- 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
-
p. 9561 - 9568
(2021/08/06)
-
- 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 0043; 0044; 0045; 0046
(2019/02/04)
-
- Niobium oxide prepared through a novel supercritical-CO2-assisted method as a highly active heterogeneous catalyst for the synthesis of azoxybenzene from aniline
-
High-surface area Nb2O5 nanoparticles were synthesised by a novel supercritical-CO2-assisted method (Nb2O5-scCO2) and were applied for the first time as a heterogeneous catalyst in the oxidative coupling of aniline to azoxybenzene using the environmentally friendly H2O2 as the oxidant. The application of scCO2 in the synthesis of Nb2O5-scCO2 catalyst resulted in a significantly enhanced catalytic activity compared to a reference catalyst prepared without scCO2 (Nb2O5-Ref) or to commercial Nb2O5. Importantly, the Nb2O5-scCO2 catalyst achieved an aniline conversion of 86% (stoichiometric maximum of 93% with the employed aniline-to-H2O2 ratio of 1?:?1.4) with an azoxybenzene selectivity of 92% and with 95% efficiency in H2O2 utilisation in 45 min without requiring external heating (the reaction is exothermic) and with an extremely low catalyst loading (weight ratio between the catalyst and substrate, Rc/s = 0.005). This performance largely surpasses that of any other heterogeneous catalyst previously reported for this reaction. Additionally, the Nb2O5 catalyst displayed high activity also for substituted anilines (e.g. methyl or ethyl-anilines and para-anisidine) and was reused in consecutive runs without any loss of activity. Characterisation by means of N2-physisorption, XRD, FTIR and TEM allowed the correlation of the remarkable catalytic performance of Nb2O5-scCO2 to its higher surface area and discrete nanoparticle morphology compared to the aggregated larger particles constituting the material prepared without scCO2. A catalytic test in the presence of a radical scavenger proved that the reaction follows a radical pathway.
- Tao, Yehan,Singh, Bhawan,Jindal, Vanshika,Tang, Zhenchen,Pescarmona, Paolo P.
-
p. 5852 - 5864
(2019/11/11)
-
- Pd-poly(N-vinyl-2-pyrrolidone)/MCM-48 nanocomposite: a novel catalyst for the Ullmann reaction
-
Abstract: Homocoupling of aryl halides (Ullmann-type reaction) promoted by a Pd-poly(N-vinyl-2-pyrrolidone)/MCM-48 (Pd–PVP/MCM-48) nanocomposite catalyst is described. In situ polymerization method was employed to prepare composite poly(N-vinyl-2-pyrrolidone)/MCM-48 (PVP/MCM-48) which was used as a support for palladium nanoparticles obtained by reducing Pd(OAc)2 with hydrazine hydrate. FT-IR, XPS, XRD, UV–Vis, SEM, and BET techniques were used to study the chemical and physical properties of the catalyst. The catalytic performance of this heterogeneous catalyst was specified for Ullmann-type reaction between aryl halies in DMF. The catalyst was good with regard to its stability and it can be reused up to six times without significant loss of its activity.
- Mosaddegh, Neda,Yavari, Issa
-
p. 2013 - 2021
(2018/07/29)
-
- A Predictive Model for the Decarboxylation of Silver Benzoate Complexes Relevant to Decarboxylative Coupling Reactions
-
Decarboxylative coupling reactions offer an attractive route to generate functionalized arenes from simple and readily available carboxylic acid coupling partners, yet they are underutilized due to limitations in the scope of carboxylic acid coupling partner. Here we report that the field effect parameter (F) has a substantial influence on the rate of decarboxylation of well-defined silver benzoate complexes. This finding provides the opportunity to surpass current substrate limitations associated with decarboxylation and to enable widespread utilization of decarboxylative coupling reactions.
- Crovak, Robert A.,Hoover, Jessica M.
-
p. 2434 - 2437
(2018/02/28)
-
- Ipso-nitration of arylboronic acids with copper nitrate and trifluoroace-tic acid
-
An efficient and novel nitrating reagent has been developed for ipso-nitration of arylboronic acids. By using inexpensive and commercially available Cu(NO3)2/CF3COOH as nitrating reagent, various nitroarenes are produced in moderate to excellent yields (51-96%). Advantages of this procedure are the operational simplicity and no need of extra catalyst.
