- Electrophilic Amination of Methylbenzenes with the System NaN 3-AlCl3-HCl. Effects of the Solvent, Crown Ether, and Substrate Structure
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Using mesitylene and o-xylene as examples, it was shown that the solvent nature strongly affects the conversion of methylbenzenes in electrophilic amination with the system NaN3-AlCl3-HCl. Two-parameter correlations were found between the substrate conversion, on the one hand, and dielectric constant and number of heavy atoms in the solvent, on the other. A considerable solvent effect on the regioselectivity of amination of o-xylene was observed. The presence of 18-crown-6 weakly affects the ratio of isomeric amines, but the conversion of o-xylene sharply decreases. Solid aromatic substrates, such as durene and pentamethylbenzene can also be involved in electrophilic amination with the system NaN3-AlCl3-HCl. On the basis of the experimental data and the results of quantum-chemical calculations, participation of a nitrenium intermediate in this reaction was postulated.
- Borodkin,Elanov,Popov,Pokrovskii,Shubin
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Read Online
- Aluminum Metal-Organic Framework-Ligated Single-Site Nickel(II)-Hydride for Heterogeneous Chemoselective Catalysis
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The development of chemoselective and heterogeneous earth-abundant metal catalysts is essential for environmentally friendly chemical synthesis. We report a highly efficient, chemoselective, and reusable single-site nickel(II) hydride catalyst based on robust and porous aluminum metal-organic frameworks (MOFs) (DUT-5) for hydrogenation of nitro and nitrile compounds to the corresponding amines and hydrogenolysis of aryl ethers under mild conditions. The nickel-hydride catalyst was prepared by the metalation of aluminum hydroxide secondary building units (SBUs) of DUT-5 having the formula of Al(μ2-OH)(bpdc) (bpdc = 4,4′-biphenyldicarboxylate) with NiBr2 followed by a reaction with NaEt3BH. DUT-5-NiH has a broad substrate scope with excellent functional group tolerance in the hydrogenation of aromatic and aliphatic nitro and nitrile compounds under 1 bar H2 and could be recycled and reused at least 10 times. By changing the reaction conditions of the hydrogenation of nitriles, symmetric or unsymmetric secondary amines were also afforded selectively. The experimental and computational studies suggested reversible nitrile coordination to nickel followed by 1,2-insertion of coordinated nitrile into the nickel-hydride bond occurring in the turnover-limiting step. In addition, DUT-5-NiH is also an active catalyst for chemoselective hydrogenolysis of carbon-oxygen bonds in aryl ethers to afford hydrocarbons under atmospheric hydrogen in the absence of any base, which is important for the generation of fuels from biomass. This work highlights the potential of MOF-based single-site earth-abundant metal catalysts for practical and eco-friendly production of chemical feedstocks and biofuels.
- Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Dwivedi, Ashutosh,Manna, Kuntal
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p. 3943 - 3957
(2021/04/12)
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- Pd nanoparticles/graphene quantum dot supported on chitosan as a new catalyst for the reduction of nitroarenes to arylamines
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A new heterogeneous catalyst was obtained by growing graphene quantum dots on chitosan and subsequent immobilization of Pd nanoparticles. The catalyst after characterization was used in the reduction of nitroarenes to the corresponding amines by NaBH4 as a weak reducing agent of nitro compounds. The catalyst exhibited excellent catalytic activity and selectivity under mild reaction conditions in water as a green solvent during 1?h. Additionally, the catalyst can be reused for five consecutive runs without any significant decrease in its activity and selectivity.
