- Continuous flow nitration of salicylic acid
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Continuous flow nitration of salicylic acid using HNO3/AcOH was studied in the SS316 tubular microreactor. At specific reaction conditions, complete conversion of the reactant was achieved in less than 7 min. It yielded only mononitro derivatives with a higher selectivity of 5-nitrosalicylic acid. Presence of the lower amount of acetic acid in the reaction mixture was seen to be detrimental, leading to precipitation of the desired product (5-nitrosalicylic acid). Reaction at higher temperatures yielded byproducts. The continuous mode operation using the system comprising the microdevices was demonstrated for 2 h with consistent composition at the outlet
- Kulkarni, Amol A.,Nivangune, Nayana T.,Kalyani, Vishwanath S.,Joshi, Ramesh A.,Joshi, Rohini R.
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Read Online
- Method for selectively synthesizing 3-nitrosalicylic acid in continuous flow region
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The invention provides a method for selectively synthesizing 3-nitrosalicylic acid in a continuous flow region. According to the method, salicylic acid and nitric acid are used as raw materials and react in a micro-channel reactor in the presence of a cat
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Paragraph 0047-0087
(2021/03/24)
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- Advanced Real-Time Process Analytics for Multistep Synthesis in Continuous Flow**
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In multistep continuous flow chemistry, studying complex reaction mixtures in real time is a significant challenge, but provides an opportunity to enhance reaction understanding and control. We report the integration of four complementary process analytical technology tools (NMR, UV/Vis, IR and UHPLC) in the multistep synthesis of an active pharmaceutical ingredient, mesalazine. This synthetic route exploits flow processing for nitration, high temperature hydrolysis and hydrogenation reactions, as well as three inline separations. Advanced data analysis models were developed (indirect hard modeling, deep learning and partial least squares regression), to quantify the desired products, intermediates and impurities in real time, at multiple points along the synthetic pathway. The capabilities of the system have been demonstrated by operating both steady state and dynamic experiments and represents a significant step forward in data-driven continuous flow synthesis.
- Sagmeister, Peter,Lebl, René,Castillo, Ismael,Rehrl, Jakob,Kruisz, Julia,Sipek, Martin,Horn, Martin,Sacher, Stephan,Cantillo, David,Williams, Jason D.,Kappe, C. Oliver
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supporting information
p. 8139 - 8148
(2021/03/01)
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- 2-Methyl-1,3-disulfoimidazolium polyoxometalate hybrid catalytic systems as equivalent safer alternatives to concentrated sulfuric acid in nitration of aromatic compounds
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Ionic liquid-derived polyoxometalate salts [mdsim]3[PM12O40] (where M?=?W and Mo) of two heteropolyacids H3PW12O40.nH2O and H3PMo12O40.nH2O were synthesized using 2-methyl-1,3-disulfoimidazolium chloride ([mdsim][Cl]) ionic liquid and the corresponding heteropolyacids. Three equivalents of [mdsim][Cl] were treated with the respective Keggin-structured heteropolyacids (one equivalent) in aqueous medium at room temperature to afford the water-stable ionic polyoxometalates as acidic solids. They were completely characterized using spectroscopic and other analytical techniques including thermal analysis and Hammett acidity studies. The inherent Br?nsted acidic properties of ─SO3H group of these polyoxometalate salts were studied for the nitration of aromatic compounds with 69% HNO3 at normal temperature and 80°C without use of any external concentrated sulfuric acid. These strongly acidic polyoxometalates display good recyclability and efficient reusability.
- Saikia, Susmita,Borah, Ruli
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- Fast and efficient nitration of salicylic acid and some other aromatic compounds over H3PO4/TiO2-ZrO2 using nitric acid
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TiO2-ZrO2 (1/1)-surf with Ti and Zr molar ratio of 1/1 was prepared with surfactant through a sol-gel method. The optimum experimental condition was investigated for nitration of salicylic acid. Then, a number of nitration reactions were carried out with a variety of aromatic compounds in the optimum condition. The 25 wt% H3PO4/TiO2-ZrO2 (1/1)-surf catalyst showed good selectivity and yield in a short time for the nitration of salicylic acid and some other aromatic compounds.