- Wang, Zhu-Qing,Guo, Meng-Ping,Wen, Yong-Ju,Shen, Xiu-Li,Lv, Mei-Yun,Zhou, Xiu-Ling
-
p. 891 - 894
(2018/11/06)
-
- Organocatalytic oxidation of substituted anilines to azoxybenzenes and nitro compounds: Mechanistic studies excluding the involvement of a dioxirane intermediate
-
An organocatalytic and environmentally friendly approach for the selective oxidation of substituted anilines was developed. Utilizing a 2,2,2-trifluoroacetophenone-mediated oxidation process, substituted anilines can be transformed into azoxybenzenes, while a simple treatment with MeCN and H2O2 leads to the corresponding nitro compounds, providing user-friendly protocols that can be easily scaled up. Various substitution patterns and functional groups were tolerated leading to products in high to excellent yields. Mechanistic studies utilizing HRMS provide clear evidence for the distinct mechanistic intermediates that are involved. This study constitutes an indirect proof excluding the involvement of a dioxirane intermediate in the green organocatalytic oxidation, utilizing 2,2,2-trifluoroacetophenone as the catalyst.
- Voutyritsa, Errika,Theodorou, Alexis,Kokotou, Maroula G.,Kokotos, Christoforos G.
-
supporting information
p. 1291 - 1298
(2017/06/06)
-
- Sulfated SO4 2?/WO3 as an efficient and eco-friendly catalyst for solvent-free liquid phase nitration of toluene with NO2
-
With the increase in environmental awareness, developing a highly efficient and environmentally benign nitration process has very important academic and applied industrial values in the synthesis of nitro-compounds. Towards this goal, we have developed an efficient and environmentally friendly approach for solvent-free liquid phase nitration of toluene by employing NO2 as a nitrating agent and sulfated SO4 2?/WO3 as a catalyst replacing traditional nitric acid–sulfuric acid under mild conditions. The results indicate that SO4 2?/WO3 as an effective and eco-friendly catalyst exhibits excellent catalytic activity and reusability for the nitration of toluene with NO2. In addition, the possible pathway for liquid phase nitration of toluene with NO2 over sulfated SO4 2?/WO3 catalyst was suggested. The present method makes this nitration process safe and environmentally friendly, and has the potential to enable a sustainable production of nitro-compounds from the liquid phase nitration of aromatic hydrocarbon with NO2 in industrial applications.
- Jiao, Yinchun,Zhu, Man,Deng, Renjie,Jian, Jian,Yin, Yi,You, Kuiyi
-
p. 3961 - 3974
(2017/06/20)
-
- NH4I/tert-butyl hydroperoxide-promoted oxidative C–N cleavage of tertiary amines leading to nitroaromatic compounds
-
A NH4I/tert-butyl hydroperoxide-promoted oxidation of tertiary N-aryl-N,N-dialkylamines in DMSO has been developed to access nitroaromatic compounds. This methodology involves sequential N-dealkylation reactions in one-pot and a radical pathway is proposed.
- Shao, Ying,Zheng, Hao,Wu, Zhuhong,Huang, Lei,Tong, Jingjing,Wu, Ming,Sun, Xiaoqiang
-
p. 504 - 508
(2017/10/03)
-
- Convenient, metal-free ipso-nitration of arylboronic acids using nitric acid and trifluoroacetic acid
-
A feasible protocol for the direct ipso-nitration of arylboronic acids using trifluoroacetic acid and nitric acid as nitration reagent has been developed. Various aromatic nitro compounds are produced in moderate to good yields under the metal-free conditions. The method is operationally simple and regioselective, and might have potential application in industry.
- Shen, Guodong,Zhao, Lingyu,Liu, Wanxing,Huang, Xianqiang,Song, Huina,Zhang, Tongxin
-
supporting information
p. 10 - 14
(2016/12/30)
-
- Highly efficient reduction of carbonyls, azides, and benzyl halides by NaBH4 in water catalyzed by PANF-immobilized quaternary ammonium salts
-
A series of polyacrylonitrile fiber-supported quaternary ammonium salts (PANF-QAS) were prepared and applied to the catalytic reduction of aldehydes, ketones, azides, and benzyl halides in water using NaBH4 as the reducing reagent in a highly efficient, economic, and environmentally benign way. The structure-activity relationships were investigated, which showed that the catalysts made up of quaternary ammonium salts with longer alkyl chains, larger cationic radii and better lipophilicity speed up the reduction reaction to afford the products in excellent yield. Moreover, the optimized catalyst can be applied to the reduction of 1-naphthaldehyde in a continuous flow process with outstanding reactivity and recyclability.
