- Fluoropolymer-Coated PDMS Microfluidic Devices for Application in Organic Synthesis
-
In recent years there has been huge interest in the development of microfluidic reactors for the synthesis of small molecules and nanomaterials. Such reaction platforms represent a powerful and versatile alternative to traditional formats since they allow for the precise, controlled, and flexible management of reactive processes. To date, the majority of microfluidic reactors used in small-molecule synthesis have been manufactured using conventional lithographic techniques from materials such as glasses, ceramics, stainless steel, and silicon. Surprisingly, the fabrication of microfluidic devices from such rigid materials remains ill-defined, complex, and expensive. Accordingly, the microfluidic toolkit for chemical synthesis would significantly benefit from the development of solvent-resistant microfluidic devices that can be manufactured using soft-lithographic prototyping methods. Whilst significant advances in the development of solvent-resistant polymers have been made, only modest steps have been taken towards simplifying their use as microfluidic reactors. Herein, we emphasize the benefits of using a commercially available, amorphous perfluorinated polymer, CYTOP, as a coating with which to transform PDMS into a chemically inert material for use in organic synthesis applications. Its efficacy is demonstrated through the subsequent performance of photooxidation reactions and reactions under extremely acidic or basic conditions.
- Yang, Tianjin,Choo, Jaebum,Stavrakis, Stavros,de Mello, Andrew
-
-
Read Online
- Urea nitrate and nitrourea: powerful and regioselective aromatic nitration agents
-
Urea nitrate (UN) and nitrourea (NU), easily prepared from urea and nitric acid, convert deactivated aromatic compounds to the corresponding nitrated derivatives with a high yield and a high regioselectivity under very mild conditions. The performance of the two reagents is quite similar indicating that NU is an intermediate in the UN nitration process.
- Almog, Joseph,Klein, Asne,Sokol, Anat,Sasson, Yoel,Sonenfeld, Dana,Tamiri, Tsippy
-
-
Read Online
- Control over m-nitrotoluene concentration in products of heterogeneous mononitration of toluene
-
Heterogeneous mononitration of toluene with sulfuric-nitric acid mixtures, occurring in the charged interfacial monolayer with high para selectivity, was studied. Ways to suppress the meta substitution in the toluene mononitration stage by controlling the nitrating mixture composition, process parameters, and catalytic additives were found.
- Artemov,Tselinskii,Kukushkin,Filatova,Ashikhin
-
-
Read Online
- The efficacy of 'Claycop' in the dinitration of toluene
-
Claycop and acetic anhydride in tetrachloromethane are modestly catalytic and regioselective in the mononitration of toluene, but are neither catalytic nor regioselective in the nitration of 2-nitrotoluene.
- Lancaster, N. Llewellyn,Moodie, Roy B.,Sandall, John P. B.
-
-
Read Online
- Regioselective double Kyodai nitration of toluene and chlorobenzene over zeolites. High preference for the 2,4-dinitro isomer at the second nitration stage
-
(matrix presented) The Kyodai nitration of toluene and chlorobenzene has been examined in the presence of a solid inorganic catalyst (montmorillonite K10, zeolite HZSM-5, or HBEA-25). Regioselection was quite low at the mononitration stage, but a considerably high preference for the 2,4-isomer was observed at the dinitration stage.
- Peng, Xinhua,Suzuki, Hitomi
-
-
Read Online
- Copper-cobalt synergy in Cu1-xCoxFe2O4 spinel ferrite as a highly efficient and regioselective nanocatalyst for the synthesis of 2,4-dinitrotoluene
-
Highly regioselective dinitration of toluene with nitric acid as nitrating agent in the presence of Cu1-xCoxFe2O4 (0 ≤ x ≤ 1) as nanocatalysts is described. The results of this protocol show that this nitration system can significantly improve the selectivity and the yield of 2,4-dinitrotoluene. The prepared spinel ferrites were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). Copper and cobalt synergy (50%:50%) in spinel ferrite also shows the best catalytic activity in the selectivity of dinitrotoluene under solvent-free conditions.
- Fareghi-Alamdari, Reza,Zandi, Farzad,Keshavarz, Mohammad Hossein
-
-
Read Online
- Heterophase nitration of o-nitrotoluene with sulfuric-nitric acid mixtures of low nitrating activity in gas-containing emulsions
-
Heterophase nitration of o-nitrotoluene, in which an increase in the contribution of the reaction in the boundary adsorption monolayer under conditions of surface aeration leads to a higher yield of 2,4-dinitrotoluene and larger 2,4-/2,6-dinitrotoluene isomer ratio, was studied.
