- Ipso Nitration of Aryl Boronic Acids Using Fuming Nitric Acid
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The ipso nitration of aryl boronic acid derivatives has been developed using fuming nitric acid as the nitrating agent. This facile procedure provides efficient and chemoselective access to a variety of aromatic nitro compounds. While several activating agents and nitro sources have been reported in the literature for this synthetically useful transformation, this report demonstrates that these processes likely generate a common active reagent, anhydrous HNO3. Kinetic and mechanistic studies have revealed that the reaction order in HNO3 is >2 and indicate that the ?NO2 radical is the active species.
- Baucom, Kyle D.,Brown, Derek B.,Caille, Seb,Murray, James I.,Quasdorf, Kyle,Silva Elipe, Maria V.
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supporting information
(2021/06/30)
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- Method for continuously synthesizing 4-ethylnitrobenzene and 2-ethylnitrobenzene
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The invention belongs to the technical field of chemical engineering, and particularly relates to a method for continuously synthesizing 4-ethylnitrobenzene and 2-ethylnitrobenzene by adopting a micro-channel reactor. The method sequentially comprises the
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Paragraph 0081-0103
(2020/08/09)
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- Regioselective mononitration of aromatic compounds with N2O5 by acidic ionic liquids via continuous flow microreactor
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We employed N2O5 as highly active nitrating reagents and a host of acidic ionic liquid as catalysts in these reactions which were conducted in a continuous flow microreactor. When we utilized PEG400-DAIL as catalysts, the conversion of toluene was increased to 95.5 % and the yield of mononitration product (o/p ratio reached 1.10) significantly improved to 99 %, meanwhile the reaction time was drastically shortened to 1/120 of the conventional reactor. Nitration in ionic liquids was surveyed using a host of aromatic substrates with similar reactivity. The ionic liquid recycling procedures had also been devised.
- Liu, Jianhua,Li, Bindong,Wang, Huan
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p. 513 - 516
(2016/01/20)
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- Conformations, equilibrium thermodynamics and rotational barriers of secondary thiobenzanilides
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The article deals with conformational behaviour of 2-methoxy-2′-hydroxythiobenzanilides. The CS-NH group of these compounds preferentially adopts the Z-conformation. Entropy favours the Z-conformer over the E-conformer, whereas enthalpy slightly favours the E-conformer over the Z-conformer. The rotational barrier about the CS-NH bond was determined to be (81.5±0.4) kJ/mol. No significant rotational barrier was found on the Ar-CS and Ar-NH bonds. All experimental outcomes are compared with the results of quantum-chemical calculations.
- Kozic, Ján,Novák, Zdeněk,?ímal, Václav,Profant, Václav,Kune?, Ji?í,Vin?ová, Jarmila
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p. 2072 - 2083
(2016/04/09)
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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.
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Paragraph 0049
(2016/08/17)
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- Poly(4-vinylpyridine)-nitrating mixture complex (PVP-NM): Solid nitrating mixture equivalent for safe and efficient aromatic nitration
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Friedel-Crafts type aromatic nitration has served as an indispensable reaction within both industrial and academic applications. However, growing concern over the use of copious amounts of strong acids has prompted the search for more environmentally friendly alternatives. Polymer-bound Bronsted acids, on the other hand, have been shown useful as convenient alternatives to liquid acids. Nitric acid and sulfuric acids have, therefore, been combined, both individually and as a mixture, with poly(4-vinylpyridine). The new solid acid systems have been used to nitrate both activated and deactivated arenes under mild conditions and proved to be effective nitrating agent.
- Surya Prakash,Gurung, Laxman,Glinton, Kevin E.,Belligund, Kavita,Mathew, Thomas,Olah, George A.
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supporting information
p. 3446 - 3451
(2015/06/25)
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- Eco-friendly nitration of benzenes over zeolite-β-SBA-15 composite catalyst
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Direct synthesis of microporous-mesoporous zeolite-β-SBA-15 (ZBS-15) composite catalyst from the synthetic precursors of SBA-15and zeolite-β seeds under acidic hydrothermal conditions through the simultaneous self-assembly of mesoporous silica SBA-15 and zeolite-β has been accomplished and characterized the ZBS-15 catalyst by XRD, N2 sorption, FT-IR, TPD of ammonia and SEM techniques. The activity of the ZBS-15 composite catalyst for the nitration of benzenes under solvent-free conditions has been investigated, which revealed that there is a significant synergistic influence of both zeolite-β and SBA-15 materials on the activity of the ZBS-15 catalyst.
