- Activation of a Non-Heme FeIII-OOH by a Second FeIII to Hydroxylate Strong C?H Bonds: Possible Implications for Soluble Methane Monooxygenase
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Non-heme iron oxygenases contain either monoiron or diiron active sites, and the role of the second iron in the latter enzymes is a topic of particular interest, especially for soluble methane monooxygenase (sMMO). Herein we report the activation of a non-heme FeIII-OOH intermediate in a synthetic monoiron system using FeIII(OTf)3 to form a high-valent oxidant capable of effecting cyclohexane and benzene hydroxylation within seconds at ?40 °C. Our results show that the second iron acts as a Lewis acid to activate the iron–hydroperoxo intermediate, leading to the formation of a powerful FeV=O oxidant—a possible role for the second iron in sMMO.
- Kal, Subhasree,Que, Lawrence
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- Kinetics Study of the Esterification Reaction of Cyclohexene to Cyclohexyl Acetate Catalyzed by Novel Br?nsted–Lewis Acids Bifunctionalized Heteropolyacid Based Ionic Liquids Hybrid Solid Acid Catalysts
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A series of Br?nsted–Lewis acids bifunctionalized heteropolyacid based ionic liquids hybrid solid acid catalysts (BLA-HPA-ILs) were synthesized by combining the Br?nsted acidic ionic liquid [Bis–Bs–BDMAEE]HPW12O40 with metallic oxide in different composition ratios and applied in the esterification of cyclohexene to cyclohexyl acetate. Among the synthesized catalysts, the 1/2Cu[Bis–Bs–BDMAEE]HPW12O40 catalyst with Br?nsted and Lewis acidities shown the most excellent catalytic performance for the esterification of cyclohexene with acetic acid. The BLA-HPA-ILs catalysts were characterized by elemental analysis, FT-IR, Py-IR, TG, 1H NMR, SEM and EDX. The effects of reaction temperature, catalyst dosage, and initial reactant molar ratio has been investigated in detail. A pseudohomogeneous (PH) kinetic model was used to correlate the kinetic data in the temperature range of 333.15–363.15?K, and the kinetic parameters were estimated, indicating the results calculated by the kinetic model are well coincidence with the experimental results. Moreover, as a heterogeneous reaction catalyst, 1/2Cu[Bis–Bs–BDMAEE]HPW12O40 could be easily recovered by a simple treatment and reused six times without any obvious decrease in catalytic activity, displaying good reusability. Graphic Abstract: [Figure not available: see fulltext.]
- Guang, Binxiong,Wu, Yuefeng,Liu, Weihua,Wang, Jianhong,Xiao, Yahui,Liu, Yong
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- The DMAP-catalyzed acetylation of alcohols - A mechanistic study (DMAP = 4-(dimethylamino)pyridine)
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The acetylation of tert-butanol with acetic anhydride catalyzed by 4-(dimethylamino)pyridine (DMAP) has been studied at the Becke3 LYP/6-311+G(d,p)//Becke3LYP/6-31G(d) level of theory. Solvent effects have been estimated through single-point calculations
- Xu, Shangjie,Held, Ingmar,Kempf, Bernhard,Mayr, Herbert,Steglich, Wolfgang,Zipse, Hendrik
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Read Online
- Noncross-linked polystyrene nanoencapsulation of ferric chloride: A novel and reusable heterogeneous macromolecular Lewis acid catalyst toward selective acetylation of alcohols, phenols, amines, and thiols
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Ferric chloride has been successfully nanoencapsulated for the first time on a non-cross-linked polystyrene matrix as the shell material via the coacervation technique. The resulting polystyrene nanoencapsulated ferric chloride was used as a novel and rec
- Alinejad, Sara,Donyapeyma, Ghazaleh,Rahmatpour, Ali
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- Dehydrogenative ester synthesis from enol ethers and water with a ruthenium complex catalyzing two reactions in synergy
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We report the dehydrogenative synthesis of esters from enol ethers using water as the formal oxidant, catalyzed by a newly developed ruthenium acridine-based PNP(Ph)-type complex. Mechanistic experiments and density functional theory (DFT) studies suggest that an inner-sphere stepwise coupled reaction pathway is operational instead of a more intuitive outer-sphere tandem hydration-dehydrogenation pathway.
- Ben-David, Yehoshoa,Diskin-Posner, Yael,Kar, Sayan,Luo, Jie,Milstein, David,Rauch, Michael
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supporting information
p. 1481 - 1487
(2022/03/07)
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- An efficient, economical and eco-friendly acylation of alcohols and amines by alum doped nanopolyaniline under solvent free condition
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We report acylation of alcohols and amines employing acetic acid as an acylating agent in solvent free condition by using alum doped nanopolyaniline (NDPANI) as a catalyst. This environmentally benign method does not use corrosive acid anhydrides and acid chlorides for acylation and does not produce waste product. Also, a non-toxic potash alum was used for doping of polyaniline rather than corrosive acids. The reaction conditions represent an advance over established method not only in omitting the need for expensive catalysts or solvents but also in shortening the reaction time significantly. The advantages of this catalyst are non-hazardous, cheap, reusable, easy to prepare and handling.
- Behera, Satyaranjan,Patra, Braja N.
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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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- Cyclohexene esterification-hydrogenation for efficient production of cyclohexanol
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A novel process based on cyclohexene esterification-hydrogenation for the production of cyclohexanol, the key intermediate in the production of ε-caprolactam, was devised and validated for the first time. In this process, cyclohexene obtained from the partial hydrogenation of benzene is esterified with acetic acid to cyclohexyl acetate, followed by hydrogenation to cyclohexanol. The experimentally determined equilibrium conversion of cyclohexene for cyclohexene esterification at the stoichiometric ratio is always ≥68% in the temperature range of 333-373 K over the commercial Amberlyst 15 catalyst, which is substantially higher than that of cyclohexene hydration. The apparent activation energy (Ea) for the esterification of cyclohexene with acetic acid is 60.0 kJ mol?1, which is lower than that of cyclohexene hydration. In the hydrogenation of cyclohexyl acetate to cyclohexanol, high conversion of 99.5% and high selectivity of 99.7% are obtained on the La-promoted Cu/ZnO/SiO2catalyst prepared by the co-precipitation method. This process shows both a high overall atom economy of 99.4% comparable to that of the cyclohexene hydration process and a much higher catalytic efficiency than the phenol hydrogenation process. On the basis of the above fundamental works, a pilot-scale demonstration unit with a capacity of 8000 tonnes per annum was developed and operated smoothly for more than 1000 h with no indication of deactivation.
