- Insights into the Pyridine-Modified MOR Zeolite Catalysts for DME Carbonylation
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Pyridine-modified mordenite (MOR) zeolite catalysts have attracted great attention in recent years due to their unique shape selectivity within eight-membered ring (8-MR) side pockets for dimethyl ether (DME) carbonylation to methyl acetate (MA) and syngas conversion to ethylene. Herein, aimed at elucidating pyridine modification-carbonylation activity relationships and developing high-performance catalysts, we investigated the adsorption/desorption behaviors of pyridine on MOR zeolites with varying Si/Al ratios and their impact on DME carbonylation. Instead of the previously proposed selective adsorption of pyridine in 12-MR channels, pyridine is revealed to penetrate into 8-MR side pockets of MOR zeolites and interact with acidic hydroxyls therein. Upon heating, pyridine in pockets desorbs preferentially, likely arising from the lower stability of pyridine adspecies in constrained spaces. This well explains the observed increment of carbonylation activity following the increase of pretreatment temperature. Unprecedentedly, high MA yield (7.2 mmol/(h g)) has been achieved on pyridine-modified MOR (Si/Al = 13.8) under controlled pyridine desorption conditions, resulting from the joint contributions of better diffusion properties and larger amounts of active acid sites. Moreover, the catalytic activity of Br?nsted acid sites within 8-MR pockets is demonstrated to be inhomogeneous, closely associated with their locations.
- Cao, Kaipeng,Fan, Dong,Li, Lingyun,Fan, Benhan,Wang, Linying,Zhu, Dali,Wang, Quanyi,Tian, Peng,Liu, Zhongmin
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- Mesoporous MCM-48 Immobilized with Aminopropyltriethoxysilane: A Potential Catalyst for Transesterification of Triacetin
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Abstract: The ordered mesoporous silicas MCM-48, MCM-41, and SBA-15 were synthesized and functionalized with 3-aminopropyltriethoxysilane (APTES). The X-ray diffraction patterns before and after functionalization revealed no structural degradation during the process. FT-IR spectra of the materials clearly indicated the anchoring of the aminopropyl moiety with silanol groups. The amine concentrations were calculated using TG-DTA and CHN analysis. The amine-loaded materials were assessed as catalysts for the transesterification of triacetin with methanol. MCM-48-NH2, in which the pores are interconnected in a three-dimensional manner, exhibited superior catalytic activity to one- dimensional MCM41-NH2 and SBA-15-NH2, even with lower concentrations of the amine group. Graphical Abstract: [Figure not available: see fulltext.]
- Bandyopadhyay, Mahuya,Tsunoji, Nao,Sano, Tsuneji
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- Chemiluminescence upon isomerization of dimethyldioxirane in the gas phase and on a sorbent surface
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Chemiluminescence (CL) was found upon the isomerization of dimethyldioxirane in the gas phase under argon atmosphere. The intensity of CL increases as temperature increases and decreases with time at constant temperature. If Silipor is placed in a cell containing the dimethyldioxirane vapor in argon, the intensity of CL sharply increases (more than 10 times) and then decreases following the exponential law. In all cases tripletly excited methyl acetate is the emitter of Chemiluminescence. 1997 Plenum Publishing Corporation.
- Kazakov,Voloshin,Kabal'Nova,Shereshovets,Kazakov
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- Direct observation of DME carbonylation in the different channels of H-MOR zeolite by continuous-flow solid-state NMR spectroscopy
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The dynamic evolution of acetyl intermediates in the two different channels of H-mordenite (H-MOR) zeolite during dimethyl ether (DME) carbonylation is tracked by using in situ solid-state NMR spectroscopy under continuous-flow conditions. Thus, the reaction path via methyl acetate produced over active sites in 8 member ring (MR) channels, followed by diffusion into 12 MR channels, is proposed.
- He, Ting,Ren, Pengju,Liu, Xianchun,Xu, Shutao,Han, Xiuwen,Bao, Xinhe
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- Purification of EMIMOAc used in the acetylation of lignocellulose
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Up to now, several methods of purifying ionic liquids (ILs), such as the extraction with supercritical carbon dioxide, crystallization, column chromatography, and so forth were reported. The IL that was used in the acetylation of lignocellulose with the help of acetic anhydride contains an elevated amount of acetic acid. In this paper our investigations on the separation of acetic acid from synthetic mixtures with 1-ethyl-3- methylimidazolium acetate (EMIMOAc) are described. The separation was performed by evaporation, extraction, and esterification. While impurities like ethyl acetate, n-propyl acetate, isopropyl acetate, and tetrahydrofuran (THF) can easily be evaporated from EMIMOAc, it is difficult to remove acetic acid from EMIMOAC or EMIMCl by evaporation below certain concentration levels. In extraction tests acetic acid could be separated from EMIMOAc to some degree, especially with extractants immiscible with EMIMOAc having a high value of ET(30) and a dielectric constant near that of acetic acid. The most successful removal of acetic acid was found to be an esterification of acetic acid at a large excess of alcohol, a long reaction time, and an intensive contact of the educts in the liquid phase at elevated temperature and pressure with subsequent evaporation of the produced acetic acid ester.
- Shi, Jin-Zhi,Stein, Juergen,Kabasci, Stephan,Pang, Hao
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- Selective dealumination of mordenite for enhancing its stability in dimethyl ether carbonylation
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Selective dealumination of mordenite by high-temperature steam treatment improved its stability in dimethyl ether carbonylation. Most of the framework Al species in the 12-membered ring channels of mordenite was removed while those in the 8-membered ring
- Xue, Huifu,Huang, Xiumin,Zhan, Ensheng,Ma, Meng,Shen, Wenjie
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- Novel synthesis and catalytic performance of hierarchical MOR
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A novel route was developed to synthesize hierarchical MOR through introduction of BEA/MOR zeolite embryos as the structural growth inducer (SGI) in the presence of hexadecyltrimethylammonium (CTA+). The morphologies, physicochemical properties and possible formation mechanism of the hierarchical MOR were studied systematically. In the process of crystallization, CTA+ might act as a crystal growth inhibitor for the formation of BEA zeolite; therefore, the MOR embryos have the chance to induce the growth of MOR. Besides, CTA+ ions interact with the primary crystals formed and result in the formation of mesopores. Through changing the addition of CTAB and SGI, the crystal sizes, the mesopore volume and the acidity of the hierarchical MOR could be adjusted. Compared with commercial MOR, the catalytic stability of the hierarchical MOR is much higher in the carbonylation of dimethyl ether.
- Lu, Jiaxin,Wang, Yaquan,Sun, Chao,Zhao, Taotao,Zhao, Jingjing,Wang, Ziyang,Liu, Wenrong,Wu, Shuhui,Shi, Mingxue,Bu, Lingzhen
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- Dimethyl ether carbonylation to methyl acetate over highly crystalline zeolite seed-derived ferrierite
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Gas-phase carbonylation of dimethyl ether (DME) to methyl acetate (MA) was investigated on ferrierite (FER) zeolite having different Si/Al molar ratios of 10.4-12.5 as well as high crystallinity synthesized by using various zeolite seed materials such as MOR, ZSM-5 and USY. The enhanced crystallinity of the FER prepared by simply using FER seeds (denoted as FER@FER) having newly formed mesopore structures was responsible for an increased amount of active Br?nsted acid sites, which resulted in a higher MA productivity of 2.94 mmol gcat h-1 with MA selectivity of above 99%. The highly crystalline FER@FER revealed the suppressed deposition of aromatic coke precursors due to the presence of fewer defect sites. Compared to other zeolite seed-derived FER zeolites, the lesser amount of defect sites (extra-framework Lewis acid Al species, EFAL) on the FER@FER was successfully controlled through a recrystallization process. The active Br?nsted acid sites for the DME carbonylation reaction mainly originated from the preferential formation of stable tetrahedral Al sites (especially the T2 sites of the Al-O-Si-O-Al framework of FER) on the 8- and 10-membered ring channels of the FER@FER. On those stable T2 sites having proper acid strength, the adsorbed methyl intermediates formed by the dissociation of DME can be transformed to acetyl adsorbates by a relatively faster CO insertion rate on the vicinal Br?nsted acid sites, which results in a high catalytic stability and activity of the highly crystalline FER@FER.
- Kim, Jihyeon,Ham, Hyungwon,Jung, Hyun Seung,Wang, Yang,He, Yingluo,Tsubaki, Noritatsu,Cho, Sung June,Han, Gui Young,Bae, Jong Wook
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- Stability enhancement of H-mordenite in dimethyl ether carbonylation to methyl acetate by pre-adsorption of pyridine
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The carbonylation of dimethyl ether to methyl acetate over H-mordenite (HMOR) and pyridine-modified HMOR was compared. The catalytic stability of HMOR was improved significantly by pyridine pre-adsorption, and a yield of methyl acetate ～30 was still obtained after 48 h on stream at 473 K. In situ infrared spectroscopy and ammonia temperature-programmed desorption revealed that pyridine preferentially occupied the acidic sites in 12-membered ring pores but not the acidic sites in 8-membered ring pores. 129Xe NMR studies suggested that the channels of HMOR were blocked by coke in the reaction but those in the pyridine-modified HMOR were not. The acidic sites in the 12-membered ring pores were responsible for the deactivation of HMOR, and the reaction can be directed to occur mainly on the acidic sties in the 8-membered ring pores by the selective adsorption of pyridine in the 12-membered ring pores.
- Liu, Junlong,Xue, Huifu,Huang, Xiumin,Wu, Pei-Hao,Huang, Shing-Jong,Liu, Shang-Bin,Shen, Wenjie
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- Selective carbonylation of dimethyl ether to methyl acetate catalyzed by acidic zeolites
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(Chemical Equation Presented) A simpler way: Acidic zeolites catalyze dimethyl ether carbonylation to methyl acetate at low temperatures with high selectivity and catalyst stability. This approach provides a halide-free heterogeneous catalytic route to acetic acid and methyl acetate.
- Cheung, Patricia,Bhan, Aditya,Sunley, Glenn J.,Iglesia, Enrique
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- Specificity of sites within eight-membered ring zeolite channels for carbonylation of methyls to acetyls
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The acid-catalyzed formation of carbon-carbon bonds from C1 precursors via CO insertion into chemisorbed methyl groups occurs selectively within eight-membered ring (8-MR) zeolite channels. This elementary step controls catalytic carbonylation rates of dimethyl ether (DME) to methyl acetate. The number of O-H groups within 8-MR channels was measured by rigorous deconvolution of the infrared bands for O-H groups in cation-exchanged and acid forms of mordenite (M,H-MOR) and ferrierite (H-FER) after adsorption of basic probe molecules of varying size. DME carbonylation rates are proportional to the number of O-H groups within 8-MR channels. Na+ cations selectively replaced protons within 8-MR channels and led to a disproportionate decrease in carbonylation turnover rates (per total H+). These conclusions are consistent with the low or undetectable rates of carbonylation on zeolites without 8-MR channels (H-BEA, H-FAU, H-MFI). Such specificity of methyl reactivity upon confinement within small channels appears to be unprecedented in catalysis by microporous solids, which typically select reactions by size exclusion of bulkier transition states.