- Kalanpour, Nastaran,Nejati, Saeid,Keshipour, Sajjad
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p. 1243 - 1250
(2020/10/29)
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- Single-atom Fe-N4site for the hydrogenation of nitrobenzene: theoretical and experimental studies
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The hydrogenation of nitrobenzene to aniline is an important process in the industry of fine chemicals, but developing inexpensive catalysts with expected activity and selectivity still remains a challenge. By using density functional theory calculations, we demonstrated that the isolated Fe atom not only can weaken the adsorption of reactants and reaction intermediates as compared to Fe nanoparticles, but also remarkably decrease the reaction barrier for the hydrogenation of nitrobenzene to aniline. Thus, the Fe single-atom (Fe SA) catalyst is considered as an ideal catalyst for this reaction. This theoretical prediction has been subsequently confirmed by experimental results obtained for the Fe SAs loaded on N-doped hollow carbon spheres (Fe SAs/NHCSs) which achieved a conversion of 99% with a selectivity of 99% for the hydrogenation of nitrobenzene. The results significantly outperformed the Fe nanoparticles for this reaction. This work provides theoretical insight for the rational design of new catalytic systems with excellent catalytic properties.
- Dong, Panpan,He, Rong,Liu, Yan,Lu, Ning,Mao, Junjie,Wu, Konglin,Zhang, Wenzhuang,Zheng, Yamin
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supporting information
p. 7995 - 8001
(2021/06/21)
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- The immobilized Cu nanoparticles on magnetic montmorillonite (MMT?Fe3O4?Cu): As an efficient and reusable nanocatalyst for reduction and reductive-acetylation of nitroarenes with NaBH4
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In this study, the immobilization of copper nanoparticles on superparamagnetic montmorillonite, MMT?Fe3O4?Cu, was studied. Magnetically nanoparticles (MNPs) of iron oxide (Fe3O4) were primarily prepared by a chemical co-precipitation method. Next, the prepared Fe3O4 MNPs were intercalated within the interlamellar spaces and external surface of sodium-exchanged montmorillonite. Finally, Cu NPs were immobilized on magnetic montmorillonite by a simply mixing of an aqueous solution of CuCl2·2H2O with MMT?Fe3O4 followed by the reduction with NaBH4. Characterization of MMT?Fe3O4 clay system represented that through the immobilization of Fe3O4 MNPs, disordered-layers structure of MMT was easily reorganized to an ordered-layers arrangement. The synthesized composite systems were characterized using FT-IR, SEM, EDX, XRD, VSM, BET and ICP-OES analyses. SEM analysis exhibited that dispersion of Cu NPs, with the size distribution of 15–25 nm, on the surface of magnetic clay was taken place perfectly. BET surface analysis indicated that after the immobilization of Fe3O4 and Cu species, the surface area and total pore volume of MMT?Fe3O4?Cu system was decreased. Next, the Cu-clay nanocomposite system showed a perfect catalytic activity towards reduction of nitroarenes to anilines as well as reductive-acetylation of nitroarenes to acetanilides using NaBH4 and Ac2O in water as a green and economic solvent. The copper magnetic clay catalyst can be easily separated from the reaction mixture by an external magnetic field and reused for six consecutive cycles without the significant loss of its catalytic activity.
- Zeynizadeh, Behzad,Rahmani, Soleiman,Tizhoush, Hengameh
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- The immobilized copper species on nickel ferrite (NiFe2O4@Cu): a magnetically reusable nanocatalyst for one-pot and quick reductive acetylation of nitroarenes to N-arylacetamides
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In this study, a green protocol for synthesis of N-arylacetamides was introduced. Magnetically, nanoparticles of the immobilized copper species on nickel ferrite, NiFe2O4@Cu, were synthesized and then characterized using SEM, EDX, XRD, VSM, ICP-OES, BET and XPS analyses. The XPS analysis approved that the immobilized copper species on NiFe2O4 only contain Cu(0) and its oxide form as CuO. The prepared nanocomposite system represented a perfect catalytic activity toward one-pot and quick reductive acetylation of various nitroarenes to the corresponding N-arylacetamides. All reactions were carried out in a mixture of H2O–EtOH (1.5–0.5) within 2–10?min using the combination system of NaBH4 and Ac2O in a one-pot approach and via a two-step procedure. The utilized Cu nanocomposite was magnetically separated from the reaction mixture and reused for 5 consecutive cycles without the significant loss of its catalytic activity.
