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Manganese Catalyzed Hydrogenation of Azo (N=N) Bonds to Amines
We report the first example of homogeneously catalyzed hydrogenation of the N=N bond of azo compounds using a complex of an earth-abundant-metal. The hydrogenation reaction is catalyzed by a manganese pincer complex, proceeds under mild conditions, and yields amines, which makes this methodology a sustainable alternative route for the conversion of azo compounds. A plausible mechanism involving metal-ligand cooperation and hydrazine intermediacy is proposed based on mechanistic studies. (Figure presented.).
Ben-David, Yehoshoa,Das, Uttam Kumar,Diskin-Posner, Yael,Kar, Sayan,Milstein, David
supporting information
p. 3744 - 3749
(2021/07/09)

Rhodium-terpyridine Catalyzed Transfer Hydrogenation of Aromatic Nitro Compounds in Water
A rhodium terpyridine complex catalyzed transfer hydrogenation of nitroarenes to anilines with i-PrOH as hydrogen source and water as solvent has been developed. The catalytic system can work at a substrate/catalyst (S/C) ratio of 2000, with a turnover frequency (TOF) up to 3360 h?1, which represents one of the most active catalytic transfer hydrogenation systems for nitroarene reduction. The catalytic system is operationally simple and the protocol could be scaled up to 20 gram scale. The water-soluble catalyst bearing a carboxyl group could be recycled 15 times without significant loss of activity.
Liu, Yuxuan,Miao, Wang,Tang, Weijun,Xue, Dong,Xiao, Jianliang,Wang, Chao,Li, Changzhi
supporting information
p. 1725 - 1729
(2021/06/01)

Commercially Available CuO Catalyzed Hydrogenation of Nitroarenes Using Ammonia Borane as a Hydrogen Source
Tandem ammonia borane dehydrogenation and nitroarenes hydrogenation has been reported as a novel strategy for the preparation of aromatic amines. However, the practical application of this strategy is subjected to the high-cost and tedious preparation of supported noble metal nanocatalysts. The commercially available CuO powder is herein demonstrated to be a robust catalyst for hydrogenation of nitroarenes using ammonia borane as a hydrogen source under mild conditions. Numerous amines (even sterically hindered, halogenated, and diamines) could be obtained through this method. This monometallic catalyst is characteristic of support-free, excellent chemoselectivity, low-cost, and high recyclability, which will favor its future utilization in preparative reduction chemistry. Mechanistic studies are also carried out to clarify that diazene and azoxybenzene are key intermediates of this heterogeneous reduction.
Du, Jialei,Chen, Jie,Xia, Hehuan,Zhao, Yiwei,Wang, Fang,Liu, Hong,Zhou, Weijia,Wang, Bin
p. 2426 - 2430
(2020/03/30)

Synthesis method of aniline compound
The invention provides a synthesis method of an aniline compound. The synthesis comprises the following steps: taking a carbon-coated nickel nano composite material containing alkali metals as a catalyst, and catalyzing a hydrogenation reduction reaction of a nitrobenzene compound in a hydrogen atmosphere, wherein the nano composite material contains a core-shell structure with a shell layer and an inner core, the shell layer is a graphitized carbon layer containing alkali metal, nitrogen and oxygen, and the inner core is nickel nano particles. According to the method, the nano composite material is used as a catalyst; a carbon material and the nickel nano particles generate a synergistic effect and a good catalytic effect, the alkali metals of the shell layer further synergistically improve the catalytic performance of the nano composite material, and the catalyst is used for hydrogenation reduction of nitrobenzene compounds to synthesize aniline compounds, and has excellent activity,selectivity and safety.
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Paragraph 0136-0138

(2020/08/09)

Synthesis method of aniline compound
The invention provides a synthesis method of an aniline compound. The synthesis method comprises the following steps: taking a carbon-coated nickel nano composite material containing alkaline-earth metals as a catalyst, and catalyzing a hydrogenation reduction reaction of a nitrobenzene compound in a hydrogen atmosphere; wherein the nano composite material contains a core-shell structure with a shell layer and an inner core, the shell layer is a graphitized carbon layer containing alkaline-earth metals, nitrogen and oxygen, and the inner core is nickel nano particles. According to the method,the nano composite material is used as a catalyst; the carbon material and the nickel nano particles generate a synergistic effect and a good catalytic effect, the alkaline-earth metals of the shell layer further synergistically improve the catalytic performance of the nano composite material, and the catalyst is used for hydrogenation reduction of nitrobenzene compounds to synthesize aniline compounds, and has excellent activity, selectivity and safety.
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Paragraph 0135-0137

(2020/08/09)

