- 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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- NITRATION OF AROMATIC COMPOUNDS
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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)
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- Competition between electron-donor and electron-acceptor substituents in nitrotoluene isomers: A photoelectron spectroscopy and ab initio investigation
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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
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p. 5272 - 5282
(2014/01/23)
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- 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.
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p. 301 - 309
(2014/10/16)
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- Regioselective dinitration of simple aromatics over zeolite Hβ/nitric acid/acid anhydride systems
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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.
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p. 107 - 123
(2014/04/17)
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- Oxidation of aromatic amines into nitroarenes with m-CPBA
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A versatile and highly efficient approach for the synthesis of nitroarenes from aromatic amine using m-CPBA has been developed. This oxidation reaction was operationally straightforward and proceeded to afford products in good isolated yields.
- Liu, Jia,Li, Jue,Ren, Jiangmeng,Zeng, Bu-Bing
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p. 1581 - 1584
(2014/03/21)
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- 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
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p. 2197 - 2202
(2013/03/14)
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- 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
-
-
- METHODS FOR THE NITRATION OF AROMATIC COMPOUNDS
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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.
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-
Page/Page column 14-15
(2012/05/04)
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- PROCESS FOR THE PREPARATION OF NITRATED AROMATICS AND MIXTURES THEREOF
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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.
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-
Page/Page column 4-5
(2012/01/03)
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- Aromatic nitration using nitroguanidine and EGDN
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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
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p. 4449 - 4451
(2008/12/21)
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- Heterophase nitration of o-nitrotoluene with sulfuric-nitric acid mixtures of low nitrating activity in gas-containing emulsions
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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
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p. 1871 - 1877
(2008/04/05)
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- Control over m-nitrotoluene concentration in products of heterogeneous mononitration of toluene
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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
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p. 2063 - 2072
(2008/09/17)
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- Highly efficient dinitration of aromatic compounds in fluorous media using ytterbium perfluorooctanesulfonate and perfluorooctanesulfonic acid as catalysts
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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
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p. 2957 - 2961
(2007/10/03)
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- Urea nitrate and nitrourea: powerful and regioselective aromatic nitration agents
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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
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p. 8651 - 8652
(2007/10/03)
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- Acetyl nitrate nitrations in [bmpy][N(Tf)2] and [bmpy][OTf], and the recycling of ionic liquids
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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
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p. 682 - 686
(2007/10/03)
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- METHOD FOR PRODUCING DINITROTOLUENE
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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.
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-
Page/Page column 9-11
(2008/06/13)
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- Atom-efficient electrophilic aromatic nitration by dinitrogen pentoxide catalysed by zirconium(IV) 2,4-pentanedionate
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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
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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.
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p. 707 - 710
(2007/10/03)
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- A Practical Approach of Continuous Processing to High Energetic Nitration Reactions in Microreactors
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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
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p. 2827 - 2830
(2007/10/03)
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- Counterion effects in indium-catalysed aromatic electrophilic substitution reactions
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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
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p. 4789 - 4791
(2007/10/03)
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- Faujasite catalysis of aromatic nitrations with dinitrogen pentoxide. The effect of aluminium content on catalytic activity and regioselectivity: The nitration of pyrazole
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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.
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p. 197 - 200
(2007/10/03)
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- Regioselective double Kyodai nitration of toluene and chlorobenzene over zeolites. High preference for the 2,4-dinitro isomer at the second nitration stage
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(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
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p. 3431 - 3434
(2007/10/03)
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- Nitration of aromatic compounds on solid catalysts
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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
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p. 173 - 187
(2007/10/03)
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- A fast and mild method for the nitration of aromatic rings
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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.
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p. 6767 - 6769
(2007/10/03)
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- Improved nitrations using metal nitrate-sulfuric acid systems
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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.
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p. 8019 - 8024
(2007/10/03)
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- A novel method for the nitration of deactivated aromatic compounds
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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.
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p. 2753 - 2758
(2007/10/03)
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- 14C-TNT Synthesis Revisited
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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
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p. 217 - 228
(2007/10/03)
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- Zeolite catalysis of aromatic nitrations with dinitrogen pentoxide
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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.
