- One-pot synthesis of N-substituted diaza[12]annulenes
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(Chemical Equation Presented) N-Substituted diaza[12]annulenes are obtained by one -pot reaction of n-(2,4-dinitrophenyl)pyridinium chloride with amines in moderate to high yields. The 1H NMR spectrum reveals that diamagnetic ring current is generated in the diaza[12]annulene ring. The N-substituted diaza[12]annulenes are electrochemically active in solution.
- Yamaguchi, Isao,Gobara, Yoshiaki,Sato, Moriyuki
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- Synthesis, characterisation and photoswitchability of a new [2]rotaxane of α-cyclodextrin with a diazobenzene containing π-conjugated molecular dumbbell
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In this work, a new [2]rotaxane consisted of a diazobenzene containing α-conjugated linear compartment, including the 4,4-bipyridyl moiety and α-cyclodextrin (-CD) as the macrocyclic compartment, was synthesised with yields of nearly 57% and fully characterised. α-CD easily assembled with the linear compartment and suitable bulky ends (stoppers) in water to give a new [2]rotaxane. The characterisation of this supramolecular compound was accomplished using several spectroscopic techniques such as 1H NMR, 13C NMR and 2D NMR spectroscopy, powder X-ray diffraction, fourier transform infrared spectroscopy, induced circular dichroism and UV-vis spectrophotometry, as well as scanning electron microscopy and Energy Dispersive X-ray. Furthermore, the reversible E-Z photoisomerisation of both [2]rotaxane and its molecular dumbbell was investigated by irradiation with UV light.
- Deligkiozi, Ioanna,Papadakis, Raffaello,Tsolomitis, Athanase
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- Hydride Transfer from Cyclohexadienyl Anions: The Reaction between the Hydride Meisenheimer Adduct of 2,4-dinitroaniline and 1,3,5-trinitrobenzene
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The hydride Meisenheimer adduct of 2,4-dinitroaniline transfers hydride to 1,3,5-trinitrobenzene to form its corresponding hydride Meisenheimer adduct.The reaction is practically irreversible.In dilute solution in dimethyl sulphoxide it exhibits second-order kinetics and the observation of several sharp isosbestic points shows that it occurs without formation of any detectable intermediate species.
- Atkins, Paul J.,Gold, Victor,Wassef, Wasfy N.
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Read Online
- Preparation method of 2,4-dinitroaniline
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The invention relates to the field of pharmaceutical chemicals, and discloses a preparation method of 2,4-dinitroaniline. The preparation method comprises the following four steps: (1) adding 2,4-dinitrochlorobenzene and urea in a molar ratio of 1: (1.5-2.5) into a reaction kettle; (2) adding an ethanol water solvent into the reaction kettle, wherein the ethanol concentration of the ethanol water solvent is 30%-100%, and the adding amount of the ethanol water solvent is 1.5-3 times of the mass of the 2,4-dinitrochlorobenzene; (3) heating the reaction kettle to 110-135 DEG C, controlling a pressure to be 0.2-0.3 MPa, and carrying out a heat preservation reaction for 3-5 hours; and (4) after the reaction is finished, centrifugally filtering and washing a reaction product to obtain the 2,4-dinitroaniline. According to the invention, the urea is used for replacing ammonia water and ammonia gas, and relatively low reaction temperature and pressure are adopted, so the explosion risk of ammonia gas volatilization is avoided, production cost is reduced, product purity and yield are improved, and the method has remarkable safety benefit, economic benefit and quality benefit.
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Paragraph 0018-0022
(2021/08/07)
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- 1-Aryl-3-(4-methoxybenzyl)ureas as potentially irreversible glycogen synthase kinase 3 inhibitors: Synthesis and biological evaluation
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Glycogen synthase kinase 3 (GSK-3)has become known for its multifactorial involvement in the pathogenesis of Alzheimer's disease. In this study, a benzothiazole- and benzimidazole set of 1-aryl-3-(4-methoxybenzyl)ureas were synthesised as proposed Cys199-targeted covalent inhibitors of GSK-3β, through the incorporation of an electrophilic warhead onto their ring scaffolds. The nitrile-substituted benzimidazolylurea 2b (IC50 = 0.086 ± 0.023 μM)and halomethylketone-substituted benzimidazolylurea 9b (IC50 = 0.13 ± 0.060 μM)displayed high GSK-3β inhibitory activity, in comparison to reference inhibitor AR-A014418 (1, IC50 = 0.072 ± 0.043)in our assay. The results suggest further investigation of 2b and 9b as potential covalent inhibitors of GSK-3β, since a targeted interaction might provide improved kinase-selectivity.
