- Pillared cobalt-amino acid framework catalysis for styrene carbonate synthesis from CO2 and epoxide by metal-sulfonate-halide synergism
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The sulfonate anion is proposed as a remarkable partaker in catalyzing epoxide-CO2 cycloaddition for cyclic carbonate synthesis. The role is illustrated by the concerted action of a sulfonate-rich cobalt-amino acid framework catalyst [{Co(4,4′-bipy)(L-cys)(H2O)}×H 2O]n (2 D-CCB) and a quaternary ammonium bromide co-catalyst in synthesizing styrene carbonate (SC) at a turnover number of 228. SC yield at atmospheric pressure is presumed to result from the activation of CO2 by the sulfonate group. The involvement of SO3 - anions as basic sites in 2 D-CCB is ascertained from the initial rate (r0) for catalyzing Knoevenagel condensation reactions and by using CO2 temperature programmed desorption. Microwave pulses are used for synthesizing 2 D-CCB at a rate that is 288-fold faster than conventionally employed solvothermal methods. Unambiguous evidence for the pulsating role-play of sulfonate groups in 2 D-CCB is perceived by comparing the activity of an analogous metal organic framework (3 D-CCB) in which the sulfonate oxyanions are jammed by coordination with cobalt. 2 D-CCB is analyzed for heterogeneity, and reused four times. Copyright
- Kathalikkattil, Amal Cherian,Roshan, Roshith,Tharun, Jose,Soek, Han-Geul,Ryu, Hyeong-Seok,Park, Dae-Won
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- Syntheses, structures and reactivity of dinuclear organoruthenium-nickel complexes with N,N′-bis(2-thiobenzylidene)-1,2-phenylenediaminato (tsalphen) ligand
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Treatment of metalloligand [Ni(tsalphen)] (tsalphen = N,N′-bis(2-thiobenzylidene)-1,2-phenylenediaminato) with [(η6-p-cymene)RuCl(μ-Cl)]2 or [CpRu(PPh3)2Cl] afforded cationic “Ni(μ-S)2Ru” bimetallic complexes [(η6-p-cymene)Ru{Ni(tsalphen)}(MeCN)](OTf)2 (1) and [CpRu{Ni(tsalphen)}(PPh3)]2(NiCl4)?4MeOH (2), respectively, which are characterized by single-crystal X-ray diffraction, and their catalytic activity for acetalation of benzaldehyde in the presence of H2 was also investigated.
- Jia, Ai-Quan,Tang, Li-Hua,Dong, Xian-Ping,Xin, Zhifeng,Zhang, Qian-Feng
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- Syntheses, characterization and reactivity of dinuclear ruthenium-nickel complexes with hexane-2,5-dione bis(thiosemicarbazonato) ligands
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Treatment of hexane-2,5-dione bis(thiosemicarbazones) ([CH3?C{= N?NH?C(=S)?NHR}?CH2]2, R = H, L1H2; CH3, L2H2?Me; CH2CH3, L3H2?Et; C6H5, L4H2?Ph) with nickel(II) acetate hydrate in refluxing ethanol gave a series of NiIIN2S2 metalloligands [Ni(L-R)] for the generation of hetero-bimetallic complexes. The reaction of equal mole each of [Ni(L1)], [Ni(L2?Me)], [Ni(L3?Et)], or [Ni(L4?Ph)] with [RuCl2(dmso)4] (dmso = dimethyl sulfoxide) at reflux resulted in isolation of neutral dinuclear ruthenium-nickel complexes [RuCl2{(Ni(L1)}(dmso)2] (1), [RuCl2{(Ni(L2?Me)}(dmso)2] (2), [RuCl2{(Ni(L3?Et)}(dmso)2] (3), and [RuCl2{(Ni(L4?Ph)}(dmso)2] (4). Interaction of [Ni(L-R)] with [CpRu(PPh3)2Cl] (Cp? = cyclopentadienyl) at room temperature led to formation of cationic dinuclear organoruthenium-nickel complexes [CpRu{(Ni(L1)}(PPh3)]Cl (5), [CpRu{(Ni(L2?Me)}(PPh3)]Cl (6), [CpRu{(Ni(L3?Et}(PPh3)]Cl (7), and [CpRu{(Ni(L4?Ph}(PPh3)]Cl (8). New bimetallic ruthenium-nickel complexes 1–8 have been characterized spectroscopically, of which molecular structures of three complexes [RuCl2{(Ni(L2?Me)}(dmso)2]·CH2Cl2 (2·CH2Cl2), [CpRu{(Ni(L2?Me)}(PPh3)]Cl?EtOH (6?EtOH), and [CpRu{(Ni(L3?Et}(PPh3)]Cl (7?H2O) have been established by single-crystal X-ray crystallography. Their catalytic activities for the acetalation of benzaldehyde in the presence of molecular H2 have been also investigated in this paper.
- Fang, Duo-Wen,Jia, Ai-Quan,Dong, Xian-Ping,Xin, Zhifeng,Zhang, Qian-Feng
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- Conjugate addition of acetal-derived benzyl radicals generated from low-valent titanium-mediated CO bond cleavage
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A new method for the generation of benzyl radicals from acetals via low-valent titanium-mediated homolytic CO bond cleavage is presented. The low cost and availability of the developed titanium reagent enable efficient access to α-alkoxy carbon radical species via the developed reaction.
- Suga, Takuya,Nakamura, Masaharu,Takada, Ryusei,Ukaji, Yutaka
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supporting information
p. 1258 - 1260
(2021/05/17)
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- Thiol-initiated photocatalytic oxidative cleavage of the C=C bond in olefins and its extension to direct production of acetals from olefins
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The oxidative cleavage of olefins to produce aldehydes/ketones is an important reaction in organic syntheses. In this manuscript, a mild and operationally simple protocol for the aerobic oxidation of olefins to produce carbonyl compounds was realized over ZnIn2S4under visible light, using air as the oxidant and a thiol as the initiator. It was proposed that the photogenerated holes over ZnIn2S4attack the thiol to produce thiyl radicals, which initiate the oxidative cleavage of the C=C bond in olefins to produce aldehydes/ketones. By further coupling with the condensation between the as-obtained aldehydes/ketones and alcohols, this strategy can also be applied to the production of different acetals directly from the olefins. This study demonstrates a new pathway to realize the oxidative cleavage of olefins to produce aldehydes/ketones, and also provides a new protocol for the production of acetals directly from the olefins.
