- Radical Anion Promoted Chemoselective Cleavage of Csp2-S Bond Enables Formal Cross-Coupling of Aryl Methyl Sulfones with Alcohols
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A novel formal cross-coupling of aryl methyl sulfones and alcohols affording alkyl aryl ethers via an SRN1 pathway is developed. Two marketed antitubercular drugs were efficiently prepared employing this approach as the key step. A dimsyl-anion initiated radical chain process was revealed as the major pathway. DFT calculations indicate that the formation of a radical anion via nucleophilic addition of alkoxide to the aryl radical is the key step in determining the observed chemoselectivity.
- Bai, Jixiang,Wang, Tianxin,Dai, Botao,Liu, Qingchao,Yu, Peiyuan,Jia, Tiezheng
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Read Online
- Nucleophilic aromatic cine-substitution of hydrogen: The ionic liquid-promoted von Richter reaction
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Conversion of 4-R-nitrobenzenes into 3-R-benzoic acids under the action of KCN in the EtOH-H2O mixture (the von Richter reaction) is significantly accelerated by ionic liquids thus allowing to extend the scope of the reaction. The finding is pi
- Epishina, Margarita A.,Kulikov, Alexander S.,Ignat'ev, Nikolai V.,Schulte, Michael,Makhova, Nina N.
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Read Online
- Microwave chemistry in silicon carbide reaction vials: Separating thermal from nonthermal effects
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Running oil-bath chemistry in a microwave! Using reaction vials made out of strongly microwave-absorbing silicon carbide (SiC) in a microwave reactor simulates experiments conducted in an autoclave with conductive heating because of the efficient shielding of the electromagnetic field by the SiC vial. This technology makes it possible to study the significance of microwave effects.
- Obermayer, David,Gutmann, Bernhard,Oliver Kappe
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Read Online
- Ethoxylation of o, p-nitrochlorobenzene using phase transfer catalysts by microwave irradiation
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Microwave irradiation is very efficient to accelerate the rate of ethoxylation of o, p - nitrochlorobenzene. The enhancement of reaction rate is 144-240 fold
- Yungcheng,Dabin,Yulin
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Read Online
- Chromogenic nitrophenolate-based substrates for light-driven hybrid P450 BM3 enzyme assay
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The incorporation of a p-nitrophenoxy moiety in substrates has enabled the development of colorimetric assays to rapidly screen for O-demethylation activity of P450 enzymes. For the light-driven hybrid P450 BM3 enzymes, where a Ru(II) photosensitizer powers the enzyme upon visible light irradiation, we have investigated a family of p-nitrophenoxy derivatives as useful chromogenic substrates compatible with the light-driven approach. The validation of this assay and its adaptability to a 96-well plate format will enable the screening of the next generation of hybrid P450 BM3 enzymes towards C-H bond functionalization of non-natural substrates.
- Lam, Quan,Cortez, Alejandro,Nguyen, Thanh Truc,Kato, Mallory,Cheruzel, Lionel
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Read Online
- Valorisation of urban waste to access low-cost heterogeneous palladium catalysts for cross-coupling reactions in biomass-derived γ-valerolactone
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Herein we report a simple protocol for the valorisation of a common urban biowaste. The lignocellulosic biomass obtained after the pre-treatment of pine needle urban waste is efficiently transformed into a low-cost support (PiNe) for the immobilization of Pd nanoparticles. The final Pd/PiNe heterogeneous catalyst features a small particle size (4.5 nm) and a metal loading (9.9 wt%) comparable with most commercially available and generally used counterparts. In this contribution, we tested the catalytic efficiency of the Pd/PiNe system in two representative cross-couplings, Heck and Hiyama reactions, and compared the results obtained with commercial Pd/C catalyst. The good reactivity in the biomass-derived solvent (GVL) confirms that the Pd/PiNe heterogeneous catalyst is a valid system that can be integrated into a waste valorization chain within a circular economy approach. In addition, the efficiency of the catalyst has also been extended to perform the challenging consecutive Hiyama-Heck reaction to afford differently substituted (E)-1,2-diarylethenes.
- Valentini, Federica,Ferlin, Francesco,Lilli, Simone,Marrocchi, Assunta,Ping, Liu,Gu, Yanlong,Vaccaro, Luigi
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p. 5887 - 5895
(2021/08/23)
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- Photoinduced Iron-Catalyzed ipso-Nitration of Aryl Halides via Single-Electron Transfer
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A photoinduced iron-catalyzed ipso-nitration of aryl halides with KNO2 has been developed, in which aryl iodides, bromides, and some of aryl chlorides are feasible. The mechanism investigations show that the in situ formed iron complex by FeSO4, KNO2, and 1,10-phenanthroline acts as the light-harvesting photocatalyst with a longer lifetime of the excited state, and the reaction undergoes a photoinduced single-electron transfer (SET) process. This work represents an example for the photoinduced iron-catalyzed Ullmann-type couplings.