- Zhu, Yunfeng,Gao, Liang,Wen, Langyou,Zong, Baoning,Wang, Hao,Qiao, Minghua
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supporting information
p. 1185 - 1192
(2021/02/26)
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- METHOD FOR PRODUCING DICARBOXYLIC ACID
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A method for producing dicarboxylic acid. The method includes: subjecting a raw material system including a cyclic olefin and a lower monocarboxylic acid to an addition reaction in the presence of an addition reaction catalyst to generate an intermediate product system including cyclic carboxylic acid ester; and subjecting the intermediate product system including cyclic carboxylic acid ester to a ring-opening and oxidation reaction in the presence of an oxidant and an oxidation catalyst to generate a corresponding dicarboxylic acid product. The addition reaction in the dicarboxylic acid synthesis route achieves a high single-pass conversion rate, and the selectivity of the corresponding cyclic carboxylic acid ester is high. The addition-oxidation synthesis route achieves faster reaction rates for both the addition reaction and oxidation reaction, and high yield of corresponding dicarboxylic acid product. The addition-oxidation based synthesis route is suitable for continuous, stable and large-scale production of corresponding dicarboxylic acid product.
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Paragraph 0056-0108; 0112; 0126; 0124
(2021/05/21)
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- Enhancing Chemo- And Stereoselectivity in C-H Bond Oxygenation with H2O2by Nonheme High-Spin Iron Catalysts- And Role of Lewis Acid and Multimetal Centers
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Spin states of iron often direct the selectivity in oxidation catalysis by iron complexes using hydrogen peroxide (H2O2) on an oxidant. While low-spin iron(III) hydroperoxides display stereoselective C-H bond hydroxylation, the reactions are nonstereoselective with high-spin iron(II) catalysts. The catalytic studies with a series of high-spin iron(II) complexes of N4 ligands with H2O2 and Sc3+ reported here reveal that the Lewis acid promotes catalytic C-H bond hydroxylation with high chemo- and stereoselectivity. This reactivity pattern is observed with iron(II) complexes containing two cis-labile sites. The enhanced selectivity for C-H bond hydroxylation catalyzed by the high-spin iron(II) complexes in the presence of Sc3+ parallels that of the low-spin iron catalysts. Furthermore, the introduction of multimetal centers enhances the activity and selectivity of the iron catalyst. The study provides insights into the development of peroxide-dependent bioinspired catalysts for the selective oxygenation of C-H bonds without the restriction of using iron complexes of strong-field ligands.
- Das, Abhishek,Jana, Rahul Dev,Paine, Tapan Kanti
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p. 5969 - 5979
(2021/05/04)
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- Trimethylsilyl Esters as Novel Dual-Purpose Protecting Reagents
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Trimethylsilyl esters, AcOTMS, BzOTMS, TCAOTMS, etc., are inexpensive and chemically stable reagents that pose a negligible environmental hazard. Such compounds prove to serve as efficient dualpurpose reagents to respectively achieve acylation and trimethylsilylation of alcohols under acidic or basic conditions. Herein, a detailed study on protection of various substrates and new methodological investigations is described.
- Chang, Ting-Shuo,Chen, Jyun-Siao,Hsieh, Ya-Chi,Hsu, Hsiao-Lin,Huang, Po-Hsun,Liu, Jen-Wei,Liu, Yu-Hao,Luo, Shun-Yuan,Wu, Hsin-Ru,Wu, Ren-Tsung,Zhang, Kai-Min
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supporting information
(2021/12/02)
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- Synthesis of task-specific imidazolium ionic liquid as an efficient catalyst in acetylation of alcohols, phenols, and amines
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Herein, we report the synthesis of task-specific amino-functionalized imidazolium ionic liquid, acetate1-(2-tert-butoxycarbonylamino-ethyl)-3-methyl-3H-imidazol-1-ium; (Boc-NH-EMIM.OAc), as an efficient catalyst for the acetylation of alcohols, phenols, and amines in the presence of acetic anhydride (acetylating reagent). Remarkably, acetic anhydride in the presence of 10?molpercent of catalyst (Boc-NH-EMIM.OAc) under solvent-free conditions showed excellent acetylation activity in shorter duration of time. On the basis of this, a general procedure for acetylation of alcohols, phenols, and amines has been developed. The ionic liquid (Boc-NH-EMIM.OAc) can be readily recovered and reused successfully up to four consecutive cycles without any significant loss of its catalytic activity. We have been able to show that this acetylating method has many advantages. It gives high yields, takes shorter time, and develops the possibility of benign environmental-friendly process.
- Chaubey, Snehkrishn A.,Mishra, Roli
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p. 3259 - 3268
(2020/04/17)
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- Tropolonate salts as acyl-transfer catalysts under thermal and photochemical conditions: Reaction scope and mechanistic insights
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Acyl-transfer catalysis is a frequently used tool to promote the formation of carboxylic acid derivatives, which are important synthetic precursors and target compounds in organic synthesis. However, there have been only a few structural motifs known to efficiently catalyze the acyl-transfer reaction. Herein, we introduce a different acyl-transfer catalytic paradigm based on the tropolone framework. We show that tropolonate salts, due to their strong nucleophilicity and photochemical activity, can promote the coupling reaction between alcohols and carboxylic acid anhydrides or chlorides to give products under thermal or blue light photochemical conditions. Kinetic studies and density functional theory calculations suggest interesting mechanistic insights for reactions promoted by this acyl-transfer catalytic system.
- Mai, Binh Khanh,Koenigs, Rene M.,Nguyen, Thanh Vinh,Lyons, Demelza J.M.,Empel, Claire,Pace, Domenic P.,Dinh, An H.
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p. 12596 - 12606
(2020/11/18)
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- IrIII-Catalyzed direct syntheses of amides and esters using nitriles as acid equivalents: A photochemical pathway
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An unprecedented IrIII[df(CF3)ppy]2(dtbbpy)PF6-catalyzed simple photochemical process for direct addition of amines and alcohols to the relatively less reactive nitrile triple bond is described herein. Various amides and esters are synthesized as the reaction products, with nitriles being the acid equivalents. A mini-library of different types of amides and esters is made using this mild and efficient process, which uses only 1 mol% of photocatalyst under visible light irradiation (λ = 445 nm). The reaction strategy is also efficient for gram-scale synthesis.