- Kalbasi, Roozbeh Javad,Massah, Ahmad Reza,Zamani, Farzad,Hamid, Javaherian Naghash
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experimental part
p. 397 - 403
(2010/10/20)
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- Improved synthesis of 3-nitrosalicylic acid
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Nitration of salicylic acid using 2-propyl nitrate/sulfuric acid/tetrabutylammonium hydrogensulfate/dichloromethane/water yielded a mixture of 3-nitro and 5-nitrosalicylic acids in the ratio 56:44. Pure potassium 3-nitrosalicylate was crystallized and converted to 3-nitrosalicylic acid in 30% overall yield. Copyright
- Hummel, Michael,Laus, Gerhard,Nerdinger, Sven,Schottenberger, Herwig
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experimental part
p. 3353 - 3357
(2010/12/24)
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- NITRATION OF ACTIVATED AROMATICS IN MICROREACTORS
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The invention relates to the nitration of aromatic or heteroaromatic compounds, wherein an activated aromatic or heteroaromatic compound and a nitration agent, optionally in the presence of a solvent, are mixed intensely in a microreactor, and wherein the proportion of the nitration agent to the activated aromatic or heteroaromatic compound, the concentration of nitration agent in the reaction mixture, and the temperature are selected at levels such high that the nitration begins autocatalytically, and wherein the nitration product is obtained after leaving the microreactor and, optionally after an after-reaction time outside the microreactor.
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Page/Page column 6; 8
(2010/12/29)
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- Synthesis, structural investigations, hydrogen-deuterium exchange studies, and molecular modeling of conformationally stablilized aromatic oligoamides
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Biasing the conformational preferences of aromatic oligoamides by internally placing intramolecular hydrogen bonds has led to a series of stably folded molecular strands. This article presents the results from extensive solid-state, solution, and computational studies on these folding oligomers. Depending on its backbone length, an oligoamide adopts a crescent or helical conformation. Surprisingly, despite the highly repetitive nature of the backbone, the internally placed, otherwise very similar intramolecular hydrogen bonds showed significantly different stabilities as demonstrated by hydrogen-deuterium exchange data. It was also observed that the hydrogen-bonding strength can be tuned by adjusting the substituents attached to the exterior of the aromatic backbones. Examining the amide hydrogen-deuterium exchange rates of trimers revealed that a six-membered hydrogen bond nearing the ester end is the weakest among all the four intramolecular hydrogen bonds of a molecule. This observation was verified by ab initio quantum mechanical calculations at the level of B3LYP/6-31G. Such a "weak point" creates the "battle of the bulge" where backbone twisting is centered, which is consistently observed in the solid-state structures of the four trimer molecules studied. In the solid state, the oligomers assemble into interesting one-dimensional structures. A pronounced columnar packing of short oligomers (i.e., dimers, trimers, and tetramer) and channel-like, potentially ion-conducting stacks of longer oligomers (i.e., tetramer, pentamer, and hexamer) were observed.
- Yan, Yan,Qin, Bo,Ren, Changliang,Yip, Yeow Kwan,Ye, Ruijuan,Zeng, Huaqiang,Chen, Xiuying,Su, Haibin,Zhang, Dawei
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supporting information; experimental part
p. 5869 - 5879
(2010/07/13)
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- A simple and practical copper-catalyzed approach to substituted phenols from aryl halides by using water as the solvent
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Water surprise! A simple and practical copper-catalyzed approach to substituted phenols by hydroxylation of aryl halides has been developed by using environmentally benign water as the solvent (see scheme). The method proceeds under mild conditions and is tolerant towards various functional groups in the substrates.
- Yang, Daoshan,Fu, Hua
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supporting information; experimental part
p. 2366 - 2370
(2010/06/15)
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- Helical organization in foldable aromatic oligoamides by a continuous hydrogen-bonding network
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Introduction of a continuous internal hydrogen-bonding network suppressed the conformational flexibility of a series of oligoaromatic foldamers with a lengthened backbone. The helical ordering over up to six aromatic repeating units was established in solution by a 2D NOESY study and in the solid state by an X-ray diffraction method. Computational molecular modeling further corroborates the experimentally observed helical propagation in this class of foldable molecular strands.