COMPOUNDS FOR THIOL-TRIGGERED COS AND/OR H2S RELEASE AND METHODS OF MAKING AND USING THE SAME
Disclosed herein are embodiments of a compound that is capable of releasing COS and/or H2S upon reaction with a thiol-containing compound. The compound embodiments also can produce a detectable signal (e.g., a fluorescent signal) substantially concomitantly with COS and/or H2S release and/or can release an active agent, such as a therapeutic agent. Methods of making and using the compound embodiments also are disclosed.
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(2019/12/25)

Superfine CoNi alloy embedded in Al2O3 nanosheets for efficient tandem catalytic reduction of nitroaromatic compounds by ammonia borane
Aromatic amino compounds are important and universally used chemical intermediates in a wide range of industrial fields. Thus, their production with high efficiency and selectivity under ambient conditions is expected and demanded in modern industry. Herein, a series of superfine CoNi alloy nanoparticles embedded in Al2O3 nanosheet (CoxNi1-x/Al2O3, where x represents the content of Co in the precursor) catalysts was fabricated from CoNiAl-LDH and used to catalyze the tandem dehydrogenation of ammonia borane (AB) and hydrogenation of nitroaromatics to the corresponding amines. Systematic experiments indicate that the composition, size, morphology and catalytic performance of the CoxNi1-x/Al2O3 catalysts can be easily controlled by changing the content of Ni in the CoNiAl-LDH precursor. Particularly, Co0.67Ni0.33/Al2O3 exhibited the best tandem catalytic performance among the six samples. This as-prepared catalyst not only showed a moderate turn-over-frequency value (TOF: 34.5 molH2 molCo0.67Ni0.33-1 min-1 at 298 K without base or additives) and relatively low activation energy (32.4 kJ mol-1) for the dehydrogenation of AB, but also superior catalytic activity (conversion yield reaching up to 100%) and selectivity (>99%) for the tandem reductive transformation of in excess of sixteen types of nitroaromatics to aromatic amines. Density functional theory (DFT) calculations suggest that the construction of the CoNi alloy optimized the electronic structure with respect to the pure component, promoting its activity for AB hydrolysis and nitroaromatics hydrogenation. Finally, the catalyst could be easily recycled using a magnet due to the magnetic properties of the Co0.67Ni0.33 alloy.
Cheng, Sihang,Liu, Yanchun,Zhao, Yingnan,Zhao, Xinyu,Lang, Zhongling,Tan, Huaqiao,Qiu, Tianyu,Wang, Yonghui
p. 17499 - 17506
(2019/12/23)

Metal-free chemoselective reduction of nitroaromatics to anilines via hydrogen transfer strategy
A novel protocol for chemoselective reduction of aromatic nitro compounds to aromatic amines has been established. The metal-free reduction goes through a hydrogen transfer process. Various easily reducible functional groups can be well tolerated under the optimized reaction conditions.
Shuai, Qi,Li, Jun,Zhao, Feng,Su, Weike,Deng, Guojun
p. 965 - 975
(2019/04/13)

A switchable-selectivity multiple-interface Ni-WC hybrid catalyst for efficient nitroarene reduction
Selective reduction of nitroarenes is extremely valuable in industrial chemical production. The main reduced products are usually aniline derivatives obtained using single-component noble- or transition-metal catalysts; however, other important products such as hydrazobenzene derivatives always involve in harsh conditions and multiple reaction steps. Here, we realize an unexpected switchable reduction of nitroarenes into aniline or hydrazobenzene derivatives with high yield and selectivity just by controlling the molar ratio of nitroarenes to N2H4·H2O with a nickel–tungsten carbide composite nanocatalyst loaded on carbon (Ni-WC/C). A series of control experiments and density functional theory (DFT) calculations indicate that the multiple interfaces between Ni and WC can induce a synergistic effect, significantly modulating the electronic structure of the Ni-WC/C catalyst, and endowing the catalyst with switchable selectivity and high activity for the reduction of nitroarenes by hydrogenation. This synergistic multi-interfacial catalyst may offer a new way to design and explore highly efficient and selective catalysts for the controllable reduction of nitroarenes and similar hydrogenation reactions.
Ma, Yuanyuan,Lang, Zhongling,Du, Jing,Yan,Wang, Yonghui,Tan, Huaqiao,Khan, Shifa Ullah,Liu, Yang,Kang, Zhenhui,Li, Yangguang
p. 174 - 182
(2019/08/06)