- Du, Jianguo,Xu, Gang,Lin, Huikun,Wang, Guangwei,Tao, Minli,Zhang, Wenqin
-
supporting information
p. 2726 - 2735
(2016/05/24)
-
- A simple protocol for Cu-catalyzed protodecarboxylation of (hetero)aromatic carboxylic acids
-
A simple and practical protodecarboxylation of o-nitrobenzoic acids as well as heteroaromatic carboxylic acids with various substituents via using CuI/Et3N has been established. This transformation provides a viable and low-cost approach to generating previously unavailable substituted arenes from readily accessible aryl carboxylic acids as the starting materials.
- Li, Zhaojie,Fu, Zhengjiang,Zhang, Haixia,Long, Jiao,Song, Yuanyuan,Cai, Hu
-
supporting information
p. 3014 - 3018
(2016/05/09)
-
- Steric-Hindrance-Induced Regio- and Chemoselective Oxidation of Aromatic Amines
-
Unusual regio- and chemoselective oxidation of aromatic amines hindered with ortho substituents (except -NH2, -NHCH3, and -OH) to the corresponding nitro compounds is described by use of nonanebis(peroxoic acid). The mechanistic investigation for selective oxidation of amines ortho-substituted with -NH2 or -OH showed the involvement of H-bonding between the ortho hydrogen of the adjacent -XH group (where X = NH, NR, or O) and an oxygen atom from the diperoxy acid. Various mono- and diamines are oxidized into corresponding mononitro derivatives in high yield and purity without employing any protection strategies. The protocol was also found to successful on the gram scale.
- Patil, Vilas Venunath,Shankarling, Ganapati Subray
-
p. 7876 - 7883
(2015/09/01)
-
- A novel transition metal free [bis-(trifluoroacetoxy)iodo]benzene (PIFA) mediated oxidative ipso nitration of organoboronic acids
-
A mild, convenient and transition metal free methodology for oxidative ipso nitration of diversely functionalized organoboronic acids, including heteroaryl- and alkylboronic acids, has been developed at ambient temperature using a combination of [bis-(trifluoroacetoxy)]iodobenzene (PIFA) - N-bromosuccinimide (NBS) and sodium nitrite as the nitro source. It is anticipated that the reaction proceeds through in situ generation of NO2 and O-centred organoboronic acid radicals followed by the formation of an O-N bond via combination of the said radicals. Finally transfer of the NO2 group to the aryl moiety occurs through 1,3-aryl migration to provide the nitroarenes.
- Chatterjee, Nachiketa,Bhatt, Divya,Goswami, Avijit
-
supporting information
p. 4828 - 4832
(2015/05/05)
-
- Copper-mediated ortho-nitration of (hetero)arenecarboxylates
-
Various (hetero)arenecarboxylic acids were converted to the corresponding Daugulis amides and nitrated selectively in the ortho-position in the presence of [CuNO3(PPh3)2] and AgNO2 at 50 °C. A microwave-assisted saponification allows regenerating the carboxylate group within minutes, which may then be removed tracelessly by protodecarboxylation, or substituted by aryl- or alkoxy-groups via decarboxylative cross-coupling.
- Katayev, Dmitry,Pfister, Kai F.,Wendling, Timo,Goossen, Lukas J.
-
p. 9902 - 9905
(2014/08/18)
-
- The ortho-substituent effect on the Ag-Catalysed decarboxylation of benzoic acids
-
A combined experimental and computational investigation on the Ag-catalysed decarboxylation of benzoic acids is reported herein. The present study demonstrates that a substituent at the ortho position exerts dual effects in the decarboxylation event. On one hand, ortho-substituted benzoic acids are inherently destabilised starting materials compared to their meta- And para-substituted counterparts. On the other hand, the presence of an ortho-electron-withdrawing group results in an additional stabilisation of the transition state. The combination of both effects results in an overall reduction of the activation energy barrier associated with the decarboxylation event. Furthermore, the Fujita- Nishioka linear free energy relationship model indicates that steric bulk of the substituent can also exert a negative effect by destabilising the transition state of decarboxylation.
- Grainger, Rachel,Cornella, Josep,Blakemore, David C.,Larrosa, Igor,Campanera, Josep M.
