- High-efficiency green production process of o-aminoanisole
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The invention discloses a high-efficiency green production process of o-aminoanisole, which comprises o-chloronitrobenzene and methanol, and the production process comprises the following steps: a, respectively adding the o-chloronitrobenzene, the methanol and a catalyst A into a methoxylation solvent, controlling the temperature at 20-80 DEG C, and adding an alkali in batches to carry out methoxylation reaction, b, filtering and washing the catalyst A-containing mixed solution obtained in the step a to obtain a high-purity intermediate product o-nitroanisole solution; c, directly carrying out hydrogenation reaction on the o-nitroanisole solution in the step b without separation to obtain an o-aminoanisole solution; and d, filtering the o-aminoanisole solution in the step c, removing the solvent, and carrying out reduced pressure distillation to obtain the o-aminoanisole with the purity of 99.5% or above. According to the process, the catalyst A capable of improving the reaction rate is adopted, so that the reaction conditions become milder, the reaction time is shortened, side reactions are greatly inhibited, the catalyst is easy and convenient to recycle, and the continuous application frequency is not less than 20.
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Paragraph 0031-0041
(2021/08/19)
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- Selective Mild Oxidation of Anilines into Nitroarenes by Catalytic Activation of Mesoporous Frameworks Linked with Gold-Loaded Mn3O4 Nanoparticles
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This work reports the synthesis and catalytic application of mesoporous Au-loaded Mn3O4 nanoparticle assemblies (MNAs) with different Au contents, i. e., 0.2, 0.5 and 1 wt %, towards the selective oxidation of anilines into the corresponding nitroarenes. Among common oxidants, as well as several supported gold nanoparticle platforms, Au/Mn3O4 MNAs containing 0.5 wt % Au with an average particle size of 3–4 nm show the best catalytic performance in the presence of tert-butyl hydroperoxide (TBHP) as a mild oxidant. In all cases, the corresponding nitroarenes were isolated in high to excellent yields (85–97 %) and selectivity (>98 %) from acetonitrile or greener solvents, such as ethyl acetate, after simple flash chromatography purification. The 0.5 % Au/Mn3O4 catalyst can be isolated and reused four times without a significant loss of its activity and can be applied successfully to a lab-scale reaction of p-toluidine (1 mmol) leading to the p-nitrotulene in 83 % yield. The presence of AuNPs on the Mn3O4 surface enhances the catalytic activity for the formation of the desired nitroarene. A reasonable mechanism was proposed including the plausible formation of two intermediates, the corresponding N-aryl hydroxylamine and the nitrosoarene.
- Armatas, Gerasimos S.,Daikopoulou, Vassiliki,Koutsouroubi, Eirini D.,Lykakis, Ioannis N.,Skliri, Euaggelia
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- Cu-Catalyzed Phenol O-Methylation with Methylboronic Acid
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A Cu-catalyzed oxidative cross-coupling of phenols with methylboronic acid to form aryl methyl ethers has been developed, expanding the scope of Chan-Evans-Lam alkylation. Electron-deficient phenol derivatives with a broad array of functional groups are methylated in high yields. Increased reaction temperature and catalyst loading enables the methylation of substrates incorporating pyridine and dihydroquinolone motifs. Electron-rich phenol derivatives are poor substrates for the methylation; the characterization of C?H homodimerization products formed from these substrates illuminates a competing mechanistic pathway.
- Bartlett, Mairead E.,Chavez, Angela K.,Gaffney, Uma Bhagwat,Gorin, David J.,Lee, Joyce,Sharew, Betemariam,Wu, Miranda,Zhu, Yingchuan
-
supporting information
p. 5661 - 5664
(2021/11/11)
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- Photoinduced Iron-Catalyzed ipso-Nitration of Aryl Halides via Single-Electron Transfer
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A photoinduced iron-catalyzed ipso-nitration of aryl halides with KNO2 has been developed, in which aryl iodides, bromides, and some of aryl chlorides are feasible. The mechanism investigations show that the in situ formed iron complex by FeSO4, KNO2, and 1,10-phenanthroline acts as the light-harvesting photocatalyst with a longer lifetime of the excited state, and the reaction undergoes a photoinduced single-electron transfer (SET) process. This work represents an example for the photoinduced iron-catalyzed Ullmann-type couplings.
- Wu, Cunluo,Bian, Qilong,Ding, Tao,Tang, Mingming,Zhang, Wenkai,Xu, Yuanqing,Liu, Baoying,Xu, Hao,Li, Hai-Bei,Fu, Hua
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p. 9561 - 9568
(2021/08/06)
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- Eco-Friendly Methodology for the Formation of Aromatic Carbon–Heteroatom Bonds by Using Green Ionic Liquids
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A new sustainable method is reported for the formation of aromatic carbon–heteroatom bonds under solvent-free and mild conditions (no co-oxidant, no strong acid and no toxic reagents) by using a new type of green ionic liquid. The bromination of methoxy arenes was chosen as a model reaction. The reaction methodology is based on only using natural sodium bromine, which is transformed into an electrophilic brominating reagent within an ionic liquid, easily prepared from the melted salt FeCl3 hexahydrate. Bromination reactions with this in-situ-generated reagent gave good yields and excellent regioselectivity under simple and environmentally friendly conditions. To understand the unusual bromine polarity reversal of sodium bromine without any strong oxidant, the molecular structure of the reaction medium was characterised by Raman and direct infusion electrospray ionisation mass spectroscopy (ESI-MS). An extensive computational investigation using density functional theory methods was performed to describe a mechanism that suggests indirect oxidation of Br? through new iron adducts. The versatility of the methodology was successively applied to nitration and thiocyanation of methoxy arenes using KNO3 and KSCN in melted hexahydrated FeCl3.