- Bhan, Aditya,Allian, Ayman D.,Sunley, Glenn J.,Law, David J.,Iglesia, Enrique
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- Construction, photoluminescence, and catalytic reactivity study of Cd(II) complexes containing amide ligand with hydrogen-bond capable backbone: 1-Dimensional looped chain
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Three new Cd(II) complexes containing 3-bpdb ligands with amide moiety as hydrogen-bond capable backbone, formulated as [Cd(3-bpdb)X2] n (3-bpdb = N,N′-dipyridin-3-ylpyridine-2,6-dicarboxamide, X = Cl (1), Br (2), and I (3)), have been synthesized. All three compounds show 1-dimensional looped chain structures, and intra- and inter-molecular hydrogen bonding interactions provide 2-dimensional sheets. Among three pausible conformers of ligand 3-bpdb, all three halide compounds show only anti-anti conformation to provide 1-dimensional looped chains. In addition, emissions of compounds 1 and 2 were observed at 424 nm and 431 nm, respectively, suggesting that they might be a good candidate for a potential hybrid inorganic-organic photoactive material. Moreover, compounds 1-3 carried out an efficient transesterification of vinyl acetate.
- Lee, Tae Geum,Lee, Ju Hoon,Hyun, Min Young,Jang, Seung Pyo,Lee, Hong Gyu,Kim, Cheal,Kim, Sung-Jin,Kim, Youngmee
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- Mechanism of acetic acid esterification over sulfonic acid-functionalized mesoporous silica
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The kinetics of acetic acid esterification with methanol using a propylsulfonic acid-functionalized SBA-15 catalyst were investigated. To determine whether a different mechanism was applicable for heterogeneous or homogeneous catalyzed esterification, propane sulfonic acid was also examined as this homogeneous acid has the same structure as the functional groups tethered onto SBA-15. In isothermal experiments at 323 K, the apparent reaction orders using the heterogeneous catalyst were determined to be 0.72 for methanol and 0.87 for acetic acid. Reactant adsorption studies showed that pre-adsorption of acetic acid hindered the reaction rate, while pre-adsorption of methanol or acetic acid with methanol increased the reaction rate, indicating that acetic acid adsorbs more strongly than methanol over the heterogeneous acid catalyst. The experimental results demonstrated that acetic acid esterification with methanol followed a dual-site Langmuir-Hinshelwood type reaction mechanism, which required both the adsorption of acetic acid and methanol over propylsulfonic acid-functionalized SBA-15. In contrast, esterification reaction with the homogeneous catalyst followed an Eley-Rideal mechanism. The kinetic data were successfully fit with a model in which the surface reaction was the rate-limiting step.
- Miao, Shaojun,Shanks, Brent H.
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- Isolated zinc in mordenite stabilizing carbonylation of dimethyl ether to methyl acetate
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Herein, we prepared a series of H-Zn-mordenite (H-Zn-MOR) catalysts by adding zinc source into the initial sols during the synthesis of mordenite (MOR). The results indicated that isolated Zn ions were highly dispersed in the catalysts. The addition of zinc led to the increase of Si/Al in the framework of MOR, the change of the distribution of acid sites and the change of acid strength. We investigated the catalytic performance of the H-Zn-MOR catalysts and the HMOR catalysts for carbonylation of dimethyl ether to methyl acetate. The addition of zinc improved the catalytic performance and made the drop of the conversion over the Zn-0.003 and Zn-0.005 catalysts to be about the half of that over the HMOR catalyst. We attributed it to the change of the acid properties, which further change the rate of coke deposition.
- Zhang, Zhitao,Zhao, Na,Ma, Kui,Cheng, Qingpeng,Zhang, Jing,Zheng, Lirong,Tian, Ye,Li, Xingang
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- DME carbonylation over a HSUZ-4 zeolite
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Zeolite-catalyzed carbonylation of dimethyl ether to methyl acetate represents a new route to synthesize acetyls. A rod-shaped HSUZ-4 zeolite, with intersecting 10-member ring and 8-member ring channels, showed exceptionally high activity and durability, as compared to the HZSM-35 sharing a similar pore structure. The abundant openings of 8-member ring pores, as determined by the shape of HSUZ-4, facilitated the diffusion of the reactive molecules.
- Xiong, Zhiping,Zhan, Ensheng,Li, Mingrun,Shen, Wenjie
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- Solid-state NMR study of the kinetics and mechanism of dimethyl ether carbonylation on cesium salt of 12-tungstophosphoric acid modified with Ag, Pt, and Rh
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By using 13C magic angle spinning (MAS) NMR, the mechanism of dimethyl ether (DME) carbonylation with carbon monoxide has been studied on solid metal-containing acidic cesium salt of 12-tungstophosphoric acid, M/Cs2HPW12O40 (M/HPA, M = Ag, Pt, and Rh). The kinetics of the reaction has been monitored with 1H MAS NMR in situ. Activation of DME occurs on acidic OH groups of M/HPA and gives rise to the surface methoxy groups at 293-473 K. Carbon monoxide forms the surface metal-carbonyl complexes on M/HPA at 293-473 K. The insertion of CO from the carbonyl into the CH3O bond of surface methoxide results in the acetate group attached to the Keggin anion, from which the target product, methyl acetate, is produced under the interaction with dimethyl ether. The reaction rate decreases in the following order: Rh/Cs2HPW 12O40 a‰ Pt/Cs2HPW 12O40 > Ag/Cs2HPW12O 40, which correlates well with concentration of the reaction intermediates, methoxy groups, and metal-carbonyls. The higher concentration of these intermediates detected on Rh/Cs2HPW12O40 is in charge of the higher carbonylation rate on this catalyst with respect to M/HPA (M = Ag, Pt) catalysts.
- Luzgin, Mikhail V.,Kazantsev, Maxim S.,Volkova, Galina G.,Stepanov, Alexander G.
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- Chemiluminescence in the reaction of the RuII trisbipyridyl complex with dimethyldioxirane
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The reaction of dimethyldioxirane (1) with the RuII trisbipyridyl complex accompanied by chemiluminescence (CL) was studied. It is established that the intensity of CL and the rate of its decay increase proportionally with the concentration of RuII. The bimolecular rate constant (k2) of the reaction of 1 with RuII was determined. The activation parameters (Ea and logA) for this reaction were calculated from the temperature dependence of k2. The excitation yield of RuII* (η*Ru) was estimated. The quenching of RuII* by dioxirane was studied, and the bimolecular quenching constant and the coefficient of excitation regeneration were determined. It was suggested that the catalysis of the decomposition of 1 and the excitation of RuII occur via a mechanism of chemically initiated electron exchange.
- Kazakov,Voloshin,Kabal'nova,Shereshovets,Kazakov
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- Chemiluminescence and catalysis of decomposition of dimethyldioxirane adsorbed from the gas phase on silipore containing tris(bipyridyl)ruthenium complex Ru(bpy)3Cl2 and 9,10-diphenylanthracene
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The kinetics of decomposition of dimethyldioxirane (DMD) adsorbed from the gas phase on the silipore surface was studied by the chemiluminescence (CL) technique. The lower boundary of the CL yield in the reaction of DMD decomposition (4 · 10-9 Einstein mol-1) and chemiexcitation yield of methyl acetate (4 · 10-4) were estimated. Chemiluminescence upon decomposition of DMD on the silipore surface in the presence of activators of CL such as tris(bipyridyl)ruthenium complex Ru(bpy)3Cl2 and 9,10-diphenylanthracene was revealed. Ru(bpy)3Cl2 activates the luminescence according to chemically induced electron exchange mechanism.
- Kazakov,Voloshin,Kabal'nova,Khursan,Shereshovets,Kazakov
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- Identifying the Active Silver Species in Carbonylation of Dimethyl Ether over Ag?HMOR
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As one of the key steps in ethanol production from syngas, dimethyl ether (DME) carbonylation to methyl acetate (MA) catalyzed by zeolite has drawn much attention. H-mordenite (HMOR) modified with metal has been continuously developed for improving catalytic performance. Here, we investigated the role of Ag species through three series of Ag?HMOR catalysts prepared through altering Ag loading, varying reduction temperature and additional ion exchange. TEM, XPS, CO FTIR and UV-Vis spectroscopy were employed to identify the nature and the amount of Ag species in xAg?HM with different Ag loading. Taken together with catalytic performance evaluation, 5Ag?HM with the moderate size of Ag0 species (Agnδ+ and Agm clusters) was proved to have greatest promotion effect on DME carbonylation. This was also evidenced by further improved MA formation rate over catalysts via elevating reduction temperature or via additional NH4Cl ion exchange, which contained more Ag0 and fewer Ag+ species respectively. These provide insight into metal-modified HMOR, inspiring design and fabrication of zeolite catalysts with multi-active sites.
- Li, Shiyue,Cai, Kai,Li, Ying,Liu, Shuaipeng,Yu, Man,Wang, Yue,Ma, Xinbin,Huang, Shouying
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- Synthesis of nano-sized protonic acid catalyst and initial kinetic study of esterification reaction of methanol with acetic acid
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Nano-sized protonic acid catalysts were synthesized and their catalytic properties in the esterification reaction over methanol whith acetic acid were evaluated. The surface chemistry of the synthesized catalysts was investigated using solid-state magic-angle spinning nuclear magnetic resonance, X-ray photoelectron spectroscope and elemental analysis techniques (CHNS-O). The results showed that the appropriate increment of sulfonation temperature can facilitate the attachment of -SO3H groups and also benefit for the enhancement of acetic acid conversion. The initial kinetic study of esterification reaction of methanol and acetic acid, which was catalyzed by synthesized nano-sized protonic acid catalysts, indicates that only one active site was involved in the surface reaction and thus the initial reaction mechanistic paths under our reaction conditions were proposed.
- Zhu, Jianjun,Cui, Qiuqing,Peng, Jiangping,Zhang, Li Li,Jiang, Zhongqing,Luo, Lijuan,Tian, Xiaoning
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- An Enzyme Model Which Mimics Chymotrypsin and N-Terminal Hydrolases
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Enzymes are the most efficient and specific catalysts to date. Although they have been thoroughly studied for years, building a true enzyme mimic remains a challenging and necessary task. Here, we show how a three-dimensional geometry analysis of the key catalytic residues in natural hydrolases has been exploited to design and synthesize small-molecule artificial enzymes which mimic the active centers of chymotrypsin and N-terminal hydrolases. The optimized prototype catalyzes the methanolysis of the acyl enzyme mimic with a half-life of only 3.7 min at 20 °C, and it is also able to perform the transesterification of vinyl acetate at room temperature. DFT studies and X-ray diffraction analysis of the catalyst bound to a transition state analogue proves the similarity with the geometry of natural hydrolases.
