the active sites for the hydrogenolysis of C?O bond, can be obtained by the reduction of NiFe2O4 (IM) or phyllosilicate (DP and AE) by H2. The AE strategy can generate more phyllosilicate structure, which improves the dispersion of both Ni?Fe alloy and metallic Ni sites and allows the formation of more interface between these two kinds of sites as well. Therefore, the NiFe/SiO2?AE exhibits a significantly high catalytic performance in the HDO of phenol to cyclohexane. Moreover, the turnover frequency of Ni?Fe alloy sites over NiFe/SiO2?AE catalysts is much higher than those of other two catalysts. It is suggested that the enhanced synergy between the two kinds of active sites in the adsorption of C?O groups and hydrogen molecules ensures the superior intrinsic activity in HDO process.
- Han, Qiao,Wang, Hui,Rehman, Mooeez Ur,Shang, Xin,Chen, Haijun,Ji, Na,Tong, Xinli,Shi, Hui,Zhao, Yujun
-
supporting information
p. 5069 - 5076
(2021/12/14)
-
- The green and sustainable synthesis of nanometer ZSM-5 without organotemplates via utilizing the recycled mother liquid
-
The development of green and sustainable techniques for synthesizing classes of significant industrial materials, like zeolites, has been recognized as an inevitable trend in recent years. Herein, an efficient and environmentally friendly route was exploited for the synthesis of nanometer ZSM-5 zeolites with recycled mother liquid and seed-assistance. Physical characterization and component analysis revealed that the unutilized species in the raw materials remain in a stable concentration range during the nine recycling experiments, and these recyclable species were successfully applied for the preparation of ZSM-5 zeolites as part of the raw materials. It is noticed that the particle size of the ZSM-5 aggregates (~0.3-0.5 μm) synthesized from the recycled mother liquid sharply decreases compared to that using fresh catalyst (~1.1-1.4 μm), which is attributed to the synergetic effect of the self-made S-1 seeds and the primary structural units with memory effects in the mother liquid, which is helpful for promoting the formation of small-sized particles. Furthermore, the as-obtained samples possess almost the same catalytic performance in cyclohexene hydration as fresh catalyst, even though the mother liquid was recycled nine times. These satisfactory results indicate that this cycled synthesis process effectively utilized the ingredients in the mother liquid and avoided waste liquid discharge to achieve clean and efficient synthesis. Additionally, the green process opens a pathway to sustainable zeolite preparation in industry compared to conventional methods.
- Zong, Lukuan,Xu, Hongxia,Wang, Xiangyu,Wei, Huijuan
-
p. 8582 - 8590
(2021/05/26)
-
- Tandem hydroformylation/hydrogenation over novel immobilized Rh-containing catalysts based on tertiary amine-functionalized hybrid inorganic-organic materials
-
Non-phosphorous rhodium-containing catalysts for direct conversion of olefins to alcohols via tandem hydroformylation/hydrogenation have been designed and synthesized. Interaction between Rh(acac)(CO)2 and tertiary amino groups on the surface of mesoporous hybrid organic-inorganic supports yielded materials which were successfully used in the tandem process. Data obtained for a selected catalyst KN demonstrate that rhodium is in the Rh+1 state highly dispersed on the surface and is bonded with nitrogen atoms both before and after use. Evaluation of the catalytic performance shows high activity (hydroformylation TOF 312 h?1), chemoselectivity and stable hydroformylation yield at least in the first 5 cycles with a decrease in alcohol selectivity. The influence of temperature, reaction time, total pressure, and molar CO/H2 ratio of syngas on oxygenate yields is described. Type of the hydroformylation active sites and possible pathways for the observed decrease in hydrogenation are discussed.