- Talukdar, Ranadeep
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supporting information
p. 5303 - 5308
(2020/04/17)
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- Application of Yttrium Iron Garnet as a Powerful and Recyclable Nanocatalyst for One-Pot Synthesis of Pyrano[2,3-c]pyrazole Derivatives under Solvent-Free Conditions
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The application of yttrium iron garnet (YIG) superparamagnetic nanoparticles as a new recyclable and highly efficient heterogeneous magnetic catalyst for one-pot synthesis of pyrano[2,3-c]pyrazole derivatives under solvent-free conditions, as well as etherification and esterification reactions are described. The advantages of the proposed method include the lack of organic solvents, clean reaction, rapid removal of the catalyst, short reaction times, excellent yields, and recyclability of the catalyst.
- Sedighinia,Badri,Kiasat
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p. 1755 - 1763
(2020/01/11)
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- Developing two-dimensional solid superacids with enhanced mass transport, extremely high acid strength and superior catalytic performance
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Solid acids have been widely used as heterogeneous catalysts in developing green and sustainable chemistry. However, it remains a challenge to improve the mass transport properties and acid strength of solid acids simultaneously. Herein, we report a class of two dimensional (2D) layered hybrid solid acids with outstanding mass transfer and extremely high acid strength by incorporating sulfonated polymers in-between montmorillonite layers. The 2D layered structure and broad distribution of pore sizes allow for highly efficient mass transport of substrate molecules into and out of the solid acids. The acid strength of these solid acids was found to be stronger than that of 100% H2SO4, H3PW12O40 and any other reported solid acids to date, as determined by 1H and 31P solid-state NMR. These 2D solid acids show extraordinary catalytic performance in biomass conversion to fuels, superior to that of H3PW12O40, HCl and H2SO4. Theoretical calculations and control experiments reveal that H-bond based interactions between the polymer and montmorillonite facilitate the unusually high acid strengths found in these samples.
- Liu, Fujian,Yi, Xianfeng,Chen, Wei,Liu, Zhiqiang,Qi, Chen-Ze,Song, Yu-Fei,Zheng, Anmin
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p. 5875 - 5883
(2019/06/19)
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- Consecutive addition esterification and hydrolysis of cyclic olefins catalyzed by multi-SO3H functionalized multi heteropolyanion-based ionic hybrids undersolvent-free conditions
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An efficient protocol for the synthesis of cycloalkyl carboxylates and alcohols from cyclic olefins is described. The cyclic olefins were converted to corresponding target molecules under solvent-free conditions catalyzed by two novel multi-SO3H functionalized multi heteropolyanion-based ionic hybrids through one-pot consecutive addition esterification and hydrolysis reactions. This approach has several advantages, including high yield, simple workup and simple purification.
- Zheng, Guocai,Li, Xinzhong
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p. 933 - 941
(2019/03/17)
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- 4-Imidazol-1-yl-butane-1-sulfonic acid ionic liquid: Synthesis, structural analysis, physical properties and catalytic application as dual solvent-catalyst
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4-Imidazol-1-yl-butane-1-sulfonic acid (ImBu-SO3H) has been successfully synthetized and fully characterized by FT-IR and high-resolution NMR spectroscopy (1H, 13C). The “plausible” alternative structures of ImBu-SO3H were discussed on the basis of its NMR data. The ionic liquid showed interesting dual solvent-catalyst property, which was studied experimentally for the acetylation of a variety of functionalized alcohols, phenols, thiols, amines and α-tocopherol (α-CTP) as the most active form of vitamin E with acetic anhydride and which provided good yields within a short reaction time. ImBu-SO3H was successfully recycled by product extraction with an average recovered yield of 82% for 5 subsequent runs. The catalytic activity of the recycled ImBu-SO3H showed almost no loss even after five consecutive runs.
- Khaligh, Nader Ghaffari,Mihankhah, Taraneh,Johan, Mohd Rafie,Juan, Joon Ching
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p. 866 - 878
(2019/07/12)
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- Fe3O4@PEG core/shell nanoparticles as magnetic nanocatalyst for acetylation of amines and alcohols using ultrasound irradiations under solvent-free conditions
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Abstract: Ultrasound irradiation was used to prepare one-pot Fe3O4@PEG core/shell nanostructure for the first time. The morphology, structure, and physicochemical properties were specified by different analytical techniques including field emission scanning electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray powder diffraction, and vibrating sample magnetometer. For acetylation of phenols, alcohols, and amines, the synthesized Fe3O4@PEG core/shell nanoparticles were used as an efficient heterogeneous and green catalyst with acetic anhydride under sonication applying mild reaction conditions. Different electron-withdrawing and electron-donating substrates indicate a prominent yield of desired products with the merit of reusability of Fe3O4@PEG nanocatalyst and magnetic separation. Graphical Abstract: [Figure not available: see fulltext.].
- Veisi, Hojat,Nikseresht, Ahmad,Rostami, Afsaneh,Hemmati, Saba
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p. 507 - 520
(2018/10/24)
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- Manganese-mediated acetylation of alcohols, phenols, thiols, and amines utilizing acetic anhydride
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Manganese(II) chloride-catalyzed acetylation of alcohols, phenols thiols and amines with acetic anhydride is reported. This method is environment-friendly and economically viable as it involves inexpensive, relatively benign catalyst, mild reaction condition, and simple workup. Acetylation is performed under the solvent-free condition at ambient temperature and acetylated products obtained in good to excellent yields. Primary, secondary heterocyclic amines, and phenols with various functional groups are smoothly acetylated in good yields. This method exhibits exquisite chemoselectivity, the amino group is preferentially acetylated in the presence of a hydroxyl/thiol group.
- Jain, Isha,Sharma, Ramandeep,Malik, Payal
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supporting information
p. 2952 - 2960
(2019/09/13)
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- Enzymatic chemical transformations of aldehydes, ketones, esters and alcohols using plant fragments as the only biocatalyst: Ximenia americana grains
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The present study demonstrated the ability of Ximenia american as a biocatalyst in reduction, hydrolysis and esterification reactions. The reduction reactions of aldehydes and ketones, ester hydrolysis and esterification of alcohols were carried out with interesting results. Reduction of ketones afforded yields of 6–60% with ee in the range of 35–>99% and that of aldehydes in yields of 51–99%. On the other hand, ester hydrolysis afforded yields of 58–98% with ee in the range 34–87%, while esterification of alcohols in 18–99% yields. Experimental conditions for all reactions have been defined using standard substrates as indicated in results and discussion. Some of the products are the potential building blocks for the synthesis of molecules which are of pharmaceutical and agrochemical importance.
