- Photoinduced Iron-Catalyzed ipso-Nitration of Aryl Halides via Single-Electron Transfer
-
A photoinduced iron-catalyzed ipso-nitration of aryl halides with KNO2 has been developed, in which aryl iodides, bromides, and some of aryl chlorides are feasible. The mechanism investigations show that the in situ formed iron complex by FeSO4, KNO2, and 1,10-phenanthroline acts as the light-harvesting photocatalyst with a longer lifetime of the excited state, and the reaction undergoes a photoinduced single-electron transfer (SET) process. This work represents an example for the photoinduced iron-catalyzed Ullmann-type couplings.
- Wu, Cunluo,Bian, Qilong,Ding, Tao,Tang, Mingming,Zhang, Wenkai,Xu, Yuanqing,Liu, Baoying,Xu, Hao,Li, Hai-Bei,Fu, Hua
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p. 9561 - 9568
(2021/08/06)
-
- Self-powered continuous nitration method and device
-
The invention belongs to the technical field of organic synthesis application, and particularly relates to a self-powered continuous nitration method and device. According to the method, a raw material (or a raw material solution) and mixed acid (or nitric acid) are added into a self-powered continuous reactor at the same time, reaction feed liquid continuously and circularly flows, is mixed and reacts in a tube pass through self-propelling force generated by stirring of an impeller, the mass and heat transfer process is completed, and the target requirement is met. According to the invention, the mass transfer and heat transfer efficiency can be improved, the heat exchange and heat transfer capabilities are improved, the reaction time is shortened, the risk degree of art is reduced, the thermal runaway risk is avoided, the reaction safety is improved, and the realization of chemical industry intrinsic safety large scale production is facilitated.
- -
-
Paragraph 0057-0060
(2021/07/17)
-
- Cyhalofop-containing pesticide composition and application thereof
-
The invention discloses a pesticide composition containing cyhalofop-butyl and application thereof, belongs to the technical field of pesticide preparation and comprises 10 - 20 parts of cyhalofop-butyl. Tetramethyl chloride 3-5 parts, synergistic microcapsule 8-13 parts, wetting agent 1.5 - 4.5 parts, dispersing agent 1-3 parts, defoaming agent 0.5 - 1.5 parts and water 40 - 50 parts. When the water in the soil is less, the weed is absorbed by the chitosan so as to accelerate the absorption of A the synergic microcapsule and the cyhalofop-butyl ester, so that the pesticide composition is greatly reduced per mu.
- -
-
Paragraph 0016; 0035; 0040-0041; 0046; 0051-0052; 0057; ....
(2021/11/26)
-
- Base promoted peroxide systems for the efficient synthesis of nitroarenes and benzamides
-
A useful and efficient approach for the synthesis of nitroarenes from several aromatic amines (including heterocycles) using peroxide and base has been developed. This oxidative reaction is very easy to handle and afforded the products in good yields. Formation of benzamides from benzylamine was also successfully carried out with this metal-free catalytic system in good to excellent yields.
- Gupta, Sampa,Ansari, Alisha,Sashidhara, Koneni V.
-
supporting information
(2019/09/07)
-
- Method and device for preparing methylnitro-benzene by channelization
-
The invention discloses a method and a device for preparing methylnitro-benzene by channelization. The device comprises a storage tank, a nitrogen dioxide cylinder, an ozone generator, a flow pump, agas flowmeter, a reaction pipeline filled with a catalyst, a mixing pipeline, two T-shaped mixed joints, a cooling system, a heating system, a back pressure valve and a receiving tank. The method specifically comprises the following steps: opening the cooling system and the heating system; opening the ozone generator; arranging the flow pump and the gas flowmeter; and mixing raw materials liquid methyl benzene and nitrogen dioxide through the first T-shaped mixing joint and feeding the mixture into the mixing pipeline, then mixing the mixture with ozone in the second T-shaped mixing joint, feeding the mixture into the reaction pipeline filled with the catalyst for a nitrifying reaction, and post-treating a reaction liquid to obtain methylnitro-benzene. The method is controlled precisely and automatically, and is simple to operate, mild in reaction condition, simple in post treatment, quick to transfer mass and heat, high in safety and good in economical benefit.