- Zeynizadeh, Behzad,Shokri, Zahra,Mohammadzadeh, Iman
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p. 859 - 870
(2019/12/24)
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- C-H Amination of Arenes with Hydroxylamine
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This Letter describes the development of a TiIII-mediated reaction for the C-H amination of arenes with hydroxylamine. This reaction is applied to a variety of electron-rich (hetero)arene substrates, including a series of natural products and pharmaceuticals. It offers the advantages of mild conditions (room temperature), fast reaction rates (30 min), compatibility with ambient moisture and air, scalability, and the use of inexpensive commercial reagents.
- See, Yi Yang,Sanford, Melanie S.
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supporting information
p. 2931 - 2934
(2020/04/09)
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- The immobilized Ni(II)-thiourea complex on silica-layered copper ferrite: A novel and reusable nanocatalyst for one-pot reductive-acetylation of nitroarenes
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In this study, magnetically nanoparticles of CuFe2O4@SiO2@PTMS@Tu@Ni(II) as novel and reusable catalyst were prepared. Synthesis of the Ni (II)-nanocatalyst was carried out through the complexation of Ni(OAc)2·4H2O with the immobilized thiourea on silica-layered CuFe2O4. The prepared nanocomposite system was then characterized using SEM, EDX, XRD, VSM, ICP-OES, Raman, UV–Vis and FT-IR analyses. Catalytic activity of the Ni(II)-CuFe2O4 system was investigated towards rapid reduction of aromatic nitro compounds to arylamines with sodium borohydride as well as one-pot reductive-acetylation of nitroarenes to acetanilides with NaBH4/Ac2O system without the isolation of intermediate arylamines. All reactions were carried out in H2O within 3–7?min to afford the products arylamines/acetanilides in high to excellent yields. Reusability of the Ni(II)-nanocatalyst was examined for seven consecutive cycles without the significant loss of the catalytic activity.
- Zeynizadeh, Behzad,Shokri, Zahra,Hasanpour Galehban, Morteza
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- Photocatalytic hydrogenation of nitroarenes: supporting effect of CoOx on TiO2 nanoparticles
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Cobalt oxide visible light-active photo-catalysts supported on TiO2 nanoparticles with varying amount of cobalt oxide [3% CoOx/TiO2 (A), 4% CoOx/TiO2 (B), 5% CoOx/TiO2 (C)] were synthesized by solid-state method followed by calcination. The as-synthesized catalysts were characterized by various techniques such as powder XRD, TEM, EDX, UV-Vis-DRS and XPS analysis. The photocatalytic activity of the as-synthesized materials was studied for the reduction of nitroarenes to the corresponding amines using hydrazine monohydrate as the reductant. Cobalt(ii) oxide is responsible for the reduction of nitroarenes and then, cobalt(iii) is reduced back to the original compound by hydrazine hydrate, thus ascertaining the catalytic nature of this hydrogenation process. XPS suggests the presence of Co(ii) in CoOx/TiO2.
- Amanchi, Srinivasa Rao,Ashok Kumar,Lakshminarayana, Bhairi,Satyanarayana,Subrahmanyam
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p. 748 - 754
(2019/01/10)
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- Synthesis of magnetic Fe3O4@SiO2@Cu–Ni–Fe–Cr LDH: an efficient and reusable mesoporous catalyst for reduction and one-pot reductive-acetylation of nitroarenes
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Abstract: Magnetically recoverable Fe3O4@SiO2@Cu–Ni–Fe–Cr LDH was prepared under co-precipitation conditions. Characterization of the mesoporous catalyst was confirmed using Fourier-transformed infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, vibration sample magnetometer, Brunauer–Emmett–Teller, thermogravimetric, differential thermogravimetric analyses and transmission electron microscopy. Reduction of nitroarenes to the corresponding arylamines and one-pot reductive-acetylation of nitroarenes to acetanilides were carried out successfully by nanoparticles of the immobilized Cu–Ni–Fe–Cr layered double hydroxide on silica-coated Fe3O4 in water as a green solvent. All reactions were carried out within 6–22?min affording arylamines and N-arylacetamides in high-to-excellent yields. Reusability of the core–shell nanocatalyst was examined six times without significant loss of its catalytic activity.