- Artemov,Veretennikov,Tselinskii
-
-
Read Online
- Hafnium(IV) and zirconium(IV) triflates as superior recyclable catalysts for the atom economic nitration of o-nitrotoluene
-
The hydrated group 4 metal triflates, Hf(OTf)4 and Zr(OTf)4, were found to be excellent catalysts (10 mol%) for the mononitration of o-nitrotoluene using a single equivalent of concentrated (69%) nitric acid. The only side product is water and the catalysts are readily recycled from the aqueous phase and re-used.
- Waller, Francis J.,Barrett, Anthony G. M.,Braddock, D. Christopher,Ramprasad, Dorai
-
-
Read Online
- Zeolite catalysis of aromatic nitrations with dinitrogen pentoxide
-
The reactions of 2-nitrotoluene. 1-chloro-2-nitrobenzene, and 1-chloro-4-nitrobenzene with dinitrogen pentoxide in dichloromethane at 0 °C are strongly catalysed by some zeolites notably H-Faujasite-720, catalysis by which is investigated in detail. Yields of the nitrated aromatics are near-quantitative. In the first two substrates nitration occurs more regioselectively at the 4-position compared to the uncatalysed reaction. The reaction of 1-chloro-2-nitrobenzene shows a kinetic form which is close to first-order with a rate-constant independent of the concentration Of N2O5 and proportional to the mass of zeolite. Initial addition of the major product, 1-chloro-2,4-dinitrobenzene, causes rate-inhibition. Mechanisms are discussed.
- Claridge, Robert P.,Lancaster, N. Llewellyn,Millar, Ross W.,Moodie, Roy B.,Sandall, John P. B.
-
-
Read Online
- Competition between electron-donor and electron-acceptor substituents in nitrotoluene isomers: A photoelectron spectroscopy and ab initio investigation
-
We present an investigation of the close relationship between chemical structure, physical properties and reactivity of the three nitrotoluene isomers: a joint experimental and theoretical study, based on X-ray photoelectron spectroscopy (XPS) measurements and ab initio calculations, addressing the complex interplay between the competing electron-donor and electron-acceptor effects of the nitro- and methyl-substituents on the chemical properties of the nitrotoluene isomers. As the main results of the investigation we: (i) point out that accurate ab initio calculations play a key role in the complete assignment of photoemission measurements, as well as in the estimate of proton affinities in the case of all the eligible sites; (ii) revisit, at a more quantitative level, textbook models based on inductive and resonant effects of different substituents of the aromatic ring, as well as on the hyper-conjugative connection of the methyl group to the π-conjugated system; (iii) provide an accurate analysis of correlation patterns between calculated proton affinities and core-ionization energies, which represent a powerful tool, capable of predicting site-specific reactivities of polysubstituted molecules in the case of electrophilic aromatic substitution reactions.
- Rondino, Flaminia,Catone, Daniele,Mattioli, Giuseppe,Bonapasta, Aldo Amore,Bolognesi, Paola,Casavola, Anna Rita,Coreno, Marcello,O'Keeffe, Patrick,Avaldi, Lorenzo
-
-
Read Online
- Nitration of aromatics with dinitrogen pentoxide in a liquefied 1,1,1,2-tetrafluoroethane medium
-
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.
-
p. 25841 - 25847
(2021/08/09)
-
- Nitration of deactivated aromatic compounds via mechanochemical reaction
-
A variety of deactivated arenes were nitrated to their corresponding nitro derivatives in excellent yields under high-speed ball milling condition using Fe(NO3)3·9H2O/P2O5 as nitrating reagent. A radical involved mechanism was proposed for this facial, eco-friendly, safe, and effective nitration reaction.
- Wu, Jian-Wei,Zhang, Pu,Guo, Zhi-Xin
-
supporting information
(2021/05/05)
-
- The polyhedral nature of selenium-catalysed reactions: Se(iv) species instead of Se(vi) species make the difference in the on water selenium-mediated oxidation of arylamines
-
Selenium-catalysed oxidations are highly sought after in organic synthesis and biology. Herein, we report our studies on the on water selenium mediated oxidation of anilines. In the presence of diphenyl diselenide or benzeneseleninic acid, anilines react with hydrogen peroxide, providing direct and selective access to nitroarenes. On the other hand, the use of selenium dioxide or sodium selenite leads to azoxyarenes. Careful mechanistic analysis and 77Se NMR studies revealed that only Se(iv) species, such as benzeneperoxyseleninic acid, are the active oxidants involved in the catalytic cycle operating in water and leading to nitroarenes. While other selenium-catalysed oxidations occurring in organic solvents have been recently demonstrated to proceed through Se(vi) key intermediates, the on water oxidation of anilines to nitroarenes does not. These findings shed new light on the multifaceted nature of organoselenium-catalysed transformations and open new directions to exploit selenium-based catalysis.