- Wu, Cunluo,Bian, Qilong,Ding, Tao,Tang, Mingming,Zhang, Wenkai,Xu, Yuanqing,Liu, Baoying,Xu, Hao,Li, Hai-Bei,Fu, Hua
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p. 9561 - 9568
(2021/08/06)
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- Mustard Carbonate Analogues as Sustainable Reagents for the Aminoalkylation of Phenols
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N,N-dialkyl ethylamine moiety can be found in numerous scaffolds of macromolecules, catalysts, and especially pharmaceuticals. Common synthetic procedures for its incorporation in a substrate relies on the use of a nitrogen mustard gas or on multistep syntheses featuring chlorine hazardous/toxic chemistry. Reported herein is a one-pot synthetic approach for the easy introduction of aminoalkyl chain into different phenolic substrates through dialkyl carbonate (β-aminocarbonate) chemistry. This new direct alcohol substitution avoids the use of chlorine chemistry, and it is efficient on numerous pharmacophore scaffolds with good to quantitative yield. The cytotoxicity via MTT of the β-aminocarbonate, key intermediate of this synthetic approach, was also evaluated and compared with its alcohol precursor.
- Annatelli, Mattia,Trapasso, Giacomo,Salaris, Claudio,Salata, Cristiano,Castellano, Sabrina,Aricò, Fabio
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supporting information
p. 3459 - 3464
(2021/05/24)
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- Preparation method of p-nitrophenetole and special loop reactor
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The invention discloses a preparation method of p-nitrophenetole, which takes p-nitrochlorobenzene, sodium hydroxide and ethanol as raw materials to perform etherification reaction to prepare the p-nitrophenetole. Wherein p-nitrophenetole is prepared by a
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Paragraph 0033-0068
(2021/06/22)
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- Production method of o/p-nitrophenetole
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The invention discloses a production method of o/p-nitrophenetole, which comprises the following steps: (1) adding o/p-nitrochlorobenzene and ethanol into a four-neck flask provided with a heating reflux matching device, then adding N-methylmorpholine, co
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Paragraph 0036-0050
(2021/06/09)
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- Aryl Ether Syntheses via Aromatic Substitution Proceeding under Mild Conditions
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In this study, mild conditions for aromatic substitutions during the syntheses of aryl ethers were developed. In the reaction conditions, the choices of solvent, base, and the sequence for the addition of the reagents proved important. A wide variety of alcohols were used directly as nucleophiles and smoothly reacted with aryl chlorides that possessed either a nitro or a cyano group at either the ortho- or para-position. Controlled experiments we performed suggested that the reaction underwent a charge-transfer process mediated by a combination of DMF and tert-BuOK.
- Ando, Shin,Tsuzaki, Marina,Ishizuka, Tadao
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p. 11181 - 11189
(2020/10/12)
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- Reversible Formation of a Light-Responsive Catalyst by Utilizing Intermolecular Cooperative Effects
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A photoresponsive system where structure formation is coupled to catalytic activity is presented. The observed catalytic activity is reliant on intermolecular cooperative effects that are present when amphiphiles assemble into vesicular structures. Photoresponsive units within the amphiphilic pre-catalysts allow for switching between assembled and disassembled states, thereby modulating the catalytic activity. The ability to reversibly form cooperative catalysts within a dynamic self-assembled system represents a conceptually new tool for the design of complex artificial systems in water.
- Ren, Chloe Z.-J.,Solís Mu?ana, Pablo,Dupont, Julien,Zhou, Silvia Siru,Chen, Jack L.-Y.
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supporting information
p. 15254 - 15258
(2019/10/22)
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- A new alkylation of aryl alcohols by boron trifluoride etherate
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The ethylation of aryl alcohols by an ethyl moiety of boron trifluoride etherate is described. The reaction proceeded cleanly and afforded good yields of the corresponding aryl ethyl ethers. It tolerated the presence of functional groups such as aryl, alkyl, halogens, nitro, nitrile, and amino. However, the presence of amino or nitro groups ortho to a hydroxyl group of an aryl compound drastically reduced the yields of the anticipated products due to the chelation of the aforementioned functional groups with boron trifluoride etherate. A nitrogen atom in the aromatic ring system, as exemplified by hydroxypyridine and 8-hydroxyquinoline, completely inhibited the reaction. Resorcinol, hydroquinone, and aryl alcohols with aldehyde functions decomposed under the reaction conditions.
- Jumbam, Ndze Denis,Maganga, Yamkela,Masamba, Wayiza,Mbunye, Nomthandazo I.,Mgoqi, Esethu,Mtwa, Sphumusa
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- The heliconical nematic twist-bend phase from “classic” bent-core benzylideneanilines with oligomethylene cores
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We report the synthesis and properties of several new heliconical twist-bend nematic (NTB) bimesogens possessing “classic” bent-core benzylideneaniline wings combined with oligomethylene spacers of odd parity. While short alkoxy tails combined with a resorcinol diester core in the classic system appear to give SmA phases (not B2 phases), in the present system, methoxy or ethoxy tails exhibit the NTB phase as evidenced by textural analysis. Several of these compounds also exhibit microscopic helical defect structures in the NTB phase, which have been reported in other lamellar and pseudo-lamellar liquid crystal phases, but not in the NTB phase.
- Scarbrough, Alyssa N.,Tuchband, Michael R.,Korblova, Eva D.,Shao, Renfan,Shen, Yongqiang,Maclennan, Joseph E.,Glaser, Matt A.,Clark, Noel A.,Walba, David M.