- Fuentes De Arriba, ángel L.,García, Miguel Martínez,Garrido-González, José J.,Iglesias Aparicio, Ma Mercedes,Morán, Joaquín R.,Sanz, Francisca,Simón, Luis
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- Methyl acetate synthesis by esterification on the modified ferrierite: Correlation of acid sites measured by pyridine IR and NH3-TPD for steady-state activity
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The amounts of Br?nsted acid sites on K, P, and Zr-modified microporous Ferrierite zeolite were investigated through pyridine FT-IR and NH3-TPD analyses. P-modified Ferrierite showed a superior catalytic activity for methyl acetate synthesis by esterification of methanol and acetic acid. The catalytic activity at steady-state with the acidic properties of as-prepared catalysts was well correlated with the results of pyridine FT-IR (intensity ratio of Br?nsted acid sites to total acid sites) compared with that of NH3-TPD. The results can suggest the proper and simple method to estimate the esterification activity at steady-state using the measured acid sites on the as-prepared zeolites.
- Park, Jae Hyun,Pang, Changhyun,Chung, Chan-Hwa,Bae, Jong Wook
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- Octyl Co-grafted PrSO3H/SBA-15: Tunable Hydrophobic Solid Acid Catalysts for Acetic Acid Esterification
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Propylsulfonic acid (PrSO3H) derivatised solid acid catalysts have been prepared by post-modification of mesoporous SBA-15 silica with mercaptopropyltrimethoxysilane (MPTMS), and the impact of co-derivatisation with octyltrimethoxysilane (OTMS) groups to impart hydrophobicity to the catalyst was investigated. Turnover frequencies (TOFs) for acetic acid esterification with methanol increase with PrSO3H surface coverage across both families, suggesting a cooperative effect between adjacent acid sites at high acid site densities. Esterification activity is further promoted upon co-functionalisation with hydrophobic octyl chains, with inverse gas chromatography (IGC) measurements indicating that the increased activity correlates with decreased surface polarity or increased hydrophobicity.
- Manayil, Jinesh C.,dos Santos, Vannia C.,Jentoft, Friederike C.,Granollers Mesa, Marta,Lee, Adam F.,Wilson, Karen
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- Conformations and reactions of bicyclo[3.2.1]oct-6-en-8-ylidene
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Bicyclo[3.2.1]oct-6-en-8-ylidene (1) can assume either the conformation of "classical" carbene 1a or that of foiled carbene 1b in which the divalent carbon bends toward the double bond. Oxadiazoline precursors for the generation of 1 were prepared, followed by photochemical and thermal decomposition as well as flash vacuum pyrolysis (FVP) of a tosyl hydrazone sodium salt precursor, to give a number of rearrangement products. Matrix isolation experiments demonstrate the presence of a diazo intermediate and methyl acetate in all photochemical and thermal precursor reactions. The major product from rearrangements of "classical" bridged carbene 1a is bicyclo[3.3.0]octa-1,3-diene as a result of an alkyl shift, while dihydrosemibullvalene formed from a 1,3-C-H insertion. In contrast, thus far unknown strained bicyclo[4.2.0]octa-1,7-diene formed by a vinyl shift in foiled carbene 1b. The experimental results are corroborated by density functional theory (DFT), MP2, and G4 computations.
- Brinker, Udo H.,Bespokoev, Alexander A.,Reisenauer, Hans Peter,Schreiner, Peter R.
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- Sulfonic-acid-functionalized porous benzene phenol polymer and carbon for catalytic esterification of methanol with acetic acid
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Porous benzene phenol polymer and carbon were synthesized in the presence of Pluronic P123 as template. Sulfonation of the porous structures yielded solids with sulfonic acid groups. The compositions of the solid acids were characterized using elemental analysis and thermogravimetric analysis methods. Their pore structures were investigated by physical adsorption of nitrogen. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy were used to characterize surface functional groups. Carbonization of porous benzene phenol polymer at evaluated temperatures transferred the polymer to carbon as proven by X-ray diffraction and transmission electron microscope techniques. The catalytic properties of the solid acids were evaluated using esterification of methanol with acetic acid. Results showed that the catalytic activity for the sulfonated polymer increased with the increase in sulfonation temperature. Sulfonic acid groups on the polymer framework were observed to be more stable than those on the carbon framework.
- Tian, Xiaoning,Zhang, Li Li,Bai, Peng,Zhao
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- Volumetric, chromatographic, refractometric studies on the esterification of methanol with acetic acid in the presence of cation-exchange resins
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Esterification of methyl alcohol with acetic acid catalysed by commercially available polymeric ion-exchange resins Amberlyst-15, Dowex 50W and Amberlite IR-120 was carried out in the temperature ranging between 323-338 K. Mesh sizes and divinylbenzene contents had virtually no effect on the rate the data of which were correlated with a second-order homogeneous reaction. The samples were analysed with gas chromatography, refractometry and volumetry. The reproducibilities were the order of ±2.89%, ±5.07% and the order of ±6.58% respectively for the volumetric, chromatographic and refractometric methods. by Oldenbourg Wissenschaftsverlag.
- Erdem, Beyhan,Cebe, Mustafa
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- The relative importance of heterogeneous and homogeneous methanol carbonylation using supported rhodium catalysts in the liquid phase
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Rhodium catalysts supported on ZrO2, carbon, a cross-linked polystyrene with pendant Ph2P groups (SDT) or polyvinylpyrrolidone have been tested as catalysts for the heterogeneous carbonylation of methanol in the bulk liquid phase. In all cases, leaching of the catalyst into solution occurs and the observed increase in the rate of production of methyl ethanoate with time is attributed to the rate of the homogeneous reaction being faster than that of the heterogeneous. A detailed kinetic analysis for the catalyst supported on polyvinylpyrrolidone suggests that the rate constant for the homogeneous reaction is ca. 2× that of the heterogeneous at 150°C.
- De Blasio, Nicola,Wright, Margaret R.,Tempesti, Enzo,Mazzocchia, Carlo,Cole-Hamilton, David J.
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- Modifying the acidity of H-MOR and its catalytic carbonylation of dimethyl ether
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Among the reactions catalyzed by zeolites there are some that exhibit high selectivity due to the spatial confinement effect of the zeolite framework. Tailoring the acidity, particularly the distribution and location of the Br?nsted acid sites in the zeolite is effective for making it a better catalyst for these reactions. We prepared a series of H-mordenite (H-MOR) samples by varying the composition of the sol-gel, using different structure directing agents and post-treatment. NH3-TPD and IR characterization of adsorbed pyridine were employed to determine the amount of Br?nsted acid sites in the 8-membered ring and 12-membered ring channels. It was shown that controlled synthesis was a promising approach to improve the concentration of Br?nsted acid sites in MOR, even with a low Al content. Using an appropriate composition of Si and Al in the sol-gel favored a higher proportion of Br?nsted acid sites in the 8-membered ring channels. HMI as a structure-direct agent gave an obvious enrichment of Br?nsted acid sites in the 8-membered ring. Carbonylation of dimethyl ether was used as a probe reaction to examine the modification of the acid properties, especially the Br?nsted acid sites in the 8-membered ring channels. There was a linear relationship between methyl acetate formation and the number of Br?nsted acid sites in the 8-membered ring channels, demonstrating the successful modification of acid properties. Our results provide information for the rational design and modification of zeolites with spatial constraints.
- Wang, Meixia,Huang, Shouying,Lü, Jing,Cheng, Zaizhe,Li, Ying,Wang, Shengping,Ma, Xinbin
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- Effects of metal ions and ligands on transesterification: Synthesis, structures, and catalytic activities of a series of cation-anionic complexes with dipyridylamine ligands
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A series of cation-anion complexes derived by 2,2′-dipyridylamine (Hdpa) and carboxylate ligands with formulas [Ni(Hdpa)2(CH 3COO)]Cl(CH3OH) (1), [Co(Hdpa)2(CH 3COO)]Cl(CH3OH) (2), [Ni(Hdpa)2(CH 3CH2CH2COO)]Cl (3), [Co(Hdpa) 2(CH3CH2CH2COO)]Cl (4), [Ni(Hdpa)2(C6H5COO)]Cl (5), and [Co(Hdpa) 2(C6H5COO)]Cl (6), were synthesized and characterized by IR, elemental analysis, MS(ESI), TG analysis, UV-Vis, and fluorescence spectra. X-ray single crystal structural analysis showed that the coordination geometries of metal ions in these complexes are similar and they are cation-anion species. The hydrogen-bonding structures are 1-D chains through the N-H...Cl bonds. There are weak stacking interactions between pyridine rings in 1-4, while there are no stacking interactions in 5 and 6. We have investigated the transesterification of phenyl acetate with methanol catalyzed by 1-6 under mild conditions; 1-4 are homogeneous catalysts while 5 and 6 are heterogeneous catalysts due to their poor solubility in methanol. Cobalt complexes exhibit higher catalytic activities than corresponding nickel complexes. Complex 4 is the best catalyst of these six complexes.
- Deng, Yuan,Bai, Ying,Zhu, Long-Guan,Jiang, Jian-Xiong,Lai, Guo-Qiao
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- Site requirements and elementary steps in dimethyl ether carbonylation catalyzed by acidic zeolites
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Steady-state, transient, and isotopic-exchange studies of dimethyl ether (DME) carbonylation, combined with adsorption and desorption studies of probe molecules and infrared (IR) spectroscopy, were used to identify methyl and acetyl groups as surface intermediates within specific elementary steps involved in the synthesis of methyl acetate from DME-CO mixtures with >99% selectivity on H-zeolites. Carbonylation rates increased linearly with CO pressures but did not depend on DME pressures, suggesting that the addition of CO to CH3 groups present at saturation coverage controls catalytic carbonylation rates. These reactions lead to acetyl groups that subsequently react with DME to form methyl acetate (423-463 K; >99% selectivity) and regenerate methyl intermediates, consistent with kinetic studies of CO reactions with CH3 groups previously formed from DME and with kinetic and IR studies of DME reactions with acetyl groups formed by stoichiometric reactions of acetic anhydride. These studies show that CO reacts with DME-derived intermediates bound on zeolitic Al sites from the gas phase or via weakly held CO species adsorbed non-competitively with CH3 groups. These reactions, in contrast with similar reactions of methanol, occur under anhydrous conditions and avoid the formation of water, which strongly inhibits carbonylation reactions.
- Cheung, Patricia,Bhan, Aditya,Sunley, Glenn J.,Law, David J.,Iglesia, Enrique
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- Promotion effect of Fe in mordenite zeolite on carbonylation of dimethyl ether to methyl acetate
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A series of Fe-modified mordenite zeolite samples were synthesized by a template-free method and employed in dimethyl ether (DME) carbonylation reaction for the production of methyl acetate (MAc). XRD, UV-Vis, and UV-Raman characterization studies proved that Fe atoms have been introduced into the mordenite zeolite framework by partial substitution of Al atoms, which led to evident changes of activity and MAc selectivity. With the increase of iron content (as metal) from 0.0 to 3.6 wt%, DME conversion first increased and then decreased. MAc selectivity and catalyst stability were enhanced for all Fe-modified samples. TG and GC-MS analysis of deactivated catalysts showed that the amount of coke retained in the catalysts decreased as the iron content of the zeolites increased. The enhancement effects were expounded in terms of the decrease of the acid strength and acid density in the 12MR channels of mordenite after introduction of Fe, resulting in the reduction of carbon deposition.