- Wang, Xinglin,Li, Yuanyuan,Li, Zhaohui
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p. 1000 - 1006
(2021/02/26)
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- Metal nitrate-catalyzed one-pot oxidative esterification of benzaldehyde with hydrogen peroxide in alcoholic solutions at room temperature
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The activity of metal nitrate catalysts was investigated in the oxidative esterification reactions of benzaldehyde with hydrogen peroxide. Several types of metal nitrates (alkaline, alkaline earth, and transition metals) were evaluated as catalysts. Among the assessed salts, Fe(NO3)3 was the most efficient catalyst toward the formation of the target product (i.e., benzoic alkyl ester). In methyl alcohol, benzaldehyde was selectively oxidized to benzoic acid and then esterified to methyl benzoate. The efficiency of the catalyst was correlated with its higher Lewis acidity character, which was established through the pH measurements of methanolic solutions of the soluble metal nitrate salts. The influence of main variables of the reaction, such as catalyst load, temperature, and reactant stoichiometry, was investigated. The size of the carbon chain and steric hindrance played an essential role in the reaction selectivity. While methyl and ethyl alcohols selectively provided ester as the main product (ca. 70-75%) and acetal as the subproduct, the other alcohols gave ester, hemiacetal, and benzoic acid, which was formed in the least amount. The use of an inexpensive catalyst, a green oxidant, mild conditions, and short reaction times were the positive aspects of this one-pot process. The high TON (ca. 900) is evidence of the high catalytic activity of Fe(NO3)3. It is noteworthy that this methodology does not rely upon ligands and other additives.
- Da Silva, Márcio José,De Oliveira, Cesar Macedo
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p. 3683 - 3691
(2021/03/03)
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- Method for synthesizing 4-tert-butyl benzaldehyde
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The invention discloses a method for synthesizing 4-tert-butyl benzaldehyde and belongs to the technical field of organic synthesis. The method comprises the steps of subjecting benzaldehyde and triorthoformate to a reaction to produce benzaldehyde acetal, then, subjecting the benzaldehyde acetal and isobutene to a sealed reaction in the presence of a catalyst, and carrying out acid quenching, thereby obtaining the 4-tert-butyl benzaldehyde. According to the method, the 4-tert-butyl benzaldehyde is obtained through adopting benzaldehyde protection, then, firstly, becoming an electron donatingorientating group, and then, prompting selective localization of the isobutene by employing an appropriate catalyst; and a ratio of a 2-tert-butyl benzaldehyde isomer to the product is smaller than 1:14, and after the reaction ends up, the process is applicable to industrialized large-scale production.
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Paragraph 0016; 0020-0022
(2020/02/19)
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- The effect of solvents on the thermal degradation products of two Amadori derivatives
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To enrich the flavor additives of the Maillard reaction, two Amadori analogs, N-(1-deoxy-d-fructosyl-1-yl)-l-phenylalanine ester (Derivative 1) and di-O-isopropylidene-2,3:4,5-?-d-fructopyranosyl phenylalanine ester (Derivative 2), were chemically synthes
- Li, Rui,Zhang, Shiyi,Zhang, Yudan,Zhao, Mingqin
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p. 9309 - 9317
(2020/03/23)
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- Synergistic catalysis of hybrid nano-structure Pd catalyst for highly efficient catalytic selective hydrogenation of benzaldehyde
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Selective hydrogenation of benzaldehyde is a green and sustainable technology to produce benzyl alcohol. Herein, we report a hybrid nano-structure catalyst(Pd/@-ZrO2/AC) by photochemical route for selective hydrogenation of benzaldehyde under m
- Zhang, Yanji,Zhou, Jicheng,Li, Kai,Lv, Mengdie
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p. 129 - 137
(2020/01/28)
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- Formation of Acetals and Ketals from Carbonyl Compounds: A New and Highly Efficient Method Inspired by Cationic Palladium
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The development of a new, highly efficient, and simple method for masking carbonyl groups as acetals and ketals is described. This methodology relies on the nature of the palladium catalyst to direct the acetalization/ketalization reaction. This new protocol is mild and proceed with a very low catalyst loading at ambient temperatures. The method has been extended to a wide variety of different carbonyl compounds with various steric encumbrances to form the corresponding acetals and ketals in excellent yields.
- Green, Shawn D.,Kindoll, Tyler,Lazaro-Martinez, Brenda,Mensah, Enoch A.,West, Jesse
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p. 1810 - 1814
(2019/09/09)
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- Synthesis of (E)-α,β-unsaturated carboxylic esters derivatives from cyanoacetic acid via promiscuous enzyme-promoted cascade esterification/Knoevenagel reaction
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A new enzymatic protocol based on lipase-catalyzed cascade toward (E)-α,β-unsaturated carboxylic esters is presented. The proposed methodology consists of elementary organic processes starting from acetals and cyanoacetic acid leading to the formation of desired products in a cascade sequence. The combination of enzyme promiscuous abilities gives a new opportunity to synthesize complex molecules in the one-pot procedure. Results of studies on the influence of an enzyme type, solvent, and temperature on the cascade reaction course are reported. The presented methodology provides meaningful qualities such as significantly simplified process, excellent E-selectivity of obtained products and recycling of a biocatalyst.
- Wilk, Monika,Trzepizur, Damian,Koszelewski, Dominik,Brodzka, Anna,Ostaszewski, Ryszard
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- Direct anodic (thio)acetalization of aldehydes with alcohols (thiols) under neutral conditions, and computational insight into the electrochemical formation of the acetals
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A versatile protocol for the production of acetals/thioacetals by means of direct electrochemical oxidation is developed here under neutral conditions, providing (thio)acetals with good functional group tolerance and a wide scope for both aldehydes and (thio)alcohols. DFT calculations reveal that direct electron transfer from the anode plays a key role in carbonyl activation during this acid free acetalization process.