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p. 430 - 438
(2017/05/26)
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- Catalyzed preparation process of paranitrophenetole
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The invention discloses a catalyzed preparation process of paranitrophenetole. P-nitrophenol and diethyl carbonate are adopted as raw materials so as to be catalyzed for 1 to 5 hours at the temperature of 100 to 200 DEG C, the molar ratio of the diethyl carbonate to the p-nitrophenol is (5 to 15) to 1, a catalyst is a titania-silica composite material, and the additive amount of the catalyst is 6 to 10 percent of the mass of the p-nitrophenol. A preparation method of the catalyst comprises the following steps of S1, preparing a silicon solution from the following raw materials in parts by weight: 20 to 30 parts of silicon source, 5 to 15 parts of surface active agent, and 60 to 80 parts of deionized water; S2, preparing a titanium solution from the following raw materials in parts by weight: 20 to 30 parts of titanium source and 60 to 80 parts of deionized water; S3, adding the titanium solution into the silicon solution, and stirring for 1 to 2 hours at the temperature of 50 to 70 DEG C to obtain a titanium-silicon mixed solution; S4, adding zinc sulfate and nano-barium sulfate into the titanium-silicon mixed solution; S5, spray drying a solution obtained through the S4; S6, roasting a product obtained through the S5 to obtain the catalyst, wherein the molar ratio of Ti element and Si element in the titania-silica composite material is (2 to 4) to 1.
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Paragraph 0020; 0021; 0023; 0024; 0026; 0027; 0029-0044
(2017/06/22)
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- Design and Performance Validation of a Conductively Heated Sealed-Vessel Reactor for Organic Synthesis
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A newly designed robust and safe laboratory scale reactor for syntheses under sealed-vessel conditions at 250 °C maximum temperature and 20 bar maximum pressure is presented. The reactor employs conductive heating of a sealed glass vessel via a stainless steel heating jacket and implements both online temperature and pressure monitoring in addition to magnetic stirring. Reactions are performed in 10 mL borosilicate vials that are sealed with a silicone cap and Teflon septum and allow syntheses to be performed on a 2-6 mL scale. This conductively heated reactor is compared to a standard single-mode sealed-vessel microwave instrument with respect to heating and cooling performance, stirring efficiency, and temperature and pressure control. Importantly, comparison of the reaction outcome for a number of different synthetic transformations performed side by side in the new device and a standard microwave reactor suggest that results obtained using microwave conditions can be readily mimicked in the operationally much simpler and smaller conventionally heated device.
- Obermayer, David,Znidar, Desiree,Glotz, Gabriel,Stadler, Alexander,Dallinger, Doris,Oliver Kappe
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p. 11788 - 11801
(2016/12/09)
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- NITRATION OF AROMATIC COMPOUNDS
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The present invention provides a process for nitrating aromatic compounds without the need for a solid catalyst and/or any organic solvents and/or any other additives. A typical process includes combining or admixing a nitric acid and an anhydride compound under conditions sufficient to produce a reactive intermediate. The aromatic compound to be nitrated is then added to this reactive intermediate to produce a nitroaromatic compound. The nitroaromatic compound can be substituted with one or more, typically, one to three, and often one or two nitrate (-NO2) groups.
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Paragraph 0048
(2016/08/17)
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- Method for synthesis of phenacetin drug intermediate paranitrophenetole
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A method for synthesis of the phenacetin drug intermediate paranitrophenetole comprises the steps of adding 1200 ml of ethyl alcohol, 1.83 mol of paranitroaniline and 0.61 mol of cuprous chloride into a reaction vessel, controlling stirring speed to be 130-160 rpm, increasing solution temperature to 60-65 DEG C, adding 0.56 mol of sodium sulfite, increasing solution temperature to 80-85 DEG C, maintaining the backflow state for 80-120 min, adding 0.31-0.33 mol of potassium bisulfite in batches for continuous reaction lasting 18-21 h, conducting filtration, washing a filter cake with nitromethane, conducting filtrate and washing liquid combination, conducting distillation recovery of nitromethane, washing residues with potassium chloride solution for 5-7 times, conducting cooling and solidification in sequence, conducting suction filtration, conducting washing with saline solution, conducting dehydration with a dehydrating agent, conducting washing with propionitrile, and conducting recrystallization in ethyl acetate, so that paranitrophenetole crystals are obtained, wherein the mass fraction of potassium bisulfite is 30-35%, the mass fraction of nitromethane is 65-70%, the mass fraction of potassium chloride solution is 15-20%, and saline solution is potassium nitrate or sodium sulfate.
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Paragraph 0014; 0015
(2016/11/07)
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- Properties of liquid crystals and Cu2+ recognition based on Schiff bases
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Two series of new Schiff base compounds were synthesized. For Schiff base compounds with a pyridine nitrogen atom in 4-position (7a-e), their supramolecular hydrogen bonding complexes show good liquid crystal properties. However, no liquid crystal property is observed for 8a-e. Results of theoretical calculations demonstrate that it is the intermolecular hydrogen bond of Schiff base compounds (8a-e) that prevents the formation of supramolecular hydrogen bonding. The Schiff base compounds, with terminal alkoxy chains, can recognize Cu2+ selectively with a color change. Nevertheless, others cannot recognize Cu2+.