- Zhou, Hui,Zhu, Wenliang,Shi, Lei,Liu, Hongchao,Liu, Shiping,Xu, Shutao,Ni, Youming,Liu, Yong,Li, Lina,Liu, Zhongmin
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- Synthesis of Hierarchical SAPO-5 & SAPO-34 Materials by Post-Synthetic Alkali Treatment and Their Enhanced Catalytic Activity in Transesterification
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SAPO-5 and SAPO-34 materials were modified using post-synthetic alkali treatment, which results in the formation of hierarchical SAPO-5 and SAPO-34 materials. To test the generation of mesoporosity, the modified materials were thoroughly characterized usi
- Bandyopadhyay, Mahuya,Bandyopadhyay, Rajib,Jadav, Divya
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- The carbonylation of methyl iodide and methanol to methyl acetate catalysed by palladium and platinum iodides
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Palladium(II) salts catalyse the carbonylation of methyl iodide in methanol to methyl acetate (5 atm CO, 140°C) in the presence of a large excess of iodide, even without amine or phosphine co-ligands; platinum(II) salts show similar reactions but are a little less effective.
- Yang, Jun,Haynes, Anthony,Maitlis, Peter M.
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- In situ DRIFT study of dimethyl ether carbonylation to methyl acetate on H-mordenite
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In situ diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy was used to study the reaction of dimethyl ether (DME) carbonylation to methyl acetate (MAc). Methoxyl and acetyl groups were observed in situ, confirming the reaction mechanistic proposal. DME adsorption bands on Si-OH, Al-OH and SiOHAl (Br?nsted acid sites) groups were identified respectively. The effect of temperature and pressure on acetyl formation and side reactions were systematically studied. It was found that methoxyls formed by DME chemisorbed on Br?nsted acid sites could be observed above 433 K. High pressure and appropriate temperature interval promoted the formation of acetyls. Side reactions, DME transformed into olefins and then into cokes, were favored at low pressure and high temperature. Carbonylation reactions on catalysts with acid sites only in 8MR side pockets and 12MR main channels of mordenite (samples noted as HMOR-SP and HMOR-MC) were conducted by in situ DRIFT spectroscopy and catalytic testing. Pyridine molecules adsorbed in 12MR main channels resulted in the low utilization of acid sites in 8MR side pockets. The synthesis rate of MAc on HMOR-SP was stable but lower. HMOR-MC presented the lowest MAc synthesis rate with the production of coke, which was also observed in DRIFT spectra.
- Zhou, Hui,Zhu, Wenliang,Shi, Lei,Liu, Hongchao,Liu, Shiping,Ni, Youming,Liu, Yong,He, Yanli,Xu, Shuliang,Li, Lina,Liu, Zhongmin
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- Efficient methanol carbonylation to methyl acetate catalyzed by a cyclic(alkyl)(amino)carbene iridium complex
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An efficient cyclic(alkyl)(amino) carbene iridium complex (C-2) was developed for methanol carbonylation to methyl acetate (MA) directly. Compared with previous results, methanol carbonylation to MA catalyzed byC-2was performed quite well at a low temperature (120 °C). The reaction showed excellent selectivity toward MA (96%) even when the conversion was high (81%). The reaction processes were also investigated by stoichiometric experiments and theoretical calculations.
- Hu, Xingbang,Liu, Jia,Liu, Peijun,Shao, Shouyan,Yang, Guoqiang,Zhang, Dejin,Zhang, Zhibing,Zhao, Yue,Zhu, Guisheng
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- Activity enhancement of ZSM-35 in dimethyl ether carbonylation reaction through alkaline modifications
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A series of ZSM-35 zeolites with different alkaline treatment degrees were prepared. The precise effects of alkaline treatment on composition, morphology, porosity, transportation and acidity of the samples were characterized by means of multiple techniques including N2 sorption, transmission electron microscopy (TEM), intelligent gravimetric analyzer (IGA) and Fourier transform infrared spectroscopy (FTIR). ZSM-35 after moderate alkaline treatment exhibited enhanced carbonylation activity compared with the parent sample. As revealed by the N2 adsorption and TEM results, alkaline treatment could induce the deaggregation of ZSM-35 clusters and remove the amorphous debris on the surface of ZSM-35 platelets. Furthermore, an improved diffusion behavior of the dimethyl ether reactant molecule was observed on the alkali-treated sample from IGA experiments which directly led to the better catalytic performance for the carbonylation of the dimethyl ether with carbon monoxide. Mesoporosity created by severe alkaline leaching does not enhance the catalytic properties of ZSM-35 in dimethyl ether carbonylation reaction. Especially, a decrease in reaction stability was observed due to the limitation effect of carbonaceous deposit formation. The Royal Society of Chemistry 2013.
- Li, Xiujie,Liu, Xiaohang,Liu, Shenglin,Xie, Sujuan,Zhu, Xiangxue,Chen, Fucun,Xu, Longya
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- Carbonylation of dimethyl ether over Co-HMOR
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Incorporation of Co2+ into the framework of HMOR significantly enhanced the activity for the carbonylation of dimethyl ether to methyl acetate. About 68% of the Co2+ cations are located at site A in the 8-membered ring (8-MR) pores, while 32% of the metal cations are incorporated at site E of the 12-MR pores. Although the amount of the Br?nsted acid sites in the 8-MR pores that are intrinsically active for DME carbonylation decreased considerably upon Co-doping, the conversion of DME increased remarkably, almost doubled. The promotional role of Co2+ in the 8-MR channels was to facilitate the adsorption/activation of both CO and DME molecules. Meanwhile, the Co2+ cations located in the 12-MR channels effectively suppressed coke deposition and thus improved the stability of the Co-HMOR catalyst.
- Ma, Meng,Zhan, Ensheng,Huang, Xiumin,Ta, Na,Xiong, Zhiping,Bai, Luyi,Shen, Wenjie
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- A brand new zeolite catalyst for carbonylation reaction
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Carbonylation is an effective way to introduce carbonyl groups into organic chemicals. However, the known zeolite candidates for carbonylation are very few. Here, we discovered a new zeolite EU-12 that shows excellent catalytic performance for carbonylation reactions, inserting carbonyl groups into dimethyl ether (DME) to produce methyl acetate (MA). This finding adds a brand new zeolite to the solid catalyst family for carbonylation reaction.
- Feng, Xiaobo,Yao, Jie,Li, Hangjie,Fang, Yuan,Yoneyama, Yoshiharu,Yang, Guohui,Tsubaki, Noritatsu
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- Isolation of cis-dimethyl-(methoxycarbonyl)(triphenylphosphine)gold(III)
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cis-Dimethyl(methoxycarbonyl)(triphenylphosphine)gold(III) (1) has been prepared by the reaction of carbon monoxide with a mixture of cis-dimethyliodo-(triphenylphosphine)gold(III) and sodium methoxide in methanol. Thermolysis of 1 results in the competitive reductive elimination of methyl acetate and ethane.
- Komiya, Sanshiro,Ishikawa, Makoto,Ozaki, Satoshi
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- Carbon-Oxygen Bond Forming Reductive Elimination from Cycloplatinated(IV) Complexes
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The synthesis of the two cycloplatinated(IV) complexes [PtMe(OAc)2(C^N)(H2O)] (C^N = 2-phenylpyridinate (2a), benzo[h]quinolate, 2b) by reaction of [PtMe(C^N)(SMe2)] with PhI(OAc)2 is described. Complexes 2 undergo carbon-oxygen bond forming reductive elimination instead of C-C reductive elimination to produce MeOAc as protected methanol. The kinetics and mechanism of both Pt-O bond formation and C-O reductive elimination have been experimentally and theoretically investigated. The results suggest that formation of methyl acetate proceeds via nucleophilic attack of the dissociated acetate ligand at the methyl group carbon in a cationic five-coordinate intermediate cycloplatinated(IV) complex.
- Aseman, Marzieh Dadkhah,Nabavizadeh, S. Masoud,Niroomand Hosseini, Fatemeh,Wu, Guang,Abu-Omar, Mahdi M.
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- Stable ethanol synthesis via dimethyl oxalate hydrogenation over the bifunctional rhenium-copper nanostructures: Influence of support
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Addition of oxophilc rhenium to decorate small copper nanoparticles has been validated to be an efficient method to prepare a low-copper catalyst for the direct synthesis of ethanol via dimethyl oxalate (DMO) hydrogenation process, and herein we investigated the impact of supports on the catalytic performance of ReCu catalysts. A series of materials including activated carbon (AC), Al2O3, SiO2, TiO2 and ZrO2 were utilized as the support and as prepared Re2Cu5 catalysts were evaluated. The results exhibited that the Re2Cu5/ZrO2 catalyst possesses the highest DMO hydrogenation activity and ethanol yield (～93%), which may be due to its lowest Cu0/Cu+ ratio (0.13), smallest Cu particle size (～0.84 nm) a relative high reduction degree (59%). The CO adsorption behavior characterized by in situ IR spectroscopy showed that a strong metal-support interaction creates an electron deficient environment of Cu nanoparticle, resulting in a lower Cu0/Cu+ ratio that enhances the activation of C[dbnd]O bond in the DMO molecular.
- Chen, Xingkun,Ding, Yunjie,Du, Zhongnan,Li, Zheng,Lin, Ronghe,Wang, Shiyi,Wang, Xuepeng,Zhu, Hejun
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p. 241 - 252
(2022/02/22)
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- Synthesis, Characterisation, and Determination of Physical Properties of New Two-Protonic Acid Ionic Liquid and its Catalytic Application in the Esterification
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A new ionic liquid was synthesised, and its chemical structure was elucidated by FT-IR, 1D NMR, 2D NMR, and mass analyses. Some physical properties, thermal behaviour, and thermal stability of this ionic liquid were investigated. The formation of a two-protonic acid salt namely 4,4′-trimethylene-N,N′-dipiperidinium sulfate instead of 4,4′-trimethylene-N,N′-dipiperidinium hydrogensulfate was evidenced by NMR analyses. The catalytic activity of this ionic liquid was demonstrated in the esterification reaction of n-butanol and glacial acetic acid under different conditions. The desired acetate was obtained in 62-88 % yield without using a Dean-Stark apparatus under optimal conditions of 10 mol-% of the ionic liquid, an alcohol to glacial acetic acid mole ratio of 1.3: 1.0, a temperature of 75-100°C, and a reaction time of 4 h. α-Tocopherol (α-TCP), a highly efficient form of vitamin E, was also treated with glacial acetic acid in the presence of the ionic liquid, and O-acetyl-α-tocopherol (Ac-TCP) was obtained in 88.4 % yield. The separation of esters was conducted during workup without the utilisation of high-cost column chromatography. The residue and ionic liquid were used in subsequent runs after the extraction of desired products. The ionic liquid exhibited high catalytic activity even after five runs with no significant change in its chemical structure and catalytic efficiency.