- Liu, Caiyan,Shen, Yongli,Xiao, Zihui,Yang, Hui,Han, Xue,Yuan, Kedong,Ding, Yi
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p. 4030 - 4034
(2019/08/07)
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- Highly selective synthesis under benign reaction conditions of furfural dialkyl acetal using SnCl2 as a recyclable catalyst
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A new and mild route of furfural acetalization with various alkyl alcohols catalyzed by cheap and simple SnCl2 has been developed. This process consists of the conversion of furfural to alkyl acetals under benign and mild reaction conditions (i.e., room temperature, without solvent, recyclable catalyst), achieving a very good selectivity (97-100%) and almost complete conversion of furfural. Various tin(ii) salts were used as catalysts for the upgrading of furfural to alkyl acetal in an alcoholic solution at room temperature. SnCl2 was the most active and selective catalyst toward furfural diethyl acetal. Tin(ii) chloride is a commercially available and water tolerant Lewis acid and was demonstrated to be an efficient and recyclable catalyst for the synthesis of furfural alkyl acetal. The effects of the main variables of the reaction such as the catalyst load, temperature, reaction time and alcohol nature were assessed. SnCl2 was easily recovered and reused without loss of activity and selectivity.
- Da Silva, Márcio José,Teixeira, Milena Galdino,Natalino, Ricardo
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p. 8606 - 8612
(2019/06/14)
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- Ce(III)-Based frameworks: From 1d chain to 3d porous metal-organic framework
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The reaction of pyridine-2,4-dicarboxylic acid (2,4-H2 pydc) with Ce(NO3)36H2O, by applying only minor changes to the reaction conditions, generated a series of new one-, two-, and three-dimensional (1D, 2D, and 3D) coordination polymers, namely, [Ce(pydc)(Hpydc)(H2O)4]n (1), [Ce(pydc)(Hpydc)(H2O)2]n (2), and {[Ce3(pydc)4(H2O)2NO3]4H2O}n (3). The ancillary ligand interaction as well as the reaction conditions determine the specific coordination modes for the Hpydc- and pydc2- ligands and, in turn, discriminate between 1D, 2D, and 3D frameworks. Characterization of the prepared materials was performed using single-crystal and powder X-ray diffraction analysis, Fourier transform infrared spectroscopy, CHN elemental analysis, thermogravimetric analysis, and nitrogen adsorption/desorption techniques. Compound 1 consists of 1D chains, that compose of Ce3+ ions bridged by Hpydc- and pydc2- ligands, which further link via noncovalent interactions to form a 3D supramolecular architecture. Compound 2 assembles into 2D sheets with 1D channels. Similarly, via hydrogen-bonding interactions between two adjacent sheets, the 2D layers are further stacked into the final 3D supramolecular structure. Compound 3 is a 3D metal-organic framework (MOF), showing 1D helical channels. The progressive skeletal variation from the 1D chains (1) to 2D sheets (2) and 3D framework (3) is attributed to the flexibility of both the Ce(III) coordination sphere and coordination modes of the Hpydc- and pydc2- ligands under different reaction conditions. The three compounds illustrate how the tuning of the coordination geometry of Ce(III) translates into different dimensionality, which is readily influenced by reaction temperature and ancillary ligand presence. Moreover, the porosity of MOF 3 was confirmed by N2 and CO2 gas adsorption/desorption. Finally, the catalytic activity of MOF 3 was examined in acetalization reactions in a series of aromatic aldehydes with methanol.
- Derakhshandeh, Parviz Gohari,Abednatanzi, Sara,Leus, Karen,Janczak, Jan,Van Deun, Rik,Van Der Voort, Pascal,Van Hecke, Kristof
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p. 7096 - 7105
(2019/11/19)
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- Ru(II)-functionalized SBA-15 as highly chemoselective, acid free and sustainable heterogeneous catalyst for acetalization of aldehydes and ketones
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Combining electron deficient Ru(II) coordination sites with organofunctionalized SBA-15, (L)Ru(II)@SBA-15, result in a mild, neutral, water scavenger free and chemo-selective acetalization catalyst for cyclic/acyclic acetals. Vacant coordination sites of ruthenium in (L)Ru(II)@SBA-15 activates protecting groups as well as reactants simultaneously and restricts the reverse acetalization reaction. Synthesized (L)Ru(II)@SBA-15 catalyst has been thoroughly characterized and act as competitive catalyst compared to conventional acid catalysts. (L)Ru(II)@SBA-15 performs high catalytic activity as well as selectivity within 20 min with high TOF. The catalyst can be recycled and reaction parameters are optimized.
- Lazar, Anish,Betsy,Vinod,Singh
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- A Linear Trinuclear Oxidodiperoxido-molybdenum(VI) Complex with Single Triazole Bridges: Catalytic Activity in Epoxidation, Alcoholysis, and Acetalization Reactions
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The complex (Htrz)2[Mo3O6(O2)4(trz)2]?H2O (1), isolated from the reaction of MoO3 with H2O2 in the presence of 1,2,4-triazole (trz), displays singular structural features such as double bridges comprising one oxido and one triazole ligand, and peripheral oxidodiperoxido-molybdenum(VI) units. A comparative study was performed regarding the catalytic activity and stability of complex 1 and the hybrid material [MoO3(trz)0.5] (2) for the epoxidation of cis-cyclooctene (Cy8), the alcoholysis of epoxides, and the acetalization of benzaldehyde (PhCHO). Methanol or ethanol were used as solvents and reagents for the latter two reactions. For the substrates Cy8, styrene oxide, and PhCHO, the corresponding epoxide, β-alkoxy alcohol, and dialkyl acetal were obtained with 100 % selectivity at very high conversions. In general, 1 performed better than 2 for the different catalytic reactions. Under certain oxidant/co-solvent conditions used for Cy8 epoxidation, 1 was converted to 2 during the reaction.
- Antunes, Margarida M.,Amarante, Tatiana R.,Valente, Anabela A.,Almeida Paz, Filipe A.,Gon?alves, Isabel S.,Pillinger, Martyn
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p. 2782 - 2791
(2018/07/24)
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- Preparation of acetals from aldehydes and alcohols under basic conditions
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A new, simple protocol for the synthesis of acetals under basic conditions from non-enolizable aldehydes and alcohols has been reported. Such reactivity is facilitated by a sodium alkoxide along with a corresponding trifluoroacetate ester, utilizing formation of sodium trifluoroacetate as a driving force for acetal formation. The usefulness of this protocol is demonstrated by its orthogonality with various acid-sensitive protecting groups and by good compatibility with functional groups, delivering synthetically useful acetals complementarily to the synthesis under acidic conditions from aldehydes and alcohols.