- da Silva, Romézio Alves Carvalho,de Mesquita, Bruna Marques,de Farias, Iolanda Frota,do Nascimento, Patrícia Georgiana Garcia,de Lemos, Telma Leda Gomes,Queiroz Monte, Francisco José
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p. 187 - 194
(2018/01/05)
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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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- Biogenic CuFe2O4 magnetic nanoparticles as a green, reusable and excellent nanocatalyst for acetylation reactions under solvent-free conditions
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A convenient green method has been developed for the synthesis of biogenic CuFe2O4 magnetic nanoparticles using tea extracts within a very short reaction time. The prepared nanoparticles with an average size of 8.78 nm have been used as an effective catalyst for the acetylation of various alcohols, phenols and amines in good to excellent yields under solvent-free conditions. The catalyst was characterized by XRD, XPS, VSM, SEM and TEM study. A magnetic study of the fresh and recycled catalyst after the fourth cycle was performed by VSM measurement. The main advantages of this protocol are simple biogenic synthesis of the catalyst, a reusable and heterogeneous catalytic system, and short reaction times with excellent yields.
- Chutia, Rituparna,Chetia, Bolin
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p. 15200 - 15206
(2018/09/29)
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- Preparation of Polydopamine Sulfamic Acid-Functionalized Silica Gel as Heterogeneous and Recyclable Nanocatalyst for Acetylation of Alcohols and Amines Under Solvent-Free Conditions
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To fabricate SiO2/PDA–SO3H nanocatalyst, a suitable method is designed for the loading of sulfonic acid groups on the surface of polydopamine (PDA)-encapsulated SiO2 nanoparticles. To bridge the gap between heterogeneous and homogeneous catalysis, surface functionalization of silica gel is an elegant procedure. The morphology, structure, and physicochemical features were specified using different analytical techniques including field emission scanning electron microscopy (FESEM), Fourier transformed infrared spectroscopy (FT-IR), high resolution-transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDS), wavelength-dispersive X-ray spectroscopy (WDX), X-ray photoelectron spectroscopy (XPS), and back titration. The SiO2/PDA–SO3H nanoparticles are efficient nanocatalysts for the acetylation of many alcohols, phenols, and amines with acetic anhydride under solvent-free conditions in good to excellent yields. Moreover, the reuse and recovery of the catalyst was shown seven times without detectible loss in activity. Graphical Abstract: [Figure not available: see fulltext.]
- Veisi, Hojat,Vafajoo, Saba,Bahrami, Kiumars,Mozafari, Bita
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p. 2734 - 2745
(2018/07/30)
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- Zirconocene-catalyzed direct (trans)esterification of acyl acids (esters) and alcohols in a strict 1:1 ratio under solvent-free conditions
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A highly efficient way for the direct (trans)esterification of acyl acids (esters) and alcohols in a strict 1:1 ratio using a zirconocene complex (1, 1 mol%), a strong Lewis acid of good water tolerance, as a catalyst under solvent-free conditions has been developed. A wide range of acid and alcohol (esters) substrates undergo (trans)esterification to produce carboxylic ester motifs in moderate to good or excellent yields with good functional tolerance, such as that towards C-Br as well as CC and CC bonds. And complex 1 can be recycled six times without showing a significant decline in catalytic efficiency. It was demonstrated that cyclandelate, which is used to treat high blood pressure as well as heart and blood-vessel diseases, can be directly synthesized on a gram scale with 81% yield (6.70 g) using complex 1.
- Tang, Zhi,Jiang, Qiutao,Peng, Lifen,Xu, Xinhua,Li, Jie,Qiu, Renhua,Au, Chak-Tong
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supporting information
p. 5396 - 5402
(2017/11/22)
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- Preparation of acetates catalyzed by boric acid and/or tungstophosphoric acid-modified zirconia obtained employing polyethylene glycols as pore-forming agents
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Zirconia modified with boric acid and/or tungstophosphoric acid calcined at 320 °C were prepared, characterized and used as catalysts in the production of acetates from diverse alcohols and phenols. Polyethylene glycol (PEG) of different molecular weight (400, 2000, 6000 Da) were added as low cost pore-forming agents during zirconia synthesis using zirconyl chloride as precursor and ammonium hydroxide as precipitating agent. The zirconias were impregnated with aqueous solutions of boric acid and/or tungstophosphoric acid (TPA). The borated zirconias, zirconias modified with TPA and zirconias doped with both boron and TPA were amorphous mesoporous materials with very strong acid sites, and specific surface areas SBET of around 200, 100, and 150 m2/g, respectively. The FT-IR spectra of borated zirconias exhibited the bands of boron species, while the zirconias modified with TPA presented the characteristic bands of tungstophosphate anion, and the zirconias doped with both boron and TPA showed a degradation of the TPA anion, confirmed by 31P MAS-NMR. The borated zirconias and the zirconias modified with TPA gave excellent selectivity and yield in the 2-phenylethanol esterification with acetic acid. The use of these materials allows obtaining higher or similar results than those reported in the literature. Zirconias doped with both boron and TPA gave lower values, due to the transformation of the [PW12O40]3? Keggin anion in to the [P2W21O71]6? and [PW11O39]7? species. The reactivity towards acetylation with acetic acid of different alcohols and phenols using the best catalyst was ordered according to: primary alcohols > secondary alcohols > phenols. The reactivity difference of the alcohols and phenols was correlated with the electronic density on the oxygen atom and steric effects.