- Richards, Kenza,Petit, Eddy,Legrand, Yves-Marie,Grison, Claude
-
supporting information
p. 809 - 814
(2020/11/30)
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- Nitration of aromatics with dinitrogen pentoxide in a liquefied 1,1,1,2-tetrafluoroethane medium
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Regardless of the sustainable development path, today, there are highly demanded chemical productions still operating that bear environmental and technological risks inherited from the previous century. The fabrication of nitro compounds, and nitroarenes in particular, is traditionally associated with acidic wastes formed in nitration reactions exploiting mixed acids. However, nitroarenes are indispensable for industrial and military applications. We faced the challenge and developed a greener, safer, and yet effective method for the production of nitroaromatics. The proposed approach comprises the application of an eco-friendly nitrating agent, namely dinitrogen pentoxide (DNP), in the medium of liquefied 1,1,1,2-tetrafluoroethane (TFE) - one of the most non-hazardous Freons. Importantly, the used TFE is not emitted into the atmosphere but is effortlessly recondensed and returned into the process. DNP is obtainedviathe oxidation of dinitrogen tetroxide with ozone. The elaborated method is characterized by high yields of the targeted nitro arenes, mild reaction conditions, and minimal amount of easy-to-utilize wastes.
- Fauziev, Ruslan V.,Kharchenko, Alexandr K.,Kuchurov, Ilya V.,Zharkov, Mikhail N.,Zlotin, Sergei G.
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p. 25841 - 25847
(2021/08/09)
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- Clean production process for producing nitrobenzene alkoxy ether by using nitrohalogenated benzene
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The invention provides a clean production process for producing nitrobenzene alkoxy ether by using nitrohalogenated benzene. The specific production steps comprise: proportionally adding one or more than one non-polar solvents into a reactor, adding molten nitrohalogenated benzene into the reactor, uniformly stirring, and adding alkali metal alkoxide into the reactor at a constant speed; after thereaction is finished, adding water to washing the inorganic matters generated in the reaction process while recovering the solvent. According to the invention, the production process is simple, the catalyst separation efficiency in the reaction process is high, other substances irrelevant to the reaction are not added in the reaction process, the purity is high, the yield is high, byproducts arelow, the wastewater amount is low, and the reaction period is short; and the reaction device is operated in a totally-enclosed manner, so that the operation environment is improved, the harm to humanhealth is reduced, and the cost is saved.
- -
-
Paragraph 0043-0048
(2020/06/09)
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- NITRATION
-
The present invention relates to a process for preparing a nitrated compound, comprising the step of reacting a compound (A) comprising at least one substituted or unsubstituted aromatic or heteroaromatic ring, wherein said heteroaromatic ring comprises at least one heteroatom selected from the group consisting of oxygen, sulfur, phosphor, selenium and nitrogen, with a compound of formula (I) wherein Y is selected from the group consisting of hydrogen and nitro.
- -
-
Page/Page column 36; 41; 46; 64; 37; 42; 46-47
(2020/05/28)
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- Low-temperature and highly efficient liquid-phase catalytic nitration of chlorobenzene with NO2: Remarkably improving the para-selectivity in O2-Ac2O-Hβ composite system
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In this work, we developed a low-temperature and efficient approach for the highly selective preparation of valuable p-nitrochlorobenzene from the liquid-phase catalytic nitration of chlorobenzene with NO2 in O2-Ac2O-Hβ composite system. The results demonstrated that the introduction of molecular oxygen remarkably enhanced the chlorobenzene conversion and the cooperation catalysis of Hβ zeolite and Ac2O envidently improved the selectivity to para-nitro product. Under the optimized reaction conditions, 93.6 % of the selectivity to p-nitrochlorobenzene with 84.0 % of chlorobenzene conversion was obtained, and the ratio of p-nitrochlorobenzene to o-nitrochlorobenzene could reach up to 20.3. Furthermore, the selectivity distribution of nitration products was reasonably explained by the density functional theory (DFT) calculation. Finally, the possible nitration reaction pathway of chlorobenzene with NO2 was suggested in O2-Ac2O-Hβ composite catalytic system. The present work affords a new and mild nitration approach for highly selective preparation of valuable para-nitro products, and has potential industrial application prospects.
- Deng, Renjie,Liu, Pingle,Luo, He'an,Ni, Wenjin,You, Kuiyi,Zhao, Fangfang
-
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- Ligand-free Cu(ii)-catalyzed aerobic etherification of aryl halides with silanes: An experimental and theoretical approach
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Owing to their wide occurrence in nature and immense applications in various fields, the synthesis of aryl alkyl ethers has remained a focus of interest. In contrast to the conventional/traditional methods of etherification, herein, we have reported a more efficient method, which is better yielding and more general in application. The etherification of aryl halides by alkoxy/phenoxy silanes was catalyzed by copper acetate in the presence of cesium carbonate and oxygen in DMF at 145 °C. All the as-synthesized compounds were characterized via the 1H-NMR and 13C-NMR spectroscopic techniques. Density functional theory calculations using the B3LYP functional were performed to elucidate the reaction mechanism. The C-O coupling reaction between 2-nitroiodobenzene and tetramethoxysilane was used as a model reaction. The activation energy barriers for the generation of catalytic species (31.6 kcal mol-1) and the σ-bond metathesis (16.0 kcal mol-1), oxidative addition/reductive elimination (20.3 kcal mol-1), halogen atom transfer (19.2 kcal mol-1) and single electron transfer (SET) (29.5 kcal mol-1) mechanisms for the C-O coupling reaction were calculated. Calculations for the key reaction steps were repeated with the B3PW91, PBEH1PBE, wB97XD, CAM-B3LYP and mPW1LYP functionals. The formation of catalytic species via a single electron transfer reaction between tetramethoxysilane and copper acetate, formation of methoxy radicals and methoxylation of copper showed an overall energy barrier of 31.6 kcal mol-1, and therefore is the rate determining step.