- Ganjala, Venkata Siva Prasad,Neeli, Chinna Krishna Prasad,Pramod, Chodimella Venkata,Khagga, Mukkanti,Rao, Kamaraju Seetha Rama,Burri, David Raju
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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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- 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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- Regioselective nitration of aromatics with nanomagnetic solid superacid SO42-/ZrO2-MxOy-Fe 3O4 and its theoretical studies
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A series of micro- and nanosulfated zirconia loaded on Fe3O 4 or other metal oxides (SO42-/ZrO 2-MxOy-Fe3O4 (M=Ti 4+, V5+, and Zn2+)) was prepared, characterized, and used in nitration. The nitration conditions with these solid superacids were then optimized to achieve the best regioselectivity and improve the performances of the catalysts as well. In the experimental results, SZTF (SO42-/ZrO2-TiO2-Fe 3O4) showed excellent catalytic activity and it increased the surface area of SO42-/ZrO2 by up to 15 %. The increase not only facilitated the generation of NO2+, but also provided more opportunities for metal ions to interact with aromatic compounds. With chlorobenzene as substrate, theoretical research on its geometric parameters, electron clouds, and electron spin density was used to investigate the interaction between transition metals and chlorobenzene.
- Wang, Peng Cheng,Zhu, Jie,Liu, Xiang,Lu, Ting Ting,Lu, Ming
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p. 310 - 317
(2013/08/23)
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- Preparation of heteropoly acid based amphiphilic salts supported by nano oxides and their catalytic performance in the nitration of aromatics
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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
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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
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- Metal-ligand core-shell nanocomposite catalysts for the selective semihydrogenation of alkynes
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Catalysts with a sheltered upbringing: Novel core-shell nanocomposite catalysts consisting of active metal nanoparticles encapsulated by macroligands have been prepared. They have Pd nanoparticles (PdNPs) as an active core and shell ligands having sulfoxide moieties coordinated to the PdNPs. The shell protects the catalyst from coordination by alkenes and allows the lead-free selective semihydrogenation of a wide range of alkynes without any additives (see scheme). Copyright
- Mitsudome, Takato,Takahashi, Yusuke,Ichikawa, Satoshi,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information
p. 1481 - 1485
(2013/04/10)
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- Highly regioselective dinitration of toluene over reusable zeolite Hβ
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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.
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p. 244 - 247
(2013/02/22)
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- Rare earth metal triflates catalyzed electrophilic nitration using N 2O5
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A mild, efficient and eco-friendly process for the electrophilic nitration is described using N2O5 as a green nitrating agent in the presence of rare earth metal triflates [RE(OTf)3] under mild conditions.
- Ma, Xiao Ming,Li, Bin Dong,Lu, Ming,Lv, Chun Xu
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experimental part
p. 73 - 76
(2012/03/26)
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- Selective nitration of aromatic compounds catalyzed by Hβ zeolite using N2O5
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A selective and efficient process for the electrophilic nitration is described using N2O5 as a green nitrating agent, Hβ zeolite as a solid acid catalyst and shape controlling agent under mild conditions.
- Ma, Xiao Ming,Li, Bin Dong,Chen, Lei,Lu, Ming,Lv, Chun Xu
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scheme or table
p. 809 - 812
(2012/08/08)
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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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- Reusable and efficient polystryrene-supported acidic ionic liquid catalyst for mononitration of aromatic compounds
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A series of polystyrene-supported 1-(propyl-3-sulfonate)-3-methyl- imidazolium hydrosulfate acidic ionic liquid (PS-[SO3H-PMIM][HSO 4]) catalysts were prepared and tested for mononitration of simple aromatics compounds with nitric acid. It was found that the reactivity of the catalysts increased with increasing [SO3HPMIM][ HSO4] content. The para-selectivity was not only related to the [SO 3H-PMIM][HSO4] content but also the substituent groups in aromatics. A reaction mechanism of nitration over this new catalyst was proposed. The catalytic activity of this catalyst decreased slightly after fifth runs in the synthesis of nitrotoluene.