- Venter, Jana,Perez, Concepción,van Otterlo, Willem A.L.,Martínez, Ana,Blackie, Margaret A.L.
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p. 1597 - 1600
(2019/05/02)
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- A highly efficient heterogeneous copper-catalysed cascade reaction of aryl iodides with acetamidine hydrochloride leading to primary arylamines
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A highly efficient heterogeneous copper-catalysed cascade reaction of aryl iodides with acetamidine hydrochloride was achieved in DMF in the presence of 10 mol% of an MCM-41-immobilised L-proline-copper(I) complex (MCM-41-L-proline-CuI) with Cs2CO3 as base, yielding a variety of primary arylamines in good to excellent yields. The new heterogeneous copper complex can be easily prepared from commercially readily available and inexpensive reagents, recovered by a simple filtration of the reaction solution and used at least seven more times without any decrease in activity.
- Huang, Xue,Xiao, Ruian,You, Chongren,Yan, Tao,Cai, Mingzhong
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p. 315 - 320
(2017/06/19)
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- A 2,4-dinitro-aniline continuous ammonifying production process
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The invention relates to a 2,4-dinitraniline continuous ammonification production technology, which is characterized in that 2, ,4-dinitraniline and ammoniacal liquor are taken as raw materials, the raw materials are reacted at temperature of 160-170 DEG C and pressure of 0.5-1.0 MPa, and then continuously added in an ammonification reactor; when the raw materials exceeds a discharge hatch, and are successively flowed to two auxiliary reactors, wherein the reaction temperature is controlled at 160-170 DEG C, and the reaction pressure is controlled at 0.5-1.0 MPa, reaction time of an ammonification reactor is 42 minutes, and reaction time of each auxiliary reactor is 15 minutes. The production technology has the advantages of high production efficiency, low energy consumption, environmental protection, economy, low labor intensity and safety, waste heat during an ammonification reaction process can be fully used, by-product ammonium chloride can be simultaneously recovered, no waste water is generated, and the production technology has the advantages of green production and good economic benefit.
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Paragraph 0044; 0045
(2017/01/12)
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- Reagent and method for detection of carboxylic acids by mass spectrometry
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Method and reagent for converting a carboxylic acid to a positively charge amide are described. The method and reagent facilitate positive ion mass spectral analysis of carboxylic acids. The method includes reacting a carboxylic acid with a compound having formula I: wherein A and B are aromatic rings, ring A includes a quaternized nitrogen and has n additional ring atoms, each additional ring atom optionally substituted with an RA group, and n is an integer from 4 to 10, and ring B includes a carbon atom and has m additional ring atoms, each additional ring atom optionally substituted with an RB group, and m is an integer from 4 to 10. The compound includes at least one RA or RB group, and the at least one RA and RB group is -L-N(Z)H; and X? is a counterion.
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- Steric-Hindrance-Induced Regio- and Chemoselective Oxidation of Aromatic Amines
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Unusual regio- and chemoselective oxidation of aromatic amines hindered with ortho substituents (except -NH2, -NHCH3, and -OH) to the corresponding nitro compounds is described by use of nonanebis(peroxoic acid). The mechanistic investigation for selective oxidation of amines ortho-substituted with -NH2 or -OH showed the involvement of H-bonding between the ortho hydrogen of the adjacent -XH group (where X = NH, NR, or O) and an oxygen atom from the diperoxy acid. Various mono- and diamines are oxidized into corresponding mononitro derivatives in high yield and purity without employing any protection strategies. The protocol was also found to successful on the gram scale.
- Patil, Vilas Venunath,Shankarling, Ganapati Subray
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p. 7876 - 7883
(2015/09/01)
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- Ligand free open air copper(II) mediated aryl formamidation and amination of aryl halides
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A simple synthetic procedure for direct formamidation and amination of aryl halides mediated by copper(II) salts was developed in open air, without an external ligand in formamide with potassium carbonate as a base. This approach is particularly efficient when electron active aryl halides are used as substrates. In these cases almost quantitative formamidation was observed.