Telescoped Sequence of Exothermic and Endothermic Reactions in Multistep Flow Synthesis
A multistep sequential flow synthesis of isopropyl phenol is demonstrated, involving 4-step exothermic, endothermic, and temperature sensitive reactions such as nitration, reduction, diazotization, and high temperature hydrolysis. Nitration of cumene with fuming nitric acid produces 2- A nd 4-nitrocumene which are converted into respective cumidines by the hydrogenation using Pd/Ni catalyst in H-cube with gravity separation. Hydrolysis of in situ generated diazonium salts in the boiling acidic conditions is carried out using integration of flow and microwave-assisted synthesis. 58% of 4-isopropyl phenol was obtained. The sequential flow synthesis can be applied to synthesize other organic compounds involving this specific sequence of reactions.
Sharma, Yachita,Nikam, Arun V.,Kulkarni, Amol A.
p. 170 - 176
(2019/02/01)

Copper(ii)-catalyzed c-n coupling of aryl halides and n-nucleophiles promoted by quebrachitol or diethylene glycol
Herein, we report the natural ligand quebrachitol (QCT) as a promoter for a Cu(II) catalyst, which is highly effective for N-Arylation of various amines and related aryl halides. A series of diarylamine derivatives were obtained in high yields by using diethylene glycol (DEG) as both ligand and solvent. The C-N coupling reactions proceed under mild conditions and exhibit good functional group tolerance.
Chen, Guoliang,Chen, Yuanguang,Du, Fangyu,Fu, Yang,Wu, Ying,Zhou, Qifan
supporting information
p. 2161 - 2168
(2019/11/25)

Solvent-Driven Selectivity Control to Either Anilines or Dicyclohexylamines in Hydrogenation of Nitroarenes over a Bifunctional Pd/MIL-101 Catalyst
The hydrogenation of nitroarenes is one of the most important strategies to produce the corresponding anilines and dicyclohexylamines, both of which are the fundamental raw materials in the synthesis of various pharmaceuticals and fine chemicals. Nevertheless, it is still a great challenge to develop a highly versatile and flexible catalytic system to selectively generate desired amines. Herein, we report the solvent-driven selectivity control over a bifunctional Pd/MIL-101 catalyst for the hydrogenation of nitrobenzene. An almost full selectivity of 99.9% to aniline or a surprising selectivity of 99.1% to dicyclohexylamine is achieved by using dimethylformamide (DMF, a polar solvent) or n-hexane (an apolar solvent) as the solvents, respectively. It is proposed that the polarity of solvents can effectively regulate the linkage between reactants/intermediates and Pd/MIL-101, affording controllable selectivities of aniline or dicyclohexylamine at will. In addition, the Lewis acid sites in Pd/MIL-101 can also effectively activate the aromatic ring and accelerate the cross-coupling reaction of amine. This solvent-driven catalytic system also exhibits good recyclability and compatibility for a wide substrate scope in both DMF and n-hexane, showing great promise for industrial applications. This study might open an avenue for the hydrogenation of nitroarenes to selectively produce anilines or dicyclohexylamines by simply regulating the solvent polarity over a bifunctional catalyst system.
Chen, Xiaodong,Shen, Kui,Ding, Danni,Chen, Junying,Fan, Ting,Wu, Rongfang,Li, Yingwei
p. 10641 - 10648
(2018/10/31)

A Ni-Mg-Al layered triple hydroxide-supported Pd catalyst for heterogeneous acceptorless dehydrogenative aromatization
In the presence of a Ni-Mg-Al layered triple hydroxide-supported Pd catalyst, the acceptorless dehydrogenative aromatization of a wide range of cyclohexanols/cyclohexanones and cyclohexylamines efficiently proceeded to give the corresponding phenols and anilines, respectively, in moderate to high yields with the liberation of molecular hydrogen.
Jin, Xiongjie,Taniguchi, Kento,Yamaguchi, Kazuya,Nozaki, Kyoko,Mizuno, Noritaka
supporting information
p. 5267 - 5270
(2017/07/10)