-
supporting information
p. 16680 - 16687
(2015/03/05)
-
- Caged CO2 for the Direct Observation of CO2-Consuming Reactions
-
CO2-consuming reactions, in particular carboxylations, play important roles in technical processes and in nature. Their kinetic behavior and the reaction mechanisms of carboxylating enzymes are difficult to study because CO2 is inconvenient to handle as a gas, exists in equilibrium with bicarbonate in aqueous solution, and typically yields products that show no significant spectroscopic differences from the reactants in the UV/Vis range. Here we demonstrate the utility of 3-nitrophenylacetic acid and related compounds (caged CO2) in conjunction with infrared spectroscopy as widely applicable tools for the investigation of such reactions, permitting convenient measurement of the kinetics of CO2 consumption. The use of isotopically labeled caged CO2 provides a tool for the assignment of infrared absorption bands, thus aiding insight into reaction intermediates and mechanisms.
- Lommel, Katharina,Sch?fer, Gabriela,Grenader, Konstantin,Ruland, Christoph,Terfort, Andreas,M?ntele, Werner,Wille, Georg
-
p. 372 - 380
(2013/08/24)
-
- Gold(I)-catalyzed protodecarboxylation of (Hetero)aromatic carboxylic acids
-
Readily available, inexpensive and easy to handle, carboxylic acids have been shown to be very effective, greener coupling partners compared to costly organometallic reagents for the formation of C-C bonds. The use of well-defined gold complexes furnished 3 in slightly better yield with butyric acid, and in quantitative yield with adamantane-1-carboxylic acid. All reactions reached completion within 16 h. As with silver systems, this reactivity trend highlights, as previously observed, the benefits of potential coordinating groups in the ortho position to the gold binding site, which possibly facilitate the decarboxylation step. Additional reaction time and increased temperatures were necessary to afford the gold aryl products in satisfactory yields. Yet, some substrates such as 2-nitrobenzoic acids reacted poorly and could only be transformed in 50% yield.
- Dupuy, Stéphanie,Nolan, Steven P.
-
supporting information
p. 14034 - 14038
(2013/11/19)
-
- Ipso-nitration of arylboronic acids with bismuth nitrate and perdisulfate
-
An efficient and one pot synthetic method of ipso-nitration of arylboronic acids has been developed. The high efficiency, general applicability, and broader substrate scope including heterocycles and functional groups make this method advantageous. Due to its simplicity, we expect to find application of this method in synthesis.
- Manna, Srimanta,Maity, Soham,Rana, Sujoy,Agasti, Soumitra,Maiti, Debabrata
-
supporting information; experimental part
p. 1736 - 1739
(2012/05/20)
-
- Copper-catalyzed nitration of arylboronic acids with nitrite salts under mild conditions: An efficient synthesis of nitroaromatics
-
Copper-catalyzed nitration of arylboronic acids has been developed with nitrite salts as nitrating agent under mild conditions. This process provides an efficient and practical method for the synthesis of nitro aromatics, due to its simple experimental procedure and its use of convenient and inexpensive copper catalyst.
- Yan, Guobing,Zhang, Ling,Yu, Jian
-
experimental part
p. 133 - 137
(2012/07/28)
-
- Green and controllable metal-free nitrification and nitration of arylboronic acids
-
A novel and green nitrating reagent has been developed for the nitrification and nitration of arylboronic acids, which can be controlled by the reaction conditions. The process provides an attractive alternative to the traditional nitration protocols.
- Wang, Shuai,Shu, Chun Chun,Wang, Tao,Yu, Jian,Yan, Guo Bing
-
scheme or table
p. 643 - 646
(2012/08/07)
-
- Copper catalyzed ipso-nitration of iodoarenes, bromoarenes and heterocyclic haloarenes under ligand-free conditions
-
A catalytic protocol for the conversion of haloarenes into the corresponding nitroarenes is presented using copper salts under ligand-free conditions. The method was effectively utilized for the ipso-nitration of a broad variety of haloarenes that includes iodoarenes, bromoarenes, and heterocyclic haloarenes.
- Amal Joseph,Priyadarshini,Lakshmi Kantam,Maheswaran
-
supporting information; experimental part
p. 1511 - 1513
(2012/03/27)
-
- Microwave-accelerated fluorodenitrations and nitrodehalogenations: expeditious routes to labeled PET ligands and fluoropharmaceuticals
-
Methods for the expeditious fluorination of arenes have been investigated, using readily available fluoride sources. An optimized procedure for microwave-accelerated fluorodenitration has been developed, giving good to excellent yields in less than 10 min, rendering it practical for use in the preparation of F18 labeled ligands for PET imaging. Application of the method in the synthesis of CNS agents is demonstrated, and a practical method for the preparation of substrates is also presented.