- Grabowski, Jakub,Granda, Jaros?aw M.,Jurczak, Janusz
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p. 3114 - 3120
(2018/05/17)
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- Antimony(v) catalyzed acetalisation of aldehydes: An efficient, solvent-free, and recyclable process
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A highly selective, solvent-free process for the acetalisation of aldehydes was achieved by the use of a readily accessible antimony(v) catalyst which we previously prepared in our lab as a tetraarylstibonium triflate salt ([1][OTf]). High yields of the acetals were achieved in the presence of stoichimetric amounts of either triethoxymethane or triethoxysilane. It was found that triethoxymethane reactions required longer time to reach completion when compared to triethoxysilane reactions which were completed upon mixing of the reagents. The products can be easily separated from the catalyst by distillation which enabled further use of [1][OTf] in additional calytic reactions (up to 6 cycles). Moreover, [1]+ also catalyzed the deprotection of the acetals into their corresponding aldehydes using only water as a solvent.
- Ugarte, Renzo Arias,Hudnall, Todd W.
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p. 1990 - 1998
(2017/06/09)
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- Phosphorylated Polyacrylonitrile Fibers as an Efficient and Greener Acetalization Catalyst
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A novel solid acid catalyst (PANEAPF) is developed by immobilization of phosphoric acid on polyacrylonitrile fiber through covalent bonding. Various characterization techniques such as elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), etc. are utilized to confirm the successful grafting and the stability of the fiber catalysts during application. PANEAPF shows high catalytic activity in the acetalization of aldehydes owing to the high utilization efficiency of its functionalized acid sites. In addition, the strong polarity micro-environment in the surface layers of PANEAPF make it highly suitable for catalytic application in both water and alcohol. Furthermore, the fiber catalyst can be applied to the acetalization of aldehydes in a continuous-flow process at room temperature, and shows excellent reactivity and superior recyclability (over 20 times). The many advantages of PANEAPF such as simple preparation, convenient regulation of acid amount, high durability, and eco-friendly process make it very attractive for fixed-bed reactors in the chemical industry.
- Xu, Gang,Cao, Jian,Zhao, Yali,Zheng, Lishuo,Tao, Minli,Zhang, Wenqin
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supporting information
p. 2565 - 2575
(2017/09/25)
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- Facile synthesis of Cu3(BTC)2/cellulose acetate mixed matrix membranes and their catalytic applications in continuous flow process
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Metal-organic framework (MOF)-based mixed matrix membranes (MMMs) were fabricated by a combination of Cu3(BTC)2 MOF and polymer cellulose acetate. The cellulose acetate in the MMMs served as the matrix and the Cu3(BTC)2 MOF as the filler. The as-synthesized MMMs were utilized as a heterogeneous catalyst for aldehyde acetalization. The characterization techniques indicated that the Cu3(BTC)2 crystals were uniformly dispersed in the MMMs. The BET surface area of the Cu3(BTC)2-based MMM was measured to be 459 m2 g-1 at 60 wt% Cu3(BTC)2 loading. Furthermore, the MMMs served as an excellent catalyst under our continuous flow catalytic reaction conditions. The optimal catalytic result of benzaldehyde yield reached 94% with 60 wt% Cu3(BTC)2 loading of the MMMs at room temperature and the benzaldehyde diethyl acetal reached 0.59 mmol min-1 gCu-BTC-1.
- Hou, Junying,Luan, Yi,Huang, Xiubing,Gao, Hongyi,Yang, Mu,Lu, Yunfeng
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p. 9123 - 9129
(2017/08/29)
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- Knoevenagel condensation reaction catalysed by Al-MOFs with CAU-1 and CAU-10-type structures
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The metal-organic frameworks (MOFs) CAU-1-NH2 ([Al4(OH)2(OCH3)4(p-BDC-NH2)3], (p-BDC-NH2)2- = 2-aminoterephthalate) and CAU-10-NH2 ([Al(OH)(m-BDC-NH2)], (m-BDC-NH2)2- = 5-aminoisophthalate) which possess two different pore sizes were studied for their catalytic activity as heterogeneous solid base catalysts in the Knoevenagel condensation reaction between benzaldehyde and malononitrile under mild reaction conditions (40 °C, 7 h, ethanol). For comparison, isoreticular MOFs containing a smaller amount of -NH2 groups (CAU-1-NH2/H) or no -NH2 groups (CAU-10-H) were synthesized. A two-step synthesis route including the synthesis of CAU-1-NH2 and its use as crystal seeds was developed to obtain the mixed-linker CAU-1-NH2/H compound. Only for CAU-1-NH2, up to 100% selectivity towards the desired Knoevenagel condensation product is observed. Hence, the catalytic activity of CAU-1-NH2 was tested between various benzaldehydes containing different substituents with malononitrile. By employing benzaldehyde and malononitrile as the starting materials, it is found that the mixed-linker MOF CAU-1-NH2/H catalyses the formation of the acetal (benzaldehyde diethyl acetal), while both CAU-10 materials lead to mixtures of the two products. Furthermore, the catalyst stability was also examined through reusability and leaching experiments and it is observed that the catalyst can be reused with no significant drop in its activity.
- Dhakshinamoorthy, Amarajothi,Heidenreich, Niclas,Lenzen, Dirk,Stock, Norbert
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p. 4187 - 4193
(2017/08/04)
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- Effect of the degree of dispersion of Pt over MgAl2O4 on the catalytic hydrogenation of benzaldehyde
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One of the central tasks in the field of heterogeneous catalysis is to establish structure-function relationships for these catalysts, especially for precious metals dispersed on the sub-nanometer scale. Here, we report the preparation of MgAl2
- Yan, Feng,Zhao, Caixian,Yi, Lanhua,Zhang, Jingcai,Ge, Binghui,Zhang, Tao,Li, Weizhen
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p. 1613 - 1620
(2017/09/20)
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- Liquid-phase hydrogenation of benzaldehyde over Pd-Ru/C catalysts: Synergistic effect between supported metals
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Bimetallic Pd-Ru/C catalysts prepared with different carbon supports were shown to be much more active in the liquid-phase hydrogenation of benzaldehyde in comparison with their monometallic analogs. In the case of systems based on nanoglobular carbon, th
- Mironenko, Roman M.,Belskaya, Olga B.,Gulyaeva, Tatyana I.,Trenikhin, Mikhail V.,Nizovskii, Alexander I.,Kalinkin, Alexander V.,Bukhtiyarov, Valerii I.,Lavrenov, Alexander V.,Likholobov, Vladimir A.