Versatile routes for synthesis of diarylamines through acceptorless dehydrogenative aromatization catalysis over supported gold-palladium bimetallic nanoparticles
Diarylamines are an important class of widely utilized chemicals, and development of diverse procedures for their synthesis is of great importance. Herein, we have successfully developed novel versatile catalytic procedures for the synthesis of diarylamines through acceptorless dehydrogenative aromatization. In the presence of a gold-palladium alloy nanoparticle catalyst (Au-Pd/TiO2), various symmetrically substituted diarylamines could be synthesized starting from cyclohexylamines. The observed catalysis of Au-Pd/TiO2 was heterogeneous in nature and Au-Pd/TiO2 could be reused several times without severe loss of catalytic performance. This transformation needs no oxidants and generates molecular hydrogen (three equivalents with respect to cyclohexylamines) and ammonia as the side products. These features highlight the environmentally benign nature of the present transformation. Furthermore, in the presence of Au-Pd/TiO2, various kinds of structurally diverse unsymmetrically substituted diarylamines could successfully be synthesized starting from various combinations of substrates such as (i) anilines and cyclohexanones, (ii) cyclohexylamines and cyclohexanones, and (iii) nitrobenzenes and cyclohexanols. The role of the catalyst and the reaction pathways were investigated in detail for the transformation of cyclohexylamines. The catalytic performance was strongly influenced by the nature of the catalyst. In the presence of a supported gold nanoparticle catalyst (Au/TiO2), the desired diarylamines were hardly produced. Although a supported palladium nanoparticle catalyst (Pd/TiO2) gave the desired diarylamines, the catalytic activity was inferior to that of Au-Pd/TiO2. Moreover, the activity of Au-Pd/TiO2 was superior to that of a physical mixture of Au/TiO2 and Pd/TiO2. The present Au-Pd/TiO2-catalyzed transformation of cyclohexylamines proceeds through complex pathways comprising amine dehydrogenation, imine disproportionation, and condensation reactions. The amine dehydrogenation and imine disproportionation reactions are effectively promoted by palladium (not by gold), and the intrinsic catalytic performance of palladium is significantly improved by alloying with gold. One possible explanation of the alloying effect is the formation of electron-poor palladium species that can effectively promote the β-H elimination step in the rate-limiting amine dehydrogenation.
Taniguchi, Kento,Jin, Xiongjie,Yamaguchi, Kazuya,Nozaki, Kyoko,Mizuno, Noritaka
p. 2131 - 2142
(2017/03/09)

A triazine-phosphite polymeric ligand bearing cage-like P,N-ligation sites: An efficient ligand in the nickel-catalyzed amination of aryl chlorides and phenols
A novel P,N-ligand was introduced for efficient Ni-catalyzed amination of aryl chlorides. Reaction of cyanuric acid (1,3,5-triazine-2,4,6-triol) and trichlorophosphine (PCl3) resulted in the production of a new porous material (TPPM) containing triazine rings with phosphite moieties in a sheet morphology. Cavities in the prepared compound create sites on the surface of the material with appropriate ligation character to coordinate with metals for catalytic purposes. The nickel-catalyzed amination of aryl chlorides and of phenols in their 2,4,6-triaryloxy-1,3,5-triazine (TAT) protected form were efficiently accomplished in the presence of this easily prepared and reusable P,N-ligand under mild reaction conditions. More importantly, TPPM was reusable for 5 iterations following this protocol without significantly decreasing in its activity.
Panahi, Farhad,Roozbin, Fatemeh,Rahimi, Sajjad,Moayyed, Mohammadesmaeil,Valaei, Aria,Iranpoor, Nasser
supporting information
p. 80670 - 80678
(2016/10/12)

Unprecedented iron-catalyzed selective hydrogenation of activated amides to amines and alcohols
The first example of hydrogenation of amides homogeneously catalyzed by an earth-abundant metal complex is reported. The reaction is catalyzed by iron PNP pincer complexes. A wide range of secondary and tertiary N-substituted 2,2,2-trifluoroacetamides were hydrogenated to form amines and trifluoroethanol.
Garg, Jai Anand,Chakraborty, Subrata,Ben-David, Yehoshoa,Milstein, David
supporting information
p. 5285 - 5288
(2016/05/02)

The ortho effect on the acidic and alkaline hydrolysis of substituted formanilides
The kinetics of formanilides hydrolysis were determined under first-order conditions in hydrochloric acid (0.01-8 M, 20-60°C) and in hydroxide solutions (0.01-3 M, 25 and 40°C). Under acidic conditions, second-order specific acid catalytic constants were used to construct Hammett plots. The ortho effect was analyzed using the Fujita-Nishioka method. In alkaline solutions, hydrolysis displayed both first- and second-order dependence in the hydroxide concentration. The specific base catalytic constants were used to construct Hammett plots. Ortho effects were evaluated for the first-order dependence on the hydroxide concentration. Formanilide hydrolyzes in acidic solutions by specific acid catalysis, and the kinetic study results were consistent with the AAC2 mechanism. Ortho substitution led to a decrease in the rates of reaction due to steric inhibition of resonance, retardation due to steric bulk, and through space interactions. The primary hydrolytic pathway in alkaline solutions was consistent with a modified BAC2 mechanism. The Hammett plots for hydrolysis of meta- and para-substituted formanilides in 0.10 M sodium hydroxide solutions did not show substituent effects; however, ortho substitution led to a decrease in rate constants proportional to the steric bulk of the substituent.
Desai, Salil Dileep,Kirsch, Lee E.
p. 471 - 488
(2015/06/30)