- -
-
Paragraph 0047; 0048; 0049
(2019/02/04)
-
- Hydrophobic WO3/SiO2 catalyst for the nitration of aromatics in liquid phase
-
WO3/SiO2 solid acid catalyst synthesized using sol gel method has shown promising activity (up to 65% conversion) for aromatic nitration in liquid phase using commercial nitric acid (70%) as nitrating agent without using any sulfuric acid. The water formed during the reaction as well as water from dilute nitric acid (70%) was removed azeotropically, however due to the hydrophilic nature of the catalyst, some water gets strongly adsorbed on catalyst surface forming a barrier layer between catalyst and organics. This prevents effective adsorption of substrate on catalyst surface for its subsequent reaction. To improve the activity further, the hydrophilic/hydrophobic nature of the catalyst was altered by post modification by grafting with commercial short chain organosilane (Dynasylan 9896). The modified 20% WO3/SiO2 catalyst when used for o-xylene nitration in liquid phase, showed significant increase in the conversion from 65% to 80% under identical reaction conditions. Catalyst characterization revealed decrease in the surface area of 20% WO3/SiO2 from 356 m2/g to 302 m2/g after grafting with Dynasylan 9896. The fine dispersion of WO3 particles (2–5 nm) on silica support was not affected due to modification. NMR and FTIR study revealed the decrease in surface hydroxyl groups imparting hydrophobicity to the catalyst. Interestingly the total acidic sites of the catalyst remained almost unaltered (0.54 mmol NH3/g) even after modification. Even though, the acidity and other characteristics of the catalyst did not change appreciably, there was a considerable increase in the o-xylene conversion which can be ascribed to the hydrophobic nature of the catalyst.
- Kulal,Kasabe,Jadhav,Dongare,Umbarkar
-
p. 105 - 113
(2019/02/15)
-
- Highly efficient protocol for the aromatic compounds nitration catalyzed by magnetically recyclable core/shell nanocomposite
-
An efficient protocol for the nitration of aromatic compounds in the presence of a catalytic amount of sulfuric acid-functionalized silica-based magnetic core/shell nanocomposite was reported. The designed products were obtained in high yields in relatively short reaction times at room temperature under solvent-free conditions. The nanocatalyst was simply recovered from the reaction mixture by using an external magnet and efficiently reused for several times. The characterization of particle size, morphology and elemental analysis of the nanocatalyst were provided by scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy analyses, respectively.
- Maleki, Ali,Aghaei, Morteza,Paydar, Reza
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p. 485 - 490
(2017/01/10)
-
- Nucleophilic Nitration of Arynes by Sodium Nitrite and its Multicomponent Reaction Leading to Double-Functionalized Arenes
-
An unusual nucleophilic nitration of arynes by NaNO2 in the presence of water has been developed, and the concept was further demonstrated to accomplish a double functionalization of arynes using a multicomponent reaction protocol to synthesize pharmaceutically important (2-nitrophenyl)methanol derivatives. Such substitution ortho to -NO2 is difficult by other means. The reaction conditions are mild and avoid the use of strong acids, expensive transition metal catalysts, and additives.
- Dhokale, Ranjeet A.,Mhaske, Santosh B.
-
supporting information
p. 3010 - 3013
(2016/07/06)
-
- 4-nitro-o-xylene continuous synthesis system and synthesis method
-
The invention discloses a 4-nitro-o-xylene continuous synthesis system and synthesis method. The synthesis method is characterized in that after being mixed, o-xylene and nitric-sulfuric acid are pressed in a nitration system to undergo nitration reaction; a reaction liquid enters a first split phase tank to be layered and the upper oil phase enters a washing system to undergo labyrinth washing; a washing liquid is layered in a second split phase tank, the upper liquid enters a distillation system to undergo distillation treatment and 4-nitro-o-xylene is collected. Compared with existing vertical tubular nitration reactors, dual ring shaped nitration reactors provided by the invention have the advantages that material flow splitting is carried out more uniformly, backward flow of a reaction liquid can be effectively avoided, the probability of contact between o-xylene and nitric-sulfuric acid is increased, and the raw material conversion rate is increased; the heat exchange area is fuller, and the side reaction can be effectively reduced. The production system provided by the invention has the beneficial effects that all the materials are recycled, thus reducing the production cost; the raw material conversion rate of single batch production is effectively increased, thus reducing the amount of waste acid and wastewater.