- Gilanizadeh, Masumeh,Zeynizadeh, Behzad
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p. 2821 - 2837
(2018/10/31)
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- Preparation method of o-xylene through 3-nitro-o-xylene
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The invention relates to a preparation method of o-xylene through 3-nitro-o-xylene. Initially 3-nitro-o-xylene undergoes a hydrogenation reaction to produce 3-amino-o-xylene, and then 3-amino-o-xyleneundergoes a hydrogenolysis reaction in hydrogen atmosphere to produce o-xylene. According to the method, 3-nitro-o-xylene is converted into o-xylene, and o-xylene can return to the production processof 4-nitro-o-xylene to be reused, so that the reasonable conversion problem of the by-product 3-nitro-o-xylene in the production process of 4-nitro-o-xylene is effectively solved, the cost of production materials is reduced, economic benefits of 4-nitro-o-xylene production are improved, and the method has industrial application value.
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Paragraph 0024; 0025; 0026
(2018/04/03)
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- Unprecedented catalytic performance in amine syntheses: Via Pd/g-C3N4 catalyst-assisted transfer hydrogenation
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The preparation of amine compounds is very important for both the chemical industry and renewable feedstock processing. Nevertheless, difficulties remain in finding a catalytic system that is sufficiently active and environmentally benign for producing amine compounds. In this work, we report that g-C3N4 nanosheets as support materials can significantly boost the efficiency of Pd nanoparticles for the reduction of nitro compounds to primary amines. Using formic acid as a hydrogen donor and water as a solvent, the optimized 5 wt% Pd/g-C3N4 catalyst exhibited an unprecedented performance in the conversion of nitrobenzene into aniline (achieving almost full conversion with an extremely high turnover frequency of 4770 h-1 at room temperature), yielding the best activity ever reported for heterogeneously catalyzing nitro compound reduction. Pd/g-C3N4 catalyst was also active for the one-pot reductive amination of carbonyl compounds with nitro compounds to obtain the corresponding secondary amines with excellent selectivity (>90%). We proposed that the protic N-H+ and hydridic Pd-H- on Pd/g-C3N4 are the active species for the transfer hydrogenation reaction of nitro compounds. Furthermore, Pd/g-C3N4 catalyst was highly stable with a wide scope in the syntheses of various amine compounds. This work will open up a new approach for the transfer hydrogenations of nitro compounds to produce primary or secondary amines in green chemistry.
- Xu, Xingliang,Luo, Jiajun,Li, Liping,Zhang, Dan,Wang, Yan,Li, Guangshe
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p. 2038 - 2046
(2018/05/24)
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- Synthesis and characterization of copper nanoparticles on walnut shell for catalytic reduction and C-C coupling reaction
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Walnut shell-stabilized copper nanoparticles (CuNP/WS) were successfully prepared by a simple reaction of copper sulfate and Sodium borohydride. Formation of copper nanoparticles in this bio-nanocomposite was observed by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscope (EDX). CuNP/WS was found to be an efficient, inexpensive, easy to prepare, green and reusable catalyst in the reduction of aromatic nitro and nitrile compounds to their corresponding amines with NaBH4 at 35 °C in aqueous medium. We continued our studies on the application of this nanocomposite in the classic Ullman reaction to synthesize biaryl. This method has the advantages of high yields, elimination of expensive stabilizer and homogeneous catalysts, simple methodology and easy work up. The catalyst can be recovered from the reaction mixture and reused several times without any significant loss of catalytic activity.