- Capperucci, Antonella,Dalia, Camilla,Tanini, Damiano
-
supporting information
p. 5680 - 5686
(2021/08/16)
-
- NITRATION OF AROMATIC COMPOUNDS
-
The present invention provides a process for nitrating aromatic compounds without the need for a solid catalyst and/or any organic solvents and/or any other additives. A typical process includes combining or admixing a nitric acid and an anhydride compound under conditions sufficient to produce a reactive intermediate. The aromatic compound to be nitrated is then added to this reactive intermediate to produce a nitroaromatic compound. The nitroaromatic compound can be substituted with one or more, typically, one to three, and often one or two nitrate (-NO2) groups.
- -
-
Paragraph 0049; 0050
(2016/08/17)
-
- Regioselective nitration of 2- and 4-nitrotoluenes over systems comprising nitric acid, an acid anhydride and a zeolite
-
Nitration of 2-nitrotoluene using nitric acid, acetic anhydride and Hβ zeolite produces a 97% yield of 2,4-dinitotoluene along with 3% of 2,6-dinitrotoluene. Nitration of 4-nitrotoluene under similar reaction conditions produces 2,4-dinitrotoluene in 89% yield. When chloroacetic anhydride was used instead of acetic anhydride, nitration of 4-nitotoluene produced a quantitative yield (>99%) of 2,4-nitrotoluene. ARKAT-USA, Inc.
- Smith, Keith,Alotaibi, Mohammad Hayal,El-Hiti, Gamal A.
-
p. 301 - 309
(2014/10/16)
-
- Regioselective dinitration of simple aromatics over zeolite Hβ/nitric acid/acid anhydride systems
-
Various nitration systems comprising nitric acid, acid anhydride and zeolite H￡] in the absence of solvent are described. Direct double nitration of toluene with a nitric acid, propanoic anhydride and zeolite Hβ system has been developed to give 2,4-dinitrotoluene in 98% yield, with a 2,4-:2,6-dinitrotoluene ratio of 123:1. This system also nitrates activated mono-substituted benzenes (anisole and phenetole) and moderately activated mono-substituted benzenes (ethylbenzene and propylbenzene) to give mainly 2,4-dinitro derivatives. The zeolite can be recovered, regenerated and reused to give almost the same yield as that given when fresh zeolite is used. ARKAT-USA, Inc.
- Smith, Keith,Alotaibi, Mohammad Hayal,El-Hiti, Gamal A.
-
p. 107 - 123
(2014/04/17)
-
- Preparation of heteropoly acid based amphiphilic salts supported by nano oxides and their catalytic performance in the nitration of aromatics
-
A series of Keggin heteropoly acid anion based amphiphilic salts supported by nano oxides were synthesized and used as catalysts in the nitration of aromatic compounds with HNO3. The reaction conditions in the nitration of toluene were optimized and both 92.6% conversion and good para selectivity (ortho:para = 1.09) were obtained.
- Wang, Peng-Cheng,Yao, Kai,Lu, Ming
-
p. 2197 - 2202
(2013/03/14)
-
- Preparation, catalytic performance and theoretical study of porous sulfated binary metal oxides shell (SO42 -/M1xO y-M2xOy) using pollen grain templates
-
Porous micro-sized particles of binary metal oxide (SO4 2 -/M1xOy-M2xOy) shell were prepared by template-directed synthesis method employing HCl-treated pollen grains. With 150 m2/g high surface area, these solid acids could provide more acid sites and thus obtain better catalytic activity. Using aromatic nitration as the typical reaction, their catalytic performances were evaluated and showed a significant improvement in both conversion and regioselectivity. Then, with chlorobenzene as substrate, theoretical studies were performed to investigate the interaction between transition metals and chlorobenzene. The results showed that the excellent para-selectivity was closely relative to the metal ion in these solid acids.
- Wang, Peng Cheng,Yao, Kai,Zhu, Jie,Liu, Xiang,Lu, Ting Ting,Lu, Ming
-
-
- Highly regioselective dinitration of toluene over reusable zeolite Hβ
-
A nitration system comprising nitric acid, propanoic anhydride, and zeolite Hβ has been developed for dinitration of toluene to give 2,4-dinitrotoluene in 98% yield, with a 2,4-:2,6-dinitrotoluene ratio of over 120. This represents the most selective quantitative method for 2,4-dinitration of toluene; the catalyst is reusable, solvent is not needed, and an aqueous work-up is not required.
- Smith, Keith,Alotaibi, Mohammad Hayal,El-Hiti, Gamal A.