- Osiglio, Lilian,Sathicq, Gabriel,Pizzio, Luis,Romanelli, Gustavo,Blanco, Mirta
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- Catalytic activity comparison of Zr-SBA-15 immobilized by a Br?nsted-Lewis acidic ionic liquid in different esterifications
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Zirconium-incorporated SBA-15 mesoporous molecular sieves (Zr-SBA-15) with different Si/Zr molar ratios were one-pot synthesized and characterized by XRD, TEM and N2 physical adsorption. The Br?nsted-Lewis acidic ionic liquid 1-(3-sulfonic acid)-propy l-3-methylimidazole chlorozincinate ([mim-ps]Cl-ZnCl2) was prepared by a hydrothermal process and its acidity was measured by FT-IR spectroscopy using acetonitrile and pyridine as probes. The Zr-SBA-15 catalyst immobilized by [mim-ps]Cl-ZnCl2 (Zr-SBA-15/[mim-ps]Cl-ZnCl2) was prepared by a wet impregnation method and characterized by XRD, BET, FT-IR spectroscopy, TEM, XPS and TG. In particular, the catalytic activities of Zr-SBA-15 and Zr-SBA-15/[mim-ps]Cl-ZnCl2 in the esterification of acetic acid were evaluated with n-butyl alcohol (n-BuOH), benzyl alcohol (BnOH) and cyclohexanol (Naxol). The results show that Zr-SBA-15/[mim-ps]Cl-ZnCl2 exhibited enhanced catalytic properties compared to Zr-SBA-15. Under optimal conditions, the acetic acid conversion over Zr-SBA-15/[mim-ps]Cl-ZnCl2 reached 89.7, 93.6, and 84.9% for n-BuOH, BnOH and Naxol, respectively. After 5 cycles, the acetic acid conversion decreased slightly. Zr-SBA-15/[mim-ps]Cl-ZnCl2 was found to be an outstanding catalyst for esterification.
- Dai, Liming,Zhao, Qian,Fang, Minglan,Liu, Ruifeng,Dong, Mingfeng,Jiang, Tingshun
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p. 32427 - 32435
(2017/07/10)
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- Super-Hydrophobic, Stable, and Swelling Nanoporous Solid Strong Acid
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Super-hydrophobic solid strong acid with superior thermal stability and unique swelling properties has been synthesized by sulfonation of nanoporous polydivinylbenzene (PDVB) with super-acid of trifluoromethanesulfonic acid (TFMSA). The resultant PDVB–HOSO2CF3 has a well developed system of nanopores, superhydrophobic surface character and strong acid sites, and could be used as a highly efficient solid acid for catalyzing production of biodiesel and fine chemicals via transesterification, esterification and acylation. In terms of activity PDVB–HOSO2CF3 is superior to various solid acids such as SBA-15-SO3CF3, Nafion, Amberlyst 15, SBA-15-Ar-SO3H and H form USY. The preparation of PDVB–HOSO2CF3 offers the way to develop new kind of porous solid acid with strong acid strength and regulated wettability.
- Wu, Qin,Peng, Jinjun,Kong, Weiping,Zou, Yongcun
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p. 816 - 824
(2018/03/08)
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- Ethyl acetate as an acetyl surrogate for the iodine catalyzed acetylation of alcohols
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The use of readily available ethyl acetate in the presence of iodine as an alternative acetylating agent is reported. Amines and phenols were unreactive under the examined reaction conditions, indicating that the method is highly chemoselective.
- Basumatary, Grace,Bez, Ghanashyam
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supporting information
p. 4312 - 4315
(2017/10/13)
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- Polycyclic ketone monooxygenase from the thermophilic fungus Thermothelomyces thermophila: A structurally distinct biocatalyst for bulky substrates
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Regio- and stereoselective Baeyer-Villiger oxidations are difficult to achieve by classical chemical means, particularly when large, functionalized molecules are to be converted. Biocatalysis using flavin-containing Baeyer-Villiger monooxygenases (BVMOs) is a wellestablished tool to address these challenges, but known BVMOs have shortcomings in either stability or substrate selectivity. We characterized a novel BVMO from the thermophilic fungus Thermothelomyces thermophila, determined its three-dimensional structure, and demonstrated its use as a promising biocatalyst. This fungal enzyme displays excellent enantioselectivity, acts on various ketones, and is particularly active on polycyclic molecules. Most notably we observed that the enzyme can perform oxidations on both the A and D ring when converting steroids. These functional properties can be linked to unique structural features, which identify enzymes acting on bulky substrates as a distinct subgroup of the BVMO class.
- Fürst, Maximilian J.L.J.,Savino, Simone,Dudek, Hanna M.,Castellanos, J. Rúben Gómez,De Souza, Cora Gutiérrez,Rovida, Stefano,Fraaije, Marco W.,Mattevi, Andrea
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supporting information
p. 627 - 630
(2017/05/15)
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- Reusable and efficient polyvinylpolypyrrolidone-supported triflic acid catalyst for acylation of alcohols, phenols, amines, and thiols under solvent-free conditions
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Abstract: A triflic acid-functionalized polyvinylpolypyrrolidone was prepared and fully characterized by FT-IR, TGA, and SEM. This super acidic solid catalyst shows high catalytic activity for selective acylation of alcohols, phenols, amines, and thiols with anhydrides under solvent-free conditions at room temperature. In addition, this method features an easy to handle solid super acid catalyst and an operationally simple procedure, affording the desired acylated products in excellent yields. Graphical abstract: [Figure not available: see fulltext.].
- Tajbakhsh, Mahgol,Tajbakhsh, Mahmoud,Khaksar, Samad,Gazvini, Helia Janatian,Heidary, Marzieh
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p. 1117 - 1122
(2017/05/10)
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- "Click Chemistry" Mediated Functional Microporous Organic Nanotube Networks for Heterogeneous Catalysis
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The synthesis of azide functional microporous organic nanotube networks (N3-MONNs) via a Friedel-Crafts hyper-cross-linking reaction is reported. Subsequently, a general method for obtaining heterogeneous catalysts through a Cu-catalyzed alkyne-azide reaction is presented. The small-molecule catalysts such as 2,2,6,6,-tetramethylpiperidine-1-oyl and 4-(N,N-dimethylamino)pyridine can be anchored into the MONNs. Owing to the hierarchically porous structure and high surface area, these catalysts show high activity in selective oxidation of alcohols and acylation reaction, respectively.
- Yu, Wei,Zhou, Minghong,Wang, Tianqi,He, Zidong,Shi, Buyin,Xu, Yang,Huang, Kun
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supporting information
p. 5776 - 5779
(2017/11/10)
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- Highly Active Manganese-Mediated Acylation of Alcohols with Acid Chlorides or Anhydrides
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To explore further the practical uses of highly active manganese (Mn?), a variety of alcohols were treated with Mn?, and the resulting complexes were coupled with acid chlorides and/or acetic anhydride in the absence of any extra catalyst. The subsequent reactions took place smoothly under mild conditions, providing the corresponding O-acylation products in good to excellent isolated yields.