- Zamani, Asghar,Poursattar Marjani, Ahmad,Nikoo, Abbas,Heidarpour, Mojtaba,Dehghan, Ahmad
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p. 176 - 181
(2018/09/25)
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- Synthesis and characterization of magnetically nanoparticles of Fe3O4@APTMS@ZrCp2 as a novel and reusable catalyst for convenient reduction of nitro compounds with glycerol
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The present paper describes the synthesis of magnetically nanoparticles of zirconocene-modified magnetite, Fe3O4@APTMS@ZrCp2, as a new generation in heterogeneous and reusable type nanocatalysts. The prepared zirconocene nanocomposite was characterized using FT-IR, SEM, XRD, EDX, AGFM, ICP–OES, TGA and BET analyses. The core–shell nanocatalyst exhibited an excellent catalytic activity towards glycerol reduction of various nitro compounds to the corresponding amines. All reactions were carried out in H2O at room temperature (40–90?min) to afford amines in high to excellent yields. Reusability of the core–shell zirconocene was examined 5 times without significant loss of its catalytic activity.
- Zeynizadeh, Behzad,Sepehraddin, Farhad
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p. 2649 - 2657
(2017/11/06)
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- Magnetically nano core–shell Fe3O4@Cu(OH)x: a highly efficient and reusable catalyst for rapid and green reduction of nitro compounds
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Magnetically separable nano core–shell Fe3O4@Cu(OH)x with 22?% Cu content was prepared by the addition of sodium hydroxide to a mixture of CuCl2·2H2O and nano Fe3O4 in water. Characterization of the impregnated copper hydroxide was carried out by X-ray fluorescence (XRF), X-ray diffraction (XRD) atomic absorption spectroscopy (AAS), scanning electron microscopy (SEM), value stream mapping (VSM) and Brunauer–Emmett–Teller (BET) analysis. The core–shell nanocatalyst exhibited the excellent catalytic activity toward reduction of various nitro compounds to the corresponding amines with NaBH4. All reactions were carried out in H2O (55–60?°C) within 3–15?min to afford amines in high to excellent yields. Reusability of core–shell Cu(OH)x catalyst was examined 9?times without significant loss of its catalytic activity.
- Shokri, Zahra,Zeynizadeh, Behzad,Hosseini, Seyed Ali,Azizi, Behrooz
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p. 101 - 109
(2017/01/05)
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- Cu nanoparticles: a highly efficient non-noble metal catalyst for rapid reduction of nitro compounds to amines with NaBH4 in water
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The purely aqueous-phase reduction of a wide range of nitro compounds to the corresponding amines has been carried out with NaBH4 in the presence of inexpensive Cu nanoparticles as catalyst. The reactions were taken place in water (80?°C) within 4–15?min to give amines in high to excellent yields.
- Zeynizadeh, Behzad,Zabihzadeh, Mehdi,Shokri, Zahra
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p. 1487 - 1492
(2016/07/06)
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- Pd(0) supported on N-doped graphene quantum dot modified cellulose as an efficient catalyst for the green reduction of nitroaromatics
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A new efficient catalyst was introduced for the green reduction of nitroaromatics. The catalyst was obtained via modification of cellulose with N-doped graphene quantum dots and Pd nanoparticles. The new cellulose nanocomposite after characterization was applied as the catalyst in the reduction reaction of nitroaromatics using NaBH4 at room temperature. Aromatic amines were obtained as the product of the reduction reaction over 2 h. This reaction has green reaction conditions such as mild reaction conditions, high yield, green solvent and recyclable catalyst. Also, the recovered catalyst is applicable in the reduction reaction 6 times without significant decrease in activity.
- Keshipour, Sajjad,Adak, Kamran
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p. 89407 - 89412
(2016/10/03)
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- Electrophilic amination of aromatics with sodium azide in BF3-H2O
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Boron trifluoride monohydrate is an excellent Br?nsted acid catalyst system for a wide range of reactions. It is a non-oxidizing acid catalyst prepared easily by bubbling BF3 into water. We have found boron trifluoride monohydrate/sodium azide combination to be an efficient reagent system for aromatic electrophilic amination. The present method avoids the use of expensive superacids such as trifluoromethanesulfonic acid and provides a facile access to aromatic amines directly from aromatics.