-
p. 244 - 247
(2013/02/22)
-
- Photochemical activity of a key donor-acceptor complex can drive stereoselective catalytic α-alkylation of aldehydes
-
Asymmetric catalytic variants of sunlight-driven photochemical processes hold extraordinary potential for the sustainable preparation of chiral molecules. However, the involvement of short-lived electronically excited states inherent to any photochemical reaction makes it challenging for a chiral catalyst to dictate the stereochemistry of the products. Here, we report that readily available chiral organic catalysts, with well-known utility in thermal asymmetric processes, can also confer a high level of stereocontrol in synthetically relevant intermolecular carbon-carbon bond-forming reactions driven by visible light. A unique mechanism of catalysis is proposed, wherein the catalyst is involved actively in both the photochemical activation of the substrates (by inducing the transient formation of chiral electron donor-acceptor complexes) and the stereoselectivity-defining event. We use this approach to enable transformations that are extremely difficult under thermal conditions, such as the asymmetric α-alkylation of aldehydes with alkyl halides, the formation of all-carbon quaternary stereocentres and the control of remote stereochemistry.
- Arceo, Elena,Jurberg, Igor D.,Alvarez-Fernandez, Ana,Melchiorre, Paolo
-
p. 750 - 756
(2013/09/23)
-
- METHODS FOR THE NITRATION OF AROMATIC COMPOUNDS
-
According to the invention there is provided a method for the nitration of an aromatic compound including the step of reacting the aromatic compound with nitric acid in the presence of an acid anhydride and an aluminosilicate catalyst, in which the acid anhydride is at least one of: ((CnH2n+1)CO)20, where n is 1 to 4 and the moiety CnH2n+1 can be straight or branched chain; ((CHpClq)CO)20, where p is 0 to 2, q is 1 to 3, and p+q = 3; and oxoiane -2, 5-dione, with the proviso that when the acid anhydride is (CH3CO)20, the aromatic compound is toluene, 2-nitrotoluene or 4-nitrotoluene, and the nitration is performed to produce 2,4-dinitrotoluene.
- -
-
Page/Page column 14-15
(2012/05/04)
-
- PROCESS FOR THE PREPARATION OF NITRATED AROMATICS AND MIXTURES THEREOF
-
A process for the preparation of mononitroaromatics and dinitroaromatics, in which a hydrate melt of at least one metal nitrate M(NO3)3 is used as a nitrating medium, it being possible for M to be the metals Fe, Cr, Y, La, Ce, Al, Bi and In, and the metal nitrate having a water content of from 4 to 9 mol of water per M(NO3)3, leads to simplifications of the process and improved yields.
- -
-
Page/Page column 4-5
(2012/01/03)
-
- Ethylammonium nitrate (EAN)/Tf2O and EAN/TFAA: Ionic liquid based systems for aromatic nitration
-
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.
-
p. 8088 - 8094
(2011/11/13)
-
- Regioselectivity nitration of aromatics with N2O5 in PEG-based dicationic ionic liquid
-
Regioselective mononitration of simple aromatic compounds has been investigated with N2O5 as nitrating agent and a new PEG200-based dicationic acidic ionic liquid (PEG200-DAIL) as catalyst. The results of experiments show that this nitration system can significantly improve the para-selectivity of alkyl-benzenes and the ortho-selectivity of halogenated-benzenes. The PEG200-DAIL exhibits recyclable temperature-dependant phase behavior in CCl4 solvent, and it can be recycled without apparent loss of catalytic activity, and only 5% loss of weight is observed after six times recycling.
- Wang, Peng-Cheng,Lu, Ming
-
supporting information; experimental part
p. 1452 - 1455
(2011/05/16)
-
- Process For Preparing High Purity TNT
-
A process for preparing trinitrololuene (TNT) in which toluene is treated with nitric acid having a concentration of about 90% to about 99%, and preferably about 98% to about 99%, by weight at a temperature of less than about 60° C., and preferably less than 30° C., to produce high purity dinitrotoluene. The resulting dinitrotoluene is then treated with nitric acid having a concentration of about 98% to about 99% by weight and trifluoromethane sulfuric acid to produce high purity TNT.
- -
-
Page/Page column 1
(2009/12/27)
-
- Aromatic nitration using nitroguanidine and EGDN
-
Acid catalyzed nitration has been examined using a variety of novel nitration agents: guanidine nitrate (GN) and nitroguanidine (NQ) as well as the simple nitrate ester, ethylene glycol dinitrate (EGDN). Reactions with either activated or deactivated aromatic substrates proceed rapidly and in high yield. Regioselectivity was similar for all nitrating agents examined. The synthetic advantages of liquid EGDN include high solubility in organic solvents, strong nitration activity and ease of preparation.