Polymethylhydrosiloxane derived palladium nanoparticles for chemo- and regioselective hydrogenation of aliphatic and aromatic nitro compounds in water
Chemo- and regioselective hydrogenation of a wide range of aliphatic, unsaturated, aromatic and heteroaromatic nitro compounds into their corresponding amines has been achieved with highly efficient polysiloxane-stabilised "Pd" nanoparticles on NAP-magnesium oxide supports using an environmentally friendly hydrogenating agent, polymethylhydrosiloxane [PMHS] in water. Highly stable and active Pd nanoparticles were prepared by the reduction of NAP-Mg-PdCl4 with PMHS, which serves as a reducing agent as well as a capping agent. The well-dispersed palladium nanoparticles on NAP-MgO catalysts also exhibit excellent regioselectivity in the hydrogenation of dinitrobenzenes to the corresponding nitroanilines. The catalyst has high durability against sintering during the hydrogenation reaction and can be reused with no loss in its activity. This journal is the Partner Organisations 2014.
Damodara, Dandu,Arundhathi, Racha,Ramesh Babu, T. Venkata,Legan, Margaret K.,Kumpaty, Hephzibah J.,Likhar, Pravin R.
p. 22567 - 22574
(2014/06/23)

Recognition between V- and dumbbell-shaped molecules
A series of 2,6-bis(imino)pyridyl-based V-shaped compounds bearing various para-substituents on the terminal aromatic rings [C5H 3N(CHN-C6H4R)2; R = OMe, iPr, Me, H, Cl, F, and CF3] have been prepared and investigated for their reversible binding with the dumbbell-shaped cations NH2+-{CH2-C6H3(OMe-3,5) 2}2 and 9-anthryl-CH2-NH2 +-CH2-C6H3(OMe-3,5)2. Three crystalline V-shaped compounds and a dumbbell hexafluorophosphate were characterised in the solid state by X-ray structural analysis. The binding mode of the 1 : 1 V-shaped molecule·dumbbell complexes was evaluated by 1H NMR spectroscopy. The binding constants (90-400 M-1 in dichloromethane) and stoichiometries of the complexes were determined using the Method of Continuous Variations and the Rose-Drago Method based on 1H NMR spectroscopic data. In a series of V-shaped compounds, the binding strength with both dumbbell cations diminishes with the decreasing electron-donating ability of the R substituents. Specifically, one of the diimine V-shaped compounds shows a stronger binding with the symmetrical dumbbell than with the unsymmetrical anthracene-containing dumbbell. Fluorescence measurements of equimolar mixtures of the V-shaped compounds and the unsymmetrical dumbbell have revealed a reduced anthracene emission which is approximately 50% that of the original intensity. Rapid and complete dissociation (5 min) of the V-shaped compounds from the dumbbells was realised using an excess of acid or base, whereas only partial dissociation of the complexes was achieved with a large excess of water (1 h).
Wong, Wing-Yan,Lee, Siu-Fung,Chan, Hoi-Shan,Mak, Thomas C.W.,Wong, Chi-Hin,Huang, Lau-Shan,Stoddart, J. Fraser,Leung, Ken Cham-Fai
p. 26382 - 26390
(2013/12/04)

Chemoselective transfer hydrogenation to nitroarenes mediated by cubane-type Mo3S4 cluster catalysts
Chemoselective cubes: Cubane-type [Mo3S4X 3(dmpe)3]+ clusters (dmpe=1,2-(bis) dimethylphosphinoethane), in combination with an azeotropic 5:2 mixture of HCOOH and NEt3 as the reducing agent, act as selective cluster catalysts (X=H) or precatalysts (X=Cl) for the transfer hydrogenation of functionalized nitroarenes, without the formation of hazardous hydroxylamines. Copyright
Sorribes, Iván,Wienh?fer, Gerrit,Vicent, Cristian,Junge, Kathrin,Llusar, Rosa,Beller, Matthias
experimental part
p. 7794 - 7798
(2012/10/08)

Efficient and highly selective iron-catalyzed reduction of nitroarenes
Pyrolysis of iron-phenanthroline complexes supported on carbon leads to highly selective catalysts for the reduction of structurally diverse nitroarenes to anilines in 90-99% yields. Excellent chemoselectivity for the nitro group reduction is demonstrated.
Jagadeesh, Rajenahally V.,Wienhoefer, Gerrit,Westerhaus, Felix A.,Surkus, Annette-Enrica,Pohl, Marga-Martina,Junge, Henrik,Junge, Kathrin,Beller, Matthias
supporting information; experimental part
p. 10972 - 10974
(2011/10/31)