- LaBeaume, Paul,Placzek, Michael,Daniels, Mathew,Kendrick, Ian,Ng, Patrick,McNeel, Melissa,Afroze, Roushan,Alexander, Abigail,Thomas, Rhiannon,Kallmerten, Amy E.,Jones, Graham B.
-
experimental part
p. 1906 - 1909
(2010/09/07)
-
- Efficient and facile method for the nitration of aromatic compounds by nitric acid in micellar media
-
Aromatic compounds were efficiently nitrated under mild reaction conditions by employing HNO3 in the presence of anionic (sodium dodecyl sulfate, SDS), cationic (cetyl trimethyl ammonium bromide, CTAB), and nonionic (Triton-X 100) micelles. The reaction rapidly afforded corresponding mononitro derivatives in fair to good yields with high regioselectivity. This new method offers an environmentally safe reaction condition to minimize the waste products.
- Sana,Tasneem,Ali, M. Moazzam,Rajanna,Saiprakash
-
experimental part
p. 2949 - 2953
(2009/12/03)
-
- Silver-catalysed protodecarboxylation of ortho-substituted benzoic acids
-
Catalytic amounts of Ag(i) salts in DMSO have been found to promote the protodecarboxylation of a wide variety of ortho-substituted benzoic acids under mild conditions and in excellent yields, highlighting a possible role for silver in decarboxylative cross-couplings. The Royal Society of Chemistry 2009.
- Cornella, Josep,Sanchez, Carolina,Banawa, David,Larrosa, Igor
-
supporting information; experimental part
p. 7176 - 7178
(2010/03/25)
-
- Nitro-substituted aryl lithium compounds in microreactor synthesis: Switch between kinetic and thermodynamic control
-
Be quick or take your time, depending on your goal: A microflow method for the generation and transformation of o-, m-, and p-nitro-substituted aryl lithium compounds enabled the selective use of either the kinetically or the thermodynamically preferred intermediate. In the example pictured, a residence time of 0.06 s at -48 °C led to the formation of 1, whereas 2 was obtained exclusively when the residence time was extended to 63 s.
- Nagaki, Aiichiro,Kim, Heejin,Yoshida, Jun-ichi
-
supporting information; experimental part
p. 8063 - 8065
(2010/01/16)
-
- Silica sulphuric acid as an efficient catalyst for the catalytic and metal-free oxidation of aromatic amines to their corresponding nitro compounds with sodium perborate under micellar media
-
Electron-donating substituted anilines were converted to their corresponding nitro compounds with sodium perborate in the presence of a catalytic amount of silica sulphuric acid under micellar media in moderate to good yields.
- Habibi, Davood,Zolfigol, Mohammad A.,Safaiee, Maliheh
-
-
- Improved regioselective mononitration of toluene over ZSM-5 zeolite catalysts
-
We show for the first time that the NH+4 exchanged form of ZSM-5 zeolite is as effective as the H+ form of the catalyst for the regioselective conversion of toluene to mononitrotoluene (MNT) using 90% nitric acid as the sole nitrating agent. The auto-ionization of the acid in the absence of protons on the zeolite surface is sufficient for the formation of reactive nitronium ions. We also find that the regioselectivity for the formation of p-MNT is substantially increased over both forms of the zeolite catalyst by first intercalating the acid in the zeolite micropores prior to the introduction of toluene. For instance, the p / o isomer ratio is increased from values in the range 1.3-2.3 under conventional batch reaction conditions to values of 1.8-8.9 when the acid is sequestered in the zeolite. The sequestration of nitric acid in both ion exchanged forms of the zeolite confines more of the nitration reaction to the regioselective environment of the micropores and reduces the extent of reaction in homogeneous toluene solution. However, the ammonium form of the zeolite is preferred over the protonated form when the Si/Al ratio of the zeolite allows for the presence of at least one ammonium ion per unit cell (Si/Al ≤ 40), because under these conditions far less benzaldehyde and other undesired reaction products are formed in comparison to the protonated form of the zeolite at the same Si/Al ratios. The ability of NH+4-ZSM-5 derivatives to limit the formation of unwanted toluene oxidation products is not well understood, but the observed selectivity may be related to the replacement of ammonium ions by protons, the formation of ammonium nitrate, and the buffering of nitric acid within the micropores of the zeolite.