- Ahmed, Muhammad Naeem,Ahmad, Khalil,Yasin, Khawaja Ansar,Farooq, Tayyaba,Khan, Bilal Ahmad,Roy, Soumendra K.
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p. 11316 - 11333
(2019/07/31)
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- Preparation method of substituted nitrobenzene compound
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The invention discloses a preparation method of a substituted nitrobenzene compound. The method comprises the following steps: carrying out a decarboxylation reaction as shown below on a compound II under the action of alkali in a solvent at the temperature of 150 to 250 DEG C to obtain a compound I; the alkali is one or more of carbonates and bicarbonates of alkali metals. Compared with some metal-catalyzed decarboxylation methods, the preparation method of the substituted nitrobenzene compound has the advantages of simple operation, low production cost, convenient post-treatment and high yield, and more application values in industrial production.
- -
-
Paragraph 0058-0061
(2019/03/29)
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- Palladium-Catalyzed Methylation of Nitroarenes with Methanol
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A procedure for the synthesis of N-methyl-arylamines directly from nitroarenes using methanol as green methylating agent was developed. The key to success is the use of a specific catalyst system consisting of palladium acetate and the ligand 1-[2,6-bis(isopropyl)phenyl]-2-[tert-butyl(2-pyridinyl)phosphino]-1H-Imidazole (L1). The generality of this protocol is demonstrated in the synthesis of more than 20 N-methyl-arylamines under comparably mild conditions. Combining this novel methodology with subsequent coupling processes using the same catalyst allows for efficient diversification of aromatic nitro compounds to a broad variety of amines including drug molecules.
- Wang, Lin,Neumann, Helfried,Beller, Matthias
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supporting information
p. 5417 - 5421
(2019/04/04)
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- 3-(Ethoxycarbonyl)-1-(5-methyl-5-(nitrosooxy)hexyl)pyridin-1-ium cation: A green alternative to tert-butyl nitrite for synthesis of nitro-group-containing arenes and drugs at room temperature
-
Due to their remarkable properties, task-specific ionic liquids have turned out to be progressively popular over the last few years in the field of green organic synthesis. Herein, for the first time, we report that a new task-specific nitrite-based ionic liquid such as 3-(ethoxycarbonyl)-1-(5-methyl-5-(nitrosooxy)hexyl)pyridin-1-ium bis(trifluoromethanesulfonyl)imides (TS-N-IL) derived from biodegradable ethyl nicotinate indeed acted as an efficient and eco-friendly reagent for the synthesis of highly valuable nitroaromatic compounds and drugs including nitroxynil, tolcapone, niclofolan, flutamide, niclosamide and nitrazepam. The bridging of an ionic liquid with nitrite group not only increases the yield and rate of direct C[sbnd]N bond formation reaction but also allows easy product separation and recyclability of a byproduct. Nonvolatile nature, easy synthesis, merely stoichiometric need and mildness are a portion of the extra focal points of TS-N-IL while contrasted with tert-butyl nitrite an outstanding and highly-flammable reagent utilized largely in organic synthesis.
- Chaudhary, Renu,Natarajan, Palani,Rani, Neetu,Sakshi,Venugopalan, Paloth
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supporting information
(2019/12/30)
-
- Regioselective Functionalization of 9,9-Dimethyl-9-silafluorenes by Borylation, Bromination, and Nitration
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Despite the utility of 9-silafluorenes as functional materials and as building blocks, methods for efficient functionalization of their backbone are rare, probably because of the presence of easily cleavable C-Si bonds. Although controlling the regioselectivity of iridium-catalyzed direct borylation of C-H bonds is difficult, we found that bromination and nitration of 2-methoxy-9-silafluorene under mild conditions occurred predominantly at the electron-rich position. The resulting product having methoxy and bromo groups can be utilized as a building block for the synthesis of unsymmetrically substituted 9-silafluorene-containing π-conjugated molecules.
- Murai, Masahito,Nishinaka, Naoki,Kimura, Mizuki,Takai, Kazuhiko
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-
- Regioselective Functionalization of 9,9-Dimethyl-9-silafluorenes by Borylation, Bromination, and Nitration
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Despite the utility of 9-silafluorenes as functional materials and as building blocks, methods for efficient functionalization of their backbone are rare, probably because of the presence of easily cleavable C-Si bonds. Although controlling the regioselectivity of iridium-catalyzed direct borylation of C-H bonds is difficult, we found that bromination and nitration of 2-methoxy-9-silafluorene under mild conditions occurred predominantly at the electron-rich position. The resulting product having methoxy and bromo groups can be utilized as a building block for the synthesis of unsymmetrically substituted 9-silafluorene-containing ?-conjugated molecules.
- Murai, Masahito,Nishinaka, Naoki,Kimura, Mizuki,Takai, Kazuhiko
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p. 5667 - 5676
(2019/05/10)
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- Oxidation of Aniline to Nitrobenzene Catalysed by 1-Butyl-3-methyl imidazolium phosphotungstate Hybrid Material Using m-chloroperbenzoic Acid as an Oxidant
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Abstract: Keggin ion based hybrid materials, [BmIm]3[PW12O40], [TBA]3PW12O40 and [BuPy]3PW12O40, were prepared by proton exchange with organic cations, 1-butyl-3-methyl imidazolium ion, tetrabutylammonium ion and butylpyridinium ion, respectively. The formation of hybrid materials was confirmed by FTIR, PXRD, SEM, TG-DTA, DSC analysis. These hybrid compounds are active for oxidation of aniline using m-chloroperbenzoic acid as an oxidant. Among the three hybrid compounds, 1-butyl-3-methyl imidazolium phosphotungstate was found to be the best and efficient catalyst for selective aniline oxidation to nitrobenzene. It is a recoverable and reusable catalytic system. The redox property of the phosphotungstate cluster in the hybrid material is involved in the catalytic activity. Graphical Abstract: [Figure not available: see fulltext.].