- Shahnavaz, Zohreh,Zaharani, Lia,Khaligh, Nader Ghaffari,Mihankhah, Taraneh,Johan, Mohd Rafie
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p. 165 - 172
(2020/10/26)
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- Fully recyclable Br?nsted acid catalyst systems
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Homogeneous and heterogeneous sulfonic acid catalysts are some of the most common catalysts used in organic chemistry. This work explores an alternative scheme using a fully recyclable polymeric solvent (a poly-α-olefin (PAO)) and soluble PAO-anchored polyisobutylene (PIB)-bound sulfonic acid catalysts. This PAO solvent is nonvolatile and helps to exclude water by its nonpolar nature which in turn drives reactions without the need for distillation of water, avoiding the need for excess reagents. This highly nonpolar solvent system uses polyisobutylene (PIB) bound sulfonic acid catalysts that are phase-anchored in solvents like PAO. The effectivenes of these catalysts was demonstrated by their use in esterifications, acetalizations, and multicomponent condensations. These catalysts and the PAO solvent phase show excellent recyclability in schemes where products are efficiently separated. For example, this non-volatile polymeric solvent and the PIB-bound catalyst can be recycled quantitatively when volatile products are separated and purified by distillation. In other cases, product purification can be effected by product self-separation or by extraction.
- Watson, Christopher B.,Kuechle, Adrianna,Bergbreiter, David E.
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p. 1266 - 1273
(2021/02/26)
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- Oxidative Addition of a Hypervalent Iodine Compound to Cycloplatinated(II) Complexes for the C–O Bond Construction: Effect of Cyclometalated Ligands
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The complex [PtMe(Obpy)(OAc)2(H2O)], 2a, Obpy = 2,2′-bipyridine N-oxide, is prepared through the reaction of [PtMe(Obpy)(SMe2)], 1a, by 1 equiv of PhI(OAc)2 via an oxidative addition (OA) reaction. Pt(IV) complex 2a attends the process of C–O bond reductive elimination (RE) reaction to form methyl acetate and corresponding Pt(II) complex [Pt(Obpy)(OAc)(H2O)], 3a. The kinetic of OA and RE reactions are investigated by means of different spectroscopies. The obtained results show that the reaction rates of OA step of 1a are faster than its analogous complex [PtMe(ppy)(SMe2)], 1b, ppy = 2-phenylpyridine. The density functional theory (DFT) calculations signify that the OA reaction initiated by a nucleophilic attack of the platinum(II) central atom of 1b on the iodine(III) atom while it had commenced by a nucleophilic substitution reaction of coordinated SMe2 in 1a with a carbonyl oxygen atom of PhI(OAc)2. Our calculation revealed that the key step for 1a is an acetate transfer from the I(III) to Pt(II) through a formation of square pyramidal iodonium complex. This can be attributed to the more electron-withdrawing character of Obpy ligand than to ppy which reduces the nucleophilicity of Pt atom in 1a. Furthermore, 2a with electron-withdrawing Obpy ligand prone to C–O bond formation faster than complex [PtMe(ppy)(OAc)2(H2O)], 2b, with an electron-rich ppy ligand which conforms to the anticipation that REs occur faster on electron-poor metal centers.
- Dadkhah Aseman, Marzieh,Nikravesh, Mahshid,Abbasi, Alireza,Shahsavari, Hamid R.
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supporting information
p. 18822 - 18831
(2021/12/13)
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- Significant effects of the anion on the catalytic behaviour of sulfonic acid-functionalized ionic liquids in transesterification reactions – A combined electrochemical/catalytic study
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This work studies the strong influence of the counterion on the performance of ionic liquids (ILs) with sulfonic acid-functionalized butyl-imidazolic bases as homogeneous acid catalysts. Through a voltammetric analysis, it was shown that the availability
- Adam, Claudia G.,Fernández, José L.,Martini, María B.
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- More efficient ethanol synthesis from dimethyl ether and syngas over the combined nano-sized ZSM-35 zeolite with CuZnAl catalyst
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Converting syngas into ethanol (EtOH) is highly attractive but remains challenge. Dimethyl ether (DME) carbonylation with CO to methyl acetate (MA) on zeolite and its further hydrogenation to EtOH on Cu-based catalyst open a new EtOH synthesis route from syngas. In this work, a nano-sized ZSM-35 (NZ35) zeolite, possessing abundant active sites and porosity and short diffusion path, is found to realize much better activity of DME to MA than that of the conventional ZSM-35 zeolite (CZ35). In addition, a simple formic-acid-assisted solid-state method is employed for preparation an auto-reduced CuZnAl (CZAargon) catalyst under argon atmosphere. The prepared CZAargon catalyst exhibits an excellent catalytic activity for conversion of produced MA to EtOH. By investigating the effects of different integration manners of NZ35 zeolite and CZAargon catalyst, we find that EtOH can be synthesized only when the NZ35 zeolite and CZAargon catalyst pack in a dual-catalyst bed reactor. After optimizing the reaction conditions for EtOH synthesis with the combination of NZ35 zeolite and CZAargon catalyst, it is found that the DME conversion and MA selectivity are stabilized at 47.0 % and 45.6 % respectively, at 220 °C and 2.5 MPa.
- Feng, Xiaobo,Yao, Jie,Zeng, Yan,Cui, Yu,Kazumi, Shun,Prasert, Reubroycharoen,Liu, Guangbo,Wu, Jinhu,Yang, Guohui,Tsubaki, Noritatsu
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- METHOD FOR PREPARING ACRYLIC ACID AND METHYL ACRYLATE
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The present invention provides a method for preparing acrylic acid and methyl acrylate. The method comprises passing the feed gas containing dimethoxymethane and carbon monoxide through a solid acid catalyst to generate acrylic acid and methyl acrylate with a high conversion rate and selectivity at a reaction temperature in a range from 180 to 400 and a reaction pressure in a range from 0.1 MPa to 15.0 MPa, the mass space velocity of dimethoxymethane in the feed gas is in a range from 0.05 h?1 to 10.0 h?1, and the volume percentage of dimethoxymethane in the feed gas is in a range from 0.1% to 95%.
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Paragraph 0076-0081
(2021/04/23)
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- ZWITTERIONIC CATALYSTS FOR (TRANS)ESTERIFICATION: APPLICATION IN FLUOROINDOLE-DERIVATIVES AND BIODIESEL SYNTHESIS
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An amide/iminium zwitterion catalyst has a catalyst pocket size that promotes transesterification and dehydrative esterification. The amide/iminium zwitterions are easily prepared by reacting aziridines with aminopyridines. The reaction can be applied a wide variety of esterification processes including the large-scale synthesis of biodiesel. The amide/iminium zwitterions allow the avoidance of strongly basic or acidic condition and avoidance of metal contamination in the products. Reactions are carried out at ambient or only modestly elevated temperatures. The amide/iminium zwitterion catalyst is easily recycled and reactions proceed in high to quantitative yields.
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Paragraph 0010; 0026
(2021/01/29)
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- Functionalization of RhIII-Me Bonds: Use of capping Arene Ligands to Facilitate Me-X Reductive Elimination
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We show how to improve the yield of MeX from CH4 activation catalysts from 12% to 90% through the use of capping arene ligands. Four (FP)RhIII(Me)(TFA)2 {FP = capping arene ligands, including 8,8′-(1,2-phenylene)diquinoline (6-FP), 8,8′-(1,2-naphthalene)diquinoline (6-NPFP), 1,2-bis(N-7-azaindolyl)benzene (5-FP), and 1,2-bis(N-7-azaindolyl)naphthalene (5-NPFP)} complexes. These complexes and (dpe)RhIII(Me)(TFA)2 (dpe = 1,2-di-2-pyridylethane) were synthesized and tested for their performance in reductive elimination of MeX (X = TFA or halide). The FP ligands were used with the goal of blocking a coordination site to destabilize the RhIII complexes and facilitate MeX reductive elimination. On the basis of single-crystal X-ray diffraction studies, the 6-FP and 6-NPFP ligated Rh complexes have Rh-arene distances shorter than those of the 5-FP and 5-NPFP Rh complexes; thus, it is expected that the Rh-arene interactions are weaker for the 5-FP complexes than for the 6-FP complexes. Consistent with our hypothesis, the 5-FP and 5-NPFP RhIII complexes demonstrate improved performance (from 12% to ～60% yield) in the reductive elimination of MeX. The reductive elimination of MeX from (FP)RhIII(Me)(TFA)2 can be further improved by the use of chemical oxidants. For example, the addition of 2 equiv of AgOTf leads to 87(2)% yield of MeTFA and can be achieved in CD3CN at 90 °C using (5-FP)Rh(Me)(TFA)2.
- Gu, Shunyan,Chen, Junqi,Musgrave, Charles B.,Gehman, Zo? M.,Habgood, Laurel G.,Jia, Xiaofan,Dickie, Diane A.,Goddard, William A.,Gunnoe, T. Brent
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p. 1889 - 1906
(2021/05/29)
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- Ni-MoOx bifunctional catalyst on SiO2 for vapor halide-free methanol carbonylation: Insight into synergistic catalysis between Ni and MoOx
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A promising Ni-MoOx bifunctional catalyst for halide-free methanol carbonylation is developed by H2-reduction of NiO-MoO3/SiO2 obtained via facile impregnation method. Catalyst performance is strongly dependent on the calcination/reduction temperature. Over the preferable NiMo-350-600/SiO2 catalyst obtained by calcining at 350 °C and subsequently reducing at 600 °C, a methanol conversion of 4.2 % and acetyls space-time yield of 1.37 mol kgcat?1 h?1 are achieved with 22.1 % selectivity to acetyls at 290 °C and 3 MPa. Co-existence of Ni0 and MoOx (especially MoO2) markedly decreases formation of dimethyl ether (DME) and reversely increases acetyls formation, in nature, due to the catalyst acidity modulation and the partial electron transfer from Ni0 to MoOx that tunes the CO adsorption strength on Ni0 sites. MoO3 and NiMoO4 are both favorable for formation of acetyls and DME whereas the latter mainly accounts for DME formation. MoNi4 alone favors methyl formate formation while together with MoO2 enhancing DME production.
- Liu, Ye,Lu, Yong,Nie, Qiang,Shen, Mengchen,Zhao, Guofeng
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- KF-Promoted copper-catalyzed highly efficient and selective oxidation of methane and other alkanes with a dramatic additive effect
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Highly efficient oxidation of methane to methyl trifluoroacetate mediated by CuCl/KF/K2S2O8in trifluoroacetic acid (TFA) and trifluoroacetic anhydride (TFAA) is described. The additive effect has been systematically evaluated and potassium fluoride (KF) was identified as the most effective promoter among the salts screened. KF is conjectured to exhibit the salt effect to promote the [SO4˙]?radical to escape the solvent cage based on control experiments. Cyclohexane and adamantane could also be efficiently oxidized into benzene or corresponding trifluoroacetates.
- Chen, Wei,Chen, Xiaoyan,Fan, Wu,Li, Suhua,Liu, Luyao
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p. 4962 - 4968
(2021/07/26)
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- Highly efficient and selectivity-controllable aerobic oxidative cleavage of C-C bond over heterogeneous Fe-based catalysts
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A base-free selectivity-controllable aerobic oxidative cleavage of C-C bond with heterogeneous Fe-based catalysts (FexOy-N@C3N4) is developed. In the presence of oxygen, 1,2-diols are selectively transformed to the corresponding aldehyde, while the methyl esters are orientedly produced from 1,2-diones in methanol medium.