- Yan, Yan,Qin, Bo,Shu, Yingying,Chen, Xiuying,Yip, Yeow Kwan,Zhang, Dawei,Su, Haibin,Zeng, Huaqiang
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supporting information; experimental part
p. 1201 - 1204
(2009/08/07)
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- Crystallographic evidence of an unusual, pentagon-shaped folding pattern in a circular aromatic pentamer
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(Figure Presented) Introduction of a continuous hydrogen-bonding network suppressed the conformational flexibility of an oligomeric backbone. Cyclization of a rigidified, suitably sized oligomer led to a circular aromatic pentamer. Its crystal structure d
- Qin, Bo,Chen, Xiuying,Fang, Xiao,Shu, Yingying,Yip, Yeow Kwan,Yan, Yan,Pan, Siyan,Ong, Wei Qiang,Ren, Changliang,Su, Haibin,Zeng, Huaqiang
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supporting information; experimental part
p. 5127 - 5130
(2009/05/30)
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- Salicylic acid nitration by means of nitric acid/acetic acid system: Chemical and kinetic characterization
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The nitration of salicylic acid by means of HNO3/AcOH is investigated, and the results are compared with those obtained using different nitrating systems: HNO3/H2SO4/H2O (mixed acid), HNO3/Ac2O/AcOH, aqueous HNO3 (70% by weight) at 343 K. Little differences are found in terms of yield of the desired product (5-nitrosalicylic acid) among HNO3/AcOH mixture, mixed acid, and HNO3/Ac2O/AcOH systems, aqueous HNO 3 giving the poorest results. However according to the data collected during the present investigation the use of the system HNO3/AcOH presents some advantages with respect to the others for the separation and purity of desired product, waste minimization, and safety improvements. The reaction kinetics for the nitration of salicylic acid with this system is also investigated. A global second-order kinetic law (one for the substrate, one for nitric acid) is used in the analysis of the data collected for the formation of the two mononitroderivatives (3-nitro- and 5-nitrosalicylic acids) and of the side product 2-nitrophenol.
- Andreozzi, Roberto,Canterino, Marisa,Caprio, Vincenzo,Di Somma, Ilaria,Sanchirico, Roberto
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p. 1199 - 1204
(2012/12/23)
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- Nitration of aromatic compounds by Zn(NO3)2· 2N2O4 and its charcoal-supported system
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Zn(NO3)2·N2O4 and its charcoal supported system were found to be efficient nitrating agents. Mononitration of aromatic compounds such as benzene, alkyl benzenes, halobenzenes, nitrobenzene, anisol, and the highly selective mono-, di-, and trinitration of phenol, and dinitraion of substituted phenols were also performed in the presence of these reagents.
- Iranpoor, Nasser,Firouzabadi, Habib,Heydari, Reza,Shiri, Morteza
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p. 263 - 270
(2007/10/03)
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- Synthesis of salicylic acid derivatives in presence of ultrasonic irradiation using water as solvent
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An improved synthesis of salicylic acid using ultrasonic irradiation and water as solvent can be achieved with copper and pyridine as catalysts. A number of salicylic acids were prepared in good yield and in a short reaction time.
- Docampo Palacios, Maite L.,Pellon Comdom, Rolando F.
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p. 1783 - 1787
(2007/10/03)
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- Fungicidal compositions and methods, and compounds and methods for the preparation thereof
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Fungicidal compositions and methods comprising acylated aminosalicylamides (AASA) described herein. Novel cyclic amines and 3-nitrosalicylamides, and their use as pesticides and in the preparation of the antifungal AASA compounds are also disclosed.
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- Decarboxylative Nitration of Some Simple Hydroxybenzoic Acids Using Cerium(IV) Ammonium Nitrate
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The mechanistic pathways proposed earlier in the Ce(IV) induced decarboxylation of aromatic acids have been examined in the light of new observations made.A simple, non-explosive, easy to control substitute to Bechman and Biermann's decarboxylative nitration is described and a plausible mechanism suggested.
- Chawla, H. Mohindra,Mittal, Ram S.
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p. 1129 - 1131
(2007/10/02)
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- Electrophilic Catalysis of Sulphate (-SO3-) Group Transfer: Hydrolysis of Salicyl Sulphates assisted by Intramolecular Hydrogen Bonding
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The hydrolysis of substituted salicyl sulphates has been measured over a range of pH values at 70 deg C to obtain kinetic parameters for hydronium ion (kH) and carboxylic acid (kp) calalysis.A Jaffe treatment of the carboxy-catalysis parameter for a range of nuclear substituents yields ρphenol 1.51; ρcarboxy 0 indicates that the carboxy-function does not ionise on going from the ground- to the transition-state, consistent with hydrogen bonding rather than catalysis through proton transfer.The change in 'effective' charge on the phenol oxygen on going from the ground- to the transition-state confirms less build up of negative charge than in the uncatalysed hydrolysis of aryl sulphates.
- Hopkins, Andrew Ramsay,Green, Adam Llywellyn,Williams, Andrew
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p. 1279 - 1284
(2007/10/02)
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