- Komati, Rajesh,Jursic, Branko S.
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p. 1523 - 1527
(2014/03/21)
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- A novel N-N bond cleavage in 1,5-diaminotetrazole: Synthesis and characterization of 5-picrylamino-1,2,3,4-tetrazole (PAT)
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The reaction of 1,5-diaminotetrazole with picryl chloride (PiCl) forms 5-picrylamino-1,2,3,4-tetrazole (PAT) rather than the expected 1-picrylamino-5-amino-1,2,3,4-tetrazole or 5-picrylamino-1-amino-1,2,3,4- tetrazole. The structure of PAT was confirmed by single-crystal X-ray diffraction. Some of the energetic properties of the synthesized compound were also studied.
- Tang, Yongxing,Yang, Hongwei,Ju, Xuehai,Huang, Hui,Lu, Chunxu,Cheng, Guangbin
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p. 4127 - 4131
(2014/03/21)
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- The kinetics and mechanisms of aromatic nucleophilic substitution reactions in liquid ammonia
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The rates of aromatic nucleophilic substitution reactions in liquid ammonia are much faster than those in protic solvents indicating that liquid ammonia behaves like a typical dipolar aprotic solvent in its solvent effects on organic reactions. Nitrofluorobenzenes (NFBs) readily undergo solvolysis in liquid ammonia and 2-nitrofluorobenzene is about 30 times more reactive than the 4-substituted isomer. Oxygen nucleophiles, such as alkoxide and phenoxide ions, readily displace fluorine of 4-NFB in liquid ammonia to give the corresponding substitution product with little or no competing solvolysis product. Using the pKa of the substituted phenols in liquid ammonia, the Bronsted βnuc for the reaction of 4-NFB with para-substituted phenoxides is 0.91, indicative of the removal of most of the negative charge on the oxygen anion and complete bond formation in the transition state and therefore suggests that the decomposition of the Meisenheimer σ-intermediate is rate limiting. The aminolysis of 4-NFB occurs without general base catalysis by the amine and the second-order rate constants generate a Bronsted βnuc of 0.36 using either the pKa of aminium ion in acetonitrile or in water, which is also interpreted in terms of rate limiting breakdown of the Meisenheimer σ-intermediate. Nitrobenzene and diazene are formed as unusual products from the reaction between sodium azide and 4-NFB, which may be due to the initially formed 4-nitroazidobenzene decomposing to give a nitrene intermediate, which may then give diazene or be trapped by ammonia to give the unstable hydrazine which then yields nitrobenzene.
- Ji, Pengju,Atherton, John H.,Page, Michael I.
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scheme or table
p. 3286 - 3295
(2011/07/07)
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- Synthesis of N-arylpyridinium salts bearing a nitrone spin trap as potential mitochondria-targeted antioxidants
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The generation of excess reactive oxygen species (ROS) in mitochondria is responsible for much of the oxidative stress associated with ageing (aging), and mitochondrial dysfunction is part of the pathology of neurodegeneration and type 2 diabetes. Lipophilic pyridinium ions are known to accumulate in mitochondria and this paper describes a general route for the preparation of nitrone-containing N-arylpyridinium salts having a range of lipophilicities, as potential therapeutic antioxidants. The compatibility of nitrones with the Zincke reaction is the key to their synthesis. Their trapping of carbon-centred radicals and the EPR spectra of the resulting nitroxides are reported.
- Robertson, Linsey,Hartley, Richard C.
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experimental part
p. 5284 - 5292
(2009/11/30)
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- Stereocontrolled synthesis of Z-dienes via an unexpected pericyclic cascade rearrangement of 5-amino-2,4-pentadienals
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Donor-acceptor dienes known as Zincke aldehydes, which derive readily from the ring-opening reactions of pyridinium salts with secondary amines, undergo a fascinating thermal rearrangement reaction to afford Z-α,β,γ,δ-unsaturated amides with excellent stereoselectivity. Efficient, stereocontrolled access to Z-trisubstituted alkenes with two different substitution patterns is possible in three steps beginning with the appropriately substituted pyridine derivative. Preliminary studies have shown that both the amide and the monosubstituted alkene termini can be selectively functionalized. Ease of access, generality of scope, and facile product manipulation render this process attractive for the synthesis of complex polyenes. Copyright
- Steinhardt, Sarah E.,Silverston, Joel S.,Vanderwal, Christopher D.