- Oxley, Jimmie C.,Smith, James L.,Moran, Jesse S.,Canino, Jonathan N.,Almog, Joseph
-
p. 4449 - 4451
(2008/12/21)
-
- Highly efficient dinitration of aromatic compounds in fluorous media using ytterbium perfluorooctanesulfonate and perfluorooctanesulfonic acid as catalysts
-
Ytterbium perfluorooctanesulfonate [Yb(OPf)3] and perfluorooctanesulfonic acid [PfOH] catalyze the highly efficient dinitration of toluene, benzene, benzyl chloride, and chlorobenzene in fluorous media. Notably the process produces almost no waste acid, as opposed to the traditional case. The fluorous phase-containing catalyst could be easily and efficiently recovered for reuse by simple phase separation. Copyright Taylor & Francis Group, LLC.
- Yi, Wen-Bin,Cai, Chun
-
p. 2957 - 2961
(2007/10/03)
-
- Acetyl nitrate nitrations in [bmpy][N(Tf)2] and [bmpy][OTf], and the recycling of ionic liquids
-
In this work we have examined the nitration by acetyl nitrate of a range of activated and deactivated aromatic substrates in two ionic liquids and compared the results to the same reaction in dichloromethane. Both ionic liquids are stable to the reaction conditions, and in both ionic liquids the yields of reaction are higher after unit time than the same reactions in dichloromethane, although the regioselectivity is little affected by solvent choice. This result gives further support to the suggestion that in the ionic liquid, acetyl nitrate dissociates to give the nitronium ion, and that this is the effective nitrating agent here. However, it is shown that [bmpy][N(Tf)2] is a better solvent for aromatic nitration than [bmpy][OTf]. This is due to the ease of formation of nitronium ion in the former ionic liquid, and is consistent with the fact that [bmpy][N(Tf)2] is a weaker hydrogen bond acceptor solvent than [bmpy][OTf]. Finally, a method by which [bmpy][N(Tf)2] may be recovered and reused for aromatic nitration has been demonstrated.
- Dal, Emilie,Lancaster, N. Llewellyn
-
p. 682 - 686
(2007/10/03)
-
- Nitric acid in the presence of P2O5 supported on silica gel - A useful reagent for nitration of aromatic compounds under solvent-free conditions
-
A variety of aromatic compounds are nitrated to parent nitro aromatic compounds under solvent-free conditions using 65% nitric acid in the presence of P2O5 supported on silica gel is described. This methodology is useful for nitration of activated and deactivated aromatic rings.
- Hajipour, Abdol Reza,Ruoho, Arnold E.
-
p. 8307 - 8310
(2007/10/03)
-
- METHOD FOR PRODUCING DINITROTOLUENE
-
The invention relates to a method for producing dinitrotoluene, comprising the steps of a) reacting toluene with nitric acid in the presence of sulphuric acid to give mononitrotoluene, b) separating the reaction product of step a) into a mononitrotoluene-containing organic phase and a sulphuric acid-containing aqueous phase, c) reacting the mononitrotoluene-containing organic phase with nitric acid in the presence of sulphuric acid to give dinitrotoluene, d) separating the reaction product of step c) into a dinitrotoluene-containing organic phase and a sulphuric-acid containing aqueous phase, whereby the reaction product of step a) contains 3.0 to 8 wt. % of toluene, in relation to the organic phase, and 0.1 to 1.2 wt. % of nitric acid, in relation to the aqueous phase and the phase separation of step b) is carried out in such a manner that further reaction of toluene with nitric acid is prevented.
- -
-
Page/Page column 9-11
(2008/06/13)
-
- Oxidation of 2,4-dinitrotoluene with ozone in acetic acid in the presence of transition metal salts
-
The reaction of 2,4-dinitrotoluene with an ozone-oxygen mixture in glacial acetic acid in the presence of transition metal salts was studied. The ozonolysis of the aromatic ring during the process in the presence of cobalt(II) or manganese(II) acetate was prevented to a considerable degree, and selective oxidation at the methyl group of 2,4-dinitrotoluene became prevalent, producing 2,4-dinitrobenzoic acid with a yield of 87.6 or 73.1%, respectively. A decrease in the yield of 2,4-dinitrobenzoic acid with an increase in the temperature of ozonolysis in the presence of manganese(II) acetate was found to be due to partial transition of the oxidized manganese form Mn4+ into the insoluble form MnO2. Copyright
- Andreev, P. Yu.,Galstyan,Galstyan
-
p. 319 - 322
(2007/10/03)
-
- Atom-efficient electrophilic aromatic nitration by dinitrogen pentoxide catalysed by zirconium(IV) 2,4-pentanedionate
-
An atom-efficient, non-acidic, catalytic process is described for the nitration of electron deficient arenes such as o-nitrotoluene using a dinitrogen pentoxide-zirconium(IV) 2,4-pentanedionate system in dichloromethane solvent. Kinetic studies showed the nitration process to be first-order with respect to the aromatic substrate and higher than first-order with respect to the catalyst. Addition of the catalyst at ca. 0.1-1 mol% compared with both N2O5 and the organic substrate results in an increase in the first-order rate constant for nitration by a factor of approximately 5000 with a turnover number of at least 500. The orientation of the nitration products (2,4-/2,6-dinitrotoluenes) is consistent with attack of nitronium ion. The apparently high order of reaction with respect to the catalyst suggests a possible heterogeneous process.