- Kim, Seong-Su,Pinnavaia, Thomas J.,Damavarapu, Reddy
-
p. 289 - 294
(2008/09/16)
-
- Nitration of simple aromatics with NO2 under air atmosphere in the presence of novel Bronsted acidic ionic liquids
-
Aromatics nitrate with NO2/air catalyzed by novel Bronsted acidic ionic liquids (ILs) without any volatile chlorinated organic solvent under mild conditions. The ILs employed were caprolactam based, [Caprolactam]X (X-=pTSO-, BSO-, BF4-, NO3-), which are o
- Qi, Xiufang,Cheng, Guangbin,Lu, Chunxu,Qian, Desheng
-
p. 537 - 545
(2008/04/12)
-
- 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)
-
- Control over m-nitrotoluene concentration in products of heterogeneous mononitration of toluene
-
Heterogeneous mononitration of toluene with sulfuric-nitric acid mixtures, occurring in the charged interfacial monolayer with high para selectivity, was studied. Ways to suppress the meta substitution in the toluene mononitration stage by controlling the nitrating mixture composition, process parameters, and catalytic additives were found.
- Artemov,Tselinskii,Kukushkin,Filatova,Ashikhin
-
p. 2063 - 2072
(2008/09/17)
-
- BF3·2CF3CH2OH (BF 3·2TFE), an efficient superacidic catalyst for some organic synthetic transformations
-
BF3 · 2CF3CH2OH complex was found to be a very effective superacidic catalyst comparable in acid strength to at least that of 100% anhydrous sulfuric acid for various acid-catalyzed organic transformations such as isomerizations, rearrangements, ionic hydrogenation of various ketones, and aromatics with triethylsilane and nitration of aromatics with metal nitrate. Studies of the pivalaldehyde-methyl isopropyl ketone rearrangement and the benzopinacol to phenanthrene transformation suggest that the complex has an acidity comparable to that of 100% anhydrous sulfuric acid. The structure and properties of the 1:2 boron trifluoride-trifluoroethanol complex have been further studied using NMR (1H, 13C, 19F, 11B) and DFT calculations at the B3LYP/6- 311++G**//B3LYP/6-31G* level.
- Prakash, G. K. Surya,Mathew, Thomas,Marinez, Eric R.,Esteves, Pierre M.,Rasul, Golam,Olah, George A.
-
p. 3952 - 3958
(2007/10/03)
-
- Indium triflate as a recyclable catalyst for the nitration of aromatic compounds without a halogenated solvent
-
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
-
p. 549 - 551
(2007/10/03)
-
- The regiochemistry of the NO3-promoted gas phase nitration of toluene and phenol with NO2
-
Product studies, kinetic isotope effect measurements, linear free energy relationships and calculations have been used to study the NO 3-promoted nitration of toluene and phenol in presence of NO 2. The competition between of a rate-
- Bolzacchini, Ezio,Bruschi, Maurizio,Galliani, Guido,Hjorth, Jens,Orlandi, Marco,Rindone, Bruno
-
p. 570 - 578
(2007/10/03)
-
- Copper-catalyzed coupling of aryl halides and nitrite salts: A mild Ullmann-type synthesis of aromatic nitro compounds
-
Nitration of aromatic halides proceeded smoothly in the presence of catalytic amounts of Cu bronze and N,N′-dimethylethylenediamine. Sodium nitrite-18-crown-6, or tetra-n-butylammonium nitrite (n-Bu4NNO 2) turned out to be efficient nitrating agents. The aromatic nitro compounds were synthesized under essentially neutral conditions.
- Saito, Shinichi,Koizumi, Yuichiro
-
p. 4715 - 4717
(2007/10/03)
-
- Deoxygenation of aldehydes and ketones using dichloro bis(1,4- diazabicyclo[2.2.2]octane)(tetrahydroborato) zirconium(IV)
-
Saturated aldehydes and ketones are converted via their p-toluenesulfonyl hydrazones to the corresponding alkanes using dichloro bis(1,4-diazabicyclo[2.2. 2]octane)(tetrahydroborato) zirconium(IV) (ZrBDC). The reactions were performed in DMF-sulfolane at 110 °C and gave the corresponding alkanes in high yields. Regioselectivity in the reduction of α,β-unsaturated carbonyl groups was also observed.
- Alinezhad, Heshmatollah,Tajbakhsh, Mahmood,Salehian, Fatemeh
-
p. 170 - 172
(2007/10/03)
-
- Paradigm confirmed: The first use of ionic liquids to dramatically influence the outcome of chemical reactions
-
It has been an unproven paradigm that the choice of which ionic liquid to use in a chemical reaction can have a dramatic effect on the outcome of that chemical reaction. We demonstrate, for the first time, that the reaction of toluene and nitric acid in three different ionic liquids gives rise to three completely different products in high yield. Furthermore, ionic liquids can catalyze these reactions with the only byproduct being water.