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- Development of a novel Br?nsted acid UiO-66 metal-organic framework catalyst by postsynthetic modification and its application in catalysis
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A novel Br?nsted acid derived metal-organic framework (MOF) has been developed to serve as an efficient heterogeneous catalyst for the acetalization and Morita-Baylis-Hillman reaction. Aromatic sulfonic acid groups were successfully incorporated to the framework of UiO-66 by post-synthetic modifications using commercially available anhydridic reagents. The UiO-66-RArSO3H Br?nsted acid catalyst was fully characterized using SEM, PXRD, FTIR, TGA and N2 adsorption/desorption isotherms. Furthermore, efficient acetalization and Morita-Baylis-Hillman reactions were evaluated to demonstrate the high catalytic performance of the UiO-66-RArSO3H catalyst. The UiO-66-RArSO3H catalyst is compatible with a variety of substituted substrates and can be recycled five times without a compromise in the yield or selectivity.
- Miao, Zongcheng,Qi, Chao,Wensley, Allison M.,Luan, Yi
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p. 67226 - 67231
(2016/07/30)
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- Catalytic performance of MIL-100 (Fe, Cr) and MIL-101 (Fe, Cr) in the isomerization of endo- to exo-dicyclopentadiene
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MIL-100 (Fe, Cr) and MIL-101 (Fe, Cr), metal-organic frameworks (MOFs), have been assessed in solvent-free isomerization of dicyclopentadiene (DCPD) from the endo- to exo-form. In the isomerization reaction, the conversion of endo-DCPD and selectivity for the exo-dimer strongly depend on the nature of the active metal center. The MIL-100 (Fe) catalyst possessing more acid sites shows the highest catalytic activity among the MILs and it was readily recoverable and reusable in subsequent reaction cycles for the isomerization. The effects of reaction parameters such as temperature, reaction time, and catalyst loading on the reactivity were also investigated.
- Kim, Dong-Woo,Kim, Hyeon-Gook,Cho, Deug-Hee
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- Graphitic carbon nitride catalysed photoacetalization of aldehydes/ketones under ambient conditions
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Graphitic-C3N4 is shown for the first time to catalyse photoacetalization of aldehydes/ketones with alcohols to acetals in high yields using visible light under ambient conditions; transient charge separation over the material is effective to catalyse the reaction in the absence of Lewis or Br?nsted acids, giving a new green alternative catalyst.
- Abdullah Khan,Teixeira, Ivo F.,Li, Molly M. J.,Koito, Yusuke,Tsang, Shik Chi Edman
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supporting information
p. 2772 - 2775
(2016/02/18)
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- A Ta/W mixed addenda heteropolyacid with excellent acid catalytic activity and proton-conducting property
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A new HPAs H20[P8W60Ta12(H2O)4(OH)8O236]·125H2O (H-1) which comprises a Ta/W mixed addenda heteropolyanion, 20 protons, and 125 crystalline water molecules has been prepared through ion-exchange method. The structure and properties of H-1 have been explored in detail. AC impedance measurements indicate that H-1 is a good solid state proton conducting material at room temperature with a conductivity value of 7.2×10?3?S?cm?1 (25?°C, 30% RH). Cyclic voltammograms of H-1 indicate the electrocatalytic activity towards the reduction of nitrite. Hammett acidity constant H0 of H-1 in CH3CN is ?2.91, which is the strongest among the present known HPAs. Relatively, H-1 exhibits excellent catalytic activities toward acetal reaction.
- Li, Shujun,Peng, Qingpo,Chen, Xuenian,Wang, Ruoya,Zhai, Jianxin,Hu, Weihua,Ma, Fengji,Zhang, Jie,Liu, Shuxia
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- Oxidomolybdenum complexes for acid catalysis using alcohols as solvents and reactants
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The application field of dichloridodioxidomolybdenum(vi) chelate complexes, which have been intensively investigated as catalysts for liquid-phase olefin epoxidation, is broadened to encompass acid catalysis, in particular, alcoholysis and acetalisation reactions. Complex [MoO2Cl2(L)] (1) with L = 4,4′-di-tert-butyl-2,2′-bipyridine was chosen as (pre)catalyst. Depending on the reaction conditions, 1 either remained structurally intact or was transformed into different metal species, the structures of which were determined on the basis of single-crystal X-ray diffraction, spectroscopic techniques (FT-IR and 1H NMR), and elemental analysis. The first example of a mixed-ligand complex of the type [MoO2X(OR)(L)] (X = halide) is disclosed. This complex is one of only a handful of complexes known to date that exhibit an all-cis configuration instead of the usual cis-oxido, trans-X, cis-L configuration (X = anionic ligand). Mechanistic considerations of the formation of the metal species are made.
- Gomes, Ana C.,Neves, Patrícia,Cunha-Silva, Luís,Valente, Anabela A.,Gon?alves, Isabel S.,Pillinger, Martyn
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p. 5207 - 5218
(2016/07/07)
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- Method for synthesizing bis-ether compound by catalyzing benzaldehyde through mixed type heteropoly acid
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The invention discloses a method for synthesizing a bis-ether compound by catalyzing benzaldehyde through mixed type heteropoly acid. Benzaldehyde and an alcohol compound are used as raw materials and mixed type heteropoly acid is used as a catalyst, so as to conduct reaction to prepare the bis-ether compound, wherein the alcohol compound is methanol, n-butanol or ethylene glycol, the molecular formula of mixed type heteropoly acid is H20[P8W60Ta12(H2O)4(OH)8O236].125H2O, and mixed type heteropoly acid is formed by one tetrameric Ta/W mixed type heteropoly anion, 20 protons and 125 crystal water molecules. Prepared mixed type heteropoly acid has the strongest acidity in heteropoly acid known at present, and has higher acid catalytic activity due to the strong acidity.
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Paragraph 0015; 0016
(2017/05/18)
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- Efficient acetalization of benzaldehydes using UiO-66 and UiO-67: Substrates accessibility or Lewis acidity of zirconium
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Porous metal-organic frameworks of Zr6O4(OH)4 clusters connected by organic linkers of 1,4-benzenedicarboxylate (UiO-66) and biphenyl-4,4′-dicarboxylate (UiO-67) were prepared using a solvothermal method and used as efficient catalysts for acetalization of benzaldehydes with alcohols. UiO-66 showed better catalytic activity than UiO-67, (i.e. 91% vs 86%) when the catalyst was employed in the benzaldehyde acetalization in methanol for an hour at r.t. (28 °C). UiO-66 was further explored as the catalyst to observe effects of catalyst concentrations, alcohols, bulkier benzaldehydes, and recyclability. The performance of other catalysts, including the MOF precursor, was also examined to compare the activity and to explain the importance of a MOF structure. Relative Lewis acidity of Zr in UiO-66 and UiO-67 was achieved by natural bond orbital (NBO) analysis using DFT/B3LYP method. It was found that accessibility of substrates to internal active sites might play a dominant role than the Lewis acidity of Zr-MOFs.