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p. 7560 - 7561
(2008/12/22)
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- New approach for the synthesis of 1-aryl- and 1-heteroaryl-5-nitrouracil derivatives
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1-(2,4-Dinitrophenyl)-5-nitrouracil and its 3-methyl derivatives were synthesized and used as substrates in reaction with aromatic amines and amino pyridines. In the reaction of aniline with 1-(2,4-dinitrophenyl)-5-nitrouracil, only the acyclic adduct was isolated. When 1-(2,4-dinitrophenyl)-3-methyl-5-nitrouracil was treated with aniline and other aromatic amines or amino pyridines, the desired 1-aryl-5-nitrouracil derivatives were obtained in satisfactory yield. The influence of the free H-3 proton present in the uracil ring on the course of the reaction is discussed.
- Gondela, Andrzej,Walczak, Krzysztof
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p. 2859 - 2864
(2007/10/03)
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- A convenient method for N-1 arylation of uracil derivatives
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1-(4-Nitrophenyl)- and 1-(2,4-dinitrophenyl)uracil derivatives have been obtained by direct arylation of uracil and its 5-substituted derivatives using 1-fluoro-4-nitrobenzene or 1-fluoro-2,4-dinitrobenzene in the presence of a base. The application of the newly obtained uracil derivatives in further synthesis is also presented.
- Gondela, Andrzej,Walczak, Krzysztof
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p. 4653 - 4657
(2007/10/03)
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- Amination of some 1,3-dinitrobenzenes with liquid ammonia-potassium permanganate
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1,3-Dinitrobenzene and some its 2- and 4-substituted derivatives are dehydroaminated in a solution of potassium permanganate in liquid ammonia to give the corresponding mono- or diamino-1,3-dinitro-benzenes. Under the same conditions, 4-fluoro-1,3-dinitrobenzene is converted into 2,4-dinitroaniline via replacement of the fluorine atom, while 2,4-dinitrobenzaldehyde gives rise to 2,4-dinitrobenzamide.
- Szpakiewicz,Grzegozek
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p. 829 - 833
(2007/10/03)
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- Nucleophilic aromatic substitution for heteroatoms: An oxidative electrochemical approach
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The nucleophilic aromatic substitution for heteroatom through electrochemical oxidation of the intermediate σ-complexes (Meisenheimer complexes) in simple nitroaromatic compounds is reported for the first time (NASX process). The studies have been carried out with hydride, cyanide, fluoride, methoxy, and ethanethiolate anions and n-butylamine as a nucleophile, at the cyclic voltammetry (CV) and preparative electrolysis level. The cyclic voltammetry experiments allow for detection and characterization of the σ-complexes and they have led us to a proposal for the mechanism of the oxidation step. Furthermore, the power of the CV technique in the analysis of the reaction mixture throughout the whole chemical and electrochemical process is described.
- Gallardo, Iluminada,Guirado, Gonzalo,Marquet, Jordi
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p. 2548 - 2555
(2007/10/03)
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- Electrochemical synthesis of nitroanilines
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Alkylamines and amides are readily prepared by nucleophilic aromatic substitution of hydrogen in nitroarenes by electrochemical oxidation. Useful yields (15-85%) are achieved in a simple direct and regioselective amination process. The synthetic method has been examined in the absence and presence of external bases, used to promote the first step of the nucleophilic aromatic substitution reaction, i.e. the nucleophilic attack. In both cases, good results were obtained. The unreacted starting material can easily be recovered at the end of the electrochemical oxidation process. This new method represents an environmentally favourable route to amino- and amido-substituted nitroaromatic compounds.
- Gallardo, Iluminada,Guirado, Gonzalo,Marquet, Jordi
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p. 251 - 259
(2007/10/03)
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- Ammonium nickel sulphate mediated nitration of aromatic compounds with nitric acid
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Aromatic compounds were efficiently nitrated under mild conditions employing ammonium nickel sulphate and nitric acid as a reagent. This procedure works efficiently at room temperature yielding mononitro derivative in fair to good yield with high regioselectivity.