- Li, Li Xia,Ling, Qi Long,Liu, Zu Liang,Xing, Xiao Dong,Zhu, Xiao Qin,Meng, Xiao
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p. 3373 - 3377
(2013/01/15)
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- Regioselectivity nitration of aromatics with N2O5 in PEG-based dicationic ionic liquid
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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
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supporting information; experimental part
p. 1452 - 1455
(2011/05/16)
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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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- An efficient and eco-friendly MoO3-SiO2 solid acid catalyst for electrophilic aromatic nitration with N2O5
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Electrophilic aromatic nitration using N2O5 as a green nitrating agent catalyzed by MoO3-SiO2 under mild conditions has been described. A series of MoO3-SiO2 catalysts with varying MoO3 loadings (5-20 mol%) were prepared by sol-gel technique and characterized using FTIR, XRD, SEM, BET and NH 3-TPD to study its surface properties. MoO3-SiO 2 shows good catalytic activity and reusability for the nitration of alkyl and halogen aromatics giving high conversions, but less efficiency for the deactivated aromatics. Reactions conducted under non-acidic conditions using N2O5 makes the process safe and environmentally friendly. Graphical Abstract: [Figure not available: see fulltext.]
- Ma, Xiaoming,Li, Bindong,Lv, Chunxu,Lu, Ming,Wu, Jian,Liang, Linjie
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experimental part
p. 1814 - 1820
(2012/03/08)
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- A PROCESS FOR SUBSTITUTION ON AROMATIC RINGS
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A process for preparing a substituted aromatic compound, comprising combining an aromatic compound and cuprous (Cu+) ions in a reaction vessel in an essentially oxygen-free environment, and adding to said reaction vessel a source of an electrophile or a nucleophile substituent, to form an aromatic compound product which is ring-substituted with said electrophile or nucleophile at a position which was originally occupied by hydrogen, and isolating the substituted aromatic compound from the reaction mixture.
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Page/Page column 16
(2010/06/17)
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- Selective oxidation of aromatic amines to nitro derivatives using potassium iodide-tert-butyl hydroperoxide catalytic system
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The direct oxidation of aromatic primary amines to the corresponding nitro compounds selectively in 47-98% yields has been achieved by using potassium iodide as catalyst and tert-butyl hydroperoxide as the external oxidant. The present catalytic system works well for both electron-rich and electron-poor substrates.
- Reddy, K. Rajender,Maheswari, C. Uma,Venkateshwar,Kantam, M. Lakshmi
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supporting information; experimental part
p. 93 - 96
(2009/08/07)
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- Polymer-supported ytterbium perfluorooctanesulfonate [Yb(OPf)3]: A recyclable catalyst for organic reactions
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Amberlyst A-21, a kind of well-known and cheap polymeric material, was treated with ytterbium perfluorooctanesulfonate [Yb(OPf)3] giving a reagent with a ytterbium loading of 1.34 (wt%). The polymer-supported fluorous ytterbium catalyses the highly efficient nitration, esterification, Fridel-Crafts acylation, and aldol condensation. The catalyst can be recovered by simple filtration and used again without a significant loss of catalytic activity. The protocol avoids the use of fluorous solvents during the reaction or workup, which are expensive and can leach in small amounts.
- Yi, Wen-Bin,Cai, Chun
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p. 524 - 528
(2008/12/22)
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- Palladium-catalyzed cross-coupling alkylation of arenediazonium o-benzenedisulfonimides
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Arenediazonium o-benzenedisulfonimides were reacted with tetramethyltin, tetrabutyltin or trialkylboranes. The reactions, carried out in the presence of palladium(II) derivatives as precatalysts, gave the methylation and alkylation products with good over
- Barbero, Margherita,Cadamuro, Silvano,Dughera, Stefano
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p. 474 - 478
(2008/09/21)
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- Indium triflate as a recyclable catalyst for the nitration of aromatic compounds without a halogenated solvent
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Indium triflate [In(OTf)3] was found to be excellent catalyst (0.5 or 2.0 mol%) for the mononitration of aromatic compounds using a single equivalent of nitric acid (60 or 90%, 1.0 equiv.) without using a halogenated solvent. The side product is water and the indium triflate catalyst can be readily recovered from the aqueous phase and reused.