- Prakash, G.K. Surya,Gurung, Laxman,Marinez, Eric R.,Mathew, Thomas,Olah, George A.
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supporting information
p. 288 - 291
(2016/01/12)
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- Rapid and green reduction of aromatic/aliphatic nitro compounds to amines with NaBH4 and additive Ni2B in H2O
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Abstract NaBH4 with catalytic amounts of Ni2B as an additive reagent reduced aromatic and aliphatic nitro compounds to the corresponding amines in high to excellent yields. Reduction reactions were carried out in H2O within 3-30 min at room temperature or 75-80 °C. The catalytic activity of Ni2B as an additive reagent was superior to using the in situ precipitated one.
- Zeynizadeh, Behzad,Zabihzadeh, Mehdi
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p. 1221 - 1226
(2015/06/02)
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- Iridium-catalyzed transfer hydrogenation of nitroarenes to anilines
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A simple and general homogeneous catalyst system composed of commercially available [Ir(cod)Cl]2 and 1,10-phenanthroline has been developed for the selective transfer hydrogenation of nitroarenes to anilines. It utilized the readily accessible 2-propanol as a hydrogen donor and had wide substrate scope. A careful mechanistic investigation through real-time detection and a series of controlled experiments with possible intermediates was also carried out, which showed that the transformation proceeds via both phenylhydroxylamine and azobenzene intermediates and the reduction of hydrazobenzene leading to aniline might be the rate-determining step.
- Chen, Shujie,Lu, Guoping,Cai, Chun
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p. 5360 - 5365
(2015/07/07)
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- Highly efficient chemoselective N-TBS protection of anilines under exceptional mild conditions in the eco-friendly solvent 2-methyltetrahydrofuran
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A straightforward chemoselective protection of anilines as N-TBS derivatives is described by using a suitable deprotonation of the amine with methyllithium in the environmentally friendly and safer substitute of THF, 2-methyltetrahydrofuran, under exceptional mild reaction conditions (0 °C, 30 min). Interestingly, the protecting group maybe cleaved efficiently by simple treatment of N-TBS-anilines with silica gel in ethanol-water.
- Pace, Vittorio,Alcantara, Andres R.,Holzer, Wolfgang
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supporting information; experimental part
p. 1986 - 1989
(2011/09/16)
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- Liquid-liquid-liquid phase transfer catalysis: A novel and green concept for selective reduction of substituted nitroaromatics
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The selective reduction of nitroaromatics to the corresponding amines is an important transformation since many aromatic amines exhibit biological activities and find a multitude of industrial applications, being intermediates for the synthesis of dyes, pharmaceuticals and agrochemicals. A variety of nitroaromatics dissolved in organic solvents was reduced by using aqueous sodium sulfide, and tetrabutylammonium bromide (TBAB) as the phase transfer catalyst by choosing appropriate concentrations which resulted in three immiscible liquid phases. Compared to L-L PTC, the L-L-L PTC offers much higher rates of reaction, better selectivities and repeated use of catalyst. The selectivities for the desired products were 100%.
- Yadav, Ganapati D.,Lande, Sharad V.
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p. 1235 - 1241
(2007/10/03)
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- Synthesis and spectroscopic characterization of 1-13C- and 4-13C-plastoquinone-9
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This paper presents the synthesis of 1-13C- and 4-13C-plastoquinone-9 and their characterization with NMR spectroscopy and mass spectrometry. The synthetic scheme has been further adapted to introduce 13C-labeled plastoquinones on all individual and on each combination of positions in the quinone ring. Also a two-step scheme is disclosed to prepare unlabeled plastoquinone-9. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Boers, Rutger B.,Randulfe, Yolanda Pazos,Van Der Haas, Hendrikus N. S.,Van Rossum-Baan, Marleen,Lugtenburg, Johan
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p. 2094 - 2108
(2007/10/03)
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- Xenon difluoride-trimethylsilyl isocyanate-triflic acid as a new system for the amination of aromatic compounds
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In the title system, OCNXeOSO2CF3 is formed, which readily oxidises iodobenzene to [PhI+-NCO -OTf]. The direct amination of aromatic substrates is possible with the use of XeF2-Me3SiNCO-CF3SO3H.