- Liu, Zhilian,Yu, Zhenning,Zhang, Jian,Zhang, Shuxiang
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- Ipso-Nitrosation of arylboronic acids with chlorotrimethylsilane and sodium nitrite
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Nitroso compounds are versatile reagents in synthetic organic chemistry. Herein, we disclose a feasible protocol for the ipso-nitrosation of aryl boronic acids using chlorotrimethylsilane-sodium nitrite unison as nitrosation reagent system.
- Prakash, G.K. Surya,Gurung, Laxman,Schmid, Philipp Christoph,Wang, Fang,Thomas, Tisa Elizabeth,Panja, Chiradeep,Mathew, Thomas,Olah, George A.
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p. 1975 - 1978
(2014/04/03)
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- Liquid-crystalline polymorphism of 4-heptyloxybenzylidene-4′- alkyloxyanilines and their phase equilibrium with 4-octyloxyphenyl 4-nitrobenzoate
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This paper describes the synthesis and liquid-crystalline properties of the homologous series of 4-heptyloxybenzylidene-4′-alkyloxyanilines (7-n). Six of them are presented for the first time. Based on the polarization microscopy (POM and TOA methods) and the calorimetric (DSC) measurements following polymorphism has been detected: nematic, smectic C and smectic I mesophases. The presence of these mesophases was confirmed by the miscibility method, using 4-octyloxyphenyl 4-nitrobenzoate and terephtal-bis (4-butyloaniline) as a mesophase references. Extraordinary results have been found in the mixtures of the investigated compounds with 4-octyloxyphenyl 4-nitrobenzoate; Induced smectic A has been observed, which is connected with very strong intermolecular interactions. Additionally destabilization of nematic and smectic C phases was visible.
- Godzwon, Joanna,Sienkowska, Monika J.,Galewski, Zbigniew
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scheme or table
p. 75 - 82
(2012/04/04)
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- Alkoxylation of 4-chloronitrobenzene with aliphatic alcohols and glycols in the presence of NaOH
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The reaction of 4-chloronitrobenzene with aliphatic C1-n-C 4 alcohols and with mono-, di-, and triethylene glycols in the presence of NaOH in liquid ammonia at 15-50°C was studied.
- Malykhin, E. V.,Shteingarts, V. D.
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p. 1232 - 1238,7
(2020/09/09)
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- Bis(μ-iodo)bis[(-)-sparteine]-dicopper: A versatile catalyst for direct O-Arylation and O-Alkylation of phenols and aliphatic alcohols with haloarenes
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The easy to prepare dimeric bis(μ-iodo)bis[(-)-sparteine]- dicopper ([CuI{(-)-spa}]2 complex) is shown to be versatile catalyst for O-arylation and O-alkylation with various aryl halides with phenols and aliphatic alcohols respectively, including less reactive aryl chlorides, such as chlorobenzene under mild conditions.
- Satyanarayana, Ponnam,Maheswaran, Hariharasarma,Kantam, Mannepalli Lakshmi,Bhargava, Suresh
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supporting information; experimental part
p. 788 - 790
(2011/08/22)
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- Synthesis of substituted acetylenes, aryl-alkyl ethers, 2-alkene-4-ynoates and nitriles using heterogeneous mesoporous Pd-MCM-48 as reusable catalyst
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Pd-MCM-48 has been employed as a heterogeneous catalyst for the synthesis of substituted acetylenes via Sonogashira reactions under copper and amine-free reaction conditions. In addition, the catalyst exhibited excellent regioselectivity for primary alcohols towards C-O coupling leading to formation of alkyl-aryl ethers in high yields. A green procedure for the stereoselective synthesis of 2-alkene-4-ynoates and nitriles from the reactions of vic-(E)-diiodoalkenes with activated alkenes has also been demonstrated using Pd-MCM-48 catalyst. The catalyst was easily recovered from the reaction mixture by filtration and reused for at least six times with minimal loss of activity.
- Banerjee, Subhash,Khatri, Hari,Balasanthiran, Vagulejan,Koodali, Ranjit T.,Sereda, Grigoriy
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scheme or table
p. 5717 - 5724
(2011/08/21)
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- Temperature dependence of regioselectivity in nucleophilic photosubstitution of 4-nitroanisole. The activation energy criterion for regioselectivity
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Photosubstitution of the nitro group vs the methoxy group of triplet 4-nitroanisole by hydroxide ion in water leads to product yields of about 80% 4-methoxyphenol and 20% 4-nitrophenol. The ratio depends slightly on temperature from 3 to 73 °C. The slight temperature variation in the yield ratio is reproduced almost perfectly with a simple Arrhenius model for a mechanism involving bonding of hydroxide ion with the triplet state of 4-nitroanisole. The competing transition states have activation energies of 2.2 and 2.6 kcal/mol, respectively. Correct prediction of regioselectivity can be done for this case by quantum chemical calculation of the competing triplet transition-state energies, or those of the corresponding triplet σ-complexes. Other models for aromatic photosubstitution regioselectivity in mechanisms of the S N2Ar* type, such as those based on calculated electron densities, HOMO/LUMO coefficients, or energy gap sizes, are discussed and shown to be inferior to the relative activation energies model. The photoreaction in alcohol solvents, claimed by others to generate the same products as in water and to have an exceedingly large variation of the product ratio with temperature, may reflect chemical changes other than those reported.