A convenient and general ruthenium-catalyzed transfer hydrogenation of nitro- and azobenzenes
An easily accessible in situ catalyst composed of [{RuCl 2(p-cymene)}2] and terpyridine has been developed for the selective transfer hydrogenation of aromatic nitro and azo compounds. The procedure is general and the selectivity of the catalyst has been demonstrated by applying a series of structurally diverse nitro and azo compounds (see scheme).
Jagadeesh, Rajenahally V.,Wienhoefer, Gerrit,Westerhaus, Felix A.,Surkus, Annette-Enrica,Junge, Henrik,Junge, Kathrin,Beller, Matthias
experimental part
p. 14375 - 14379
(2012/01/14)

Na4W10O32/ZrO2 nanocomposite prepared via a sol-gel route: A novel, green and recoverable photocatalyst for reductive cleavage of azobenzenes to amines with 2-propanol
Sodium decatungstate-zirconia (Na4W10O32/ZrO2) nanocomposite was prepared through entrapment of Na4W10O32 into zirconia matrix by a sol-gel route. This new nanocomposite was characterized by means of X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), UV-vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and surface area measurement. The nanocomposite was used as a green and recyclable heterogeneous photocatalyst for rapid and efficient reductive cleavage of azobenzenes into their corresponding amines with 2-propanol as a hydrogen donor at room temperature under N2 atmosphere. The reductive cleavage occurs without hydrogenolysis or hydrogenation of reducible moieties, such as -NO2, -OH, -CH3, -OCH3, -COOH, -COCH3, halogen and -CN. The photocatalyst has been reused several times, without observable loss of activity and selectivity. According to the azobenzene reduction, the Na4W10O32/ZrO2 nanocomposite is more effective as a photocatalyst than pure Na4W10O32, showing that the nanocomposite approach could be an excellent choice to improve the photoactivity of POMs.
Farhadi, Saeid,Sepahvand, Shahnaz
experimental part
p. 75 - 84
(2010/06/15)

Easy copper-catalyzed synthesis of primary aromatic amines by coupling aromatic boronic acids with aqueous ammonia at room temperature
(Chemical Equation Presented) A reaction without the added extras: Aromatic boronic acids have been coupled using inexpensive aqueous ammonia to give primary aromatic amines under copper catalysis. This simple and highly efficient approach can be carried
Rao, Honghua,Fu, Hua,Jiang, Yuyang,Zhao, Yufen
supporting information; experimental part
p. 1114 - 1116
(2009/06/20)

Ecofriendly solvent free microwave enhanced alkyl migration in N-alkyl anilines in dry media conditions
A rapid, cleaner, cost effective and ecofriendly synthesis of exclusive para alkyl anilines in solvent free conditions using solid supports under microwave irradiation is achieved.
Selvakumar,Easwaramurthy,Raju
p. 713 - 715
(2008/09/18)

Nitroarene reduction using Raney nickel alloy with ammonium chloride in water
Aromatic nitroarenes are reduced in high yields using a user-friendly combination of Raney nickel alloy and ammonium chloride in water at 80-90°C.
Bhaumik, Kankan,Akamanchi
p. 197 - 198
(2007/10/03)

Biotransformation of phenylurea herbicides by a soil bacterial strain, Arthrobacter sp. N2: Structure, ecotoxicity and fate of diuron metabolite with soil fungi
In order to assess the influence of the aromatic substitution on the ability of a soil bacterial strain, Arthrobacter sp. N2, to degrade phenylurea herbicides, biotransformation assays were performed in mineral medium with resting cells of this soil bacterial strain on three phenylurea herbicides (diuron, chlorotoluron and isoproturon). Each herbicide considered, led to the formation of only one metabolite detected by HPLC analysis. After isolation, the metabolites were identified by NMR and MS, as the corresponding substituted anilines. According to the Microtox test (realized on the bacterium Vibrio fischeri), these metabolites presented non-target toxicity far more important (up to 600 times higher for 4-isopropylaniline) than the parent molecule. For isoproturon and chlorotoluron, the amount of substituted anilines obtained at the end of the biotransformation was very low, whereas the biotransformation of diuron into 3,4-dichloroaniline was almost quantitative. In this last case, the degradation product accumulated in the medium. In soil, other microorganisms are present that might degrade it. So the biotransformation of 3,4-dichloroaniline was then tested with four fungal strains: Aspergillus niger, Beauveria bassiana, Cunninghamella echinulata var. elegans and Mortierella isabellina. The aniline was further transformed with all the microorganisms tested. Only one metabolite was detected by HPLC analysis and after isolation, it was identified to be 3,4-dichloroacetanilide. This acetylated compound led to biological effects less important on V. fischeri than 3,4-dichloroaniline. These results stress the importance of identifying the degradation products to assess the impact of a polluting agent. Indeed, the pollutant may undergo transformation yielding compounds more toxic than the parent molecule.
Tixier,Sancelme,Ait-Aissa,Widehem,Bonnemoy,Cuer,Truffaut,Veschambre
p. 519 - 526
(2007/10/03)