- Guo, Pengfei,Liao, Shengyun,Wang, Shun,Shi, Jing,Tong, Xinli
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p. 399 - 403
(2021/02/27)
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- Selective Methanol Carbonylation to Acetic Acid on Heterogeneous Atomically Dispersed ReO4/SiO2Catalysts
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Methanol carbonylation to acetic acid (AA) is a large-scale commodity chemical production process that requires homogeneous liquid-phase organometallic catalysts with corrosive halide-based cocatalysts to achieve high selectivity and activity. Here, we demonstrate a heterogeneous catalyst based on atomically dispersed rhenium (ReO4) active sites on an inert support (SiO2) for the halide-free, gas phase carbonylation of methanol to AA. Atomically dispersed ReO4 species and nanometer sized ReOx clusters were deposited on a high surface area (700 m2/g) inert SiO2 using triethanolamine as a dispersion promoter and characterized using aberration corrected scanning transmission electron microscopy (AC-STEM), UV-vis spectroscopy, and X-ray absorption spectroscopy (XAS). Reactivity measurements at atmospheric pressure with 30 mbar of methanol and CO (1:1 molar ratio) showed that bulk Re2O7 and ReOx clusters on SiO2 (formed at >10 wt %) were selective for dimethyl ether formation, while atomically dispersed ReO4 on SiO2 (formed at 93% selectivity to AA with single pass conversion >60%. Kinetic analysis, in situ FTIR, and in situ XAS measurements suggest that the AA formation mechanism involves methanol activation on ReO4, followed by CO insertion into the terminal methyl species. Further, the introduction of 0.2 wt % of atomically dispersed Rh to 10 wt % atomically dispersed ReO4 on SiO2 resulted in >96% selectivity toward AA production at volumetric reaction rates comparable to homogeneous processes. This work introduces a new class of promising heterogeneous catalysts based on atomically dispersed ReO4 on inert supports for alcohol carbonylation.
- Bare, Simon R.,Christopher, Phillip,Finzel, Jordan,Hoffman, Adam S.,Pan, Xiaoqing,Qi, Ji,Robatjazi, Hossein,Xu, Mingjie
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supporting information
p. 14178 - 14189
(2020/09/16)
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- Alkyl substituted 4-N-oxazadisilinane cations: A new family of Si protic ionic liquids and its application on esterification reactions
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A series of oxazadisilinane compounds were prepared and used as Br?nsted bases to form a series of 21 siloxane protic ionic liquids (Si-PILs) with four different acids. This new family of Si-PILs were well characterized and examined to catalyze esterification reactions.
- Alhaddad, Maha,Chakraborty, Priyanka,Hu, Jinsong,Huang, Kuo-Wei
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supporting information
(2020/06/08)
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- Iron-catalysed 1,2-aryl migration of tertiary azides
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1,2-Aryl migration of α,α-diaryl tertiary azides was achieved by using the catalytic system of FeCl2/N-heterocyclic carbene (NHC) SIPr·HCl. The reaction generated aniline products in good yields after one-pot reduction of the migration-resultant imines.
- Wei, Kaijie,Yang, Tonghao,Chen, Qing,Liang, Siyu,Yu, Wei
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supporting information
p. 11685 - 11688
(2020/10/19)
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- A boron-doped carbon aerogel-supported Cu catalyst for the selective hydrogenation of dimethyl oxalate
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Carbon aerogels (CA) were applied in the synthesis of Cu/CA catalysts by the impregnation method and the catalysts with boron-doped CA supports were systematically characterized and evaluated in the hydrogenation of dimethyl oxalate (DMO). The Cu/xB-CA catalyst with 25 wt% copper showed 100% DMO conversion and the highest ethylene glycol (EG) or methyl glycolate (MG) selectivity of 70% at 230 °C as well as a lifetime of over 150 h. The characterization results disclosed the reason the performance of the catalysts could be tuned facilely by changing the amount of boron doping, which effectively influenced the interrelation between copper and CA, acidity and alkalinity of catalysts and Cu dispersion. Both the original carbon aerogels and that promoted with little B could provide larger surface areas and high dispersion of the metal. The species, size of copper particles and the ratio of Cu+/(Cu+ + Cu0) could be regulated by boron doping, thus adjusting the type of hydrogenation products.
- Lu, Xiaodong,Lu, Xiaodong,Wang, Guofu,Yang, Yu,Kong, Xiangpeng,Chen, Jiangang
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p. 3232 - 3240
(2020/03/06)
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- Designing a hierarchical nanosheet ZSM-35 zeolite to realize more efficient ethanol synthesis from dimethyl ether and syngas
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In this work, a dual-catalyst bed reactor packed with the combination of hierarchical nanosheet HZSM-35 (Hi-NZ35) zeolite and CuZnAl catalyst was proposed to realize more efficient ethanol synthesis from dimethyl ether (DME) and syngas (CO+H2). The nanosheet ZSM-35 (NZ35) zeolite was prepared via a direct hydrothermal synthesis route and the CuZnAl catalyst was prepared by co-precipitation method. Moreover, a series of Hi-NZ35x zeolites were obtained from NZ35 zeolite by further treatment with varied NaOH aqueous solution using hydrothermal process (“x” means the NaOH solution concentration of 0.2-0.6 M). The catalysts properties, such as crystallinity, porosity, acidity, morphology and composition, were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, NH3 temperature-programmed desorption (NH3-TPD), H2 temperature-programmed reduction (H2-TPR), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). It was found that Hi-NZ350.4 zeolite was more effective to obtain hierarchical porosity with mesopore volume up to 0.131 cm3 g?1. For single DME carbonylation reaction, the NZ35 zeolite exhibited superior catalytic activity (32.2%) and stability compared with conventional ZSM-35 (CZ35) zeolite. Furthermore, improved catalytic activity (42.0%) was observed on Hi-NZ350.4 zeolite owing to its abundant mesoporous structure. This result revealed that the hierarchical porosity of zeolite could effectively promote the catalytic performance of zeolite for DME carbonylation reaction. For the ethanol synthesis using the optimized catalysts combination of Hi-NZ350.4 zeolite and CuZnAl catalyst, the DME conversion was about 47.2% with higher ethanol productivity of 840.2 mmol kg?1 h?1.
- Feng, Xiaobo,Zhang, Peipei,Fang, Yuan,Charusiri, Witchakorn,Yao, Jie,Gao, Xinhua,Wei, Qinhong,Reubroycharoen, Prasert,Vitidsant, Tharapong,Yoneyama, Yoshiharu,Yang, Guohui,Tsubaki, Noritatsu
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p. 206 - 214
(2019/03/04)
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- METHOD FOR DIRECTLY PRODUCING ETHANOL FROM SYNGAS
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A method for directly producing ethanol from syngas, carried out in three reaction zones, including: feeding a raw material containing syngas and dimethyl ether into a first reaction zone to contact with a solid acid catalyst, reacting; allowing the effluent from the first reaction zone to enter a second reaction zone to contact with a metal catalyst and react; separating the effluent from the second reaction zone to obtain product ethanol and by-product methanol; allowing by-product methanol to enter a third reaction zone to perform a dehydration reaction to obtain dimethyl ether, and allowing the obtained dimethyl ether to enter the first reaction zone to recycle the reaction. This provides a novel method for directly converting syngas to ethanol and an ethanol product can be directly produced by using syngas as a raw material.
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Paragraph 0053-0056; 0060
(2020/08/05)
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- Insight into molecular packing effects on transesterification catalysis of zinc(II) coordination polymers
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Self-assembly of ZnX2 (X? = ClO4 ? and CF3SO3 ?) with naphthalene-2,6-diyl-diisonicotinate (L) gives rise to the 2D sheet structures with composition of [ZnL2(H2O)2](ClO4)2·H2O and [ZnL2(CF3SO3)2], respectively. [ZnL2(H2O)2](ClO4)2·H2O is packed in an interpenetration mode, whereas [ZnL2(CF3SO3)2] exists as a simple 2D network in the crystalline solid state. These two crystals have been employed as hetero-catalysts for transesterification reactions of phenylacetate with alcohol. The catalytic effect on the transesterification reaction shows the order of [ZnL2(H2O)2](ClO4)2·H2O > Zn(CF3SO3)2 > [ZnL2(OTf)2] > Zn(ClO4)2, which indicate that molecular packing is an important factor in the catalysis.
- Yang, Lingling,Kim, Dongwon,Hyun, Soomin,Lee, Young-A,Jung, Ok-Sang
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p. 139 - 145
(2019/12/24)
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- Ruthenium-catalyzed hydrogenation of CO2as a route to methyl esters for use as biofuels or fine chemicals
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A novel robust diphosphine-ruthenium(ii) complex has been developed that can efficiently catalyze both the hydrogenation of CO2 to methanol and its in situ condensation with carboxylic acids to form methyl esters; a TON of up to 3260 is achievable for the CO2 to methanol step. Both aromatic and aliphatic carboxylic acids can be transformed to their corresponding methyl esters with high conversion and selectivity (17 aliphatic and 18 aromatic examples). On the basis of a series of experiments, a mechanism has been proposed to account for the various steps involved in the catalytic pathway. More importantly, this approach provides a promising route for using CO2 as a C1 source for the production of biofuels, fine chemicals and methanol.
- Li, Yong,Liu, Qingbin,Ma, Yanping,Solan, Gregory A.,Sun, Wen-Hua,Wang, Zheng,Zhang, Qiuyue,Zhao, Ziwei,Zhong, Yanxia
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p. 6766 - 6774
(2020/08/25)
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- Catalytic conversion of ketones to esters: Via C(O)-C bond cleavage under transition-metal free conditions
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The catalytic conversion of ketones to esters via C(O)-C bond cleavage under transition-metal free conditions is reported. This catalytic process proceeds under solvent-free conditions and offers an easy operational procedure, broad substrate scope with excellent selectivity, and reaction scalability. This journal is
- Subaramanian, Murugan,Ramar, Palmurukan M.,Rana, Jagannath,Gupta, Virendra Kumar,Balaraman, Ekambaram
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supporting information
p. 8143 - 8146
(2020/09/09)
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- Tetrachloromethane Hydrodechlorination over Palladium-Containing Nanodiamonds
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Abstract: Using nanodiamonds of the UDD-STP brand 1 wt % palladium-containing nanodiamonds are obtained and tested as catalysts of tetrachloromethane hydrodechlorination under mild conditions (solvents, ethanol and methanol; Т = 298–318 K; PH2 = 0.1 MPa). The catalytic properties of the obtained material and a palladium-containing analog based on activated carbon are compared. It is shown that the hydrodechlorination reaction occurs in a stepwise manner via two pathways: to form products with a smaller content of chlorine, for example, chloroform, and to yield oxygen-containing products, for example, diethyl carbonate. The qualitative and quantitative compositions of reaction products are determined by gas chromatography/mass spectrometry.
- Belkina, E. G.,Gruzdev, M. S.,Kalmykov, P. A.,Klyuev, M. V.,Lysenok, A. A.,Magdalinova, N. A.