- Pirkuliev,Brel,Akhmedov,Zefirov,Stang
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p. 172 - 173
(2007/10/03)
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- 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
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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
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p. 867 - 870
(2007/10/02)
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- Electron Donor-Acceptor Complex Formation Involving 2,3-Dichloro-1,4-naphthoquinone and Aromatic Amines
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Spectrophotometric studies of donor-acceptor (D-A) equilibria involving 2,3-dichloro-1,4-naphthoquinone (DCINQ) and several aromatic amines have shown that they do not conform to 1:1 equilibria alone in dichloromethane solution.It is suggested that the results can be explained on the basis of formation of 1:2 (AD2), in addition to 1:1 (AD) complexes.The formation constants for both AD and AD2 complexes and their molar absorptivities have been evaluated by a computer analysis of the data.The calculated values of the oscillator strengths and transition moments confirm this suggestion.
- Jayadevappa, E. S.,Bundi, M. L.
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- Intramolecular Selectivity of the Alkylation of Substituted Anilines by Gaseous Cations
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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
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p. 1556 - 1561
(2007/10/02)
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- Process for producing methylhydrazines
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Methylhydrazines are produced in high yield by reaction of trimethylanilinium halide with hydrazine or monomethylhydrazine at a reaction temperature of 80° to 130° C. for at least 3 hours. Methylhydrazines are useful compounds in the fields of chemical industry, such as manufacturing pharmaceuticals or agricultural chemicals, and space weapon industry.
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- Indanthrene dyes
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A process for the preparation of a vat dye of the dianthraquinone-azine or dianthraquinone-N,N'-dihydroazine series, or a higher cyclic homologue thereof, which comprises reacting a primary amine selected from the group consisting of amino anthraquinones, their substitution products and higher cyclic homologues, with an alkaline condensing agent, wherein reaction is effected in the presence of at least one oxide of an organic derivative of a metalloid element of Group 5B of the Periodic Classification of the elements.
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- 2-Chloro-N-isopropyl-2',3'-dimethylacetanilide as a herbicidal agent
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This invention relates to 2-chloro-N-isopropyl 2',3'-dimethylacetanilide, a method for the preparation thereof, and a method for the control of undesirable plant species therewith.
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- Imides of 1,1'-dinaphthyl-4,4',5,5',8,8'-hexacarboxylic acid
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Novel dinaphthyl derivatives characterized by the general formula SPC1 heterocycle, Where X1, X2, and X3, X4 represent a group O=C--Y--C=O, wherein Y is an imino group, either unsubstituted or containing one of the following substituents: alkyl, cycloalkyl, aryl, and neterocycle, either unsubstituted or containing one of the following substituents: amino group, halogen, alkoxy, alkyl; or one X of the pair X1, X2 ; and one X of the pair X3, X4 represent a group --C=O and then the other X is in the benzimidazole or perinone cycle, the compounds of said formula being either symmetrical or non-symmetrical with respect to the 1,1'-bond. Said derivatives are produced by reacting 1,1'-dinaphthyl-4,4',5,5',8,8' hexacarboxylic acid with a compound of the general formula R-NH2, where R is hydrogen, alkyl, cycloalkyl, aryl, or heterocycle, either unsubstituted or containing one of the substituents: amino group, halogen, alkoxy, alkyl, in a solvent or in excess compound of the formula R-NH2. Said derivatives are employed for producing perylenetetracarboxylic acid derivatives either in their free form or directly on a textile material in the process of dyeing or textile printing.
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