Phenylureas. Part 1. Mechanism of the basic hydrolysis of phenylureas
The mechanism of the hydrolytic decomposition of phenylureas in basic media in the pH range 12 to 14 is investigated. In this pH range a levelling of the rate-pH curve is observed as well as a change of the substituent influence on the hydrolysis rate. These experimental findings suggest the formation of an unreactive side product of the phenylurea in a parasitic side equilibrium at sufficiently high pH. The urea dissociates at the aryl-NH group to give its conjugate base. For the hydrolytic decomposition of phenylureas an addition-elimination mechanism is proposed as has been established for the alkaline hydrolysis of carboxylic acid esters and amides.
Laudien,Mitzner
p. 2226 - 2229
(2007/10/03)

Phenylureas. Part 2. Mechanism of the acid hydrolysis of phenylureas
The mechanism of the hydrolytic decomposition of phenylureas in acid media is investigated. It includes, in part, knowledge already present in the literature. Over the investigated pH range the occurrence of a rate maximum in the pH curves due to the strongly reduced water activity at higher acid strengths is observed. An addition-elimination mechanism with rate-determining attack of water at the N-protonated substrate is proposed. The reversion of the substituent influence on the reaction rate with increasing acidity of the reaction medium points to a change of the hydrolytic decomposition mechanism in strongly acidic media.
Laudien, Robert,Mitzner, Rolf
p. 2230 - 2232
(2007/10/03)

Alkylation of aniline over base zeolites
Vapour phase alkylation of aniline with 2-propanol over Li, Na, K, Ca, Sr and Ba ion exchanged zeolites at atmospheric pressure gives N-alkylated and C-alkylated anilines. The N-alkylation selectivity increases with increase in basicity of the zeolite. The major product is the ortho-isomer. The effect of the basic nature of catalyst on the conversion and product selectivity has been evaluated. Co-existence of the acidic and basic sites in the alkali cation exchanged zeolites enhances the N-alkylation rather than the ring alkylation.
Pillai
p. 490 - 491
(2007/10/03)

Reduction of hydrazines, azo and azoxy compounds, and amine N-oxides with the NiCl2·2H2O-Li-DTBB (cat.) combination
The NiCl2·2H2O/Li/DTBB (10 mol%) combination allows the reduction of aromatic hydrazines 1 (to amines), azo compounds 2 (to primary amines), azoxy compounds 3 (to azo compounds or to primary amines, depending on the reaction conditions) or amine N-oxides 4 (to tertiary amines), under mild reaction conditions (THF, room temperature). (C) 2000 Elsevier Science Ltd.
Alonso, Francisco,Radivoy, Gabriel,Yus, Miguel
p. 8673 - 8678
(2007/10/03)

Isomerisation of N-isopropylaniline and N-n-propylaniline over zeolites
Reactions of N-isopropylaniline and N-n-propylaniline over, Ce, H and Na forms of ZSM-5 and Y type zeolites at 200-400° have been investigated. Both the secondary amines isomerised on zeolites to produce o-isopropylaniline and p-isopropylaniline through SN1 mechanism and also dealkylated to give aniline and propene. The ortho-isomer is the major C-alkylated product. Effects of temperature and flow rate on activity and selectivity have been studied.
Pillai
p. 157 - 158
(2007/10/03)

Palladium catalyzed cross-coupling reaction of Grignard reagents with halobenzoic acids, halophenols and haloanilines
Convenient syntheses of substituted benzoic acids, phenols and anilines have been achieved by using palladium catalyzed cross-coupling reactions between Grignard reagents and aryl halides containing carboxy, hydroxy and amino groups without a protection-deprotection sequence.
Bumagin, Nikolai A.,Luzikova, Elena V.
p. 271 - 273
(2007/10/03)