- Tasneem,Ali,Rajanna,Saiparakash
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p. 1123 - 1127
(2007/10/03)
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- Ring cleavage of N-arylpyridinium salts by nucleophiles - Regioselectivity and stereochemistry of the products - Part 2
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The reaction of quaternary 3-pyridinecarboxamide compounds 2, 7 and 14 with alkali does not - contrary to literature result in regiospecific ring opening, but yields mixtures of position isomer penta-2,4-dienal derivatives. With increasing steric hindrance by the 3-substituent, the hydroxide ion prefers the attack at 6-position. Usually products with all trans configuration are obtained. Only the 2-substituted aldehydes from 2 and 14 additionally occur in the 2,3-cis configuration as 5b and 2lb, explainable by a hydrogen bond between the formyl and carbamoyl group. Surprisingly the "ring opened" 5-aminopenta-2,4-dienals 5 and 6 resp. 21 and 22 in acetone solution show an equilibrium of the positional isomers in each case, which must be generated by recyclization via the intermediates 24 resp. 25. With hydroxylamine 2, 7 and 14 only react to the 4-substituted pentadienal derivatives, which represent E,Z oxime mixtures. This is proved by dehydration to uniform nitriles and the synthesis from the corresponding aldehydes by oximation.
- Moehrle,Niessen
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p. 448 - 457
(2007/10/03)
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- Reactions of isoquinolinium salts with hydroxylamine derivatives, 3rd communication. Mechanism of amine oxide generation
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2-Methylpapaverinium iodide (1) reacted with hydroxylamine to papaverine-N-oxide (2), but without a detectable intermediate and only in moderate yield, caused by the steric hindrance of the 1-substituent. The ring opened product of 2-dinitrophenylisoquinolinium salt with hydroxylamine, the enamine-oxime 3b gave rise to a 3-substituted cyclic nitrone (6), when heated with triethylamine. This alkali-stable compound was transformed with acid quantitatively to isoquinoline-N-oxide (4). The enaminonitrile 9c, treated with triethylamine showed cyclization to the iminoisoquinoline 10, which by loss of nitrous acid produced the tetracyclic azaindole 11. The 2-methoxyisoquinolinium salt 16 was cleaved with O-methylhydroxylamine to the resistant di(O-methyloximes) (20a/b), unable to form the amine oxide 4. From these and former results, a mechanism for the ring opening of cycliminium salts and the recyclization to amine oxides was proposed.
- M?hrle,Nie?en
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p. 913 - 922
(2007/10/03)
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- Synthesis and CNS activity of new 3-amino-3-arylpropionic acid derivatives
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The synthesis of new analogues of methylphenidate and modafinil, derived from 3-amino-3-arylpropionic acids, is described. Central pharmacological properties were studied in mice.
- Renault,Guillon,Huard,Miel,Stiebing,Le Bourn,Boulouard,Dallemagne,Rault
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p. 217 - 223
(2007/10/03)
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- Unusual reaction of 1,4-diamino-2-nitrobenzene derivatives toward nucleophiles: Catalysis by sodium sulphite
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Unusual substitution of amino group occurs by reactions of some 1,4diamino-2-nitrobenzenes (semipermanent hair dyes) and nucleophiles (NH3, H2O). The reaction is catalyzed by sodium sulfite. The obtained products are suspected of being toxic substances which may be present in cosmetic matrices. Apparently, this reaction is a nucleophilic aromatic substitution but it may be explained by a mechanism involving a tautomeric form of substrate.
- Forlani, Luciano,Boga, Carla,Mazza, Milena,Cavrini, Vanni,Andrisano, Vincenza
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p. 4647 - 4654
(2007/10/03)
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- Nitroarylamines via the Vicarious Nucleophilic Substitution of Hydrogen: Amination, Alkylamination, and Arylamination of Nitroarenes with Sulfenamides
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A new reaction of sulfenamides with electrophilic arenes under basic conditions is described. The σ adducts formed from nitroarenes and the anions of sulfenamides undergo elimination of thiol to produce the corresponding o- and/or p-nitroanilines. This reaction is analogous to the known alkylation and hydroxylation of nitroarenes via the vicarious nucleophilic substitution of hydrogen (VNS). The reaction gives access to a wide range of substituted nitroanilines, nitronaphthylamines, and aminoheterocycles. By means of the reaction with N-alkyl- and N-arylsulfenamides, it is possible to obtain N-alkylnitroanilines and nitrodiarylamines. By varying the structure of sulfenamide and the reaction conditions, particularly the nature and concentration of the base, it is possible to control the orientation of animation.