- Gorbunov, Dmitry,Karakhanov, Eduard,Maximov, Anton,Naranov, Evgeny,Nenasheva, Maria,Rosenberg, Edward
-
-
- Hydroxycarbonylation of alkenes with formic acid using a rhodium iodide complex and alkyl ammonium iodide
-
Hydroxycarbonylation of alkenes using formic acid (HCOOH) is ideal for the synthesis of various carboxylic acids as a means to develop a sustainable reaction system with lower environmental impact. In this study, we developed a new catalytic system for hydroxycarbonylation of alkenes with HCOOH using a Vaska-type Rh complex with an iodide ligand, RhI(CO)(PPh3)2(1), as the catalyst, and a quaternary ammonium iodide salt as the promoter for the catalyst. In comparison with similar reaction systems using Rh catalysts, our reaction system is safer and more environmentally friendly since it does not require high-pressure conditions, explosive gases, or environmentally unfriendly CH3I and extra PPh3promoters. In addition, we also experimentally clarified that the catalytic reaction proceedsviaRhHI2(CO)(PPh3)2(2), which is formed by the reaction of1with a quaternary ammonium iodide salt andp-TsOH. Furthermore, the Rh(iii) complex2can catalyze hydroxycarbonylation of alkenes with HCOOH without any promoters.
- Okada, Masaki,Takeuchi, Katsuhiko,Matsumoto, Kazuhiro,Oku, Tomoharu,Choi, Jun-Chul
-
supporting information
p. 8727 - 8734
(2021/10/22)
-
- Hydrogen-Catalyzed Acid Transformation for the Hydration of Alkenes and Epoxy Alkanes over Co-N Frustrated Lewis Pair Surfaces
-
Hydrogen (H2) is widely used as a reductant for many hydrogenation reactions; however, it has not been recognized as a catalyst for the acid transformation of active sites on solid surface. Here, we report the H2-promoted hydration of alkenes (such as styrenes and cyclic alkenes) and epoxy alkanes over single-atom Co-dispersed nitrogen-doped carbon (Co-NC) via a transformation mechanism of acid-base sites. Specifically, the specific catalytic activity and selectivity of Co-NC are superior to those of classical solid acids (acidic zeolites and resins) per micromole of acid, whereas the hydration catalysis does not take place under a nitrogen atmosphere. Detailed investigations indicate that H2 can be heterolyzed on the Co-N bond to form Hδ-Co-N-Hδ+ and then be converted into OHδ-Co-N-Hδ+ accompanied by H2 generation via a H2O-mediated path, which significantly reduces the activation energy for hydration reactions. This work not only provides a novel catalytic method for hydration reactions but also removes the conceptual barriers between hydrogenation and acid catalysis.
- Deng, Qiang,Deng, Shuguang,Gao, Ruijie,Li, Xiang,Tsang, Shik Chi Edman,Wang, Jun,Zeng, Zheling,Zou, Ji-Jun
-
p. 21294 - 21301
(2021/12/17)
-
- Chemoselective and Site-Selective Reductions Catalyzed by a Supramolecular Host and a Pyridine-Borane Cofactor
-
Supramolecular catalysts emulate the mechanism of enzymes to achieve large rate accelerations and precise selectivity under mild and aqueous conditions. While significant strides have been made in the supramolecular host-promoted synthesis of small molecules, applications of this reactivity to chemoselective and site-selective modification of complex biomolecules remain virtually unexplored. We report here a supramolecular system where coencapsulation of pyridine-borane with a variety of molecules including enones, ketones, aldehydes, oximes, hydrazones, and imines effects efficient reductions under basic aqueous conditions. Upon subjecting unprotected lysine to the host-mediated reductive amination conditions, we observed excellent ?-selectivity, indicating that differential guest binding within the same molecule is possible without sacrificing reactivity. Inspired by the post-translational modification of complex biomolecules by enzymatic systems, we then applied this supramolecular reaction to the site-selective labeling of a single lysine residue in an 11-amino acid peptide chain and human insulin.
- Morimoto, Mariko,Cao, Wendy,Bergman, Robert G.,Raymond, Kenneth N.,Toste, F. Dean
-
supporting information
p. 2108 - 2114
(2021/02/06)
-
- Photocatalytic Transfer Hydrogenation in Water: Insight into Mechanism and Catalyst Speciation
-
Organometallic catalysts with strong metal-to-ligand charge-transfer (MLCT) optical transitions and reactive metal-hydride bonds provide opportunities for new excited-state reactivity. Toward this end, we have investigated photoinduced transfer hydrogenat
- Kaphan, David M.,Brereton, Kelsey R.,Klet, Rachel C.,Witzke, Ryan J.,Miller, Alexander J. M.,Mulfort, Karen L.,Delferro, Massimiliano,Tiede, David M.