- Meenakshi,Shakeela,Kutti Rani,Ranga Rao
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p. 246 - 257
(2017/10/23)
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- Reductive Denitration of Nitroarenes
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The Pd-catalyzed reductive denitration of nitroarenes has been achieved via a direct cleavage of the C-NO2 bonds. The catalytic conditions reported exhibit a broad substrate scope and good functional-group compatibility. Notably, the use of inexpensive propan-2-ol as a mild reductant suppresses the competitive formation of anilines, which are normally formed by other conventional reductions. Mechanistic studies have revealed that alcohols serve as efficient hydride donors in this reaction, possibly through β-hydride elimination from palladium alkoxides.
- Kashihara, Myuto,Yadav, M. Ramu,Nakao, Yoshiaki
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supporting information
p. 1655 - 1658
(2018/03/23)
-
- Silica-supported perchloric acid and potassium bisulfate as reusable green catalysts for nitration of aromatics under solvent-free microwave conditions
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Silica-supported perchloric acid and bisulfate (SiO2/HClO4 and SiO2/KHSO4) have been developed as reusable green catalysts for nitration of aromatic compounds using NaNO2 in acetonitrile medium under conventional and solvent-free microwave conditions. The reaction times under microwave irradiation are significantly shorter than conventional method even though the yields obtained in microwave-assisted reactions are comparable with those obtained under reflux conditions.
- Kumar, M. Satish,Sriram, Y. Hemanth,Venkateswarlu,Rajanna,Sudhakar, M. Sai,Venkanna, Purugula,Saiprakash
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supporting information
p. 59 - 67
(2017/12/26)
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- Benzimidazolium-based high temperature ionic liquid-in-oil microemulsion for regioselective nitration reaction
-
Owing to the fascinating applications of ionic liquids (ILs) based non-aqueous microemulsions (MEs) in the field of chemical reactions due to their high thermal stability compared to that of aqueous MEs and requirement of water-free environment, we design
- Kar, Barnali,Ghosh, Prasanjit,Kundu, Kaushik,Bardhan, Soumik,Paul, Bidyut K.,Das, Sajal
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p. 122 - 130
(2018/07/25)
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- HNO3/HFIP: A Nitrating System for Arenes with Direct Observation of π-Complex Intermediates
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This report describes an efficient nitrating system for the nitration of arenes at room temperature by using an equivalent of nitric acid in HFIP (1,1,1,3,3,3-hexafluoroisopropanol). The π-complex intermediate of an arene with a nitronium ion stabilized by HFIP can be directly observed by UV-vis spectra and is supported by theoretical calculations.
- Lu, Le,Liu, Huixin,Hua, Ruimao
-
supporting information
p. 3197 - 3201
(2018/06/11)
-
- Method for nitrating aromatic compound by using nitrate under the action of auxiliary agent
-
The invention discloses a method for nitrating an aromatic compound by using a nitrate under the action of an auxiliary agent, and provides an aromatic nitro compound preparation method, which comprises: in the presence of an external action and an auxiliary agent, carrying out a nitrating reaction on an aromatic compound and a metal nitrate or a hydrate thereof to obtain the aromatic nitro compound, wherein the external action can cause the physical and/or chemical property change of a substance, the auxiliary agent is a substance having water absorbing ability, the external action can be mechanical force or heating, and the mechanical force can be any one selected from compression, shearing, impacting, friction, stretching, bending and vibration. According to the present invention, the method does not require any solvents so as to avoid the generation of the waste liquid; the acidic substance is not used, such that the treatment is simple after the reaction is completed, and the equipment is not damaged; the added auxiliary agent can be theoretically recycled; and the method has extremely high conversion rate and extremely high selectivity, and can be used for the nitration of conventional aromatic compounds.
- -
-
Paragraph 0069; 0070
(2018/09/11)
-
- Methoxylation and Direct Hydrogenative Coupling of Chloronitrobenzenes in Continuous Flow
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A novel continuous flow method for the methoxylation of chloronitrobenzenes was developed. The reaction went smoothly and high yields were achieved under the optimized conditions. Furthermore, up to 76% yield of azoxybenzenes were obtained from the corresponding nitrobenzenes in the presence of NaOH in continuous flow. Compared to batch conditions, the reaction time was significantly shortened, and the chemical waste was reduced obviously.
- Shi, Songjie,Wan, Li,Sun, Xiaoning,Zhang, Jiawei,Guo, Kai
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p. 410 - 414
(2017/04/27)
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- Organocatalytic oxidation of substituted anilines to azoxybenzenes and nitro compounds: Mechanistic studies excluding the involvement of a dioxirane intermediate
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An organocatalytic and environmentally friendly approach for the selective oxidation of substituted anilines was developed. Utilizing a 2,2,2-trifluoroacetophenone-mediated oxidation process, substituted anilines can be transformed into azoxybenzenes, while a simple treatment with MeCN and H2O2 leads to the corresponding nitro compounds, providing user-friendly protocols that can be easily scaled up. Various substitution patterns and functional groups were tolerated leading to products in high to excellent yields. Mechanistic studies utilizing HRMS provide clear evidence for the distinct mechanistic intermediates that are involved. This study constitutes an indirect proof excluding the involvement of a dioxirane intermediate in the green organocatalytic oxidation, utilizing 2,2,2-trifluoroacetophenone as the catalyst.