- Arrozi, Ubed S.F.,Wijaya, Husni W.,Patah, Aep,Permana, Yessi
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- Merging metal-organic framework catalysis with organocatalysis: A thiourea functionalized heterogeneous catalyst at the nanoscale
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A new thiourea-containing metal-organic framework (MOF) catalyst was synthesized. It overcomes recycling, self-aggregation and solvation issues that exist in homogeneous thiourea catalysts. Nanomorphology was introduced to increase the dispersion of the solid catalyst in solvent. Acetalization and Morita-Baylis-Hillman reactions were catalyzed using the new thiourea MOF catalyst. This journal is the Partner Organisations 2014.
- Luan, Yi,Zheng, Nannan,Qi, Yue,Tang, Jia,Wang, Ge
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p. 925 - 929
(2014/04/03)
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- Bronsted instead of lewis acidity in functionalized MIL-101Cr MOFs for efficient heterogeneous (nano-MOF) catalysis in the condensation reaction of aldehydes with alcohols
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Porous chromium(III) 2-nitro-, 2-amino-, and nonfunctionalized terephthalate (MIL-101Cr) metal organic frameworks are heterogeneous catalysts for diacetal formation from benzaldehyde and methanol (B-M reaction) as well as other aldehydes and alcohols. MIL-101Cr-NO2 obtained by direct reaction between CrO3 and 2-nitro-terephthalate showed the highest activity with 99% conversion in the B-M reaction in 90 min and turnover numbers of 114. The activity decreased in the order MIL-101Cr-NO2 > MIL-101Cr > MIL-101Cr-NH2. Within different samples of nonfunctionalized MIL-101Cr the activity increased with surface area. Methanol gas sorption of the different MIL materials correlates with the BET surface area and pore volume but not with the diacetalization activity. Benzaldehyde adsorption from heptane showed no significant difference for the different MILs. Gas sorption studies of CD3CN to probe for a higher Lewis acidity in MIL-101Cr-NO2 remained inconclusive. A high B-M catalytic activity of wet MIL-101Cr-NO2 excluded significant contributions from coordinatively unsaturated Lewis-acid sites. pH measurements of methanol dispersions of the MIL materials gave the most acidic pH (as low as 1.9) for MIL-101Cr-NO2, which significantly increased over MIL-101Cr (3.0) to MIL-101Cr-NH2 (3.3). The increase in acidity is of short range or a surface effect to the heterogeneous MIL particles as protons dissociating from the polarized aqua ligands (Cr-OH2) have to stay near the insoluble counteranionic framework. The variation in Bronsted acidity of MIL-101Cr-NO2 > MIL-101Cr ≈ MIL-101Cr-NH2 correlates with the withdrawing effect of NO2 and the diacetalization activity. The catalytic B-M activity of soluble, substitution-inert, and acidic Cr(NO3)3·9H2O supports the Bronsted-acid effect of the MIL materials. Filtration and centrifugation experiments with MIL-101Cr-NO2 revealed that about 2/3 of the catalytic activity comes from nano-MOF particles with a diameter below 200 nm. The MIL-101Cr-NO2 catalysts can be recycled five times with very little loss in activity. The diacetalization activity of MIL-101Cr-NO 2 decreases with the alcohol chain length from methanol over ethanol, n-propanol, n-butanol, to almost inactive n-pentanol, while conversions for benzaldehyde, paratolylaldehyde, 4-chlorobenzaldehyde, and cyclohexanone all reach 90% or more after 90 min.
- Herbst, Annika,Khutia, Anupam,Janiak, Christoph
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supporting information
p. 7319 - 7333
(2014/08/05)
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- Development of a SO3H-functionalized UIO-66 metal-organic framework by postsynthetic modification and studies of its catalytic activities
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A novel metal-organic framework UiO-66-NH2-derived Br?nsted acid catalyst was synthesized on a gram scale by employing a postsynthetic modification strategy under mild conditions. The nanomorphology of the catalyst was designed and developed to enhance its catalytic performance. Acetalization and benzimidazole formation were evaluated to demonstrate the high reactivity and selectivity of the nanoscaled UiO-66-NH-RSO3H catalyst, which were found to be comparable to the reactivity and selectivity of the strong homogeneous Br?nsted acid catalyst. Furthermore, the UiO-66-NH-RSO3H catalyst was recycled several times without compromising the yield and selectivity. A novel metal-organic framework UiO-66-NH2-derived Br?nsted acid catalyst is synthesized by employing a postsynthetic modification strategy under mild conditions. Acetalization and benzimidazole formation are evaluated to demonstrate the high reactivity and selectivity of the nanoscaled UiO-66-NH-RSO3H catalyst.
- Luan, Yi,Zheng, Nannan,Qi, Yue,Yu, Jie,Wang, Ge
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p. 4268 - 4272
(2015/03/30)
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- Zn(ii) chloride-catalyzed direct coupling of various alkynes with acetals: Facile and inexpensive access to functionalized propargyl ethers
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The coupling of acetals with various alkynes was achieved using only 1 mol% of inexpensive and mild Lewis acid ZnCl2, which furnished propargyl ethers. The coupling was catalyzed by Zn(OMe)Cl, which was generated in situ to form an alkynylzinc species. This protocol was allowed to expand to a one-pot subsequent reaction with allylchlorosilane to obtain a 1,4-enyne product.
- Suzuki, Itaru,Yasuda, Makoto,Baba, Akio
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supporting information
p. 11620 - 11622
(2013/12/04)
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- A facile and efficient protocol for esterification and acetalization in a PEG1000-D(A)IL/toluene thermoregulated catalyst-media combined systems
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A novel efficient and recyclable temperature-dependent biphasic catalyst and reaction media combined system comprised of PEG-1000 linked dicationic acidic ionic liquid and toluene was developed and applied in esterification of aromatic acids and acetalization of aromatic aldehydes with good to excellent yields. This system is characteristic of temperature-dependent reversible biphasic property, simple and facile recyclability, high catalytic activity and extensive substrate and reaction adaptability.