- Yin, Wan-Po,Shi, Min
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p. 549 - 551
(2007/10/03)
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- Clay supported ammonium nitrate "clayan": A new reagent for selective nitration of arenes
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The nitration of activated, deactivated and highly functionalized arenes is described using clay-supported ammonium nitrate in the presence of perchloric acid.
- Meshram,Ganesh,Madhavi,Eshwaraiah,Yadav,Gunasekar
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p. 2497 - 2503
(2007/10/03)
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- Electrophilic Aromatic Nitration Using a Mixed Catalyst of Lithium, Molybdenum, Ytterbium on Silica Gel
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A novel mixed catalyst of LiClO4 (15% w/w), Yb(OPf)3 (15% w/w, Pf = perfluorooctanesulfonyl), MoO3 (15% w/w) on silica gel for electrophilic aromatic nitration reaction has been explored. The nitration reactions were accomplished by this mixed catalyst and nitric acid under solvent-free conditions. Moreover, the mixed catalyst can be easily recovered from the aqueous layer by heating in an oven and reused for the next nitration reaction.
- Shi, Min,Cui, Shi-Cong
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p. 1329 - 1333
(2007/10/03)
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- Nitration of alkylbenzenes in acid medium: Regioselectivity of the reaction and acidity of the medium
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Isomer distribution in the nitration of toluene and its homologs with nitric acid in acid media (trifluoroacetic acid and solutions of sulfuric acid in acetic acid) is determined by the acidity of the medium, the degree of para substitution changing in parallel with the acidity. The ortholpara regioselectivity is governed by the polarity of the transition state. The sensitivity of the ortholpara ratio to variation of the acidity of the medium and reaction temperature is directly related to steric effects of the alkyl groups.
- Krylov
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p. 1413 - 1418
(2007/10/03)
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- Mild, efficient and selective nitration of anilides, non-activated and moderately activated aromatic compounds with ammonium molybdate and nitric acid as a new nitrating agent
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Ammonium molybdate [Mo(VI)] is operationally simple, environmentally safe and inexpensive reagent. Regioselective nitration of anilides, non-activated and moderately activated aromatic compounds could be afforded by employing ammonium molybdate and nitric acid as mild and effective nitrating agent. This procedure works efficiently under reflux conditions to prepare mononitroderivatives of anilides, non-activated and moderately activated aromatic compounds in good to excellent yield with high regioselectivity.
- Sana, Sariah,Rajanna,Ali, Mir Moazzam,Saiprakash
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- Regioselectivity of the mononitration of alkylbenzenes by immobilized acyl nitrates
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Mononitration of alkylbenzenes was studied using acyl nitrates and trimethylsilyl nitrate supported on clay-minerals. Chrysotile gave higher performance than other materials. High para-selectivity was obtained with the supported reagents. Nitration of tol
- Augusto,Rodrigues,Pedro Oliveira Filho,Moran, Paulo J. S.
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p. 2169 - 2174
(2007/10/03)
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- A novel method for the nitration of simple aromatic compounds
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Simple aromatic compounds such as benzene, alkylbenzenes, halogenobenzenes, and some disubstituted benzenes are nitrated in excellent yields with high regioselectivity under mild conditions using zeolite β as a catalyst and a stoichiometric quantity of nitric acid and acetic anhydride. The zeolite can be recycled, and the only byproduct is acetic acid, which can be separated easily from the nitration product by distillation; the process is inexpensive and represents an attractive method for the clean synthesis of a range of nitroaromatic compounds. For example, nitration of toluene gives a quantitative yield of mononitrotoluenes, of which 79% is 4-nitrotoluene; fluorobenzene gives a quantitative yield of mononitro compounds, of which 94% is 4-nitrofluorobenzene; and 2-fluorotoluene gives a 96% yield of mononitro products, of which 90% is the 5-nitro isomer and 10% is the 4-nitro isomer.
- Smith, Keith,Musson, Adam,DeBoos, Gareth A.
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p. 8448 - 8454
(2007/10/03)
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- Nitration of Alkylbenzenes in Trifluoroacetic Acid
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The substrate selectivity of alkylbenzene nitration with nitric acid in trifluoroacetic acid is controlled either by electronic or by steric effects of the substituents, depending the medium composition and temperature. The positional selectivity of this reaction is sterically controlled, even under electronic control of substrate selectivity.