- Voutyritsa, Errika,Theodorou, Alexis,Kokotou, Maroula G.,Kokotos, Christoforos G.
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supporting information
p. 1291 - 1298
(2017/06/06)
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- Transition-metal-free hydrogenation of aryl halides: From alcohol to aldehyde
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A transition-metal-and catalyst-free hydrogenation of aryl halides, promoted by bases with either aldehydes or alcohols, is described. One equivalent of benzaldehyde affords an equal yield as that of 0.5 equiv of benzyl alcohol. The kinetic study reveals that the initial rate of PhCHO is much faster than that of BnOH, in the ratio of nearly 4:1. The radical trapping experiments indicate the radical nature of this reaction. Based on the kinetic study, trapping and KIE experiments, and control experiments, a tentative mechanism is proposed. As a consequence, a wide range of (hetero)aryl iodides and bromides were efficiently reduced to their corresponding (hetero)arenes. Thus, for the first time, aldehydes are directly used as hydrogen source instead of other well-established alcohol-hydrogen sources.
- Zheng, Hong-Xing,Shan, Xiang-Huan,Qu, Jian-Ping,Kang, Yan-Biao
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p. 5114 - 5117
(2017/11/07)
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- Convenient, metal-free ipso-nitration of arylboronic acids using nitric acid and trifluoroacetic acid
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A feasible protocol for the direct ipso-nitration of arylboronic acids using trifluoroacetic acid and nitric acid as nitration reagent has been developed. Various aromatic nitro compounds are produced in moderate to good yields under the metal-free conditions. The method is operationally simple and regioselective, and might have potential application in industry.
- Shen, Guodong,Zhao, Lingyu,Liu, Wanxing,Huang, Xianqiang,Song, Huina,Zhang, Tongxin
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supporting information
p. 10 - 14
(2016/12/30)
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- Selective O-methylation of phenols and benzyl alcohols in simple pyridinium based ionic liquids
-
Synthesis of pyridinium based ionic liquids were reported and applied as catalyst for the selective O-methylation of phenols and benzyl alcohols. The reactions were carried out by using dimethylcarbonate (DMC) as the methylating agent. High selectivity, high yield and recyclability of the ionic liquids are important features of the reactions.
- Das, Pranab Jyoti,Das, Jupitara
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-
- Controlling the Course of a Two-Way Switchable Pd-Catalyzed Process by means of Empirical Multivariate Models
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A two-way switchable Pd-catalyzed process that can pursue two different mechanisms, namely hydro- and methoxy-deiodination was discovered, developed, and optimized by means of statistical experimental design, multivariate modelling, and response surface methodology. The investigation revealed that the two-way switchable process might be controlled either by ligand alone, or by ligand and other process variables in combination. The present study represents the first example of a catalytic system that provides either hydro- or methoxy-deiodination selectively by simply fine-tuning the experimental variables.
- Sandtorv, Alexander H.,Bj?rsvik, Hans-René
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p. 2196 - 2205
(2015/11/24)
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- Gold-Catalyzed Proto- and Deuterodeboronation
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A mild gold-catalyzed protodeboronation reaction, which does not require acid or base additives and can be carried out in "green" solvents, is described. As a result, the reaction is very functional-group-tolerant, even to acid- and base-sensitive functional groups, and should allow for the boronic acid group to be used as an effective traceless directing or blocking group. The reaction has also been extended to deuterodeboronations for regiospecific ipso-deuterations of aryls and heteroaryls from the corresponding organoboronic acid. Based on density functional theory calculations, a mechanism is proposed that involves nucleophilic attack of water at boron followed by rate-limiting B-C bond cleavage and facile protonolysis of a Au-σ-phenyl intermediate.
- Barker, Graeme,Webster, Stacey,Johnson, David G.,Curley, Rachel,Andrews, Matthew,Young, Paul C.,MacGregor, Stuart A.,Lee, Ai-Lan
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p. 9807 - 9816
(2015/11/03)
-
- Regioselective nitration of phenols and phenyl ethers using aluminium nitrate on silica as a nitrating system
-
Silica supported aluminum nitrate (Al(NO3)3·9H2O) was found to be an excellent reagent for the nitration of phenols and phenyl ethers. This procedure works efficiently on most of the examples at room temperature yielding nitro derivatives in fair to good yields with high regioselectivity. The present methodology evidenced a considerable enhancement in the reaction rate along with high o-selectivity, excellent yields, ease of handling and the simplicity in work up.
- Patil, Mahadeo R.,Mohite, Pravinkumar H.,Shisodia, Suresh,Keri, Rangappa S.
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p. 129 - 135
(2015/06/23)
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- N-methyl-2-chloropyridinium iodide/NaNO2/Wet SiO2: Neutral reagent system for the nitration of activated aromatic compounds under very mild conditions
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Mononitration of activated aromatic compounds using N-methyl-2-chloro-pyridinium iodide (Mukaiyama reagent)/NaNO2/wet SiO2 reagent system under neutral, very mild and environmentally safer reaction condition has been developed. Various structurally diverse aromatic rings are subjected in this condition and the corresponding nitro-aromatic compounds are prepared in moderately high yields.
