- Kinetics and mechanism of p-nitrochlorobenzene nitration with nitric acid
-
Kinetics of homogeneous nitration of p-nitrochlorobenzene with 85-95% nitric acid was investigated. An introduction of a nitro group into a chlorobenzene molecule results in 1600 times deceleration of nitration. It was presumed from comparison of kinetic parameters and correlations of log keff for the mono- and dinitration with the acidity functions of nitric acid that the limiting stage in p-nitrochlorobenzene nitration was the transformation of diffusion pairs into reaction products, whereas in chlorobenzene nitration the limiting stage consisted in diffusion pairs formation.
- Veretennikov,Lebedev,Tselinskii
-
-
Read Online
- Deaminative chlorination of aminoheterocycles
-
Selective modification of heteroatom-containing aromatic structures is in high demand as it permits rapid evaluation of molecular complexity in advanced intermediates. Inspired by the selectivity of deaminases in nature, herein we present a simple methodology that enables the NH2 groups in aminoheterocycles to be conceived as masked modification handles. With the aid of a simple pyrylium reagent and a cheap chloride source, C(sp2)?NH2 can be converted into C(sp2)?Cl bonds. The method is characterized by its wide functional group tolerance and substrate scope, allowing the modification of >20 different classes of heteroaromatic motifs (five- and six-membered heterocycles), bearing numerous sensitive motifs. The facile conversion of NH2 into Cl in a late-stage fashion enables practitioners to apply Sandmeyer- and Vilsmeier-type transforms without the burden of explosive and unsafe diazonium salts, stoichiometric transition metals or highly oxidizing and unselective chlorinating agents. [Figure not available: see fulltext.]
- Ghiazza, Clément,Faber, Teresa,Gómez-Palomino, Alejandro,Cornella, Josep
-
-
- 2,2,2-Trifluoroacetaldehyde O-(Aryl)oxime: A Precursor of Trifluoroacetonitrile
-
The preparation of 2,2,2-trifluoroacetaldehyde O-(aryl)oxime, a previously inaccessible precursor of trifluoroacetonitrile, via reaction of hydroxylamine and trifluoroacetaldehyde hydrate is reported. This precursor released CF3CN in quantitative yield under mildly basic conditions. The precursor was successfully used in the synthesis of trifluoromethylated oxadiazoles. The facile, cost-effective, scalable, and recyclable procedure makes these trifluoroacetonitrile precursors generally applicable.
- Lin, Bo,Yao, Yunfei,Huang, Yangjie,Weng, Zhiqiang
-
p. 2055 - 2058
(2022/03/31)
-
- Self-powered continuous nitration method and device
-
The invention belongs to the technical field of organic synthesis application, and particularly relates to a self-powered continuous nitration method and device. According to the method, a raw material (or a raw material solution) and mixed acid (or nitric acid) are added into a self-powered continuous reactor at the same time, reaction feed liquid continuously and circularly flows, is mixed and reacts in a tube pass through self-propelling force generated by stirring of an impeller, the mass and heat transfer process is completed, and the target requirement is met. According to the invention, the mass transfer and heat transfer efficiency can be improved, the heat exchange and heat transfer capabilities are improved, the reaction time is shortened, the risk degree of art is reduced, the thermal runaway risk is avoided, the reaction safety is improved, and the realization of chemical industry intrinsic safety large scale production is facilitated.
- -
-
Paragraph 0061-0064
(2021/07/17)
-
- Novel viologen compound and preparation thereof
-
The invention relates to novel viologen compounds and a preparation method thereof. Specifically, the invention provides a type of compounds with a structure shown by a formula I. The definitions of the groups are as in the specifications. The compounds of the formula I provided by the invention can be widely applied in the aspects of soft matter material construction, photoelectric materials, and solar cells.
- -
-
Paragraph 0154-0155
(2020/07/23)
-
- Nitrification method for preparing dinitrochlorobenzene by catalyzing chlorobenzene through ionic liquid
-
The invention discloses a nitrification method for preparing dinitrochlorobenzene by catalyzing chlorobenzene through ionic liquid, including the steps of mixing chlorobenzene and a catalyst, heatingto be 50-60 DEG C, mixing with stirring for 2-4 hours to obtain a mixture; respectively adding the mixture and nitric acid solution into a microchannel reactor, performing nitrification in the microchannel reactor, discharging from an outlet, standing for 24 hours, extracting subnatant, and then washing, neutralizing and drying the subnatant to obtain dinitrochlorobenzene. The method is green andenvironmentally friendly as generating of a great quantity of waste acid is avoided in production; reaction in the method has high selectivity and high yield, and 2,4-dinitrochlorobenzene prepared bythe method has high purity.