- Wubbels, Gene G.,Danial, Hanan,Policarpio, Danielle
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p. 7726 - 7733
(2011/03/17)
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- Sintered silicon carbide: A new ceramic vessel material for microwave chemistry in single-mode reactors
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Silicon carbide (SiC) is a strongly microwave absorbing chemically inert ceramic material that can be utilized at extremely high temperatures due to its high melting point and very low thermal expansion coefficient. Microwave irradiation induces a flow of electrons in the semiconducting ceramic that heats the material very efficiently through resistance heating mechanisms. The use of SiC carbide reaction vessels in combination with a single-mode microwave reactor provides an almost complete shielding of the contents inside from the electromagnetic field. Therefore, such experiments do not involve electromagnetic field effects on the chemistry, since the semiconducting ceramic vial effectively prevents microwave irradiation from penetrating the reaction mixture. The involvement of electromagnetic field effects (specific/nonthermal microwave effects) on 21 selected chemical transformations was evaluated by comparing the results obtained in microwave-transparent Pyrex vials with experiments performed in SiC vials at the same reaction temperature. For most of the 21 reactions, the outcome in terms of conversion/purity/product yields using the two different vial types was virtually identical, indicating that the electromagnetic field had no direct influence on the reaction pathway. Due to the high chemical resistance of SiC, reactions involving corrosive reagents can be performed without degradation of the vessel material. Examples include high-temperature fluorine-chlorine exchange reactions using triethylamine trihydrofluoride, and the hydrolysis of nitriles with aqueous potassium hydroxide. The unique combination of high microwave absorptivity, thermal conductivity, and effusivity on the one hand, and excellent temperature, pressure and corrosion resistance on the other hand, makes this material ideal for the fabrication of reaction vessels for use in microwave reactors. Simulating conductive heat transfer in a microwave: Using reaction vials made out of strongly microwave-absorbing silicon carbide (SiC) in a microwave reactor simulates a conductively heated autoclave experiment due to efficient shielding of the electromagnetic field by the SiC vial. Advantages of SiC vials for microwave processing include their excellent corrosion resistance, thermal stability, and high thermal effusivity and conductivity.
- Gutmann, Bernhard,Obermayer, David,Reichart, Benedikt,Prekodravac, Bojana,Irfan, Muhammad,Kremsner, Jennifer M.,Kappe, C. Oliver
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supporting information; experimental part
p. 12182 - 12194
(2011/02/23)
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- Solvent-free synthesis of aryl ethers promoted by tetrabutylammonium fluoride
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The reaction of aryl fluorides with silyl reagents has been shown to be efficiently promoted by tetrabutylammonium fluoride, providing aryl ethers with good to excellent yields under solvent-free conditions. The efficiency of this reaction was demonstrate
- Xiong, Wei,Ding, Quansheng,Chen, Jiuxi,Ding, Jinchang,Wu, Huayue
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experimental part
p. 395 - 398
(2010/11/18)
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- Triton B-mediated efficient and convenient alkoxylation of activated aryl and heteroaryl halides
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A simple and convenient one-pot synthesis of aryl alkyl ethers by the alkoxylation of aryl halides with alcohol in the presence of Triton B as a base is described. The procedure is applicable for a variety of aryl and heteroaryl halides, and yields are very good. The use of a nonmetallic base and solvent-free conditions are important features of the reaction. Copyright Taylor & Francis Group, LLC.
- Meshram,Goud, P. Ramesh,Reddy, B. Chennakesava,Kumar, D. Aravind
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experimental part
p. 2122 - 2129
(2010/08/13)
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- Palladium-catalysed synthesis of aryl-alkyl ethers using alkoxysilanes as nucleophiles
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Changing the activator from tetrabutyl ammonium fluoride (TBAF) to sodium hydroxide unexpectedly switches the catalytic pathway of the Hiyama coupling reaction of vinyl trialkoxysilanes with aryl bromides into a Pd catalysed C-O bond forming reaction; if
- Milton, Edward J.,Fuentes, Jose A.,Clarke, Matthew L.
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experimental part
p. 2645 - 2648
(2009/10/30)
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- Oxidation of anilines with hydrogen peroxide and selenium dioxide as catalyst
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A variety of substituted anilines are selectively oxidized to afford high yields of azoxyarenes by using 30% hydrogen peroxide and selenium dioxide as catalyst in methanol at room temperature. The oxidation of 4-alkoxyanilines under the same reaction conditions furnishes the corresponding 4-alkoxy-N-(4-nitrophenyl)anilines in reasonable yields, alongside other oxidation byproducts. The structure of 4-methoxy-N-(4-nitrophenyl)aniline is elucidated by X-ray crystal structure analysis. From these results, some general aspects of the reaction pathways of aniline oxidation are discussed.