- Earle, Martyn J.,Katdare, Suhas P.,Seddon, Kenneth R.
-
p. 707 - 710
(2007/10/03)
-
- Nitration of aromatic compounds with nitric acid catalyzed by ionic liquids
-
Nitration of simple aromatic compounds with 62% nitric acid is successfully carried out under solvent-free condition in a biphasic mode in the presence of the Bronsted acidic ionic liquids; the only by-product is water and ionic liquids are capable of being reused without any separation.
- Qiao, Kun,Yokoyama, Chiaki
-
p. 808 - 809
(2007/10/03)
-
- Lanthanide(III) nitrobenzenesulfonates as new nitration catalysts: The role of the metal and of the counterion in the catalytic efficiency
-
Lanthanide(III) complexes of p-nitrobenzenesulfonic acid, Ln(p-NBSA) 3, m-nitrobenzenesulfonic acid, Ln(m-NBSA)3, and 2,4-nitrobenzenesulfonic acid, Ln(2,4-NBSA)3, were prepared, characterized and examined as catalyst for the nitration of benzene, toluene, xylenes, naphthalene, bromobenzene and chlorobenzene. The initial screening of the catalysts showed that lanthanum(III) complexes were more effective than the corresponding ytterbium(III) complexes, and that catalysts containing the bulky 2,4-NBSA ligand were less effective than the catalyst containing p-NBSA (nosylate) or m-NBSA ligands. Examination of a series of Ln(p-NBSA)3 and Ln(m-NBSA)3 catalysts revealed that there is a clear correlation between the ionic radii of the lanthanide(III) ions and the yields of nitration, with the lighter lanthanides being more effective. The X-ray single crystal structure of Yb(m-NBSA)3·6H2O shows that two m-NBSA ligands are directly bound to the metal centre while the third ligand is not located in the first coordination sphere, but it is hydrogen bonded to one of the water molecules which is coordinated to ytterbium(III). NMR studies suggest that this structure is preserved under the conditions used in the nitration reaction. The structure of Yb(m-NBSA)3 is markedly different from the structure of the well-known ytterbium(III) triflate catalyst. The coordination of the nitrobenzenesulfonate counterion to the lanthanide(III) ion suggests that steric effects might play an important role in determining the efficiency of these novel nitration catalysts. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Parac-Vogt, Tatjana N.,Pachini, Sophia,Nockemann, Peter,Van Hecke, Kristof,Van Meervelt, Luc,Binnemans, Koen
-
p. 4560 - 4566
(2007/10/03)
-
- Lanthanide(III) nosylates as new nitration catalysts
-
Lanthanide(III) nosylates are novel, recyclable catalysts prepared from the noncorrosive and inexpensive p-nitrotoluenesulfonic acid and the corresponding lanthanide(III) oxide. With 5-10% catalyst loading, atom economic nitration of simple aromatic compounds was achieved in good to high yields.
- Parac-Vogt, Tatjana N.,Binnemans, Koen
-
p. 3137 - 3139
(2007/10/03)
-
- A mild and efficient method for the mononitration of aromatic compounds by cerium (III) ammonium nitrate in acetic anhydride
-
A mild and efficient method for the mononitration of aromatic and olefinic compounds is described. This method is especially useful for active substrates.
- Tanemura, Kiyoshi,Suzuki, Tsuneo,Nishida, Yoko,Satsumabayashi, Koko,Horaguchi, Takaaki
-
p. 497 - 499
(2007/10/03)
-
- Aromatic nitrations in ionic liquids: The importance of cation choice
-
Aromatic substrates can be nitrated in high yields and with efficient use of the nitrating agent in ionic liquids, although a suitably inert ionic liquid cation must be used.
- Lancaster, N. Llewellyn,Llopis-Mestre, Veronica
-
p. 2812 - 2813
(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)
-
- Process for the preparation of nitrotoluenes
-
The present invention relates to a process for the preparation of nitrotoluenes. More particularly, the present invention relates to a process for the preparation of nitrotoluenes with high para -selectivity from toluene using zeolite beta with different binders as a catalyst.
- -
-
Page/Page column 5
(2008/06/13)
-
- Perfluorinated rare earth metals catalyzed nitration of aromatic compounds
-
The nitration of aromatic compounds can be carried out in the presence of perfluorinated rare earth metal catalyst without halogenated organic solvent.