- Wang, Yinglei,Zhi, Huizhen,Luo, Jun
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- Bis(perfluorooctanesulfonyl)imide supported on fluorous silica gel: Application to protection of carbonyls
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The immobilization of bis(perfluorooctanesulfonyl)imide (HNPf2) on fluorous silica gel (FSG) and its utilization in protection of carbonyls have been investigated. This system is reasonably general and can be applied to converting several carbonyls to the corresponding acetals and ketals in good to excellent yields. There is no need for the use of anhydrous solvents or inert atmosphere. Recycling studies have shown that the FSG-supported HNPf2 catalyst can be readily recovered and reused several times without significant loss of activity.
- Hong, Mei,Xiao, Guomin
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experimental part
p. 121 - 126
(2012/08/28)
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- Indium(III) triflate catalysed transacetalisation reactions of diols and triols under solvent-free conditions
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Acyclic acetals and ketals undergo transacetalisation in the presence of catalytic quantities of indium(III) triflate (In(OTf)3) and diols or triols under solvent-free conditions to generate the corresponding cyclic acetals and ketals in excellent yield. The methodology has been further developed to encompass a tandem acetalisation-acetal exchange protocol, which provides a facile and high yielding route to cyclic ketals from unreactive ketones under very mild reaction conditions.
- Smith, Brendan M.,Kubczyk, Tomasz M.,Graham, Andrew E.
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supporting information; experimental part
p. 7775 - 7781
(2012/09/21)
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- Mesoporous aluminosilicate-catalyzed allylation of carbonyl compounds and acetals
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A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both carbonyl compounds and acetals with allylsilanes to afford the corresponding homoallyl silyl ethers and homoallyl alkyl ethers, respectively. Both the mesoporous structure and the presence of aluminum moiety were indispensable for the high catalytic activity of Al-MCM-41. Moreover, Al-MCM-41 could catalyze the reaction of acetals chemoselectively in the presence of the corresponding carbonyl compounds. The solid acid catalyst Al-MCM-41 could be recovered easily by filtration and could be reused three times without a significant loss of catalytic activity.
- Ito, Suguru,Hayashi, Akira,Komai, Hirotomo,Yamaguchi, Hitoshi,Kubota, Yoshihiro,Asami, Masatoshi
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supporting information; experimental part
p. 2081 - 2089
(2011/04/19)
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- Catalytic synthesis of γ-alkoxy-α-keto esters
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Copper(II) triflate effectively catalyzes the reaction of (trimethylsilyloxy)acrylic esters and acetals to form -alkoxy - keto esters. The reaction proceeds under mild conditions providing products in good to excellent yields. The substrate scope was investigated, and it was demonstrated that the products could be converted into related compounds such as γ-hydroxy -α- keto esters and α-oximes. Georg Thieme Verlag Stuttgart - New York.
- Krebs, Anke,Bolm, Carsten
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supporting information; experimental part
p. 671 - 673
(2011/05/16)
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- ACID-SENSITIVE LINKERS FOR DRUG DELIVERY
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The invention is in general directed to acid-sensitive linkers, and methods of use thereof, such as, for example, in drug delivery methods.
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- The use of anhydrous CeCl3 as a recyclable and selective catalyst for the acetalization of aldehydes and ketones
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An efficient, clean, chemoselective and solvent-free method for the synthesis of ketone and aldehyde dimethyl acetals was developed using trimethyl orthoformate and commercially available anhydrous CeCl3 as a recyclable catalyst. The method is general and affords the protected carbonyl compounds in good yields and under mild conditions, including aryl and alkyl ketones and activated aldehydes. The catalyst could be utilised directly for 3 cycles, without significant loss of activity.
- Silveira, Claudio C.,Mendes, Samuel R.,Ziembowicz, Francieli I.,Lenarda?o, Eder J.,Perin, Gelson
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body text
p. 371 - 374
(2010/09/07)
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- Metal organic frameworks as solid acid catalysts for acetalization of aldehydes with methanol
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Room temperature acetalization of aldehydes with methanol has been carried out using metal organic frameworks (MOFs) as solid heterogeneous catalysts. Of the MOFs tested, a copper-containing MOF [Cu3(BTC)2] (BTC=1,3,5-benzenetricarboxylate) showed better catalytic activity than an iron-containing MOF [Fe(BTC)] and an aluminium containing MOF [Al 2(BDC)3] (BDC=1,4-benzenedicarboxylate). The protocol was validated for a series of aromatic and aliphatic aldehydes and used to protect various aldehydes into commercially important acetals in good yields without the need of water removal. In addition, the reusability and heterogeneity of this catalytic system was demonstrated. The structural stability of MOF was further studied by characterization with powder X-ray diffraction, Brunauer-Emmett- Teller surface area measurements and Fourier-transformed infrared spectroscopic analysis of a deactivated catalyst used to convert a large amount of benzaldehyde. The performance of copper MOF as acetalization catalyst compares favourably with those of other conventional homogeneous and heterogeneous catalysts such as zinc chloride, zeolite and clay. Copyright
- Dhakshinamoorthy, Amarajothi,Alvaro, Mercedes,Garcia, Hermenegildo
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body text
p. 3022 - 3030
(2011/02/24)
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- [Hmim]3PW12O40: A high-efficient and green catalyst for the acetalization of carbonyl compounds
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[Hmim]3PW12O40 was developed and used in the acetalization of carbonyl compounds in excellent yields. The ionic liquid-heteropoly acid hybrid compound and reaction medium formed temperature-dependent phase-separation system with the ease of product as well as catalyst separation. The catalyst was recycled more than 10 times without any apparent loss of catalytic activity.
- Dai, Yan,Li, Bin Dong,Quan, Heng Dao,Lü, Chun Xu
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experimental part
p. 678 - 681
(2011/10/31)
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- Cobalt(II) schiff base functionalized mesoporous silica as an efficient and recyclable chemoselective acetalization catalyst
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Cobalt(II) Schiff base functionalized mesoporous silica was synthesized from covalent attachment via the introduction of Co(OAc)2 to salicylaldimine functionalized mesoporous silica. The catalyst proved to be chemoselective one for the acetalization of aldehydes to the corresponding acetals in alcohol. The immobilized catalyst can be easily recovered and reused for at least ten reaction cycles without significant loss of its catalytic activity.