- -
-
Paragraph 0069; 0070; 0071; 0072
(2016/11/09)
-
- N-(1-ethyl propyl)-3,4-dimethylaniline continuous production system and method
-
The invention discloses an N-(1-ethyl propyl)-3,4-dimethylaniline continuous synthesis system and method. The method is characterized in that o-xylene and nitric-sulfuric acid carry out nitration reaction in a nitration system; a reaction liquid passes through a first split phase tank, a labyrinth washing system and a distillation system in sequence to undergo distillation treatment; collected 4-nitro-o-xylene and 3-pentanone carry out catalytic hydrogenation reaction in a hydrogenation reactor; then N-(1-ethyl propyl)-3,4-dimethylaniline is prepared through treatment carried out by a falling film evaporation system. The production system provided by the invention has the beneficial effects that all the materials are recycled, thus reducing the production cost; the raw material conversion rate of single batch production is effectively increased, thus reducing the amount of waste acid and wastewater.
- -
-
Paragraph 0085; 0086; 0087; 0096; 0097
(2016/11/17)
-
- Method for synthesis of 2-aldehyde-4-aminobenzoic acid
-
The invention relates to a method for synthesis of 2-aldehyde-4-aminobenzoic acid. The method for synthesis of 2-aldehyde-4-aminobenzoic acid, which is provided by the invention, is simple and cheap, gentle in reaction condition in the preparation process, and high in yield.
- -
-
Paragraph 0006
(2017/04/03)
-
- CONTINUOUS FLOW LIQUID PHASE NITRATION OF ALKYL BENZENE COMPOUNDS
-
The invention discloses a process for continuous flow of liquid phase nitration of alkyl benzene compounds in micromixer and tubular reactors with better control on the product profile which comprises reacting alkyl benzene compounds with nitrating agent at a temperature range of 10 to 60 deg C.
- -
-
Page/Page column 10
(2015/02/19)
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- Continuous-Flow Nitration of o-Xylene: Effect of Nitrating Agent and Feasibility of Tubular Reactors for Scale-Up
-
Continuous-flow nitration of o-xylene has been studied with different nitrating agents over a wide range of conditions for different parameters such as temperature, residence time, and concentrations. A nitrating mixture comprising sulfuric acid and fuming nitric acid was seen to yield higher selectivity for the isomer 1,2-dimethyl-3-nitrobenzene over the isomer 1,2-dimethyl-4-nitrobenzene and also a non-negligible quantity of dinitro derivatives of o-xylene. With only fuming nitric acid as the nitrating agent, the reaction was selective for 1,2-dimethyl-4-nitrobenzene over 1,2-dimethyl-3-nitrobenzene. Impurities mainly come from nitration of mononitro derivatives, and this occurs more from nitration of the 3-nitro isomer because of its higher reactivity with nitric acid. An economic analysis of the continuous-flow reactor for the production of 1,2-dimethyl-4-nitrobenzene at 100 and 500 kg/h in a jacketed tubular reactor showed that numbering-up is a more economical approach for higher production capacity. A combination of large- and small-sized tubes depending upon the relative rates of heat generation during a reaction will achieve more profit and a shorter payback period than having the entire reactor made of a single tube size.