- Joo, Seong-Ryu,Youn, Young-Jin,Hwang, Young-Ran,Kim, Seung-Hoi
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p. 2665 - 2669
(2017/10/07)
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- POSS-derived solid acid catalysts with excellent hydrophobicity for highly efficient transformations of glycerol
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Novel excellent hydrophobic POSS-derived solid acid catalysts were successfully synthesized through free radical copolymerization of polyhedral oligomeric vinylsilsesquioxanes (POSS) with sodium p-styrene sulfonate (POSS-x-SO3H), and characterized by several physicochemical methods. Green routes toward valorization of glycerol via acetalization with benzaldehyde and esterification of glycerol with acetic acid have been proposed. The as-prepared catalysts showed very high activities and selectivities toward glycerol derivatives within a short reaction time, which were even higher than that of homogeneous H2SO4. The POSS-2-SO3H catalyst was recycled up to five times without any significant loss of activity. The excellent performance of these solid acid catalysts is mostly attributed to the combination of superior hydrophobicity and large specific surface area.
- Leng, Yan,Zhao, Jiwei,Jiang, Pingping,Lu, Dan
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p. 875 - 881
(2016/02/18)
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- Deep eutectic solvent choline chloride·2CrCl3·6H2O: An efficient catalyst for esterification of formic and acetic acid at room temperature
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A highly efficient and selective method for esterification of formic and acetic acid with alcohols has been achieved at room temperature, with the choline chloride (ChCl)/chromium(iii) chloride hexahydrate (CrCl3·6H2O) deep eutectic solvent as a catalyst. High yields and good selectivities of organic esters are obtained using DES [ChCl][CrCl3·6H2O]2 with the molar ratio 5:1 (carboxylic acids:alcohols) at room temperature in 24 h. The ease of recovery and reusability of DES with high catalytic activity makes this method efficient and practical.
- Cao, Jin,Qi, Bin,Liu, Jun,Shang, Yuhan,Liu, Huiwen,Wang, Wenjing,Lv, Jia,Chen, Zhiyan,Zhang, Haibo,Zhou, Xiaohai
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p. 21612 - 21616
(2016/03/08)
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- Tin-containing catalyst is used for a method of producing a calbonyl compd.
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PROBLEM TO BE SOLVED: To provide a reaction catalyst having a high reaction selectivity and being recyclable in a peroxidation reaction using a carbonyl compound, and to provide a method for highly efficiently producing, for example, ester, lactone and formyloxy compounds or derivatives thereof by subjecting a carbonyl compound to a peroxidation reaction using the reaction catalyst.SOLUTION: A specific tin-containing catalyst can be used for a peroxidation reaction of a carbonyl compound, and a recyclable specific tin-containing catalyst is reusable for the reaction. A method for producing an oxide carries out a peroxidation reaction of a carbonyl compound in the presence of the tin-containing catalyst or the tin-containing recyclable catalyst.
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Paragraph 0149
(2017/03/25)
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- Pyridinium saccharinate salts as efficient recyclable acylation catalyst: A new bridge between heterogeneous and homogeneous catalysis
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It is important to find a way for separation of concerned chemicals from product mixture after reaction, in order to avoid spreading harmful chemicals to society. The homogeneous nature of DMAP-catalyzed acylation still suffers from the problems of catalyst separation and/or residual DMAP contamination. DMAP causes acute dermal toxicity, whereas the corresponding DMAP salt exhibits only slight irritation to the skin. Very recently, we found that the DMAP saccharinate salt is also great recyclable catalyst, whose acylation of alcohols has been successfully and effectively carried out 10 times without loss in activity. This report covers our comprehensive studies on using the pyridinium saccharinate salts as efficient recyclable acylation catalysts including 4-N,N-dimethylaminopyridinium saccharinate (A), 4-(1-pyrrolidinyl) pyridinium saccharinate (B), 2-N,N-dimethylaminopyridinium saccharinate (C), and pyridinium saccharinate (D). Their structure and reactivity have been studied. The salts A, C, and D contain very interesting seven-membered synthon showing multiple H-bonding interactions for pair of pyridinium cation and saccharinate anion in the solid state. The salt B exhibits H-bonding interaction of N(sac) ... H-N(py) in the solid state, instead of seven-membered synthon. The catalytic reactivity studies show that salts A and B are both very effective, with salt B even better in reactivity, and are both recyclable in the esterification of a variety of alcohols, under solvent-free and base-free conditions at room temperature.
- Lu, Norman,Chang, Wei-Hsuan,Wei, Rong-Jyun,Fang, Yung-Cheng,Han, Tu-Wen,Wang, Guo-Quan,Chang, Jia-Yaw,Wen, Yuh-Sheng,Liu, Ling-Kang
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p. 3468 - 3476
(2016/06/06)
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- Highly efficient and recyclable acetylation of phenols and alcohols by nickel zirconium phosphate under solvent-free conditions
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Nickel zirconium phosphate nanoparticles have been used as an efficient catalyst for the acetylation of a wide range of alcohols and phenols with acetic anhydride in good to excellent yields under solvent-free conditions. The steric and electronic properties of the different substrates had a significant influence on the reaction conditions required to achieve the acetylation. The catalyst used in the current study was characterized by inductively coupled plasma optical emission spectroscopy, X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy, and transmission electron microscopy. This nanocatalyst could also be recovered and reused at least six times without any discernible decrease in its catalytic activity.
- Hajipour, Abdol Reza,Karimi, Hirbod,Kohi, Afshin
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- DMAP-based flexible polymer networks formed via Heck coupling as efficient heterogeneous organocatalysts
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Two DMAP-based flexible polymer networks TPB-DMAP and TPA-DMAP have been successfully synthesized via palladium catalyzed Heck cross-coupling. The structures of these polymers were confirmed by solid state 13C CP/MAS and Fourier transform infrared spectroscopy (FTIR). Although both polymers have negligible surface areas, they exhibit excellent catalytic efficiency for the acylation of 1-phenylethanol with acetic anhydride due to their good swelling capacities. Utilized as a typical catalyst, the polymer TPA-DMAP shows high activities for acylation of a variety of alcohols to the corresponding esters. Moreover, the catalyst can be recycled at least ten times without obvious loss of catalytic activity.