- Makosza, Mieczyslaw,Bialecki, Maciej
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p. 4878 - 4888
(2007/10/03)
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- Joint Effect of the Reactant Structure in Reactions of 4-Substituted N-Arylpyridinium Salts with Arylamines in Acetonitrile
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Reactions of 4-substituted N-arylpyridinium tetraphenylborates with arylamines proceed by a multistep ANRORC substitution mechanism and are described by isoparametric relationships with respect to the reactant structure for noncatalytic and catalytic reactions.The mechanism of changes (catalysis is canceled) in going beyond the isoparametric point with respect to the arylamine structure.
- Titskii, G. D.,Mitchenko, E. S.
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p. 1425 - 1428
(2007/10/03)
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- AROMATIC NUCLEOPHILIC SUBSTITUTION REACTIONS OF 2,4-DINITROBENZENESULFONIC ACID SODIUM-SALT WITH ALIPHATIC AMIDES
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Aromatic amines can be obtained from 2,4-dinitrobenzenesulfonic acid sodium-salt and aliphatic amides in excess at 170-180 deg C, for 6-7 hours.The steric hindrances have an important role in this reaction.
- Chiriac, Constantin I.,Sava, Mitica,Tibirna, Mihaela,Chiriac, Florentina,Ropot, Radu,et al.
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p. 1197 - 1200
(2007/10/03)
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- AROMATIC NUCLEOPHILIC SUBSTITUTION REACTIONS OF ACTIVATED N-ARYLPYRAZOLES WITH FORMAMIDES
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Different activated N-arylpyrazoles, as N-(2',4'-dinitrophenyl)-3,5-dimethylpyrazole, N-picryl-3,5-dimethylpyrazole etc., can react with excess formamides, as formamide N-methylformamide and N,N-dimethylformamide, at 165-175 deg C, for 5-6 hours, resulting amines in high yieds.This reaction is influenced by steric hindrance.
- Chiriac, Constantin I.,Lupu, Viorel,Chiriac, Florentina,Ropot, Radu,Tibirna, Mihaela,Truscan, Ion
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p. 549 - 553
(2007/10/03)
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- SYNTHESIS OF BASE-MODIFIED "ABBREVIATED" NAD ANALOGUES
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The "abbreviated" model of NAD, 1--3-carbamoylpyridinium chloride (VIIIa), and its 2,6-diaminopurine (VIIIb), 3-deazaadenine (VIIIc), guanine (VIIId) and cytosine (VIIIe) analogues were prepared by the Zincke reaction.The (R)-isomer of the adenine model VIIIa (compound IX) was prepared for chiroptical studies.As shown by NMR, UV and CD spectra, neither in dimethyl sulfoxide nor in water any intramolecular ?-? interactions exist between the heteroaromatic systems.
- Jurikova, Kristina,Smrckova, Svatava,Holy, Antonin
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p. 237 - 250
(2007/10/02)
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- Pigment compositions for solvent and water-based ink systems and the methods for producing them
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This invention is an azo pigment composition containing a water insoluble metal salt of a water soluble polymer; a method of preparing said composition and ink compositions prepared from said azo pigment compositions.