- Sharma,Joshi,Kulkarni
-
p. 1138 - 1147
(2015/09/28)
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- Regioselective nitration of m-xylene catalyzed by zeolite catalyst
-
Nitration with nitric acid and acetic anhydride via acetyl nitrate as nitrating species is efficient with the substrate m-xylene as solvent. Zeolite Hβ with an SiO2/Al2O3 ratio of 500 was found to be the most active of the catalysts tried both in yield and regioselectivity in the nitration of m-xylene. The molecular volume of the reactants was calculated with the Gaussian 09 program at the B3LYP/6-311+G(2d, p) level and compared with the size of the zeolite Hβ channels. A range of other substrates were subjected to the nitrating system under the same conditions as those optimized for m-xylene and excellent selectivity was obtained.
- Dong, Xiongzi,Peng, Xinhua
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p. 1122 - 1128
(2016/01/15)
-
- Click chemistry inspired facile synthesis and bioevaluation of novel triazolyl analogs of Ludartin
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A convenient and modular synthesis involving diastereoselective Michael addition followed by regioselective Huisgen 1,3-dipolar cycloaddition reaction was carried out to furnish 1,4-disubstituted-1,2,3-triazoles of Ludartin. This reaction scheme involving Michael addition followed by regioselective Huisgen 1,3-dipolar cycloaddition reaction leading to the formation of triazolyl analogs is being reported for the first time. All the triazolyl products were characterised using spectral data analysis. Sulphorhodamine B cytotoxicity screening of the resulting products against a panel of five human cancerous cell-lines revealed that few of the analogs display promising broad spectrum cytotoxic effect. Among all the synthesized compounds, only 3q displayed the best cytotoxic effect with IC50 values of 12, 11, 38, 39 and 8.5 μM but less than the standard Ludartin (1) with IC50 values of 6.3, 7.4, 7.5, 6.9 and 0.5 μM against human neuroblastoma (T98G), lung (A-549), prostate (PC-3), colon (HCT-116) and breast (MCF-7) cancer cell lines, respectively. The present synthesis was designed based on the previous literature reports of Ludartin as an aromatase inhibitor. Our work provides an initial study on structure-activity relationship of triazolyl analogs of sesquiterpene lactones in general and Ludartin (1) in particular.
- Lone, Shabir H.,Bhat, Khursheed A.,Majeed, Rabiya,Hamid, Abid,Khuroo, Mohd A.
-
p. 1047 - 1051
(2014/03/21)
-
- Acid-catalyzed regioselective nitration of o-xylene to 4-nitro-o-xylene with nitrogen dioxide: Br?nsted acid versus lewis acid
-
Nitration of o-xylene with nitrogen dioxide imparts remarkable selectivity to 4-nitro-o-xylene. The addition of Br?nsted acids and Lewis acids can effectively improve the selectivity for 4-nitro-o-xylene and/or yield, and the Lewis acids present a better influence on the reactions than Br?nsted acids do. A 71% yield of mononitro-o-xylene with high selectivity for 4-nitro-o-xylene (ratio 4-/3- / 3.91) has been achieved by the assistance of bismuth trichloride under solvent-free conditions. Copyright
- Tang, Bo,Wei, Songbo,Peng, Xinhua
-
p. 2057 - 2065
(2014/07/07)
-
- Eco-friendly nitration of benzenes over zeolite-β-SBA-15 composite catalyst
-
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
-
-
- Regioselective preparation of 4-nitro-o-xylene using nitrogen dioxide/molecular oxygen over zeolite catalysts. remarkable enhancement of para-selectivity
-
In the presence of molecular oxygen and zeolite H-β with Si/Al 2 = 500, o-xylene reacted regioselectively with liquid nitrogen dioxide at 35 °C to yield mononitro-o-xylenes as the main product, where the 4-nitro-o-xylene isomer predominated up to 89% and the 4-nitro-/3-nitro-o- xylene isomer ratio improved to 7.8. The process is eco-friendly, less expensive, and the zeolite could be easily regenerated by a simple workup to afford results similar to those obtained with the fresh catalyst.