- Xu, Wei,Xia, Wu,Guan, Yukun,Wang, Yiming,Lu, Cuifen,Yang, Guichun,Nie, Junqi,Chen, Zuxing
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- P4VPy–CuO nanoparticles as a novel and reusable catalyst: application at the protection of alcohols, phenols and amines
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P4VPy–CuO nanoparticles were synthesized using ultrasound irradiations. Relevant properties of the synthesized nanoparticles were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. After identification, the prepared reagent was used for the promotion of different types of protection reactions of alcohols, phenols and amines. Easy workup, short reaction times, excellent yields, relatively low cost and reusability of the catalyst are the striking features of the reported methods.
- Shirini, Farhad,Fallah-Shojaei, Abdollah,Abedini, Masoumeh,Samavi, Laleh
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p. 1699 - 1712
(2016/07/27)
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- Graphite oxide-catalyzed acetylation of alcohols and phenols
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Graphite oxide (GO) was used as a catalyst for the reactions of alcohols and phenols with acetic anhydride. The acetates of primary and secondary alcohols were prepared in good to excellent yields in short reaction time under mild conditions. Electron deficient phenols could be converted to the corresponding acetates steadily. As an efficient catalyst, GO is easily available, cheap, moderately toxic and weakly acidic.
- Liu, Yuan-Yuan,Qi, Jun-Mei,Bai, Li-Sha,Xu, Yue-Long,Ma, Ning,Sun, Fei-Fei
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supporting information
p. 726 - 730
(2016/05/19)
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- Efficient and selective N-, S- and O-acetylation in TEAA ionic liquid as green solvent. Applications in synthetic carbohydrate chemistry
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Background: The ionic liquid triethylammonium acetate (TEAA) was found to be an efficient solvent in the acetylation of alcohols, amines, oximes and thiols to their corresponding acetyl compounds using only a 10% excess of acetic anhydride under mild conditions. Moreover TEAA is not only an inexpensive and recyclable solvent but also an anomeric selective catalyst in the per-O-acetylation of sugar moieties. Methods: Simple and effective organic synthesis protocols were provided for the selective acetylation of several substrates. The products were fully characterized by 1H and 13C NMR spectroscopy and the anomeric ratios were obtained from the 1H spectra. Results: Structurally diverse alcohols, phenols, thiols, amines, carbohydrates and oximes underwent acylation under mild conditions by this procedure to provide the corresponding acetates in excellent yields. TEAA ionic liquid is unique in its capability to act as both, solvent and high selective catalyst. As expected, the reaction proceeds with high b anomeric selectivity for sugars derivatives. Moreover, the ionic liquid was regenerated, recycled and reused for three times without apparent loss of reactivity and selectivity in all cases. Conclusions: The present procedure provides a powerful and versatile acylation method for alcohols, phenols, thiols, amines, oximes and carbohydrates. This protocol is endowed with several unique merits: selectivity, cost-efficiency, atom-economy and mild reaction conditions tolerable to acid sensitive functionalities. With these features, this method may be considered as a better alternative for the acetylation of a wide range of substrates.
- Lafuente, Leticia,Díaz, Gisela,Bravo, Rodolfo,Ponzinibbio, Agustín
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p. 195 - 200
(2016/02/26)
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- Silica–ferric chloride (SiO2–FeCl3) catalyzed selective synthesis of 2-substituted benzimidazole through Csp2Csp3bond cleavage of β-ketoester/amide
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Silica–ferric chloride (SiO2–FeCl3) supported reagent was successfully utilized as recyclable catalyst for the general and highly efficient synthesis of 2-substituted benzimidazole by the condensation of 1,2-diamino benzene and β-ketoester/amide followed by original Csp2Csp3bond cleavage. Evidences in favor of C[sbnd]C (α–β) bond cleavage of β-ketoesters/amides are established.
- Majumdar, Swapan,Chakraborty, Ankita,Bhattacharjee, Subrata,Debnath, Sudipto,Maiti, Dilip K.
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supporting information
p. 4595 - 4598
(2016/09/23)
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- PROCESS AND APPARATUS FOR CO-PRODUCING CYCLOHEXANOL AND ALKANOL
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This invention relates to a process for co-producing cyclohexanol and alkanol, including a cyclohexene esterification step and a cyclohexyl ester hydrogenation step. This invention further relates to a process for further producing cyclohexanone or caprolactam, starting from the co-producing process, and an apparatus for co-producing cyclohexanol and alkanol. The process for co-producing cyclohexanol and alkanol of this invention is environment-friendly, with low production cost and highly improved atom economy.
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- Synthesis of lipase nano-bio-conjugates as an efficient biocatalyst: Characterization and activity-stability studies with potential biocatalytic applications
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In the present study, we have synthesized lipase-nano-bio-conjugates via immobilization of various lipases on multiwall carbon nano-tubes (MCNT), in order to construct an efficient and recyclable biocatalytic system. In a screening study lipase Pseudomonas fluorescens (PFL) acted as an efficient biocatalyst (lipase-nano-bio-conjugates) which showed higher retention of lipase activity and protein loading. Consequently the immobilization support : lipase (MCNT : PFL) composition was screened in which MCNT : PFL (2 : 1) was calculated as a robust biocatalyst composition which showed higher activity retention and protein loading. This nano-bio-conjugate was then characterized in detail with physical and biochemical techniques using SEM, TEM, FTIR, Km, Vmax, catalytic efficiency and (%) water content analysis. This developed biocatalyst was further used for practical biocatalytic applications such as O-acylation reactions. Various reaction parameters were optimized in detail like reactant molar ratio (2 : 3.5), solvent, MCNT : PFL biocatalyst amount (36 mg), temperature (50°C) etc. The developed biocatalytic protocol was then extended to synthesize several (twenty-two) industrially important acylated moieties with an excellent yield, these products are well characterized by 1HNMR, 13CNMR and GCMS analysis. Moreover in the present study, we have reviewed the potential industrial applications of various synthesized compounds. Also, we have studied the thermodynamic aspect which demonstrated more feasibility of use of immobilized MCNT : PFL lipase over free lipase. Interestingly, immobilized MCNT : PFL lipase showed 2.3 fold higher catalytic activity than free PFL. Besides this, the biocatalyst was efficiently recycled for up to five cycles. Thus the present protocol demonstrated, (i) synthesis of nano-bio-conjugates as a bio-catalyst, (ii) detailed physical-biochemical characterization of nano-bio-conjugates, (iii) optimization of the biocatalytic protocol (iv) practical biocatalytic applications along with a mechanistic study (v) a thermodynamic feasibility study and (vi) recyclability study. 2015
- Badgujar, Kirtikumar Chandulal,Sasaki, Takehiko,Bhanage, Bhalchandra Mahadeo
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p. 55238 - 55251
(2015/07/07)
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- Biomass derived β-cyclodextrin-SO3H as a solid acid catalyst for esterification of carboxylic acids with alcohols
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A novel β-cyclodextrin-SO3H carbon based solid acid catalyst was prepared in a convenient and ecofriendly manner and was characterized using FTIR, PXRD, EDAX and NH3TPD to illustrate that the carbon material has been functionalized with -SO3H, -COOH and -OH groups. The catalyst was studied for esterification of various carboxylic acids and alcohols under solvent free conditions and showed excellent catalytic performance and gave good yields of esters in the range 78-99% at 70°C. No solvent was used either for catalyst preparation nor for esterification reaction. The catalyst can be easily recovered by simple filtration and reused for subsequent three runs without any significant impact on yields of products. The main advantage of this methodology is easy and ecofriendly catalyst preparation, easy catalyst separation, practical simplicity, safe reaction conditions, recyclable catalyst and high product yields.