-
supporting information
p. 1482 - 1491
(2021/05/29)
-
- Manganese-catalyzed homogeneous hydrogenation of ketones and conjugate reduction of α,β-unsaturated carboxylic acid derivatives: A chemoselective, robust, and phosphine-free in situ-protocol
-
We communicate a user-friendly and glove-box-free catalytic protocol for the manganese-catalyzed hydrogenation of ketones and conjugated C[dbnd]C[sbnd]bonds of esters and nitriles. The respective catalyst is readily assembled in situ from the privileged [Mn(CO)5Br] precursor and cheap 2-picolylamine. The catalytic transformations were performed in the presence of t-BuOK whereby the corresponding hydrogenation products were obtained in good to excellent yields. The described system offers a brisk and atom-efficient access to both secondary alcohols and saturated esters avoiding the use of oxygen-sensitive and expensive phosphine-based ligands.
- Topf, Christoph,Vielhaber, Thomas
-
-
- Cationic ruthenium(II)–NHC pincer complexes: Synthesis, characterisation and catalytic activity for transfer hydrogenation of ketones
-
Cationic ruthenium pincer complexes, [Ru(CNC)(CO)(PPh3)Cl]X (CNC = 2,6-bis(1-methylimidazol-2-ylidene)-pyridine, X = Cl? [1a], PF6? [1b]), [Ru(CNC)(PPh3)2Cl]X (X = Cl? [2a], PF6? [2b]) and [Ru(CNC)(PPh3)2(H)]X (X = Cl? [3a], PF6? [3b]) with triphenylphosphine, CO and halides as coligands have been synthesised and characterised by 1H, 13C, 31P NMR, mass and single-crystal X-ray crystallography. The application of Ru complexes in the transfer hydrogenation of a wide range of ketones with 2-propanol as the hydrogen source is explored. The in situ transformations observed during the synthesis help understand and suggest a plausible mechanism via the hydride complex 3b. All complexes appear to be efficient catalyst precursors for transfer hydrogenation of ketones.
- Yadav, Dibya,Misra, Shilpi,Kumar, Dheeraj,Singh, Suryabhan,Singh, Amrendra K.
-
-
- Ruthenium-p-cymene Complex Side-Wall Covalently Bonded to Carbon Nanotubes as Efficient Hybrid Transfer Hydrogenation Catalyst
-
A half-sandwich ruthenium-p-cymene organometallic complex has been immobilized at Single Walled Carbon Nanotubes (SWNT) sidewalls through a stepwise covalent chemistry protocol. The introduction of amino groups by means of diazonium-chemistry protocols leads the grafting at the outer walls of the nanotubes. This hybrid material is active in the transfer hydrogenation of ketones to yield alcohols, using as hydrogen source 2-propanol. SWNT?NH2?Ru presents a broad scope, performing the reaction under aerobic conditions and can be recycled over 9 consecutive reaction runs without losing activity or leaching ruthenium out. Comparison of the activity with related homogeneous catalysts reveals an improved performance due to the covalent bond between the metal and the material, achieving turnover frequencies as high as 192774 h?1.
- Blanco, Matías,Cembellín, Sara,Agnoli, Stefano,Alemán, José
-
p. 5156 - 5165
(2021/11/05)
-
- Synthesis of new rhodium(III) complex by benzylic C[sbnd]S bond cleavage of thioether containing NNS donor Schiff base ligand: Investigation of catalytic activity towards transfer hydrogenation of ketones
-
A new rhodium(III)-triphenylphosphine mixed ligand complex, [Rh(PPh3)(L)Cl2] (1) is synthesized by benzylic C[sbnd]S bond cleavage of L-CH2Ph ligand (where, L-CH2Ph = 2-(benzylthio)-N-(pyridin-2-ylmethylene)aniline). The complex is thoroughly characterized by several spectroscopic techniques. Geometry of the complex is confirmed by single crystal X-ray crystallography. Electronic structure, redox properties, absorption and emission properties of the complex were studied. DFT and TDDFT calculations were carried out to interpret the electronic structure and absorption properties of the complex respectively. The synthesized Rh(III) complex was tested as catalyst towards transfer hydrogenation reaction of ketones in iPrOH and an excellent catalytic conversion was observed under mild conditions.