- Liu, Hongtao,Ji, Cheng,Dong, Xiongzi,Peng, Xinhua,Shi, Chunjie
-
supporting information
p. 817 - 819
(2014/06/23)
-
- Regioselective nitration of aromatics with nanomagnetic solid superacid SO42-/ZrO2-MxOy-Fe 3O4 and its theoretical studies
-
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
-
p. 310 - 317
(2013/08/23)
-
- 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
-
-
- 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)
-
- Design of ionic liquid 3-methyl-1-sulfonic acid imidazolium nitrate as reagent for the nitration of aromatic compounds by in situ generation of NO 2 in acidic media
-
3-Methyl-1-sulfonic acid imidazolium nitrate ([Msim]NO3) as a new Bronsted acidic ionic liquid and nitrating agent was prepared and used for the efficient nitration of aromatic compounds (even aniline derivatives). The dramatic effect of this reagent by in situ generation of nitrogen dioxide as a radical on aromatic compounds to give nitroarenes has been studied.
- Zolfigol, Mohammad A.,Khazaei, Ardeshir,Moosavi-Zare, Ahmad R.,Zare, Abdolkarim,Kruger, Hendrik G.,Asgari, Zhila,Khakyzadeh, Vahid,Kazem-Rostami, Masoud
-
experimental part
p. 3640 - 3645
(2012/06/15)
-
- PROCESS FOR THE NITRATION OF O-XYLENE AND RELATED COMPOUNDS
-
Aromatic compounds such as o-xylene are selectively nitrated by nitric acid in the presence of polyphosphoric acid and a large pore, acidic zeolite or a large pore, hydrophobic molecular sieve. This is an environmentally friendly, commercially viable, high conversion process for the selective nitration of aromatic compounds in the para position.
- -
-
Page/Page column 5-6
(2011/04/14)
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- Regioselective nitration of aromatics under phase-transfer catalysis conditions
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Mononitration of aromatics was performed in a two-phase system using phase-transfer catalyst. The most advantageous conditions for the nitration were determined (temperature, reaction time, the type and amount of phase transfer catalyst, nitrification strength of the nitro-sulfuric acid). From the results, a significant improvement in the selectivity and conversion of the nitration of xylene was observed: the ratio of 4-nitro-m-xylene to 2-nitro-m-xylene was unprecedented increased up to 91.3%:7.7%, the ratio of 4-nitro-o-xylene to 3-nitro-o-xylene was also increased to 71.1%:27.2%; both the conversions were over 96%.
- Wang, Peng-Cheng,Lu, Ming,Zhu, Jie,Song, Yan-Ming,Xiong, Xian-Feng
-
experimental part
p. 42 - 47
(2012/01/15)
-
- TiO2-SiO2 mixed oxide supported MoO3 catalyst: Physicochemical characterization and activities in nitration of phenol
-
12 wt% MoO3/TiO2-SiO2 solid acid catalyst was prepared and calcined at various temperatures. The calcined catalyst was characterized by XRD, FT-IR, BET, SEM, NH3-TPD and pyridine adsorbed FT-IR methods. The effect of calcination temperature on activity of catalyst was studied by choosing liquid phase nitration of phenol as a model reaction. For the same reaction effect of various solvents, effect of reaction time and reusability of the catalyst was also studied. Catalyst calcined at 500 °C temperature showed highest phenol conversion whereas greater o-nitrophenol selectivity is claimed over catalyst calcined at 700 °C. It was observed that high phenol conversion co-relates with the presence of greater number of strong Bro?nsted acid sites over the catalyst surface whereas the selectivity of o-nitrophenol is related to the pore size of the catalysts. No use of sulfuric acid along with the nitric acid used in its diluted form in the reaction makes the process safe and environmentally friendly.