Direct Aromatic Amination by Azides: Reactions of Hydrazoic Acid and Butyl Azides with Aromatic Compounds in the Presence of Both Trifluoromethanesulfonic Acid and Trifluoroacetic Acid
Reactions of hydrazoic acid with aromatic compounds in the presence of both trifluoromethanesulfonic acid (TFSA) and trifluoroacetic acid (TFA) efficiently gave primary arylamines without diamine contaminants.The reactions provide mainly the ortho- and para-monoamines wven for readily oxidised aromatic compounds such as cumene, mesitylene, durene, isodurene and anisole.The mechanistic investigation demonstrates that the reactions proceed via a concerted process involving both arene attack on a conjugate acid of the azide and elimination of N2 from the conjugate acid.The reaction of butyl azide with benzene and mesitylene in the presence of both TFSA and TFA produced N-butylarylamines in low yields together with high yields of butanal via a butylnitrenium ion intermediate; a similar reaction with tert-butyl azide gave no tert-butylarylamines.
Takeuchi, Hiroshi,Adachi, Taki,Nishiguchi, Hideaki,Itou, Katsutaka,Koyama, Kikuhiko
p. 867 - 870
(2007/10/02)

Alkylation of aniline by 2-propanol over zeolites
The reaction of aniline with 2-propanol over Y and ZSM-5 zeolites in the vapour phase have been studied.N-alkylation selectively decreases as contact time/temperature is increased.The main C-alkyl product is the ortho-isomer.
Pillai, R B C,Pillai, C N
p. 592 - 594
(2007/10/02)

Process for the preparation of pure, unsymmetrically disubstituted ureas
Process for the preparation of pure, unsymmetrically disubstituted ureas of the general formula STR1 in which R denotes a phenyl radical which is unsubstituted, or monosubstituted or polysubstituted by halogen atoms or alkyl, alkoxy, aryloxy or trifluoromethyl groups, an oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, benzoxazolyl or benzothiazolyl radical which is unsubstituted, or monosubstituted or polysubstituted by halogen atoms or alkyl, alkoxy or trifluoromethyl groups and R1 and R2 independently of one another denote a hydrogen atom or an alkyl group, where R1 and R2 are not simultaneously hydrogen or R1 and R2 together denote a butylene or pentylene group, by reaction of an N-alkyl- or N,N-dialkylurea with an unsubstituted or substituted arylamine or a heterocyclic amine in the presence of that amine which is already present in the starting material, the respective N-alkyl- or N,N-dialkylurea.
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(2008/06/13)

Ortho-alkylated aromatic amines via gamma alumina catalyst
This invention relates to a process for producing ring alkylated aromatic amines. In the process an aromatic amine is reacted with an olefin using gamma alumina as a catalyst. Under the conditions of the process the catalyst is extremely active and with amines that are capable of alkylation at the ortho and para positions, high selectivity to the ortho alkylated isomer can be achieved. The catalyst is also effective for producing unsymmetrical disubstituted alkyl aromatic amines, e.g., ethyl or propyl toluidine where one ortho position is substituted with a methyl group and the other substituted with an ethyl or propyl group.
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(2008/06/13)

Intramolecular Selectivity of the Alkylation of Substituted Anilines by Gaseous Cations
The intramolecular selectivity of the electrophilic reactions of Et(1+), i-Pr(1+), and Me2F(1+) cations with substituted anilines, including m-toluidine, m-anisidine, and m- and p-fluoroaniline, has been investigated in the dilute gas state at pressures ranging from 100 to 720 torr by a radiolytic technique, complemented by chemical ionization mass spectrometry.The results indicate an appreciable kinetic bias for the nitrogen atom, leading to predominant N-methylation by Me2F(1+).The reactivity of the carbenium ions is complicated by the simultaneous occurrence of proton transfer, in particular to the NH2 group, which increases the relative extent of ring alkylation.The positional selectivity is characterized, aside from the usual orienting effects of the substituents, by the enchanced reactivity of the ring positions ortho to an n-type substituent, irrespective of its activating or deactivating properties.The effect is traced to the preliminary formation of an electrostatic adduct between the aniline and the gaseous electrophile.
Attina, Marina,Cacace, Fulvio,de Petris, Giulia
p. 1556 - 1561
(2007/10/02)

Aromatic Substitution in the Gas Phase. Intramolecular Selectivity of the Reaction of Aniline with Charged Electrophiles
The intramolecular selectivity of the electrophilic reactions of radiolytically formed C2H5+, i-C3H7+, t-C4H9+, (CH3)2F+, and CH3CO+ cations with aniline has been investigated in the gas phase at nearly atmospheric pressure.Under conditions of kinetic control of products, the reactivity of the N atom and of the aromatic ring is comparable, a mixture of ring- and N-substituted products being invariably formed in proportions that depend on the nature of the electrophile.The relative rate of N-substitution increases in the order: C2H5+ ca. i-C3H7++++.The positional selectivity of the gaseous electrophiles, except CH3CO+, is characterized by predominant ortho substitution.
Attina, Marina,Cacace, Fulvio
p. 1122 - 1126
(2007/10/02)