- Hill, Adrian J.,Millar, Ross W.,Sandall, John P.B.
-
-
- Paradigm confirmed: The first use of ionic liquids to dramatically influence the outcome of chemical reactions
-
It has been an unproven paradigm that the choice of which ionic liquid to use in a chemical reaction can have a dramatic effect on the outcome of that chemical reaction. We demonstrate, for the first time, that the reaction of toluene and nitric acid in three different ionic liquids gives rise to three completely different products in high yield. Furthermore, ionic liquids can catalyze these reactions with the only byproduct being water.
- Earle, Martyn J.,Katdare, Suhas P.,Seddon, Kenneth R.
-
p. 707 - 710
(2007/10/03)
-
- Cross-coupling of aryl halides and triflates with intramolecularly stabilized group 13-metal alkylating reagents in the presence of mixed-metal catalysts
-
In the presence of tertiary phosphines, the palladium-containing mixed-metal complexes [(CO)4Fe(μ-PPh2)Pd(μ-Cl)]2(1) and [(CO)3Co]2(μ-CO)Pd[μ-(Ph2PCH 2)2] (2) catalyze the cross-coupling of aryl triflates and halides (including chlorides) with intramolecularly stabilized dialkylaluminum, -gallium and -indium reagents 3-8. The reactions are high yielding, and homocoupling and hydrodehalogenation processes are minimal even when the alkyl moieties of the alkylating reagents contain β-hydrogen atoms. As the components of the mixed-metal complexes are either poor catalysts, or completely inactive, the high catalytic activity of 1 and 2 is attributed to synergism between the different metal nuclei of the catalysts.
- Shenglof, Margarita,Gelman, Dmitri,Heymer, Bernd,Schumann, Herbert,Molander, Gary A.,Blum, Jochanan
-
p. 302 - 306
(2007/10/03)
-
- A Practical Approach of Continuous Processing to High Energetic Nitration Reactions in Microreactors
-
Continuous processing in microreactors represents a novel way for the safe and expedient conduct of high energetic reactions and potentially hazardous chemistry. Apart from handling benefits (such as minimised problems in the scale-up process), reactions in microreactors proceed under precisely controlled conditions providing improved yields and product quality compared to the batch procedure. In this paper, the potential of this technology is exemplarily determined in the crucial nitration of the pharmaceutically relevant intermediate 1-methyl-3-propyl-1H-pyrazole-5-carboxylic acid (1). Further fundamental nitration examples demonstrate the unproblematic handling of hazardous H2SO4/ HNO3 mixtures for the nitration of 2-methylindole (4) and pyridine- N-oxide (6) or even the explosive acetyl nitrate Ac2O/HNO3 (nitration of toluene, 8) in the continuous reaction mode.
- Panke, Gerhard,Schwalbe, Thomas,Stirner, Wolfgang,Taghavi-Moghadam, Shahriyar,Wille, Gregor
-
p. 2827 - 2830
(2007/10/03)
-
- Counterion effects in indium-catalysed aromatic electrophilic substitution reactions
-
Indium(III) triflamide (In(NTf2)3) has been prepared in high yield and has been demonstrated to be an efficient, recoverable catalyst for a range of aromatic electrophilic substitution reactions. When compared to other indium(III) complexes, anomalous reactivities suggest a non-innocent role for the counterion in the studied processes.
- Frost, Christopher G,Hartley, Joseph P,Griffin, David
-
p. 4789 - 4791
(2007/10/03)
-
- Faujasite catalysis of aromatic nitrations with dinitrogen pentoxide. The effect of aluminium content on catalytic activity and regioselectivity: The nitration of pyrazole
-
The reaction of 1-chloro-2-nitrobenzene with dinitrogen pentoxide in dichloromethane catalysed by H-faujasite zeolites F-712, F-720, F-780 and F-901, giving 1-chloro-2,4-dinitro- and 1-chloro-2,6-dinitrobenzene in approximately 30:1 ratio, is a kinetically first-order process. First-order rate constants are independent of the concentration of N2O5 and proportional to the mass of catalyst used. Specific rate constants, obtained by dividing the first-order rate constant by the mass of faujasite, are constant for a given faujasite. Amongst the faujasites, they increase in approximate proportion to the aluminium content. A mechanism is proposed in which the protons in the faujasite, near aluminium in the faujasite framework, are replaced by nitronium ions derived from N2O5 in a fast pre-equilibrium process. This produces active sites for transfer of nitronium ion from faujasite to aromatic in the rate-determining step. The similar reactions of 2-nitrotoluene, too fast for kinetic study, reveal that the ratio of 2,4- to 2,6-dinitrotoluene in the product increases with the aluminium content of the faujasite. Nitration of nitrobenzene is also catalysed by faujasite. Relative reactivities of nitrobenzene, 1-chloro-2-nitro- and 1-chloro-4-nitrobenzene are compared to those found in mixed-acid nitration. Pyrazole can be nitrated readily with N2O5 over faujasites, yielding 1,4-dinitropyrazole in 80% yield under mild conditions.