- Azadi, Roya,Nazari-Far, Zahra
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p. 136 - 140
(2015/06/22)
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- Controlled nitration of anisole over HNO3/PO4/MoO3/SiO2/solvent systems
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Nitroanisoles have wide applications in pharmaceuticals, perfumery and production of corresponding amines used extensively in dye industry. The presence of activated methoxy group in the aromatic ring, causes the nitration of anisole to be complex and dif
- Adamiak, Joanna
-
-
- Click chemistry inspired facile synthesis and bioevaluation of novel triazolyl analogs of Ludartin
-
A convenient and modular synthesis involving diastereoselective Michael addition followed by regioselective Huisgen 1,3-dipolar cycloaddition reaction was carried out to furnish 1,4-disubstituted-1,2,3-triazoles of Ludartin. This reaction scheme involving Michael addition followed by regioselective Huisgen 1,3-dipolar cycloaddition reaction leading to the formation of triazolyl analogs is being reported for the first time. All the triazolyl products were characterised using spectral data analysis. Sulphorhodamine B cytotoxicity screening of the resulting products against a panel of five human cancerous cell-lines revealed that few of the analogs display promising broad spectrum cytotoxic effect. Among all the synthesized compounds, only 3q displayed the best cytotoxic effect with IC50 values of 12, 11, 38, 39 and 8.5 μM but less than the standard Ludartin (1) with IC50 values of 6.3, 7.4, 7.5, 6.9 and 0.5 μM against human neuroblastoma (T98G), lung (A-549), prostate (PC-3), colon (HCT-116) and breast (MCF-7) cancer cell lines, respectively. The present synthesis was designed based on the previous literature reports of Ludartin as an aromatase inhibitor. Our work provides an initial study on structure-activity relationship of triazolyl analogs of sesquiterpene lactones in general and Ludartin (1) in particular.
- Lone, Shabir H.,Bhat, Khursheed A.,Majeed, Rabiya,Hamid, Abid,Khuroo, Mohd A.
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p. 1047 - 1051
(2014/03/21)
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- Ipso-Nitrosation of arylboronic acids with chlorotrimethylsilane and sodium nitrite
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Nitroso compounds are versatile reagents in synthetic organic chemistry. Herein, we disclose a feasible protocol for the ipso-nitrosation of aryl boronic acids using chlorotrimethylsilane-sodium nitrite unison as nitrosation reagent system.
- Prakash, G.K. Surya,Gurung, Laxman,Schmid, Philipp Christoph,Wang, Fang,Thomas, Tisa Elizabeth,Panja, Chiradeep,Mathew, Thomas,Olah, George A.
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p. 1975 - 1978
(2014/04/03)
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- Synthesis of 13C and 15N labeled 2,4-dinitroanisole
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Syntheses of [13C6]-2,4-dinitroanisole (ring- 13C6) from [13C6]-anisole (ring-13C6) and [15N2]-2,4- dinitroanisole from anisole using in situ generated acetyl nitrate and [ 15N]-acetyl nitrate, respectively, are described. Treatment of [ 13C6]-anisole (ring-13C6) with acetyl nitrate generated in 100% HNO3 gave [13C 6]-2,4-dinitroanisole (ring-13C6) in 83% yield. Treatment of anisole with [15N]-acetyl nitrate generated in 10 N [15N]-HNO3 gave [15N2]-2,4- dinitroanisole in 44% yield after two cycles of nitration. Byproducts in the latter reaction included [15N]-2-nitroanisole and [ 15N]-4-nitroanisole.
- Jagadish, Bhumasamudram,Field, Jim A.,Chorover, Jon,Sierra-Alvarez, Reyes,Abrell, Leif,Mash, Eugene A.
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p. 434 - 436
(2014/07/07)
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- Bismuth triflate catalyzed mononitration of aromatic compounds with N 2O5
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This page isvestigated that bismuth triflate catalysed the nitration of a range of simple aromatic compounds in good to excellent yields at 0-30 °C within 2 h using N2O5 and the catalyst can be recycled without apparent loss of activity. Mechanistic insights demonstrate that triflic acid is generated and that, at least, when two competing catalytic cycles are operating at the same time: a rapid one involving triflic acid and a slower one involving the bismuth triflate.
- Qian, Hua,Wang, Ya,Liu, Dabin,Lv, Chunxu
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p. 509 - 512
(2014/05/20)
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- Amino acid intercalated layered double hydroxide catalyzed chemoselective methylation of phenols and thiophenols with dimethyl carbonate
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Sixteen different amino acids are intercalated into Mg-Al layered double hydroxides (LDHs) by the reconstruction method and are characterized by powder XRD and FT-IR. The intercalated amino acid-LDHs (AA-LDHs) are used as catalysts for chemoselective O-methylation of phenol and S-methylation of thiophenol with dimethyl carbonate (DMC) as a green methylating agent. The intercalation behavior of various amino acids is influenced by various structural features of amino acids, namely, carbon chain length, structure, and physicochemical properties. In particular, amino acids possessing a hydrophobic side-chain show higher catalytic activity. A suitable reaction mechanism is proposed. The catalyst can also be recycled.
- Subramanian, Thirumeni,Dhakshinamoorthy, Amarajothi,Pitchumani, Kasi
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p. 7167 - 7170
(2013/12/04)
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- Synthesis of aryl ethers from aromatic carboxylic acids
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A silver/copper bimetallic catalyst system promotes the decarboxylative Chan-Evans-Lam alkoxylation of ortho-substituted aromatic carboxylate salts with tetraalkyl orthosilicates or triaryl borates. Non-ortho-substituted carboxylates are alkoxylated via an ortho-C-H-alkoxylation with concomitant cleavage of the carboxylate directing group via protodecarboxylation. This way, meta-substituted carboxylates are converted into para-substituted alkoxyarenes and vice versa. The combined processes provide a convenient synthetic entry to the important class of aromatic ethers from widely available carboxylic acids.
- Bhadra, Sukalyan,Dzik, Wojciech I.,Goossen, Lukas J.