- Biswas, Sujan,Das, Akash,Kumar Manna, Chandan,Kumar Mondal, Tapan,Naskar, Rahul
-
-
- Donor Functionalized Iron(II) N-Heterocyclic Carbene Complexes in Transfer Hydrogenation Reactions
-
Two piano-stool iron(II) complexes bearing N-heterocyclic carbene ligands outfitted with acetamide- and amine-pendant arms [Cp*Fe(NHCR)(CO)I] {Cp* = η5-tetramethylcyclopentadienyl; R = CH2CONEt2 (3), (CH2/
- Lopes, Rita,Raya-Barón, álvaro,Robalo, M. Paula,Vinagreiro, Carolina,Barroso, Sónia,Rom?o, Maria J.,Fernández, Ignacio,Pereira, Mariette M.,Royo, Beatriz
-
-
- Biomimetic ketone reduction by disulfide radical anion
-
The conversion of ribonucleosides to 2′-deoxyribonucleosides is catalyzed by ribonucleoside reductase enzymes in nature. One of the key steps in this complex radical mechanism is the reduction of the 3′-ketodeoxynucleotide by a pair of cysteine residues, providing the electrons via a disulfide radical anion (RSSR??) in the active site of the enzyme. In the present study, the bioinspired conversion of ketones to corresponding alcohols was achieved by the intermediacy of disulfide radical anion of cysteine (CysSSCys)?? in water. High concentration of cysteine and pH 10.6 are necessary for high-yielding reactions. The photoinitiated radical chain reaction includes the one-electron reduction of carbonyl moiety by disulfide radical anion, protonation of the resulting ketyl radical anion by water, and H-atom abstraction from CysSH. The (CysSSCys)?? transient species generated by ionizing radiation in aqueous solutions allowed the measurement of kinetic data with ketones by pulse radiolysis. By measuring the rate of the decay of (CysSSCys)?? at λmax = 420 nm at various concentrations of ketones, we found the rate constants of three cyclic ketones to be in the range of 104–105 M?1s?1 at ~22?C.
- Barata-Vallejo, Sebastian,Bobrowski, Krzysztof,Chatgilialoglu, Chryssostomos,Ferreri, Carla,Marciniak, Bronislaw,Skotnicki, Konrad
-
-
- Synthesis, crystal and structural characterization, Hirshfeld surface analysis and DFT calculations of three symmetrical and asymmetrical phosphonium salts
-
Three stable phosphonium salts of 1,4-butanediylebis(triphenylphosphonium) dibromide I, butane-4?bromo-1-(triphenylphosphonium) bromide II and 1,3-propanediylbis(triphenylphosphonium) tetrahydroborate III were synthesized and structurally characterized. Single crystal X-ray diffraction analysis, spectroscopic methods and thermal analysis methods were used for the characterization of titled compounds. Crystallographic data showed that compound I crystallized in the triclinic crystal system with Pī space group and compound II crystallized in the monoclinic crystal system with P21/c space group. The crystal packing structures of I and II were stabilized by various intermolecular interactions, especially of C–H···π contacts. The molecular Hirshfeld surface analysis and 2D fingerprint revealed that the C···H contacts have 24.3% and 18.4% contributions in the crystal packings of compounds I and II, respectively. In addition, the H···Br (28.5%) contact has a considerable contribution to the crystal architecture of compound II. Theoretical studies were performed by DFT method to investigate the structural properties of the titled compounds. The isotopic ratio of boron in tetrahydroborate anion of compound III calculated by 1H NMR spectroscopy. The isotopic ratio for 10B/11B was 19.099 / 80.900%. Reduction of some carbonyl compounds to corresponding alcohols was performed by compound III and the optimum conditions were determined.
- Delaram, Behnaz,Gholizadeh, Mostafa,Makari, Faezeh,Nokhbeh, Seyed Reza,Salimi, Alireza
-
-
- Synergistic Effect in Ir- or Pt-Doped Ru Nanoparticles: Catalytic Hydrogenation of Carbonyl Compounds under Ambient Temperature and H2Pressure
-
Poly(vinylpyrrolidone) (PVP)-stabilized Ir- or Pt-doped (10 at. ?%) Ru NPs with the average diameters of 1.3-1.5 nm (RuIr or RuPt) were prepared by a coreduction of the corresponding metal precursors. RuIr and RuPt showed remarkable activity for the hydrogenation of aromatic, cyclic, and aliphatic carbonyl compounds at 30 °C under 0.2 MPa of H2, whereas the monometallic NPs of Ru, Ir, and Pt did not show any activity under the same conditions. In particular, RuPt converted the aliphatic aldehyde and cyclohexanone to the corresponding alcohols at 30 °C under atmospheric H2 pressure. Remarkable synergistic effects were ascribed to the provision of highly active sites for H2 and enhancement of the nucleophilicity of the adsorbed hydrides.