- Thombal, Raju S.,Jadhav, Amol R.,Jadhav, Vrushali H.
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p. 12981 - 12986
(2015/02/19)
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- Sulfonic acid-functionalized periodic mesoporous organosilicas in esterification and selective acylation reactions
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The application of sulfonic acid-functionalized periodic mesoporous organosilicas (PMOs) having either phenyl (1a) or ethyl (1b) bridging groups was investigated in the esterification of a variety of alcohols and fatty acids. It was found that 1b consistently exhibited higher catalytic performance than 1a in the described reaction. In particular, it was proposed that the superior catalytic activity of 1b in esterification of fatty acids with methanol is a result of adequate hydrophobic-hydrophilic surface balance in the ethyl PMO catalyst. In addition, the study of chemoselective acylation of 1,3-butanediol with dodecanoic acid with varied mesoporous silica-supported solid sulfonic acids including both 1a and 1b implies that there is a compromise between the reaction selectivity and the surface physicochemical properties of the employed catalyst. Our results clearly show that the catalyst having high surface hydrophilic nature gives high selectivity toward the formation of mono-acylated products whereas those with relatively high hydrophobic characteristics showed enhanced selectivity toward the formation of di-acylated products.
- Karimi, Babak,Mirzaei, Hamid M.,Mobaraki, Akbar,Vali, Hojatollah
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p. 3624 - 3631
(2015/07/01)
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- Sulfated Carbon Quantum Dots as Efficient Visible-Light Switchable Acid Catalysts for Room-Temperature Ring-Opening Reactions
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Acid catalytic processes play a classic and important role in modern organic synthesis. How well the acid can be controlled often plays the key role in the controllable synthesis of the products with high conversion yield and selectivity. The preparation of a novel, photo-switchable solid-acid catalyst based on carbon quantum dots is described. The carbon quantum dots are decorated with small amounts of hydrogensulfate groups and thus exhibit a photogenerated acidity that produces a highly efficient acid catalysis of the ring opening of epoxides with methanol and other primary alcohols. This reversible, light-switchable acidity is shown to be due to photoexcitation and charge separation in the carbon quantum dots, which create an electron withdrawing effect from the acidic groups. The catalyst is easily separated by filtration, and we demonstrate multiple cycles of its recovery and reuse.
- Li, Haitao,Sun, Chenghua,Ali, Muataz,Zhou, Fengling,Zhang, Xinyi,MacFarlane, Douglas R.
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supporting information
p. 8420 - 8424
(2015/11/28)
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- On the understanding of BF3·Et2O-promoted intra- and intermolecular amination and oxygenation of unfunctionalized olefins
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BF3·Et2O was found to be effective for both intra- and intermolecular amination and oxygenation of unfunctionalized olefins. In the presence of 3 equiv. of BF3·Et2O, intramolecular hydroamination of N-(pent-4-enyl)-p-toluenesulfonamides, N-(hex-5-enyl)-p-toluenesulfonamides, intermolecular hydroamination between sulfonamides and cyclohexene, norbornene or styrene, lactonization of pent-4-enoic acid or hex-5-enoic acid compounds and esterification of cyclohexene with different carboxylic acids all proceeded readily, leading to the corresponding amination or oxygenation products in up to 99% isolated yields. Preliminary NMR experiments and DFT calculations suggested that the intramolecular hydroamination reactions proceeded via a sulfonimidic acid intermediate (N=S-OH), and formation of the corresponding Bronsted acid HF or HBF4 was less likely.
- Yang, Chun-Hua,Fan, Wen-Wen,Liu, Gong-Qing,Duan, Lili,Li, Lin,Li, Yue-Ming
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p. 61081 - 61093
(2015/08/03)
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- Acetylation of alcohols and phenols under solvent-free conditions using iron zirconium phosphate
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Iron zirconium phosphate (ZPFe) nanoparticles were found to function as an efficient catalyst for the acetylation of a wide range of alcohols and phenols using acetic anhydride, generating good to excellent yields under solvent-free conditions. The steric and electronic properties of various substrates had a significant influence on the reaction conditions required to achieve the acetylation. The catalyst used in the current study was characterized by inductively coupled plasma-optical emission spectrometry, X-ray diffraction, N2 adsorption-desorption, scanning electron microscopy, and transmission electron microscopy. These analyses revealed that the interlayer distance in the catalyst increased from 7.5 to 9.3 ? when Fe3+ was intercalated between the layers, whereas the crystallinity of the material was reduced. This nanocatalyst could also be recovered and reused at least six times without any discernible decrease in its catalytic activity. This new method for the acetylation of alcohols and phenols has several important advantages, including mild and environmentally friendly reaction conditions, as well as good to excellent yields and a facile work-up.
- Hajipour, Abdol R.,Karimi, Hirbod,Masti, Amir
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p. 595 - 602
(2015/09/28)
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- Efficient approach for the chemoselective acetylation of alcohols catalyzed by a novel metal oxide nanocatalyst CuO-ZnO
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A new method has been developed for the chemoselective acetylation of alcohols with acetic anhydride in the presence of phenols using a novel, recyclable CuO-ZnO nanocatalyst. The catalyst was synthesized using the co-precipitation method and characterized by N2 adsorption-desorption, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersion scanning analyses. Furthermore, this catalyst could be recycled up to six times without significant loss in its activity.
- Albadi, Jalal,Alihosseinzadeh, Amir,Mardani, Mehdi
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p. 308 - 313
(2015/09/28)
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