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supporting information
p. 2387 - 2390
(2013/09/23)
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- A continuous methylation of phenols and N, H -heteroaromatic compounds with dimethyl carbonate
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The methylation of phenolic substrates has been reevaluated using sulfolane as solvent instead of DMF. The change of solvent gave in all cases cleaner production of the anisole products in very good yields. The reaction requires 0.1 equiv of DBU, 2-3 equiv of DMC, and 2-5 vols of sulfolane depending on the substrate. At 220 C the reaction time is 10 min. Sulfolane is completely stable under the reaction conditions, excluding unwanted impurities from the solvent. The reaction could also be extended to NH-indole and NH-imidazole derivatives utilizing 0.1 equiv of DBU and 2-3 equiv of DMC in 2 vols of sulfolane. All NH-heteroaromatic compounds gave clean N-methylation.
- Tilstam, Ulf
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p. 1974 - 1978
(2013/02/25)
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- A continuous base-catalyzed methylation of phenols with dimethyl carbonate
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We have found that the use of a conventional, heated, standard 316 stainless steel or steel-braided PTFE tube reactor is a good and easily scalable alternative to the use of continuous microwave-heated reactors. The heat-up is almost as fast as with microwave heating, and the reactors can easily be scaled towards large-scale production. The transfer of the reported microwave procedure to the continuous flow method went very smoothly, and we found that we could further optimize the reaction to a catalytic procedure where only 10 mol % of DBU is needed with only 3 equiv of DMC. The reaction can be run neat in cases where the starting material is soluble in DMC as phenol is, or with a small amount of DMF (2-3 vol). The reaction is efficient for different types of phenols, giving a clean reaction in high yields.
- Tilstam, Ulf
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experimental part
p. 1150 - 1153
(2012/08/27)
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- Decarboxylative etherification of aromatic carboxylic acids
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Decarboxylative Chan-Evans-Lam-type couplings are presented as a new strategy for the regiospecific construction of diaryl and alkyl aryl ethers starting from easily available aromatic carboxylic acids. They allow converting various aromatic carboxylate salts into the corresponding aryl ethers by reaction with alkyl orthosilicates or aryl borates, under aerobic conditions in the presence of silver carbonate as the decarboxylation catalyst and copper acetate as the cross-coupling catalyst.
- Bhadra, Sukalyan,Dzik, Wojciech I.,Goossen, Lukas J.
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p. 9938 - 9941
(2012/08/08)
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- Aromatic nitration under neutral conditions using N-bromosuccinimide/ silver(I) nitrate
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The use of N-bromosuccinimide and silver nitrate as a convenient reagent system for the nitration of aromatic compounds under neutral and environmentally safer reaction conditions is described.
- Nowrouzi, Najmeh,Mehranpour, Abdol Mohammad,Bashiri, Elham,Shayan, Zohre
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experimental part
p. 4841 - 4842
(2012/09/22)
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- Aromatic nitration with bismuth nitrate in ionic liquids and in molecular solvents: A comparative study of Bi(NO3)3·5H 2O/[bmim][PF6] and Bi(NO3)3· 5H2O/1,2-DCE systems
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A suspension of bismuth nitrate pentahydrate (BN) in [bmim][PF6] or [bmim][BF4] imidazolium ionic liquid (IL) is an effective reagent for ring nitration of activated aromatics under mild conditions without the need for external promoters. Nitration can also be effected in 1,2-DCE, MeCN, or MeNO2 without additives. Nitration of activated arenes (anisole, toluene, ethylbenzene, cumene, p-xylene, mesitylene, durene, and 1,3-dimethoxybenzene) is considerably faster (time to completion) in BN/[bmim][PF6] relative to BN/1,2-DCE and there are also differences in isomer distributions (for anisole, toluene, and ethylbenzene). With introduction of strongly deactivating substituents (-CHO; -MeCO; -NO 2) the BN/IL system is no longer active but reactions still proceed with BN/1,2-DCE in reasonable yields. The ready availability and low cost of BN, simple operation, and absence of promoters, coupled to recycling and reuse of the IL, provide an attractive alternative to classical nitration methods for activated arenes. Switching from Bi(NO3)3·5H 2O/[bmim][PF6] to Bi(NO3)3· 5H2O/1,2-DCE increases the scope of the substrates that can be nitrated.
- Jacoway, Jonathan,Kumar, G. G. K. S. Narayana,Laali, Kenneth K.
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p. 6782 - 6785,4
(2012/12/12)
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- Nitration of aromatic compounds under neutral conditions using the Ph 2PCl/I2/AgNO3 reagent system
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Aromatic compounds were nitrated efficiently under essentially neutral conditions by employing Ph2PCl in the presence of I2 and AgNO3. This method minimizes waste products compared to traditional methods and gives the corresponding mononitro derivatives in good to excellent yields in dichloromethane at room temperature.
- Nowrouzi, Najmeh,Zareh Jonaghani, Mohammad
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experimental part
p. 5081 - 5082
(2011/10/09)
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- Ethylammonium nitrate (EAN)/Tf2O and EAN/TFAA: Ionic liquid based systems for aromatic nitration
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Acting as in situ sources of triflyl nitrate (TfONO2) and trifluoroacetyl nitrate (CF3COONO2), the EAN/Tf 2O and EAN/TFAA systems, generated via metathesis in the readily available ethylammonium nitrate (EAN) ionic liquid as solvent, are powerful electrophilic nitrating reagents for a wide variety of aromatic and heteroaromatic compounds. Comparative nitration experiments indicate that EAN/Tf2O is superior to EAN/TFAA for nitration of strongly deactivated systems. Both systems exhibit low substrate selectivity (K T/KB = 5-10) in (Figure presented) between values reported for covalent nitrates and preformed nitronium salts.
- Aridoss, Gopalakrishnan,Laali, Kenneth K.