- Shi, Min,Cui, Shi-Cong
-
p. 207 - 209
(2007/10/03)
-
- Counterion effects in indium-catalysed aromatic electrophilic substitution reactions
-
Indium(III) triflamide (In(NTf2)3) has been prepared in high yield and has been demonstrated to be an efficient, recoverable catalyst for a range of aromatic electrophilic substitution reactions. When compared to other indium(III) complexes, anomalous reactivities suggest a non-innocent role for the counterion in the studied processes.
- Frost, Christopher G,Hartley, Joseph P,Griffin, David
-
p. 4789 - 4791
(2007/10/03)
-
- Electrophilic nitration of aromatics in ionic liquid solvents
-
Potential utility of a series of 1-ethyl-3-methylimidazolium salts [emim][X] with X = OTf-, CF3COO-, and NO3- as well as [HNEtPri2][CF3COO] (protonated Huenig's base) ionic liquids were explored as solvent for electrophilic nitration of aromatics using a variety of nitrating systems, namely NH4NO3/TFAA, isoamyl nitrate/BF3·Et2O, isoamyl nitrate/TfOH, Cu(NO3)/TFAA, and AgNO3/Tf2O. Among these, NH4NO3/TFAA (with [emim][CF3COO], [emim][NO3]) and isoamyl nitrate/BF3·Et2O, isoamyl nitrate/TfOH (with [emim][OTf]) provided the best overall systems both in terms of nitration efficiency and recycling/reuse of the ionic liquids. For [NO2][BF4] nitration, the commonly used ionic liquids [emim][AlCl4] and [emim][Al2Cl7] are unsuitable, as counterion exchange and arene nitration compete. [Emim][BF4] is ring nitrated with [NO2][BF4] producing [NO2-emim][BF4] salt, which is of limited utility due to its increased viscosity. Nitration in ionic liquids is surveyed using a host of aromatic substrates with varied reactivities. The preparative scope of the ionic liquids was also extended. Counterion dependency of the NMR spectra of the [emim][X] liquids can be used to gauge counterion exchange (metathesis) during nitration. Ionic liquid nitration is a useful alternative to classical nitration routes due to easier product isolation and recovery of the ionic liquid solvent, and because it avoids problems associated with neutralization of large quantities of strong acid.
- Laali,Gettwert
-
-
- Zeolite-assisted nitration of neat toluene and chlorobenzene with a nitrogen dioxide/molecular oxygen system. Remarkable enhancement of para-selectivity
-
In the presence of molecular oxygen and HZSM-5, neat toluene reacted with liquid nitrogen dioxide in a regioselective manner at room temperature to yield mononitrotoluenes as the main product, where the para isomer predominated up to 90% and the ortho-para isomer ratio improved to 0.08. Chlorobenzene behaved similarly, giving a para-predominant nitration product.
- Peng, Xinhua,Suzuki, Hitomi,Lu, Chunxu
-
p. 4357 - 4359
(2007/10/03)
-
- An exceptionally stable Ti superoxide radical ion: A novel heterogeneous catalyst for the direct conversion of aromatic primary amines to nitro compounds
-
A matrix-bound superoxide radical anion, generated by treating Ti(OR)4 (R =iPr, nBu) with H2O2, is a selective heterogeneous catalyst for the oxidation of anilines to the corresponding nitroarenes with 50 % aqueous H2O2 [Eq. (1)]. Yields of 82-98 % are obtained, even with anilines bearing electron-withdrawing substituents (R = NO2, COOH).
- Dewkar, Gajanan K.,Nikalje, Milind D.,Ali, Iliyas Sayyed,Paraskar, Abhimanyu S.,Jagtap,Sudalai
-
p. 405 - 408
(2007/10/03)
-
- A fast and mild method for the nitration of aromatic rings
-
The use of N2O5 and a Fe(III) catalyst for the nitration of aromatic rings is described. This methodology is compatible with most functional groups and results in near quantitative yields in 4 min. The reaction conditions are non-oxidising: benzaldehyde and benzyl alcohols are readily nitrated with little or no oxidation (4%) occurring. The addition of the iron catalyst activates the system to such an extent that nitration of an activated aromatic ring, such as toluene, occurs quantitatively at -100°C. This high activity allows compounds with sensitive functional groups such as alkenes to be smoothly nitrated.
- Bak, Radoslaw R.,Smallridge, Andrew J.
-
p. 6767 - 6769
(2007/10/03)
-