- Rajabi
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scheme or table
p. 695 - 701
(2010/11/16)
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- A facile procedure for acetalization of aldehydes and ketones catalyzed by cerium(III) trifluoromethanesulfonate
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Aldehydes and ketones are readily protected in the presence of trialkyl orthoformate and a catalytic amount of cerium(III) trifluoromethanesulfonate under mild conditions to give the corresponding acetals in good to excellent yields. Due to the mild reaction conditions, this method is compatible with acid-sensitive substrates. Copyright
- Ono, Fumiaki,Inatomi, Yoshiko,Tada, Yuusuke,Mori, Masaki,Sato, Tsuneo
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experimental part
p. 96 - 97
(2009/11/30)
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- Indium(III)trifluoromethanesulfonate as a mild, efficient catalyst for the formation of acetals and ketals in the presence of acid sensitive functional groups
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Aldehydes and ketones, including acetophenone and benzophenone, are readily protected under mild, neutral conditions in the presence of various alcohols or orthoformates and catalytic amounts of indium(III) trifluoromethanesulfonate (0.8 mol %) under either room temperature or mild heating conditions to give the corresponding cyclic and acyclic acetals and ketals in good to excellent yields. Acid sensitive functional groups, N-Boc, THP, and TBDMS do not undergo competitive deprotection under the reported conditions.
- Gregg, Brian T.,Golden, Kathryn C.,Quinn, John F.
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p. 3287 - 3295
(2008/09/21)
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- Gallium triiodide as a highly efficient and mild catalyst for the diethyl acetalization of carbonyl compounds
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Diethyl acetals were obtained from carbonyl compounds in good to excellent yields under mild reaction conditions in the presence of triethyl orthoformate and a catalytic amount of gallium triiodide in anhydrous ethanol.
- Ding, Jin-Chang,Xu, Rong,Liu, Miao-Chang,Chen, Xi-An,Wu, Hua-Yue
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experimental part
p. 566 - 568
(2009/07/18)
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- Tetrafluoroboric acid adsorbed on silica gel as a reusable heterogeneous dual-purpose catalyst for conversion of aldehydes/ketones into acetals/ketals and back again
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Aldehydes and ketones can be protected as acetals and ketals by treatment with trimethyl orthoformate (TMOF) or triethyl orthoformate (TEOF) under the catalytic influence of tetrafluoroboric acid adsorbed on silica gel (HBF 4-SiO2). In the case of aldehydes or ketones with highly electrophilic carbonyl group, the reactions are carried out under solvent-free conditions. Aryl alkyl ketones, aryl styryl ketones, aldehydes with weakly electrophilic carbonyl groups, and aldehydes with substituents that can coordinate with the catalyst require the presence of the corresponding alcohol as solvent. For substrates that can be converted into acetals under neat conditions, the acetal formation takes place at a faster rate when the alcohol is used as the solvent. The catalyst can be recovered and reused/recycled four times (after reactivation after each use) without any significant decrease in its catalytic efficiency. The parent aldehydes/ketones are regenerated from the corresponding acetals/ketals in high yields by the treatment with water-alcohol in the presence of HBF4-SiO2 at room temperature for short times. Excellent selectivity was observed during inter- and intramolecular competition studies involving carbonyl substrates with varying electronic and steric environments. Selective acetal formation of benzaldehyde takes place in the presence of 4-(dimethylamino)benzaldehyde, thiophene-2-carboxaldehyde, 1-naphthaldehyde, 9-anthraldehyde, or acetophenone, but 3-nitrobenzaldehyde undergoes selective acetal formation in preference to benzaldehyde. In the case of 4-acetylbenzaldehyde, exclusive acetal formation of the aldehyde carbonyl group occurs. Georg Thieme Verlag Stuttgart.
- Kumar, Dinesh,Kumar, Raj,Chakraborti, Asit K.
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p. 1249 - 1256
(2008/12/22)
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- A laser flash photolysis, matrix isolation, and DFT investigation of (η6-C6H5Y)Cr(CO)3 (Y = NH2, OCH3, H, CHO, or CO2CH3)
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The quantum yield for arene displacement from (η6-C6H5Y)Cr(CO)3 was measured in 1,1,2-trifluorotrichloroethane (Y = NH2, OCH3, H, CHO, or CO2CH3). Values of 0.24, 0.27, 0.15, 0.17, and 0.32 were obtained respectively (λexc. = 355 nm). These values are significantly higher than those measured for photoinduced arene loss in hydrocarbon solvents using the same excitation wavelength. Laser flash photolysis of (η6-C6H5Y)Cr(CO)3 in 1,1,2-trifluorotrichloroethane (λexc. = 355 nm) resulted in the rapid formation (6. Matrix isolation experiments on (η6-C6H5Y)Cr(CO)3 (Y = H or CHO) at 12 K in CH4 or CO-doped CH4 matrixes using monochromatic irradiation confirmed the presence of two discrete excited states, one leading to CO-loss and the other to arene-loss. The results correlate with the calculated electron drift in the excited state derived from density functional theory and time dependent density functional theory calculations.
- Alamiry, Mohammed A.H.,Brennan, Peter,Long, Conor,Pryce, Mary T.
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p. 2907 - 2914
(2008/12/21)
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- Nucleophilic phosphine-catalyzed [3+2] cycloaddition of allenes with N-(thio)phosphoryl imines and acidic methanolysis of adducts N-(thio)phosphoryl 3-pyrrolines: a facile synthesis of free amine 3-pyrrolines
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In this report, the dipolarophile imines with easily removable activating group O,O-diethyl(thio)phosphoryl have been investigated in the nucleophilic phosphine-catalyzed [3+2] cycloaddition reaction of electron-deficient allenes. Under the catalysis of a tertiary phosphine, N-(thio)phosphorylimines readily undergo the [3+2] cycloaddition reaction with ethyl 2,3-butadienoate or ethyl 2,3-pentadienoate, affording the corresponding N-(thio)phosphoryl 3-pyrrolines in moderate to high yields with good diastereoselectivity. Removal of the (thio)phosphoryl group from the adducts has been successfully achieved via the acidic methanolysis of the P-N bond, giving the free amine 3-pyrrolines in fair to good yields without severe aromatization. Thus, a facile synthesis of N-unsubstituted 3-pyrrolines is established from the phosphine-catalyzed [3+2] cycloaddition reaction of allenes with imines.
- Zhang, Bo,He, Zhengrong,Xu, Silong,Wu, Guiping,He, Zhengjie
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p. 9471 - 9479
(2008/12/22)
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