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p. 1815 - 1818
(2007/10/03)
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- Hafnium(IV) and zirconium(IV) triflates as superior recyclable catalysts for the atom economic nitration of o-nitrotoluene
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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
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p. 1641 - 1642
(2007/10/03)
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- Chemistry of superacids: 35. * NO2Cl-3MXN systems: Superelectrophilic aprotic nitrating agents for deactivated aromatics
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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
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p. 924 - 927
(2007/10/03)
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- Vanadium(v) oxytrinitrate, VO(NO3)3. A powerful reagent for the nitration of aromatic compounds at room temperature under non-acidic conditions
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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.
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p. 1589 - 1590
(2007/10/03)
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- The efficacy of 'Claycop' in the dinitration of toluene
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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.
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p. 847 - 848
(2007/10/03)
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- Thermal Stability Studies on a Homologous Series of Nitroarenes
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The thermal stabilities of a number of nitroarenes were examined in solution and in condensed phase.In general, increasing the number of nitro groups decreased thermal stability.Changing the substituent on 1-X-2,4,6-trinitrobenzene from X = H to NH2 to CH3 to OH accelerated decomposition; this effect was attributed to increased ease of intramolecular proton transfer to an ortho nitro group, thus weakening the carbon-nitrogen bond.In solution, the effect of increasing substitution from n = 1 to n = 3 on Xn(NO2)3C6H3-n was uniformly that of decreasing the thermal stability of the species.However, in condensed phase, results suggested that crystal habit may be more important than molecular structure; for X = Br, CH3, and NH2, the more substituted species was the more stable.
- Oxley, Jimmie C.,Smith, James L.,Ye, Hong,McKenney, Robert L.,Bolduc, Paul R.
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p. 9593 - 9602
(2007/10/02)
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- Mild and Selective Nitration by "Claycop"
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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
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p. 3445 - 3447
(2007/10/02)
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- Ozone-mediated Nitration of Alkylbenzenes and Related Compounds with Nitrogen Dioxide
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In the presence of ozone, nitrogen dioxide exhibits a strong nitrating ability for alkylbenzenes at low temperatures, converting them into the corresponding nitro derivatives in high yield.The addition of a protonic acid as catalyst enhances considerably the ability of this nitrating system and leads to a good yield of polynitro compounds.The reaction is clean and proceeds rapidly without any accompanying side-chain substitution or aryl-aryl coupling.It shows no kinetic dependence on the concentration of substrates and, as far as can be judged from relative reactivities and isomer distributions of products, it gives the appearance of being an electrophilic aromatic process.A possible role for nitrogen trioxide has been suggested as the initial electrophilic agent for the nitration of alkylbenzenes.
- Suzuki, Hitomi,Murashima, Takashi,Kozai, Iku,Mori, Tadashi
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p. 1591 - 1598
(2007/10/02)
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- Catalytic reduction of nitro aromatic compounds with hydrogen sulfide and carbon monoxide
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In the reduction of di- or polynitro aromatic compounds by gaseous H2 S over a solid catalyst, addition of CO gas promotes formation of amino groups from all nitro groups in the molecule. A preferred embodiment is reduction of 2,4- and/or 2,6-dinitrotoluene in vapor phase at 325° C. over a supported iron or supported cobalt catalyst on a support comprising alumina. The amino products are useful for production of polyurethane resins.
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- Continuous reduction process
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A process for the reduction of aromatic nitro compounds to amino compounds in the liquid phase using iron as reducing agent, which comprises carrying out the reduction continuously such that the reducing iron, based on the amount of nitro compound present in the reactor, is present in an amount substantially in excess of the stoichiometric amount, and effecting the continuous removal of the reaction products such that the substantial excess of reducing iron is also constantly present in the reactor during the reduction.
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- Process for the production of nitro derivatives of aromatic compounds
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Nitroderivates of aromatic compounds which are difficult to nitrate, can readily be obtained by nitration providing that the aromatic compound is treated with nitric acid or another nitrating agent in the presence of aliphatic or cycloaliphatic hydrocarbons monosubstituted or polysubstituted by halogen, the nitro group or an alkyl sulphonyl group, and the nitro derivative formed subsequently isolated.
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