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p. 1148 - 1153
(2020/10/14)
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- In situ structural study of manganese and iron oxide promoted rhodium catalysts for oxygenate synthesis
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In situ x-ray diffraction (XRD) and absorption spectroscopy (XAS) was used to characterize the structure and phase composition of a novel Mn and Fe double-promoted Rh-based catalyst for CO hydrogenation to oxygenates. Catalysts with different Mn:Rh molar ratios were prepared by combining Mn and Rh precursors with Fe2O3 powder, which were then calcined in air and reduced under hydrogen. The resulting MnRh/Fe2O3 catalysts are found to be highly selective for ethanol synthesis (～40 %) for CO hydrogenation under mild conditions (～1 bar, 240 °C). Comparison of the reactivity results with quantitative phase information from in situ XRD measurements suggest that reduced metal oxides, MnO and FeOx, and metallic Rh co-exist as active phases to promote oxygenate selectivity. The results of this work also highlight the importance of in situ characterization for extracting meaningful information on the active phases of such complex, ternary catalysts which can vary under reaction conditions.
- Carrillo, Pamela,Senanayake, Sanjaya D.,Shi, Rui,White, Michael G.
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- Synthesis of an Oxathiolane Drug Substance Intermediate Guided by Constraint-Driven Innovation
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A new route was developed for construction of the oxathiolane intermediate used in the synthesis of lamivudine (3TC) and emtricitabine (FTC). We developed the presented route by constraining ourselves to low-cost, widely available starting materials - we refer to this as supply-centered synthesis. Sulfenyl chloride chemistry was used to construct the framework for the oxathiolane from acyclic precursors. This bond construction choice enabled the use of chloroacetic acid, vinyl acetate, sodium thiosulfate, and water to produce the oxathiolane.
- Burns, Justina M.,Gupton, B. Frank,Kashinath, K.,McQuade, D. Tyler,Snead, David R.,Stringham, Rodger W.
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p. 2266 - 2270
(2020/11/23)
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- Method for synthesizing propionate through ester-ester exchange path
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The invention provides a method for synthesizing propionate through an ester-ester exchange path and relates to a method for synthesizing the propionate. According to the method, reaction raw materials include, but are not limited to ethyl formate, propyl formate, butyl formate, ethyl acetate, propyl acetate, butyl acetate and the like; the method for synthesizing the propionate through an ester exchange one-step method is adopted. A catalyst comprises alkaline materials including ionic liquid, soluble strong base, solid base and the like respectively; the catalyst has the advantages of high catalysis efficiency and no pollution. By taking methyl propionate and ethyl acetate reaction as an example, KOH is used as the catalyst, the mol ratio of the raw materials is 1 to 1, the reaction temperature is 60 DEG C and the reaction time is 5 min; the conversion ratios of the methyl propionate and the ethyl acetate can reach 70 percent or more; products comprise ethyl propionate and the methylacetate. The whole reaction path has the characteristics of short synthetic route, simple technological flow and high yield and the catalyst is stable, does not become inactive and can be repeatedlyutilized.
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Paragraph 0030-0031
(2019/04/04)
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- Thermal Behavior Analysis of Two Synthesized Flavor Precursors of N-alkylpyrrole Derivatives
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To expand the library of pyrrole-containing flavor precursors, two new flavor precursors—methyl N-benzyl-2-methyl-5-formylpyrrole-3-carboxylate (NBMF) and methyl N-butyl-2-methyl-5-formylpyrrole-3-carboxylate (NUMF)—were synthesized by cyclization, oxidation, and alkylation reactions. Thermogravimetry (TG), differential scanning calorimeter, and pyrolysis–gas chromatography/mass spectrometry were utilized to analyze the thermal degradation behavior and thermal degradation products of NBMF and NUMF. The TG-DTG curve indicated that the maximum mass loss rates of NBMF and NUMF appear at 310 and 268°C, respectively. The largest peaks of NBMF and NUMF showed by the differential scanning calorimeter curve were 315 and 274°C, respectively. Pyrolysis–gas chromatography/mass spectrometry detected small molecule fragrance compounds appeared during thermal degradation, such as 2-methylpyrrole, 1-methylpyrrole-2-carboxylic acid methyl ester, limonene, and methyl formate. Finally, the thermal degradation mechanism of NBMF and NUMF was discussed, which provided a theoretical basis for their application in tobacco flavoring additives.
- Ai, Lvye,Liu, Mengzhen,Ji, Xiaoming,Lai, Miao,Zhao, Mingqin,Ren, Tianbao
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p. 2389 - 2397
(2019/08/01)
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- Esterification of Tertiary Amides by Alcohols Through C?N Bond Cleavage over CeO2
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CeO2 has been found to promote ester forming alcoholysis reactions of tertiary amides. The present catalytic system is operationally simple, recyclable, and it does not require additives. The esterification process displays a wide substrate scope (>45 examples; up to 93 % isolated yield). Results of a density functional theory (DFT) study combined with in situ FT-IR observations indicate that the process proceeds through rate limiting addition of a CeO2 lattice oxygen to the carbonyl group of the adsorbed acetamide species with energy barrier of 17.0 kcal/mol. This value matches well with experimental value (17.9 kcal/mol) obtained from analysis of the Arrhenius plot. Further studies by in situ FT-IR and temperature programmed desorption using probe molecules demonstrate that both acidic and basic properties are important, and consequently, CeO2 showed the best performance for the C?N bond cleavage reaction.
- Toyao, Takashi,Nurnobi Rashed, Md.,Morita, Yoshitsugu,Kamachi, Takashi,Hakim Siddiki,Ali, Md. A.,Touchy,Kon, Kenichi,Maeno, Zen,Yoshizawa, Kazunari,Shimizu, Ken-ichi
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p. 449 - 456
(2018/09/11)
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- Photolysis of Tp′Rh(CNneopentyl)(PhNCNneopentyl) in the presence of ketones and esters: Kinetic and thermodynamic selectivity for activation of different aliphatic C-H bonds
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The active fragment [Tp′Rh(CNneopentyl)], generated from the precursor Tp′Rh(CNneopentyl)(PhNCNneopentyl), underwent oxidative addition of substituted ketones and esters resulting in Tp′Rh(CNneopentyl)(R)(H) complexes (Tp′ = tris-(3,5-dimethylpyrazolyl)borate). These C-H activated complexes underwent reductive elimination at varying temperatures (24-70 °C) in C6D6 or C6D12. Using previously established kinetic techniques, the relative Rh-C bond strengths were calculated. Analysis of the relative Rh-C bond strengths vs. C-H bond strengths shows a linear correlation with slope RM-C/C-H = 1.22 (12). In general, α-substituents increase the relative Rh-C bond strengths compared to the C-H bond that is broken.
- Jones, William D.,Parsons, Astrid M.
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supporting information
p. 10945 - 10952
(2019/08/01)
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- HETERGENOUS CATALYSIS FOR THE ACETIC ACID PRODUCTION BY METHANOL CARBONYLATION
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Disclosed is a heterogeneous catalyst for producing acetic acid by carbonylation of methanol. In the heterogeneous catalyst, a rhodium complex ion is ionically bonded to an insoluble catalyst support, and the insoluble catalyst support includes a fluoropolymer having a quaternary pyridine radical alone or in combination with an acetate radical grafted on the surface thereof. According to the disclosure, a fixed-bed bubble column reactor can be easily designed. In addition, a special device for catalyst separation is not required, and thus the device manufacturing cost can be saved, the operating cost can be reduced due to process simplification, and productivity can be greatly increased.
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Paragraph 0062; 0064; 0065; 0066
(2019/03/08)
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- Synergy effects of Al2O3 promoter on a highly ordered mesoporous heterogeneous Rh-g-C3N4 for a liquid-phase carbonylation of methanol
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The effects of Lewis acid Al2O3 on Rh-incorporated mesoporous g-C3N4 (AlRh-CN) were investigated to verify an enhanced activity and stability in a liquid-phase carbonylation of methanol. The novel AlRh-CN with 2.0 wt%Al (Al(2)Rh-CN) revealed a higher yield of acetic acid (AA) and methyl acetate (MA) with a small Rh leaching. The enhanced activity on the optimal Al(2)Rh-CN was attributed to the highly dispersed and partially reduced Rh nanoparticles by preserving initial oxidation states as well as by maintaining its stronger interaction on the Al-modified g-C3N4 surfaces. Its superior activity was originated from the highly dispersed Lewis acid Al3+ sites assigned to Al2O3 phases due to an increased reverse esterification reaction rate. The higher activity on the Al(2)Rh-CN was originated from synergy effects such as a larger Lewis acid Al2O3 sites acting as a pillaring material to increase specific surface area of Al(2)Rh-CN and to increase a reverse esterification reaction.
- Kim, Da Mi,Kim, A Rong,Chang, Tae Sun,Koo, Hyun Mo,Kim, Jung Kyu,Han, Gui Young,Shin, Chae-Ho,Bae, Jong Wook
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- Zn(II) Complexes with Quinoline Supported Amidate Ligands: Synthesis, Fluorescence, and Catalytic Activity
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Zn(II) complexes of N-(quinolin-8-yl)picolinamide (HL1) (1) and N2,N6-di(quinolin-8-yl)pyridine-2,6-dicarboxamide (H2L2) (2) have been synthesized by deprotonation of the ligands and characterized by IR, NMR, and Single crystal X-ray crystallography. The mononuclear [Zn(L1)2] (3) and homodinuclear [Zn2(L2)2] (4) complexes are characterized by distorted octahedral geometries stabilized by hydrogen bonding and weak π···π interaction. The complexes demonstrate intense fluorescence bands in comparison with their corresponding ligands with well-distinguished intensity. The complexes act as efficient catalysts in various transesterification reactions. Among those, the best results have been achieved with complex 3 in conversion of 4-nitrophenylacetate into methyl acetate within 3 h.
- Malik, A.,Mughal, E. U.,Nazar, M. F.,Rafique, H.,Rehman, F.,Sumrra, S. H.,Yousuf, S.,Zafar, M. N.
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p. 2516 - 2521
(2020/02/25)
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- Selective Photo-Oxygenation of Light Alkanes Using Iodine Oxides and Chloride
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Partial oxidation of light alkanes to generate alkyl esters has been achieved under photochemical conditions using mixtures of iodine oxides and chloride salts in trifluoroacetic acid (HTFA). The reactions are catalytic in chloride and are successful using compact fluorescent light, but higher yields are obtained using a mercury lamp. In this photo-initiated oxyesterification process, the robust alkyl ester products are resistant to over-oxidation, and under optimized conditions yields for alkyl ester production of ～50 % based on methane, ～60 % based on ethane (with a total functionalized yield of EtX (X=TFA or Cl) of 80 %) and ～30 % based on propane have been demonstrated. The reaction also proceeds in aqueous HTFA and dichloroacetic acid with lower yields. Mechanistic studies indicate that the process likely operates by a chlorine hydrogen atom abstraction pathway wherein alkyl radicals are generated, trapped by iodine, and converted to alkyl trifluoroacetates in situ.