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- Metal ion promoted hydroxide ion and water catalyzed hydrolysis of amides. Effects of the acyl group and the leaving group
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The hydrolysis of anilide derivatives of N-methyl-4-nitroaniline in H2O is hydroxide ion catalyzed; plots of log kobsd vs pH are linear with slopes of 1.0 at pH > 8. When there is a chelating functional group in the acyl portion of the molecule (1,10-phenanthrolinyl or 6-carboxypicolinoyl) and in the presence of saturating concentrations of Cu2+, Co2+, or Zn2+, hydroxide ion catalyzed reactions are observed at pH > 4 (rate enhancements range from 104- to 105-fold), and pH-independent reactions occur from pH 1 to 4. Rate constants are very nearly the same in the metal ion promoted hydrolysis reactions for the anilides with these acyl groups. Thus, the negatively charged carboxylate ligand of N-(6-carboxypicolinoyl)-N-methyl-4-nitroaniline is equally good in facilitating the metal ion promoted hydrolysis reactions as the neutral ligands of the 1,10-phenanthroline derivative. A trifluoroacetyl acyl group produces the same general effect as a chelated metal ion, i.e., a facile OH--catalyzed reaction and a pH-independent reaction at pH 6 is favorable (kOH' = 1.0 × 104 M-1 s-1 at 50 °C), even though the pKa of the anilide N-H function is 5.5 and the second-order rate constant (kOH') is tnat for attack of OH- on the ionized species. Amide deprotonation does not have a large effect on the rate of hydrolysis; ionization of the amide N-H function of N-(trifluoroacetyl)-2-carboxy-4-nitroaniline produces only a 7-fold decrease in kOH. An N-methyl group accelerates the rate of hydrolysis of the (trifluoroacetyl)-2,4-dinitroanilide. N-(Trifluoroacetyl)-N-methyl-2,4-dinitroaniline hydrolyzes very rapidly at 50 °C, kOH = 5 × 106 M-1 s-1 and k0 = 10-2 s-1. The pH-independent reaction governed by k0 proceeds 2.1-fold more slowly in D2O than in H2O. General base catalysis occurs, and the Bronsted coefficient β is 0.3.
- Fife, Thomas H.,Bembi, Ramesh
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p. 11358 - 11363
(2007/10/02)
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- REACTIONS OF N,N'-DIARYLBIPYRIDINIUM SALTS WITH ARYLAMINES IN ACETONITRILE
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The kinetics of the reactions of N,N'-bis(2,4-dinitrophenyl)-4,4'-bipyridinium bistetraphenylborate with substituted anilines in acetonitrile at 298 k were studied.The change of the rate-controlling stage in the multistage ANRORC substitution in relation to the structure of the arylamine is discussed.
- Titskii, G. D.,Mitchenko, E. S.
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p. 154 - 158
(2007/10/02)
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- Azo pigment compositions and process for their preparation
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This invention is that of an azo pigment composition containing about 1 to 10 percent by weight of a nonionic alkyl polyglycoside dispersing agent. The polyglycosides useful in the invention have the general formulae: wherein: M is an oxygen, sulfur, nitrogen phosphorous or silicon atom; n is an integer from 8 to 18, preferably 8 to 11 and X represents the number average degree of polymerization having a numerical value from about 1 to about 2. These azo pigment compositions are prepared by conducting the azo pigment coupling reaction in the presence of said alkyl polyglycoside. The resulting pigment exhibit superior application properties in water based ink systems.
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- Reaction of N-Acyloxy-2-nitrobenzenamines.I. Thermolysis in Benzene or Bromobenzene
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N-Acyloxy-2-nitro- and N-acyloxy-2,4-dinitro-benzenamines have been pyrolysed at 140 deg C in benzene or bromobenzene solution.Homolysis ( to form RCO2-radical and ArNH-radical) is ruled out since virtually all the carboxylate is isolated as carboxylic acid.This acid might arise via a concerted elimination process ( the other product being a benzofurazan 1-oxide), or via heterolysis to ArNH01+, RCO21- with subsequent transfer of proton, and cyclization of the singlet 2-nitrophenylnitrene.These simple reactions compete with bimolecular reactions of products with substrate, in which the corresponding amine, azoxy compound and acid anhydride are generated.Attempts to synthesize N-tosyloxy derivatives of nitrobenzenamines gave only thermal decomposition products.N-Trifluoroacetoxy-2,4-dinitrobenzenamine was isolated as a crude product which detonated violently.
- Bryant, Ian R.,Dyall, Leonard K.
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p. 2275 - 2288
(2007/10/02)
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- REACTIVITY OF NUCLEOPHILES IN DIMETHYL SULFOXIDE AND ITS COMPARISON WITH NUCLEOPHILIC REACTIVITY IN PROTIC MEDIUM
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Reactions of 2,4-dinitrophenyl acetate and 2,4-dinitrofluorobenzene as model substrates with 12 nucleophiles have been studied in dimethyl sulfoxide.The rate constants obtained have been discussed with regard to the nucleophilic reactivity differences in dimethyl sulfoxide and protic solvents inclusive of the different manifestations of the charge of nucleophiles.The applicability of an earlier-suggested correlation equation to the data obtained has been verified.The reaction medium markedly affects the reactivity of nucleophiles, the effect of charge being substantially greater in aprotic solvents (electrostatic interaction) than in protic ones (solvation).In spite of these differences the correlation with application of an empirical nucleophilicity scale suggested earlier is satisfactory, the regression coefficients obtained reflect changes in the nature of medium.