- Claridge, Robert P.,Lancaster, N. Llewellyn,Millar, Ross W.,Moodie, Roy B.,Sandall, John P.B.
-
p. 197 - 200
(2007/10/03)
-
- Nitration of aromatic compounds on solid catalysts
-
o-Xylene, phenol and toluene were nitrated with 100% nitric acid on MoO3/SiO2, WO3/SiO2, TiO2/SiO2, and TiO2-WO3/SiO2 systems. Phenol and toluene were nitrated with yields higher than 90%, and the 10% and 15% MoO3/SiO2 catalysts were most active in the nitration of o-xylene. The most active catalysts exhibited the para-position selectivity of nitration.
- Milczak,Jacniacki,Zawadzki,Malesa,Skupinski
-
p. 173 - 187
(2007/10/03)
-
- Microwave-induced synthesis of nitrostilbenes under neat condition
-
Nitrostilbenes 3a-e were synthesized in good yield using microwave under neat conditions, whereas heating at 90°C resulted in poorer yields of products.
- Saravanan,Srinivasan
-
p. 823 - 826
(2007/10/03)
-
- A fast and mild method for the nitration of aromatic rings
-
The use of N2O5 and a Fe(III) catalyst for the nitration of aromatic rings is described. This methodology is compatible with most functional groups and results in near quantitative yields in 4 min. The reaction conditions are non-oxidising: benzaldehyde and benzyl alcohols are readily nitrated with little or no oxidation (4%) occurring. The addition of the iron catalyst activates the system to such an extent that nitration of an activated aromatic ring, such as toluene, occurs quantitatively at -100°C. This high activity allows compounds with sensitive functional groups such as alkenes to be smoothly nitrated.
- Bak, Radoslaw R.,Smallridge, Andrew J.
-
p. 6767 - 6769
(2007/10/03)
-
- Improved nitrations using metal nitrate-sulfuric acid systems
-
Procedures for efficient mono- and di-nitration of aromatic substrates have been developed using ceric ammonium nitrate suspended in dichloromethane in the presence of 2 equiv. of sulfuric acid. By suspending the sulfuric acid on silica gel following nitration, products are easily isolated by filtration and evaporation of solvent. In these nitrations ceric ammonium nitrate can be replaced by other metal nitrates, for example potassium- or tetrabutylammonium-nitrate. In contrast the nitration of naphthalene by ceric ammonium nitrate in the presence of methanol and sulfuric acid affords a mixture of 1,4- and 1,2-methoxynitronaphthalenes, but these nitrations cannot be achieved using potassium or tetrabutylammonium nitrate. The mechanism of this nitration/oxidation is discussed. (C) 2000 Elsevier Science Ltd.
- Mellor, John M.,Mittoo, Stifun,Parkes, Rachel,Millar, Ross W.
-
p. 8019 - 8024
(2007/10/03)
-
- A novel method for the nitration of deactivated aromatic compounds
-
Novel nitration systems comprising nitric acid, trifluoroacetic anhydride and zeolite Hβ, with or without acetic anhydride, are described. The system having no acetic anhydride is more active and readily nitrates deactivated substrates such as nitrobenzene, benzonitrile, benzoic acid or 4-nitrotoluene to give predominantly the product substituted meta to the deactivating group. The system incorporating acetic anhydride is more moderate in activity, and nitrates moderately deactivated systems such as halogenobenzenes quantitatively within two hours at ice-salt bath temperature, and provides very high selectivity for the para-nitrated product. This system also nitrates 2-nitrotoluene to give high selectivity for 2,4-dinitrotoluene production. Furthermore, the system can be used for direct double nitration of toluene and gives a 92% yield of 2,4-dinitrotoluene with a 2,4- : 2,6-dinitrotoluene ratio of 25:1. Even greater selectivity (96% yield and 70:1 selectivity) can be achieved in the latter reaction by conducting the reaction in one flask but in two stages, with trifluoroacetic anhydride added only in the second stage. The Royal Society of Chemistry 2000.
- Smith, Keith,Gibbins, Tracy,Millar, Ross W.,Claridge, Robert P.