- Ichikuni, Nobuyuki,Masuda, Shinya,Matsuda, Shotaro,Takano, Shinjiro,Tsukuda, Tatsuya
-
p. 10502 - 10507
(2021/08/31)
-
- Selective Aerobic Oxidation of Secondary C (sp3)-H Bonds with NHPI/CAN Catalytic System
-
Abstract: The direct aerobic oxidation of secondarty C(sp3)-H bonds was achieved in the presence of N-hydroxyphthalimide (NHPI) and cerium ammonium nitrate (CAN) under mild conditions. Various benzylic methylenes could be oxidized to carbonyl compounds in satisfied selectivity while saturated cyclic alkanes could be further oxidized to the corresponding lactones with the catalytic system. Remarkably, 25% of isochroman was converted to corresponding ketone with a selectivity of 96%. The reaction was initiated by hydrogen atom abstraction from NHPI by cerium and nitrates under oxygen atmosphere to form PINO radicals. 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO) addition experiments showed that the oxidation proceeded via a complex radical chain mechanism and an ion pathway. Graphic Abstract: [Figure not available: see fulltext.]
- Wang, Lingyao,Zhang, Yuanbin,Yuan, Haoran,Du, Renfeng,Yao, Jia,Li, Haoran
-
p. 1663 - 1669
(2020/10/21)
-
- Palladium Nanoparticles in Hypercrosslinked Polystyrene: Synthesis and Application in the Hydrogenation of Arenes
-
Abstract: A novel method for incorporation of palladium nanoparticles into a poroushypercrosslinked polystyrene matrix has been developed. The composite obtainedby reduction of [Pd(π-allyl)Cl]2 with hydrogen insupercritical CO2 shows high catalytic activity in thehydrogenation of benzene and can be used twelve (12) times in a row without anydecrease in conversion rate. The catalyst is also suitable for quantitativehydrogenation of toluene, tetralin and phenol. The obtained catalytic system iscompared with the palladium composite synthesized by a conventional method basedon hypercrosslinked polystyrene.
- Lyubimov,Zvinchuk,Korlyukov,Davankov,Parenago
-
-
- Passing the framework skeleton and properties of coordination materials onto organic framework materials
-
A practically applicable strategy for transforming fragile metal-organic frameworks (MOFs) into highly stable and ordered organic framework materials (OFMs) is developed by replacing the labile coordination bonds in MOFs with stable covalent bonds in OFMs, which exhibit hypothetically approximated topology, porosity and properties of the parent MOFs by merging the advantages of MOFs and porous organic materials, thus providing a general pathway for the synthesis of highly ordered OFMs with merged advantages of MOFs and organic polymers.
- Wang, Xuan,Dong, Ming-Jie,Chen, Kai,Liu, Zi-Kun,Wu, Chuan-De
-
supporting information
p. 1348 - 1351
(2021/02/22)
-
- RhNPs supported onN-functionalized mesoporous silica: effect on catalyst stabilization and catalytic activity
-
Amine and nicotinamide groups grafted on ordered mesoporous silica (OMS) were investigated as stabilizers for RhNPs used as catalysts in the hydrogenation of several substrates, including carbonyl and aryl groups. Supported RhNPs on functionalized OMS were prepared by controlled decomposition of an organometallic precursor of rhodium under dihydrogen pressure. The resulting materials were characterized thoroughly by spectroscopic and physical techniques (FTIR, TGA, BET, SEM, TEM, EDX, XPS) to confirm the formation of spherical rhodium nanoparticles with a narrow size distribution supported on the silica surface. The use of nicotinamide functionalized OMS as a support afforded small RhNPs (2.3 ± 0.3 nm), and their size and shape were maintained after the catalyzed acetophenone hydrogenation. In contrast, amine-functionalized OMS formed RhNP aggregates after the catalytic reaction. The supported RhNPs could selectively reduce alkenyl, carbonyl, aryl and heteroaryl groups and were active in the reductive amination of phenol and morpholine, using a low concentration of the precious metal (0.07-0.18 mol%).