- Zima, Vitezslav,Pytela, Oldrich,Kavalek, Jaromir,Vecera, Miroslav
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p. 2715 - 2720
(2007/10/02)
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- A STUDY OF NUCLEOPHILICITY IN SELECTED SYSTEMS
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Kinetic studies have been carried out of the reactions of 15 nucleophiles with 2,4-dinitrophenyl acetate and 14 nucleophiles with 2,4-dinitrofluorobenzene in 52percent (w/w) methanol at 25 deg C.The rate constant values obtained and literature data have been treated by the factor analysis.It has been found that the description of nucleophilicity at least needs two factors.The nucleophiles studied are divided into two groups (ionic and nitrogen-containing ones).In each group, the nucleophilic properties are affected by linear combination of both factors.
- Zima, Vitezslav,Pytela, Oldrich,Vecera, Miroslav
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p. 814 - 821
(2007/10/02)
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- A CONVENIENT SYNTHESIS OF N-ALKYL AND N,N-DIALKYLTRIFLUOROACETAMIDES IN A SOLID-LIQUID TWO-PHASE SYSTEM IN THE PRESENCE OF PHASE-TRANSFER CATALYSTS
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Trifluoroacetamide is easily monoalkylated in a K2CO3-organic solvent solid-liquid two-phase system affording in good to excellent yields N-alkyltrifluoroacetamides.Under the same conditions, the latter, in turn, ract with alkylating agents giving N,N-dialkyltrifluoroacetamides in high yields.
- Landini, Dario,Penso, Michele
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p. 791 - 800
(2007/10/02)
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- The Effect of Phase-transfer Catalysis on Ammonolysis of Alkyl and Aryl Halides
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Quaternary ammonium salts improve the solubility of ammonia in organic media and accelerate its reactions with some alkyl and aryl halides.
- Barak, Gabriela,Sasson, Yoel
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p. 1267 - 1268
(2007/10/02)
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- Catalysts for alkoxylation reactions
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Catalysts producing a sharply peaked alkoxylation distribution during the alkoxylation of organic materials comprise mixtures of BF3 and metal alkyls or metal alkoxides, SiF4 and metal alkyls or metal alkoxides, or mixtures of these catalysts.
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- Methods of alkoxylation
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Catalysts comprising mixtures of HF and metal alkoxides and mixed metal alkoxides produce a sharply peaked alkoxylation distribution during the alkoxylation of organic materials.
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- Catalysts for alkoxylation reactions
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Catalysts and a method of using said catalysts for the alkoxylation of a variety of materials is disclosed. Catalysts so described produce alkoxylates having a very sharp alkoxylate distribution. The catalysts are supported and unsupported dialkoxy and dialkyl metal fluorides and halides and alkyl metal difluorides and dihalides.
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- A Comparison of the Reactions of Some Ethyl N-Arylcarbamates with Those of the Corresponding Acetanilides. I. Nitration
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The reactions of some ethyl N-arylcarbamates and of the corresponding acetanilides towards 1 equiv. of sodium nitrate in concentrated sulfuric acid at 0-5 deg have been compared with one another and have been found to exhibit significant differences.Except in the case of the unsubstituted analogues, nitration of the carbamates was found to occur significantly more quickly than that of the acetanilides as shown by (i) a representative competitive nitration, and (ii) the fact the carbamates containing a nitro group are nitrated smoothly whereas the corresponding nitroacetanilides are slow to react.On the basis of competitive reactions, it is suggested that this difference in reactivity is due to steric factors.
- Rosevear, Judi,Wilshire, John F. K.
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p. 723 - 733
(2007/10/02)
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- Cycloaddition of Cyclic Vinyl Ethers to an Isoquinolinium Salt: Application to the Preparation of a Model C-Naphthylglycoside
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The cycloaddition of cyclic enol ethers, including sugar glycals, to 2-(2,4-dinitrophenyl)isoquinolinium chloride leads to new substituted naphthaldehydes in useful yields.
- Franck, Richard W.,Gupta, Ram B.
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p. 761 - 762
(2007/10/02)
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