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experimental part
p. 8088 - 8094
(2011/11/13)
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- Synthesis and biological evaluation of novel N-(alkoxyphenyl)-aminocarbonylbenzoic acid derivatives as PTP1B inhibitors
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Based on the fact that petroselinic acid showed good inhibitory activity (IC50=6.99μmol/L) against protein tyrosine phophatase 1B(PTP1B) in vitro, a series of novel N-(alkoxyphenyl)-aminocarbonylbenzoic acid derivatives were designed and synthesized. The results indicated that most of the derivatives showed more potent activities against PTP1B. Especially, compound 13 had obvious activity with an IC50 of 106nmol/L in vitro.
- Tong, Yuan Feng,Zhang, Pei,Chen, Feng,Hao, Ling Hua,Ye, Fei,Tian, Jin Ying,Wu, Song
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scheme or table
p. 1415 - 1418
(2011/10/09)
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- Sparing the Ortho-position in Nucleophilic Aromatic Substitution-Specific Displacement of the 4-SePh Group in 2,4-Bis(phenylseleno)nitrobenzene
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Upon treatment of o- and p- (phenylseleno)nitrobenzenes with sodium methoxide quantitative exchange reactions took place, affording the corresponding methoxynitrobenzenes. Upon reaction between 2,4-bis(phenylseleno) nitrobenzene 2 and sodium methoxide, an unusual regiopure formation of 4-methoxy-2-(phenylseleno)nitrobenzene 3 was observed. This product remained unreactive toward an excess of sodium methoxide, thus preventing the formation of 2,4-dimethoxynitrobenzene 6. The nature of the reactants and of the intermediate Meisenheimer complexes was examined by synthetic investigations, x-ray crystallography, and DFT calculations. We found that the observed selectivity can be understood in terms of traditional resonance considerations.
- Nicolai, Stuhr-Hansen,Goetze, Thorstein Finn,Henriksen, Lars,Solling, Theis Ivan,Langkilde, Annette,Sorensen, Henning Osholm
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experimental part
p. 101 - 108
(2009/09/25)
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- Nitration of simple aromatics with NO2 under air atmosphere in the presence of novel Bronsted acidic ionic liquids
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Aromatics nitrate with NO2/air catalyzed by novel Bronsted acidic ionic liquids (ILs) without any volatile chlorinated organic solvent under mild conditions. The ILs employed were caprolactam based, [Caprolactam]X (X-=pTSO-, BSO-, BF4-, NO3-), which are o
- Qi, Xiufang,Cheng, Guangbin,Lu, Chunxu,Qian, Desheng
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p. 537 - 545
(2008/04/12)
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- Palladium-catalyzed C-O bond formation: direct synthesis of phenols and aryl/alkyl ethers from activated aryl halides
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A simple and efficient palladium-catalyzed carbon-oxygen bond formation is reported. The palladium-tri-tert-butylphosphine complex was found to be effective in converting haloarenes to corresponding substituted phenols. This methodology offers a direct transformation of aryl halides to phenols, as well as the straightforward application to generate a wide variety of diaryl or alkyl/aryl ethers.
- Chen, Guoshu,Chan, Albert S.C.,Kwong, Fuk Yee
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p. 473 - 476
(2008/02/03)
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- Imidazolium ionic liquids as solvents for cerium(IV)-mediated oxidation reactions
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Use of imidazolium ionic liquids as solvents for organic transformations with tetravalent cerium salts as oxidizing agents was evaluated. Good solubility was found for ammonium hexanitratocerate(IV) (ceric ammonium nitrate, CAN) and cerium(IV) triflate in 1-alkyl-3-methylimidazolium triflate ionic liquids. Oxidation of benzyl alcohol to benzaldehyde in 1-ethyl-3-methylimidazolium triflate was studied by in-situ FTIR spectroscopy and 13C NMR spectroscopy on carbon-13-labeled benzyl alcohol. Careful control of the reaction conditions is necessary because ammonium hexanitratocerate(IV) dissolved in an ionic liquid can transform benzyl alcohol not only into benzaldehyde but also into benzyl nitrate or benzoic acid. The selectivity of the reaction of cerium(IV) triflate with benzyl alcohol in dry ionic liquids depends on the degree of hydration of cerium(IV) triflate: anhydrous cerium(IV) triflate transforms benzyl alcohol into dibenzyl ether, whereas hydrated cerium(IV) triflate affords benzaldehyde as the main reaction product. Reactions of ammonium hexanitratocerate(IV) with organic substrates other than benzyl alcohol have been explored. 1,4-Hydroquinone is quantitatively transformed into 1,4-quinone. Anisole and naphthalene are nitrated. For the cerium-mediated oxidation reactions in ionic liquids, high reaction temperatures are an advantage because under these conditions smaller amounts of byproducts are formed.
- Mehdi, Hasan,Bodor, Andrea,Lantos, Diana,Horvath, Istvan T.,De Vos, Dirk E.,Binnemans, Koen
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p. 517 - 524
(2007/10/03)
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- Nitration of aromatic compounds catalyzed by divanadium-substituted molybdophosphoric acid, H5[PMo10V2O 40]
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The nitration of aromatic compounds was carried out in the presence of divanadium-substituted molybdophosphoric acid, H5PMo 10V2O40, as catalyst and a mixture of nitric acid and acetic anhydride as nitrating agent. In the presence of this heteropolyacid the ortho- and para-nitro compounds were obtained in good to excellent yields under mild reaction conditions. Springer-Verlag 2007.
- Heravi, Majid M.,Bakhtiari, Khadijeh,Benmorad, Tina,Bamoharram, Fatemeh F.,Oskooie, Hossein A.,Tehrani, Maryam H.
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p. 449 - 452
(2008/02/02)
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