- Krylov,Gvozdareva
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p. 1618 - 1623
(2007/10/03)
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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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- GAS-PHASE NITRATION OF AROMATIC COMPOUNDS AT ZEOLITES WITH NITROGEN DIOXIDE
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The gas-phase nitration of benzene, toluene, ethylbenzene, chlorobenzene, and isomeric xylenes at various zeolites was studied. The dependence of the isomeric composition of the obtained products on the reaction conditions was investigated. A possible reaction mechanism is proposed.
- Salakhutdinov, N. F.,Ione, K. G.,Kobzar', E. A.,Malysheva, L. V.
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p. 457 - 466
(2007/10/02)
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- PARA-SELECTIVE MONONITRATION OF ALKYLBENZENES UNDER MILD CONDITIONS BY USE OF BENZOYL NITRATE IN THE PRESENCE OF A ZEOLITE CATALYST
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Toluene and other alkylbenzenes are mononitrated in essentially quantitative yield at ambient temperature by benzoyl nitrate in the presence of aluminium/proton exchanged large port mordenite; the reaction is highly para-selective.
- Smith, Keith,Fry, Karl,Butters, Michael,Nay, Barry
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p. 5333 - 5336
(2007/10/02)
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- THE SELECTIVITY OF ELECTROPHILIC AROMATIC NITRATION AND THE EFFECT OF THE ORGANIC SOLVENTS
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The nitrating agent prepared by mixing Bu4NNO3 and (CF3CO)2O has been used to nitrate in homogeneous conditions eight aromatic substrates, ranging in reactivity from benzene to mesitylene, in several organic solvents.From competitive kinetic experiments and glc analysis, partial rate factors were obtained.The nature of the solvent significantly affects selectivity in the whole activation range.Selectivity was quantitatively measured by the selectivity factor for toluene, and, more properly, by the slopes in the correlations between log values of partial rate factors in a given solvent and the corresponding values in a reference solvent.Good correlations were obtained also including ortho positions and polysubstituted substrates, and the following order of relative selectivity could be established: MeNO2 MeCN /= sulfolane CH2ClCH2Cl CH2Cl2 /= EtOAc /= i-PrBr = n-BuCl = n-BuBr /= CHCl3.Correlation between partial rate factors has been extended to compare the selectivity of different nitrating agents in the same solvent, and the method can be used to ascertain whether the same electrophilic species actually operates in the two systems.
- Masci, Bernardo
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p. 2719 - 2730
(2007/10/02)
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- REGIOSELECTIVE NITRATION OF AROMATIC HYDROCARBONS BY METALLIC NITRATES ON THE K10 MONTMORILLONITE UNDER MENKE CONDITIONS
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Aromatic hydrocarbons are nitrated with good regioselectivities by clay-supported cupric nitrate in the presence of acetic anhydride.The procedure commends itself by its simplicity and gives useful yields (75-98percent).In each case, the predominant product can be predicted by consideration of the Hueckel HOMO for the aromatic ring.
- Laszlo, Pierre,Vandormael, Joseph
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p. 1843 - 1846
(2007/10/02)
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- Electrophilic Aromatic Nitration in the Gas Phase
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Aromatic nitration by MeO+(H)NO2, in essence nitronium ion solvated by one methanol molecule, has been studied in the gas phase by using an integrated approach, based on the coordinate application of ICR, Cl, and CID mass spetrometric methods with a highly complementary radiolytic technique.The latter can be used in gases at atmospheric pressure and allows direct evaluation of key mechanistic features, in particular of substrate and positional selectivity.The results resolve early discrepancies between gas-phase and liquid-phase studies, characterizing the reaction as a typical, well-behaved electrophilic substitution of moderate selectivity.The date from the gas-phase nitration of ten monosubstituted benzenes fit a Hammett's type linear plot, characterized by a ρ value of -3.87.The correlation does not extend to highly activated substrates, such as anisole and mesitylene, since the nitration rate tends to a limiting value that cannot be increased by further enhancing the activation of the substrate, exactly as in "encounter-rate" nitrations occurring in solution.The mechanism and the energetics of the gas-phase nitration have been investigated, and the relative stability of the charged intermediates involved, in particular of the isomeric protonated nitrobenzenes, has been estimated by theoretical approaches at two different levels, using STO-3G minimal basis and 4-31G split-valence basis sets.