- Liebov, Nichole S.,Goldberg, Jonathan M.,Boaz, Nicholas C.,Coutard, Nathan,Kalman, Steven E.,Zhuang, Thompson,Groves, John T.,Gunnoe, T. Brent
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p. 5045 - 5054
(2019/10/28)
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- The carbonylation of dimethyl ether catalyzed by supported heteropoly acids: The role of Br?nsted acid properties
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The carbonylation of dimethyl ether (DME) to methyl acetate (MA) is a vital step in a direct route of ethanol production from syngas. Heteropoly acids (HPAs) as a kind of solid acid catalysts can facilitate the reaction. To improve the accessibility of Br?nsted acid sites, we prepared a series of supported HPAs catalysts by wetness impregnation on SBA-15. The impact of the HPAs loading and composition on the textural structure and acidic properties was investigated by comparing with the bulk HPAs. Taking acidity analysis (Pyridine-IR and TPD) and catalytic measurement results, we explored the effect of the amount and strength of Br?nsted acid site on this reaction. The observations demonstrated that more and stronger acid sites are prone to MA formation.
- Shen, Hongbao,Li, Ying,Huang, Shouying,Cai, Kai,Cheng, Zaizhe,Lv, Jing,Ma, Xinbin
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p. 117 - 123
(2018/04/20)
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- Amide/Iminium Zwitterionic Catalysts for (Trans)esterification: Application in Biodiesel Synthesis
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A class of zwitterionic organocatalysts based on an amide anion/iminium cation charge pair has been developed. The zwitterions are easily prepared by reacting aziridines with aminopyridines. They are catalytically applicable to transesterifications and dehydrative esterifications. Mechanistic studies reveal that the amide anion and iminium cation work synergistically in activating the reaction partners, with the iminium cationic moiety interacting with the carbonyl substrates through nonclassical hydrogen bonding. The reaction can be applied to large-scale synthesis of biodiesel under mild conditions.
- Lam, Ying-Pong,Ng, Wing-Hin,Tan, Fei,Tse, Ying-Lung Steve,Wang, Xinyan,Yeung, Ying-Yeung
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p. 8083 - 8092
(2019/08/26)
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- Direct Conversion of Syngas into Methyl Acetate, Ethanol, and Ethylene by Relay Catalysis via the Intermediate Dimethyl Ether
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Selective conversion of syngas (CO/H2) into C2+ oxygenates is a highly attractive but challenging target. Herein, we report the direct conversion of syngas into methyl acetate (MA) by relay catalysis. MA can be formed at a lower temperature (ca. 473 K) using Cu-Zn-Al oxide/H-ZSM-5 and zeolite mordenite (H-MOR) catalysts separated by quartz wool (denoted as Cu-Zn-Al/H-ZSM-5|H-MOR) and also at higher temperatures (603–643 K) without significant deactivation using spinel-structured ZnAl2O4|H-MOR. The selectivity of MA and acetic acid (AA) reaches 87 % at a CO conversion of 11 % at 643 K. Dimethyl ether (DME) is the key intermediate and the carbonylation of DME results in MA with high selectivity. We found that the relay catalysis using ZnAl2O4|H-MOR|ZnAl2O4 gives ethanol as the major product, while ethylene is formed with a layer-by-layer ZnAl2O4|H-MOR|ZnAl2O4|H-MOR combination. Close proximity between ZnAl2O4 and H-MOR increases ethylene selectivity to 65 %.
- Zhou, Wei,Kang, Jincan,Cheng, Kang,He, Shun,Shi, Jiaqing,Zhou, Cheng,Zhang, Qinghong,Chen, Junchao,Peng, Luming,Chen, Mingshu,Wang, Ye
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p. 12012 - 12016
(2018/09/10)
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- Hyper-Cross-Linked Polyacetylene-Type Microporous Networks Decorated with Terminal Ethynyl Groups as Heterogeneous Acid Catalysts for Acetalization and Esterification Reactions
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Heterogeneous catalysts based on materials with permanent porosity are of great interest owing to their high specific surface area, easy separation, recovery, and recycling ability. Additionally, porous polymer catalysts (PPCs) allow us to tune catalytic activity by introducing various functional centres. This study reports the preparation of PPCs with a permanent micro/mesoporous texture and a specific surface area SBET of up to 1000 m2 g?1 active in acid-catalyzed reactions, namely aldehyde and ketone acetalization and carboxylic acid esterification. These PPC-type conjugated hyper-cross-linked polyarylacetylene networks were prepared by chain-growth homopolymerization of 1,4-diethynylbenzene, 1,3,5-triethynylbenzene and tetrakis(4-ethynylphenyl)methane. However, only some ethynyl groups of the monomers (from 58 to 80 %) were polymerized into the polyacetylene network segments while the other ethynyl groups remained unreacted. Depending on the number of ethynyl groups per monomer molecule and the covalent structure of the monomer, PPCs were decorated with unreacted ethynyl groups from 3.2 to 6.7 mmol g?1. The hydrogen atoms of the unreacted ethynyl groups served as acid catalytic centres of the aforementioned organic reactions. To the best of our knowledge, this is first study describing the high activity of hydrogen atoms of ethynyl groups in acid-catalyzed reactions.
- Sekerová, Lada,Lhotka, Miloslav,Vysko?ilová, Eli?ka,Faukner, Tomá?,Slováková, Eva,Brus, Ji?í,?erveny, Libor,Sedlá?ek, Jan
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p. 14742 - 14749
(2018/09/25)
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- Acidic ionic liquid based UiO-67 type MOFs: A stable and efficient heterogeneous catalyst for esterification
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A facile strategy for the synthesis of acidic ionic liquid based UiO-67 type MOFs was developed in this study. Br?nsted acids (H2SO4, CF3SO3H and hifpOSO3H (hexafluoroisopropyl sulfuric acid)) were introduced into UiO-67-bpy (bpy = 2,2′-bipyridine-5,5′-dicarboxylic acid) frameworks by reacting with bipyridyl nitrogen to introduce the properties of an acidic ionic liquid into the frameworks. The prepared catalysts, denoted as UiO-67-HSO4, UiO-67-CF3SO3 and UiO-67-hifpOSO3, were characterized by XRD, SEM, FT-IR, EA, TGA and N2 adsorption-desorption studies. The relatively high surface area was still maintained and acidic active groups were uniformly dispersed in the frameworks. The catalytic performance of UiO-67-HSO4, UiO-67-CF3SO3 and UiO-67-hifpOSO3 was evaluated by the esterification of acetic acid with isooctyl alcohol. The prepared catalysts showed good catalytic activities in the esterification, of which UiO-67-CF3SO3 gave the maximum isooctyl alcohol conversion of 98.6% under optimized conditions. The catalyst could be reused five times without a significant decrease in the conversion of isooctyl alcohol, and almost no active species were leached, indicating the excellent stability and reusability of the catalyst. Our study provides one effective way to synthesize heterogeneous acidic ionic liquid catalysts consisting of isolated, well defined acidic groups that will probably attract interest in acid catalyst chemistry.
- Xu, Zichen,Zhao, Guoying,Ullah, Latif,Wang, Meng,Wang, Aoyun,Zhang, Yanqiang,Zhang, Suojiang
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p. 10009 - 10016
(2018/03/23)
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- Synthesis and characterization of a novel Mn(III)-(γ-diketone) complex with catalytic and antifungal activity
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A novel Mn(III) complex with γ-diketone having general formula [Mn(hdo)3], where hdo = hexane-2,5-dione ligand, has been synthesized and characterized using UV–vis, FT-IR, ESI-mass and EPR spectra, elemental analysis, powder X-ray diffraction, SEM, and magnetic susceptibility measurements. The X-ray diffraction studies reveal that it has monoclinic lattice system with C2/C space group and the unit cell dimensions are a = 9.92245 ?, b = 10.50696 ?, and c = 9.80835 ?. The particle size of this complex has been found to be 32.1 nm. The complex was evaluated for its antifungal activity against Aspergillus flavus, Aspergillus niger, and Aspergillus terreus fungal species. The results indicate that the minimum inhibitory concentration of the synthesized complex was 8 ppm for A. niger while for A. flavus and A. terreus it was 6 ppm. β-Diketone Mn(III) complexes inhibit the fungal growth only partially. This communication is the first report of transformation of a keto-group to an ester group catalyzed by a metal complex.
- Dubey, Priti,Yadava, Sudha
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p. 3392 - 3404
(2018/10/20)
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- New Architectures for Designed Catalysts: Selective Oxidation using AgAu Nanoparticles on Colloid-Templated Silica
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A highly modular synthesis of designed catalysts with controlled bimetallic nanoparticle size and composition and a well-defined structural hierarchy is demonstrated. Exemplary catalysts—bimetallic dilute Ag-in-Au nanoparticles partially embedded in a porous SiO2 matrix (SiO2–AgxAuy)—were synthesized by the decoration of polymeric colloids with the bimetallic nanoparticles followed by assembly into a colloidal crystal backfilled with the matrix precursor and subsequent removal of the polymeric template. This work reports that these new catalyst architectures are significantly better than nanoporous dilute AgAu alloy catalysts (nanoporous Ag3Au97) while retaining a clear predictive relationship between their surface reactivity with that of single-crystal Au surfaces. This paves the way for broadening the range of new catalyst architectures required for translating the designed principles developed under controlled conditions to designed catalysts under operating conditions for highly selective coupling of alcohols to form esters. Excellent catalytic performance of the porous SiO2–AgxAuy structure for selective oxidation of both methanol and ethanol to produce esters with high conversion efficiency, selectivity, and stability was demonstrated, illustrating the ability to translate design principles developed for support-free materials to the colloid-templated structures. The synthetic methodology reported is customizable for the design of a wide range of robust catalytic systems inspired by design principles derived from model studies. Fine control over the composition, morphology, size, distribution, and availability of the supported nanoparticles was demonstrated.
- Shirman, Tanya,Lattimer, Judith,Luneau, Mathilde,Shirman, Elijah,Reece, Christian,Aizenberg, Michael,Madix, Robert J.,Aizenberg, Joanna,Friend, Cynthia M.
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p. 1833 - 1837
(2017/11/20)
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- Photodegradation of methyl thioglycolate particles as a proxy for organosulphur containing droplets
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Understanding the formation and transformation of sulphur-rich particles is of prime importance since they contribute to the global atmospheric sulphur budget. In this work, we performed a series of experiments on a photoactive organosulphur compound namely, methyl thioglycolate, as a model of an organosulphur species of marine origin. By investigating the photoproducts within levitated droplets, we showed that elemental sulphur (α-S8) and sulphate (SO42-) can be photochemically generated at the gas-liquid interface by heterogeneous interaction with gaseous O2 and H2O. These results demonstrate that the surface of levitated droplets facilitate the oxidation of methyl thioglycolate in the dark, while illumination is necessary to produce the oxidation in bulk experiments.
- Seng, Samantha,Picone, A. Lorena,Bava, Yanina B.,Juncal, Luciana C.,Moreau, Myriam,Ciuraru, Raluca,George, Christian,Romano, Rosana M.,Sobanska, Sophie,Tobon, Yeny A.
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p. 19416 - 19423
(2018/08/09)
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