- Gebhardt, Christin,Priewisch, Beate,Irran, Elisabeth,Rueck-Braun, Karola
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body text
p. 1889 - 1894
(2009/04/04)
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- An efficient intermolecular BINAM-copper(I) catalyzed Ullmann-type coupling of aryl iodides/bromides with aliphatic alcohols
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A wide range of alkyl aryl ethers are synthesized from the corresponding aryl iodides and aliphatic alcohols through Ullmann-type intermolecular coupling reactions in the presence of a catalytic amount of easily available BINAM-CuI complex. Less reactive aryl bromides have also been shown to react with aliphatic alcohols under identical reaction conditions to give good yields of the alkyl aryl ethers without increasing the reaction temperature and time.
- Naidu, Ajay B.,Sekar
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p. 3147 - 3151
(2008/09/20)
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- Smectic polymorphism of 4-nonyloxybenzylidene-4′-alkyloxyanilines
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This paper describes liquid-crystalline polymorphism of the homologous series of 4-nonyloxybenzylidene-4′-alkyloxyanilines. Based on the polarization microscopy (POM, TOA) and the calorimetric (DSC) measurements the following mesophases were detected: nematic, smectic A, smectic C, smectic B, smectic I and smectic G. The presence of these mesophases was confirmed by the miscibility method, using: 4-heptyloxybenzilidene-4′-pentylaniline, 4-hexyl-4′-decyloxyazobenzene and 4-nonyloxybenzilidene-4′-butylaniline as mesophase references. Influence of the alkyl chain length on the type of mesophases and entropic effects of phase transition are discussed.
- Godzwon, Joanna,Sienkowska, Monika J.,Galewski, Zbigniew
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p. 259 - 267
(2008/03/13)
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- Diastereoselective synthesis of meso-bisphosphonates from trialkyl(aryl) phosphites and activated acetylenes in the presence of 4-nitrophenol
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The reaction between trialkyl(aryl) phosphites and dibenzoylacetylene or dimethyl acetylenedicarboxylate in the presence of 4-nitrophenol leads to stable meso-bisphosphonate derivatives in good yields. Springer-Verlag 2006.
- Yavari, Issa,Hossaini, Zinatossadat,Alizadeh, Abdolali
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p. 1083 - 1088
(2007/10/03)
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- Aqueous biphasic oxidation: A water-soluble polyoxometalate catalyst for selective oxidation of various functional groups with hydrogen peroxide
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A "sandwich" type polyoxometalate, Na12[(WZn 3(H2O)2][(ZnW9O34) 2], was used as an oxidation catalyst in aqueous biphasic reaction media to effect oxidation of alcohols, diols, pyridine derivatives, amines and aniline derivatives with hydrogen peroxide. The catalyst was shown by 183W NMR to be stable in aqueous solutions in the presence of H 2O2 and showed only minimal non-productive decomposition of the oxidant. Secondary alcohols were selectively oxidized to ketones, while primary alcohols tended to be oxidized to the corresponding carboxylic acids, although secondary alcohols were selectively oxidized in the presence of primary alcohols. Vicinal diols yielded carbon-carbon bond cleavage products in very high yields. Pyridine derivatives were oxidized to the respective TV-oxides, but strongly electron-withdrawing moieties inhibited the oxidation reaction. Primary amines were oxidized to the oximes, but significantly hydrolyzed in situ. Aniline derivatives were oxidized to the corresponding azoxy or nitro products depending on the substitution pattern in the aromatic ring. Catalyst recovery and recycle was demonstrated.
- Sloboda-Rozner, Dorit,Witte, Peter,Alsters, Paul L.,Neumann, Ronny
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p. 339 - 345
(2007/10/03)
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- Mechanistic study on nitrosation-deaminocyclization of mono-carbamoylated vicinal amino alcohols and diols: a new preparative in situ formation of ethanediazo hydroxide for the ethylation of carboxylates under mild conditions
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While the cyclization of N-carbamoylamino alcohols into oxazolidinones via the activation with NO(1+) underwent smoothly, we found that similar reactions of vicinal diol monocarbamates were very slow. Mechanistic studies by means of time-resolved IR measurements of the former reaction suggested that the initial O-nitrosation was the rate-determining step. Indeed, the introduction of an ethyl group on the nitrogen terminus of diol monocarbamate promoted the desired cyclic carbonate formation. The concomitantly formed ethanediazo hydroxide, the precursor of the protonated form of diazoethane, was evidenced by trapping with p-nitrobenzoic acid as an ethyl ester. The formation of ethyl ester accelerates the reaction in an irreversible manner. Based on an elaboration of the substrates and reaction conditions, 2,3-dimethyl-2,3-butanediol mono-N-ethyl-N-nitrosocarbamate, which is easily prepared in situ from the corresponding ethylcarbamate and t-butyl nitrite, was developed as a new ethylation reagent of various carboxylic acids under mild conditions.
- Suzuki, Masumi,Sugai, Takeshi
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p. 1217 - 1228
(2007/10/03)
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- The newborn surface of dull metals in organic synthesis. Bismuth-mediated solvent-free one-step conversion of nitroarenes to azoxy- and azoarenes
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When milled together with bismuth shots, nitroarenes are readily converted to azoxy- and/or azoarenes depending on substrates and conditions employed. Simple extraction with organic solvent followed by evaporation of the resulting dark pasty solid gave the product in good yield.