- Kemdeo,Sapkal,Chaudhari
-
scheme or table
p. 70 - 77
(2010/09/04)
-
- Palladium-catalyzed cross-coupling alkylation of arenediazonium o-benzenedisulfonimides
-
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
-
p. 474 - 478
(2008/09/21)
-
- Process for the preparation of 4-nitro-o-xylene
-
The present invention relates to the process for vapor phase nitration of o-xylene using dilute nitric acid over H-beta zeolite. More particularly it relates to the selective formation of 4-nitro o-xylene by vapor phase nitration of 0-xylene using dilute nitric acid over commercially available H-beta catalyst. The continuous process of nitration of o-xylene comprises of a reaction carried out in a downflow reactor using o-xylene and dilute nitric acid with mole ratio of 2:1 to 1:2 and WHSV of 0.1-0.5 at 100-250° C. at atmospheric pressure.
- -
-
-
- Clay supported ammonium nitrate "clayan": A new reagent for selective nitration of arenes
-
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
-
p. 2497 - 2503
(2007/10/03)
-
- Electrophilic Aromatic Nitration Using a Mixed Catalyst of Lithium, Molybdenum, Ytterbium on Silica Gel
-
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
-
p. 1329 - 1333
(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)
-
- Reductive coupling of nitrobenzene or nitrobenzenes substituted on the nucleus to give the corresponding azobenzenes and azoxybenzenes by means of redox catalysts
-
Nitrobenzene or a nitrobenzene substituted on the nucleus is subjected to reductive coupling to give the corresponding azobenzene and azoxybenzene under heterogeneous catalysis with substantial avoidance of overreduction to aniline derivatives by means of a redox catalyst in its reduced or partly reduced form, the redox catalyst containing at least one active metal component capable of a change of oxidation state.
- -
-
-
- A novel method for the nitration of simple aromatic compounds
-
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.
-
p. 8448 - 8454
(2007/10/03)
-
- Iron(III)-catalysed nitration of non-activated and moderately activated arenes with nitrogen dioxide-molecular oxygen under neutral conditions
-
In the presence of molecular oxygen and a catalytic amount of tris(pentane-2,4-dionato)iron(III), non-activated and moderately activated arenes, which include alkylbenzenes, halogenobenzenes, phenolic ethers, naphthalene and derivatives, can be nitrated with nitrogen dioxide at ice-bath temperature or below to give the corresponding nitro derivatives in fair to good yields. An electron-transfer mechanism has been proposed, where an activated NO2-FeIII complex plays a key role in the cyclic process for converting arenes into nitroarenes.
- Suzuki, Hitomi,Yonezawa, Shuji,Nonoyama, Nobuaki,Mori, Tadashi
-
p. 2385 - 2389
(2007/10/03)
-
- Sulfuric acid on silica-gel: An inexpensive catalyst for aromatic nitration
-
Solid acidic catalysts made of sulfuric acid supported on silica-gel and their application to the nitration of aromatics with nitric acid and isopropyl nitrate are described. Substrates with very different levels of activation were investigated. Methods to overcome the poisoning produced by water and to tune the catalysts activity according to the reactivity of the substrate are outlined.
- Riego, Juan M.,Sedin, Zeno,Zaldivar, Jose M.,Marziano, Nunziata C.,Tortato, Claudio
-
p. 513 - 516
(2007/10/02)
-
- Direct Nitrosation of Aromatic Hydrocarbons and Ethers with the Electrophilic Nitrosonium Cation
-
Various polymethylbenzenes and anisoles are selectively nitrosated with the electrophilic nitrosonium salt NO(1+)BF4(1-) in good conversions and yields under mild conditions in which the conventional procedure (based on nitrile neutralization with strong acid) is ineffective.The reactivity patterns in acetonitrile deduced from the various time/conversions in Tables 2 and 3 indicate that aromatic nitrosation is distinctly different from those previously established for electrophilic aromatic nitration.The contrasting behavior of NO(1+) in aromatic nitrosation is ascribed to a rate-limiting deprotonation of the reversibly formed Wheland intermediate, which in the case of aromatic nitration with NO2(1+) occurs with no deuterium kinetic isotope effect.Aromatic nitroso derivatives (unlike the nitro counterpart) are excellent electron donors that are subject to a reversible one-electron oxidation at positive potentials significantly less than that of the parent polymethylbenzene or anisole.As a result, the series of nitrosobenzenes are also much better Broensted bases than the corresponding nitro derivatives, and this marked distinction, therefore, accounts for the large differentiation in the deprotonation rates of their respective conjugate acids (i.e.Wheland intermediates).