- Attina, Marina,Cacace, Fulvio,Yanez, Manuel
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p. 5092 - 5097
(2007/10/02)
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- NITRATION OF ALKYLBENZENES WITH NITRIC ACID IN ORGANIC SOLVENTS. SUBSTRATE AND POSITION SELECTIVITY
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The substrate and position selectivity in the nitration of alkylbenzenes (with normal and iso C1-C4 alkyl groups) in organic solvents (protic and bipolar aprotic solvets) with and without sulfuric acid in the range of 25-75 deg C is determined mainly by the steric affect of the substituents.Nathan-Bacer substrate and position effects are observed.Linear correlations are found between the result of the orientation of the nitro group and the steric parameters of the substituets.The substrate selectivity varies inversely and the position selectivity varies directly with the latter.The sensitivity of the orientation to change in the geometry of the substituets varies directly with temperature.
- Krylov, E. N.,Khromova, I. N.
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p. 2179 - 2186
(2007/10/02)
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- GRIGNARD REAGENTS SELECTIVE ATTACK TO NITROARENIC FUNCTION IN THE PRESENCE OF OTHER ELECTROPHILIC GROUPS
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Exclusive alkylation of the nitroarenic system takes place in competitive reactions of RMgX with nitrobenzene and various electrophiles such as ketones, esters, cyanoand iodo-derivatives and in reactions with some functionalized nitrobenzenes, only aldehy
- Bartoli, G.,Bosco, M.,Dalpozzo, R.
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p. 115 - 118
(2007/10/02)
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- Reactions of Cerium(IV) Ammonium Nitrate with Aromatic Compounds in Acetonitrile. Part 2. Nitration; Comparison with Reactions of Nitric acid
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The nitration of benzene and a number of alkylbenzenes by cerium(IV) ammonium nitrate in acetonitrile shows the same intra- and inter-molecular selectivity as nitration with nitric acid under the same conditions but the extent of the other products formed in the two sets of reactions is very different.Nitration by cerium(IV) ammonium nitrate (but not side-chain substitution) is suppressed by the addition of water.The results suggest that these nitration reactions by cerium(IV) ammonium nitrate occur through the intermediate formation of a nitronium ion from the cerium(IV) complex but the order with recpect to the aromatic compound shows that this nitronium ion must then be formed in the presence of the aromatic substrate as a 'spectator'.The relative reactivities with respect to benzene in the nitration of anisole and naphthalene are much greater than those observed in nitration by nitric acid and, with both, the isomer proportions are also anomalous.
- Dinctuerk, Suphi,Ridd, John H.
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p. 965 - 970
(2007/10/02)
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- Aromatic Substitution. 471. Acid-Catalyzed Transfer Nitration of Aromatics with N-Nitropyrazole, a Convenient New Nitrating Agent
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N-Nitropyrazole in the presence of Lewis or Bronsted acid catalysts was found to be an effective transfer nitrating agent for aromatic substrates.The nature of the acid catalyst both substrate and positional selectivies of the nitration of alkylbenzenes.No relationship was found between substrate and positional selectivities, which are considered to be determined in two separate steps.
- Olah, George A.,Narang, Subhash C.,Fung, Alexander P.
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p. 2706 - 2709
(2007/10/02)
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- Aromatic Substitution. 48. Boron Trifluoride Catalyzed Nitration of Aromatics with Silver Nitrate in Acetonitrile Solution
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Benzene, alkylbenzenes, halobenzenes, and anisole were nitrated with silver nitrate/boron trifluoride in acetonitrile solution.Correlation of competitive rates with ?- and ?-complex stabilities indicated that the transition state of highest energy lies relatively early on the reaction coordinate.Data indicate that nitrations occur via a polarized complex of the nitrating agent, with the catalyst undergoing nucleophilic displacement by the aromatic substrate.
- Olah, George A.,Fung, Alexander P.,Narang, Subhash C.,Olah, Judith A.
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p. 3533 - 3537
(2007/10/02)
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