- Wada, Shinobu,Urano, Mika,Suzuki, Hitomi
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p. 8254 - 8257
(2007/10/03)
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- Relative reactivity of methyl iodide to ethyl iodide in nucleophilic substitution reactions in acetonitrile and partial desolvation accompanying activation
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Through the examination of empirical correlations involving activation parameters for nucleophilic substitution of methyl iodide and of ethyl iodide, nucleophiles have been classified into three series: (1) nucleophiles with two equivalent reaction sites, (2) nucleophiles with a chlorine atom in the para-position, and (3) nucleophiles with a single reaction site. Three types of partial desolvation processes accompanying activation have been deduced on the basis of these classifications. A major factor determining the relative reactivity of methyl iodide to ethyl iodide in the substitution reaction of an anionic nucleophile having a single reaction site in acetonitrile (kMeI/kEtI) is suggested to be partial desolvation around the nucleophilic center on going from reactant to transition-state.
- Kondo, Yasuhiko,Urade, Miyuki,Yamanishi, Yukari,Chen, Xinyu
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p. 1449 - 1454
(2007/10/03)
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- Nitro compound-reducing process
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PCT No. PCT/EP96/03415 Sec. 371 Date May 23, 1998 Sec. 102(e) Date May 23, 1998 PCT Filed Aug. 2, 1996 PCT Pub. No. WO97/07087 PCT Pub. Date Feb. 27, 1997The invention concerns a process for the reduction of nitro groups to amino groups, characterized that a nitro compound is reacted with hydrogen in the presence of an aqueous solution of a water-soluble metal catalyst of the formula M (L)n(Y)m wherein M is ruthenium, rhodium, nickel, or palladium; L, is a water soluble ligand; Y is a further ligand or an alkaline earth ion; n is 1, 2, 3, or 4; and m is 0, 1, or 2.
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- Chemoselective O-methylation of phenols under non-aqueous condition
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Chemoselective O-methylation of substituted phenols takes place in dry. tetrahydrofuran (THF) in the presence of LiOH.H2O and dimethylsulfate (DMS). Quantitative methyl transfer from DMS preserves the atom economy.
- Basak, Anindita,Nayak, Mrinal K.,Chakraborti, Asit K.
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p. 4883 - 4886
(2007/10/03)
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- Reaction enthalpy of nucleophilic substitution of ethyl iodide in acetonitrile and its mechanistic significance
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Enthalpies of reaction for nucleophilic substitution of ethyl iodide have systematically been determined in acetonitrile. Through the concurrent analysis of empirical correlations between the reaction enthalpies and the specific interaction enthalpies for relevant anions with those between the logarithmic rates and the specific interaction enthalpies, partial desolvation accompanying activation has been deduced to be the major contributor to activation thermodynamic parameters, while the propensity of the reacting central atom in the nucleophilic anion plays a crucial role in determining reaction thermodynamic parameters. Semi-empirical molecular orbital calculations have supported these ideas. The application of the Marcus equation to the analysis of reaction characteristics in these reactions is discussed.
- Kondo, Yasuhiko,Tsukamoto, Tamio,Kimura, Naoko
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p. 1765 - 1769
(2007/10/03)
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- Cobalt schiff base complex-catalyzed oxidation of anilines with tert-butyl hydroperoxide
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Cobalt Schiff base complexes [Co(SB)] catalyze the oxidation of anilines (1) with tert-butyl hydroperoxide to give nitrobenzenes 2 and 4-(tert-butylperoxy)-2,5-cyclohexadien-1-imine derivatives 3 in yield distributions depending on the substitution mode of the substrate. 4-Alkyl- and 4-aryl-2,6-di-tert-butylanilines gave mixtures of 2 and 3, where the higher the bulkiness of the 4-substituent, the higher the yield of 2. With 2,4,6-trimethylaniline, the ratio of oxidations of the nitrogen and C-4 atoms was almost the same; but a hydrolyzed product 5 of the imine was obtained. 2,4,6-Triphenylaniline gave only 2. Nitrobenzene derivatives were also obtained from 2,6-dialkylanilines and 4-substituted anilines. The catalytic activity of Co(SB) depended on the nature of the SB ligand: the formal potential E° and steric factors seem to affect the reaction rate. Kinetic studies showed that the key step may involve hydrogen abstraction from the aniline, presumably by t-BuO? generated from homolytic decomposition of initially formed CoIII(SB)(OO-t-Bu). A precursor of 2 was found to be the nitrosobenzene derivative.
- Foerster, Stefan,Rieker, Anton,Maruyama, Kazushige,Murata, Kunihiko,Nishinaga, Akira
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p. 3320 - 3326
(2007/10/03)
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- Mesogenic properties of liquid crystals having a chiral semiflexible joint
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Two homologous series of mesogenic enantiomers with chiral semiflexible joint, -C*H(CH3)CH2COO-, are examined. High twist power and presence of blue phases with short lattice period are found for eleven examined compounds. Some effects of chirality in reentrant system are discussed. On phase diagram of enantiomers the SmAd phase area is shifted toward longer homologues as compared to racemates. In result, an island of the SmAd phase in the cholesteric sea exists on binary phase diagrams of R- and S- enantiomers. Triple divergence of the pitch in the cholesteric phase of a pure compound is observed.