- Bosch, Eric,Kochi, Jay K.
-
p. 5573 - 5586
(2007/10/02)
-
- Thermal and Photochemical Nitration of Aromatic Hydrocarbons with Nitrogen Dioxide
-
Aromatic hydrocarbons (ArH) are readily nitrated by nitrogen dioxide (NO2) in dichloromethane at room temperature and below (in the dark).The red colors, transiently observed, arise from the metastable precursor complex NO3(1-), which is formed in the prior disproportionation of nitrogen dioxide induced by the aromatic donor (eq 7).The deliberate irradiation of the diagnostic (red) charge-transfer absorption band (hνCT) of NO3(1-) at low temperatures results directly in aromatic nitration, even at -78 deg C, where the thermal nitration is too slow to complete.The mechanism of the photochemical (charge-transfer) nitration is established by time-resolved laser spectroscopy to proceed via the aromatic cation radical (ArH.+) formed spontaneously upon the charge-transfer excitation of NO3(1-) in Scheme 1.The related thermal activation of NO3(1-) derives from the adiabatic electron transfer that produces the same radical pair as the reactive intermediate in Scheme 3.The close relationship between the thermal/photochemical nitrations with nitrogen dioxide and those conventionally carried out with nitric acid (in the presence of nitrous acid) is delineated by Scheme 4.
- Bosch, E.,Kochi, J. K.
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p. 3314 - 3325
(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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- 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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- 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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- ipso Nitration. XXVI. Nitration of 1,2-dimethyl-4-nitrobenzene. Formation and reactions of adducts
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Nitration of 1,2-dimethyl-4-nitrobenzene in a mixture of acetic anhydride and trifluoroacetic anhydride gives the diastereoisomers of 4,5-dimethyl-2,4-dinitrocyclohexa-2,5-dienyl acetate (50percent), in addition to the 1,2-dimethyldinitrobenzenes.In moderate and more strongly acid conditions the adduct gives 4-nitro-, 3,4-dinitro-, and 3,5-dinitro-o-xylene.In neutral and weakly acid solutions 4-nitro- and 3,5-dinitro-o-xylene are formed by a radical and a sigmatropic pathway.The adduct reacts facilely with nucleophiles by allylic substitution to give a 5,6-dimethyl-6-nitrocyclohexa-2,4-dienyl derivative which, in many instances, undergoes a second allylic substitution to a new 4,5-dimethyl-2,4-dinitrocyclohexa-2,5-dienyl derivative.Depending on the nature of the introduced substituent, these 2,4- and 2,5-dienyl products may eliminate nitrous acid, under the reaction conditions, to give the corresponding aromatic compound.The dienyl acetates undergo acid-catalysed transesterification to the corresponding dienols.
- Fischer, Alfred,Henderson, George N.,Iyer, Lokanathan M.
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p. 2390 - 2400
(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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- 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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- Photooxidation of o-Xylene in the NO-H2O-Air System
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The reaction products in the photooxidation of o-xylene were analyzed by a new gas chromatograph/photoionization mass spectrometer.There were two types of reaction products, i.e., high- and low-boiling point products.Tolualdehyde, dimethylphenols, and dimethylnitrobenzene were the main high-boiling point products and formaldehyde, acetaldehyde, glyoxal, methylglyoxal, and biacetyl were identified as low-boiling point products.The ratio of the total amount of high-boiling point products formed to the amount of o-xylene consumed was about 17percent.On the other hand, the low-boiling point products collected amounted to about 45percent of the o-xylene consumed.The reaction mechanisms and the importance of the cleavage reaction of the aromatic ring were discussed.
- Takagi, H.,Washida, N.,Akimoto, H.,Nagasawa, K.,Ususi, Y.,Okuda, M.
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p. 478 - 483
(2007/10/02)
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