- Pulido-Díaz, Israel T.,Serrano-Maldonado, Alejandro,López-Suárez, Carlos César,Méndez-Ocampo, Pedro A.,Portales-Martínez, Benjamín,Gutiérrez-Alejandre, Aída,Salas-Martin, Karla P.,Guerrero-Ríos, Itzel
-
p. 3289 - 3298
(2021/03/16)
-
- Catalytic transfer hydrogenation of 4-O-5 models in lignin-derived compounds to cycloalkanes over Ni-based catalysts
-
There is an urgent need to develop a selective hydrogenolysis of Caryl-O bonds in lignin to produce valued-added chemicals and fuels. Recently, hydrogen has been used in the hydrogenation reaction, which hides inevitable danger and is not economical. Therefore, isopropanol, as a hydrogen-donor solvent, is employed for aryl ether hydrogenolysis in lignin models over nickel supported on a carbon nanotube (CNT). Except for aromatic ether (4-O-5), the Ni/CNT catalyst is also found to be suitable for alkyl-aryl ether (α-O-4 and β-O-4) cleavage in control experiments. The physicochemical characterizations were carried out by means of H2-temperature-programmed reduction, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. The catalyst can be magnetically recovered and efficiently reused for five consecutive recycling tests in the transfer hydrogenation of aromatic ethers. A mechanism study indicated that the hydrogenolysis cleavage of the ether bond is the first step in the reaction process, and hydrogenation of aromatic rings is only a successive step in which phenol and benzene are intermediate states and are then further hydrogenated. Furthermore, it has been demonstrated that aryl groups play an important role in the hydrogenation of phenol in the competitive catalytic hydrogenation reaction of phenol.
- Chen, Changzhou,Liu, Peng,Xia, Haihong,Zhou, Minghao,Jiang, Jianchun
-
p. 582 - 591
(2020/12/01)
-
- Reaction of Diisobutylaluminum Borohydride, a Binary Hydride, with Selected Organic Compounds Containing Representative Functional Groups
-
The binary hydride, diisobutylaluminum borohydride [(iBu)2AlBH4], synthesized from diisobutylaluminum hydride (DIBAL) and borane dimethyl sulfide (BMS) has shown great potential in reducing a variety of organic functional groups. This unique binary hydride, (iBu)2AlBH4, is readily synthesized, versatile, and simple to use. Aldehydes, ketones, esters, and epoxides are reduced very fast to the corresponding alcohols in essentially quantitative yields. This binary hydride can reduce tertiary amides rapidly to the corresponding amines at 25 °C in an efficient manner. Furthermore, nitriles are converted into the corresponding amines in essentially quantitative yields. These reactions occur under ambient conditions and are completed in an hour or less. The reduction products are isolated through a simple acid-base extraction and without the use of column chromatography. Further investigation showed that (iBu)2AlBH4 has the potential to be a selective hydride donor as shown through a series of competitive reactions. Similarities and differences between (iBu)2AlBH4, DIBAL, and BMS are discussed.
- Amberchan, Gabriella,Snelling, Rachel A.,Moya, Enrique,Landi, Madison,Lutz, Kyle,Gatihi, Roxanne,Singaram, Bakthan
-
supporting information
p. 6207 - 6227
(2021/05/06)
-
- Tropylium-Promoted Hydroboration Reactions: Mechanistic Insights Via Experimental and Computational Studies
-
Hydroboration reaction of alkynes is one of the most synthetically powerful tools to access organoboron compounds, versatile precursors for cross-coupling chemistry. This type of reaction has traditionally been mediated by transition-metal or main group catalysts. Herein, we report a novel method using tropylium salts, typically known as organic oxidants and Lewis acids, to promote the hydroboration reaction of alkynes. A broad range of vinylboranes can be easily accessed via this metal-free protocol. Similar hydroboration reactions of alkenes and epoxides can also be efficiently catalyzed by the same tropylium catalysts. Experimental studies and DFT calculations suggested that the reaction follows an uncommon mechanistic pathway, which is triggered by the hydride abstraction of pinacolborane with tropylium ion. This is followed by a series ofin situcounterion-activated substituent exchanges to generate boron intermediates that promote the hydroboration reaction.