- Gorecha,Pyzuk,Mieczkowski
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- The Reaction of Some N-(Nitrophenyl)azoles with Alkali: Preparation of the Corresponding Azoxybenzenes. X-Ray Structure of 2,2'-Bis(1'',2'',4''-triazol-1''-yl)azoxybenzene
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The reactions of some representative N-(nitrophenyl)azoles with boiling aqueous ethanolic potassium hydroxide solution gave the corresponding bis(azolyl)azoxybenzenes.It is deduced that, in these reactions, the N-attached azolyl groups concerned are acting as weak electron-withdrawing groups.The structure of 2,2'-bis(1'',2'',4''-triazol-1''-yl)azoxybenzene was determined in the solid state by X-ray crystallography.The monoclinic crystals belong to the space group P21/c with a 8.815(1), b 7.863(1), c 11.836(1) Angstroem, β 109.96(1) deg and Z 2.The structure was refined to an R index of 0.041 for 1172 observed terms.The midpoint of the exocyclic N=N bond lies on an inversion centre so that the azoxy oxygen is statistically distributed between two sites.The benzene ring atoms are coplanar to within experimental error, as are the triazole ring atoms, and the dihedral angle between the perpendiculars to the two rings is 35.3(3) deg.
- Mackay, Maureen F.,Trantino, Giuseppe J.,Wilshire, John F. K.
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p. 417 - 425
(2007/10/02)
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- Solvation and Nucleophilic Reactivity towards Ethyl Iodide of p-Nitrophenolate and p-Nitro-m-cresolate Ions in Acetonitrile - Methanol Mixtures.
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Dissection of transfer enthalpy into constituent terms for the conjugate-base anions of weak acids in acetonitrile-methanol mixtures plays a crucial role in rationalizing the dissociation behavior of these acids in protic solvents.Characterization of solv
- Kondo, Yasuhiko,Hara, Toshio,Kusabayashi, Shigekazu
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p. 101 - 113
(2007/10/02)
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- Kinetics of Phase-transfer Etherification Reactions of p-Chloronitrobenzene by Alkoxides
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The substitution reaction of chloride by alkoxide anions in p-chloronitrobenzene in a phase-transfer catalytic system has been studied and succesfully performed in high yield and without the occurrence of side reactions.The effect of several parameters has been experimentally investigated.In particular, the poisoning effect of the chloride anion produced throughout the reaction is studied and a practical answer to succesfully overcome this problem and increase yields is presented.A kinetic model based on the collected data is proposed.
- Lerner, Jaime de la Zerda,Cohen, Sasson,Sasson, Yoel
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- PHASE-TRANSFER CATALYSIS OF THE REACTION OF 2- AND 4-NITROCHLOROBENZENE WITH METHOXIDE AND ETHOXIDE ANIONS
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It was established that the reactions of 2- and 4-nitrochlorobenzene with methoxide and ethoxide anions are accelerated most effectively by crown ethers and quaternary ammonium salts while nonionic surfactants are less active.The activity of the catalyst
- Artamanova, N. N.,Seregina, V. F.,Shner, V. F.,Salov, B. V.,Kokhlova, V. M.,Zhdamarova, V. N.
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p. 554 - 556
(2007/10/02)
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- THE ROLE OF WATER IN PHASE TRANSFER CATALYSIS
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Water is shown to be an essential component in anion exchange process between metal salts and quaternary onium salts in organic solvents.Hydration of ion pairs in organic phases, on the other hand, reduces the nucleophilicity of anions in displacement rea
- Sasson, Yoel,Arrad, Onn,Dermeik, Salman,Zahalka, Hayder A.,Weiss, Minda,Wiener, Harold
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p. 495 - 516
(2007/10/02)
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- Comparative Structure-Activity Relationships of Antifolate Triazines Inhibiting Murine Tumor Cells Sensitive and Resistant to Methotrexate
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The inhibitory effect of 108 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazines on murine L5178Y tumor cells, resistant and sensitive to methotrexate (MTX), has been studied.From the pI50 values, quantitative structure-activity relationships have been formulated which show that the lipophilic triazines are much more inhibitory against resistant cells than methotrexate or hydrophilic triazines.The results are compared with the behavior of other antifolate drugs that have been used in chemotherapy, as well as with eight antitumor drugs that are notantifolates.The acquired resistance of these cells toward hydrophilic antifolates may be attributed to the combined effect of an impaired active-transport system, a change in the conformation of dihydrofolate reductase in the resistant cells, and an amplified production of dihydrofolate reductase in the resistant cells.
- Selassie, Cynthia Dias,Hansch, Corwin,Khwaja, Tasneem A.,Dias, Cecilia B.,Pentecost, Stephanie
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p. 347 - 357
(2007/10/02)
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- REACTIONS OF 4-CHLORONITROBENZENE WITH ALKOXIDES IN THE PRESENCE OF CROWN ETHERS
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The reaction of 4-chloronitrobenzene (1) with secondary and tertiary potassium alkoxides leads to the reduction of the nitro group.The addition of 18-crown-6 ether completely changes the reaction pathway to afford only products of substitution of the chlo
- Prato, Maurizio,Quintily, Ugo,Salvagno, Susanna,Scorrano, Giangranco
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p. 413 - 416
(2007/10/02)
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