-
p. 2753 - 2758
(2007/10/03)
-
- Palladium-catalyzed cross-methylation of aryl chlorides by stabilized dimethylaluminium and -gallium reagents
-
Two methods for palladium-catalyzed cross-methylation of aryl chlorides by intramolecularly stabilized dialkylaluminium and -gallium complexes 6-13 have been studied. In one method, in which either tetrakis(triphenylphosphine)palladium (1) or dichloro- bis(triphenylphosphine)palladium (2) is used as the catalyst at 80-90°C, the activation of the chlorine atom is affected by introduction of strong electron-withdrawing groups into the aromatic moiety. The second method is based on the application of either [1,3- bis(diisopropylphosphino)propane)]palladium (4) or homologous electron-rich palladium complexes as catalysts. Although 4 promotes smooth cross-alkylation of aryl chlorides it fails to activate simple aryl bromides.
- Blum, Jochanan,Berlin, Olga,Milstein, David,Ben-David, Yehoshua,Wassermann, Birgit C.,Schutte, Stefan,Schumann, Herbert
-
p. 571 - 575
(2007/10/03)
-
- 14C-TNT Synthesis Revisited
-
Mineralization experiments requiring the synthesis of substantial amounts of [ring-14C]trinitrotoluene, led us to reinvestigate the published procedures for labeled TNT. Here we describe an efficient, economical and reproducible procedure that results in crystalline 14C-TNT in 83 percent yield with chemical and radiochemical purity of > 99 percent. Determination of the specific activity (1.12 GBq/mmol) by mass spectrometry disclosed that the radioactive TNT molecules exhibit an uneven distribution of four to six aromatic 14C-atoms.
- Kroeger, Mario,Fels, Gregor
-
p. 217 - 228
(2007/10/03)
-
- Chemistry of superacids: 35. * NO2Cl-3MXN systems: Superelectrophilic aprotic nitrating agents for deactivated aromatics
-
Superelectrophilic nitration of deactivated aromatics with NO2Cl-3MXn complexes in aprotic nonpolar solvents such as CH2Cl2 makes it possible to obtain the corresponding nitro derivatives in good to almost quantitative yields under mild conditions.
- Olah,Orlinkov,Ramaiah,Oxyzoglou,Prakash
-
p. 924 - 927
(2007/10/03)
-
- Vanadium(v) oxytrinitrate, VO(NO3)3. A powerful reagent for the nitration of aromatic compounds at room temperature under non-acidic conditions
-
Vanadium(v) oxytrinitrate is an easy to handle reagent which can be used to nitrate a range of substituted aromatic compounds in dichloromethane at room temperature, leading to >99% yields of nitration products in most cases.
- Dove, Michael F. A.,Manz, Berthold,Montgomery, John,Pattenden, Gerald,Wood, Simon A.
-
p. 1589 - 1590
(2007/10/03)
-
- Biotransformation of 2,4,6-trinitrotoluene (TNT) by ectomycorrhizal basidiomycetes
-
The ability of four ectomycorrhizal basidiomycetes to biotransform 2,4,6-trinitrotoluene (TNT) in axenic culture was tested. All species were capable of TNT biotransformation to a greater or lesser extent. When biotransformation was expressed on a biomass basis 4 out of the 5 isolates tested were equally efficient at transforming TNT. The factors regulating TNT biotransformation were investigated in detail for one fungus, Suillus variegatus. When the fungus was grown under nitrogen limiting conditions the rate of biotransformation decreased relative to nitrogen sufficient conditions, but no decrease was observed under short term carbon starvation. Extracellular enzymes of S. variegatus could transform TNT, but transformation was greater in intact cells. The mycelial cell wall fraction did not degrade TNT. The TNT concentration that caused 50% reduction in biomass (EC50) for S. variegatus was within the range observed for other basidiomycete fungi being between 2-10 μg mL-1. The potential use of ectomycorrhizal basidiomycetes as in-situ bioremediation agents for TNT contaminated soils is discussed.
- Meharg,Dennis,Cairney
-
p. 513 - 521
(2007/10/03)
-
- Mild and Selective Nitration by "Claycop"
-
A one-pot nitration of aromatic compounds by "claycop", a reagent consisting of an acidic montmorillonite clay impregnated with anhydrous cupric nitrate, is reported.Simply by varying the conditions, it is possible to drive the reaction at will toward either mono- or polynitration.Both the yields and selectivities are superior to those obtained under homogeneous reaction conditions.
- Gigante, Barbara,Prazeres, Angela O.,Marcelo-Curto, Maria J.,Cornelis, Andre,Laszlo, Pierre
-
p. 3445 - 3447
(2007/10/02)
-
This product is a nationally controlled contraband, and the Lookchem platform doesn't provide relevant sales information.