- Mai, Binh Khanh,Nguyen, Thanh Vinh,Ton, Nhan N. H.
-
p. 9117 - 9133
(2021/07/19)
-
- Primary Alcohols via Nickel Pentacarboxycyclopentadienyl Diamide Catalyzed Hydrosilylation of Terminal Epoxides
-
The efficient and regioselective hydrosilylation of epoxides co-catalyzed by a pentacarboxycyclopentadienyl (PCCP) diamide nickel complex and Lewis acid is reported. This method allows for the reductive opening of terminal, monosubstituted epoxides to form unbranched, primary alcohols. A range of substrates including both terminal and nonterminal epoxides are shown to work, and a mechanistic rationale is provided. This work represents the first use of a PCCP derivative as a ligand for transition-metal catalysis.
- Lambert, Tristan H.,Steiniger, Keri A.
-
p. 8013 - 8017
(2021/10/25)
-
- Hydroxylation of Unactivated C(sp3)-H Bonds with m-Chloroperbenzoic Acid Catalyzed by an Iron(III) Complex Supported by a Trianionic Planar Tetradentate Ligand
-
Hydroxylation of cyclohexane with m-chloroperbenzoic acid was examined in the presence of an iron(III) complex supported by a trianionic planar tetradentate ligand. The present reaction system shows a high turnover number of 2750 with a high product selectivity of alcohol (93%). The turnover frequency was 0.51 s-1, and the second-order rate constant (k) for the C-H bond activation of cyclohexane was 1.08 M-1 s-1, which is one of the highest values among the iron complexes in the oxidation of cyclohexane so far reported. The present catalytic system can be adapted to the hydroxylation of substrates having only primary C-H bonds such as 2,2,3,3-tetramethylbutane as well as gaseous alkanes such as butane, propane, and ethane. The involvement of an iron(III) acyl peroxido complex as the reactive species was suggested by spectroscopic measurements of the reaction solution.
- Morimoto, Yuma,Hanada, Shinichi,Kamada, Ryusuke,Fukatsu, Arisa,Sugimoto, Hideki,Itoh, Shinobu
-
supporting information
p. 7641 - 7649
(2021/02/03)
-
- Cu6- And Cu8-Cage Sil- And Germsesquioxanes: Synthetic and Structural Features, Oxidative Rearrangements, and Catalytic Activity
-
This study reports intriguing features in the self-assembly of cage copper(II) silsesquioxanes in the presence of air. Despite the wide variation of solvates used, a series of prismatic hexanuclear Cu6 cages (1-5) were assembled under mild conditions. In turn, syntheses at higher temperatures are accompanied by side reactions, leading to the oxidation of solvates (methanol, 1-butanol, and tetrahydrofuran). The oxidized solvent derivatives then specifically participate in the formation of copper silsesquioxane cages, allowing the isolation of several unusual Cu8-based (6 and 7) and Cu6-based (8) complexes. When 1,4-dioxane was applied as a reaction medium, deep rearrangements occurred (with a total elimination of silsesquioxane ligands), causing the formation of mononuclear copper(II) compounds bearing oxidized dioxane fragments (9 and 11) or a formate-driven 1D coordination polymer (10). Finally, a "directed"self-assembly of sil- and germsesquioxanes from copper acetate (or formate) resulted in the corresponding acetate (or formate) containing Cu6 cages (12 and 13) that were isolated in high yields. The structures of all of the products 1-13 were established by single-crystal X-ray diffraction, mainly based on the use of synchrotron radiation. Moreover, the catalytic activity of compounds 12 and 13 was evaluated toward the mild homogeneous oxidation of C5-C8 cycloalkanes with hydrogen peroxide to form a mixture of the corresponding cyclic alcohols and ketones.
- Astakhov, Grigorii S.,Levitsky, Mikhail M.,Zubavichus, Yan V.,Khrustalev, Victor N.,Titov, Aleksei A.,Dorovatovskii, Pavel V.,Smol'Yakov, Alexander F.,Shubina, Elena S.,Kirillova, Marina V.,Kirillov, Alexander M.,Bilyachenko, Alexey N.
-
p. 8062 - 8074
(2021/05/26)
-