- -
-
Paragraph 0029-0071
(2019/04/17)
-
- Preparation method of nitrification organic matter and prepared nitrification organic matter
-
The invention discloses a preparation method of nitrification organic matter and the prepared nitrification organic matter, and relates to the technical field of organic synthesis. The preparation method of the nitrification organic substance comprises the following steps: introducing a nitrification acid liquid and molten-state organic matter to be nitrified into a microchannel reactor, and performing a reaction, wherein the organic matter to be nitrified is solid at normal temperature, and solidification and/or dissolution in the nitrification acid liquid does not occur in the organic matterto be nitrified after the organic matter to be nitrified is introduced into the microchannel reactor. According to the preparation method of the nitrification organic matter provided by the invention, the nitrification organic matter prepared by the method has a very good yield and purity without a solvent removal post-treatment process; in the whole process, no solvent participates in the reaction, so that the post-treatment process of solvent removal is avoided; and the method has high safety in the whole reaction process, adopts automation control, has high production efficiency and a greatly-improved production environment, and has larger industrial application value.
- -
-
Paragraph 0097-0100
(2019/07/29)
-
- NITRATION OF AROMATIC COMPOUNDS
-
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.
- -
-
Paragraph 0051
(2016/08/17)
-
- The novel usage of thiourea nitrate in aryl nitration
-
Thiourea nitrate (TN) was easily prepared from thiourea and nitric acid to explore its use as a new nitration reagent. Nitrations of various aromatic compounds utilizing TN in concentrated sulfuric acid were studied. TN could convert aromatic compounds to the corresponding nitrated derivatives with various abnormal yields under mild conditions. The results suggested that the reaction mechanism might be different from those of traditional nitration reagents.
- Meng, Ge,Zheng, Mei-Lin,Zheng, A-Qun,Wang, Mei,Shi, Juan
-
-
- Application of screening experimental designs to assess chromatographic isotope effect upon isotope-coded derivatization for quantitative liquid chromatography-mass spectrometry
-
Isotope effect may cause partial chromatographic separation of labeled (heavy) and unlabeled (light) isotopologue pairs. Together with a simultaneous matrix effect, this could lead to unacceptable accuracy in quantitative liquid chromatography-mass spectrometry assays, especially when electrospray ionization is used. Four biologically relevant reactive aldehydes (acrolein, malondialdehyde, 4-hydroxy-2-nonenal, and 4-oxo-2-nonenal) were derivatized with light or heavy (d3-, 13C6-, 15N2-, or 15N4-labeled) 2,4-dinitrophenylhydrazine and used as model compounds to evaluate chromatographic isotope effects. For comprehensive assessment of retention time differences between light/heavy pairs under various gradient reversed-phase liquid chromatography conditions, major chromatographic parameters (stationary phase, mobile phase pH, temperature, organic solvent, and gradient slope) and different isotope labelings were addressed by multiple-factor screening using experimental designs that included both asymmetrical (Addelman) and Plackett-Burman schemes followed by statistical evaluations. Results confirmed that the most effective approach to avoid chromatographic isotope effect is the use of 15N or 13C labeling instead of deuterium labeling, while chromatographic parameters had no general influence. Comparison of the alternate isotope-coded derivatization assay (AIDA) using deuterium versus 15N labeling gave unacceptable differences (>15%) upon quantifying some of the model aldehydes from biological matrixes. On the basis of our results, we recommend the modification of the AIDA protocol by replacing d 3-2,4-dinitrophenylhydrazine with 15N- or 13C-labeled derivatizing reagent to avoid possible unfavorable consequences of chromatographic isotope effects.
- Szarka, Szabolcs,Prokai-Tatrai, Katalin,Prokai, Laszlo
-
p. 7033 - 7040
(2014/08/05)
-
- Regioselective mononitration of chlorobenzene using caprolactam-based Br?nsted acidic ionic liquids
-
Three kinds of Br?nsted acidic ionic liquids caprolactam benzenesulfonate ([CP]BSA), caprolactam hydrosulfate ([CP]HSO4) and caprolactam p-toluenesulfonate ([CP]pTSA) were synthesized. The structures of the ILs were confirmed by 1HNM
- Zhang, Cun,Yu, Mei-Jing,Pan, Xiao-Yu,Wu, Guo,Jin, Liang,Gao, Wei-Dan,Du, Meng,Zhang, Jun-Chao
-
p. 101 - 105
(2014/01/06)
-
- Preparation, catalytic performance and theoretical study of porous sulfated binary metal oxides shell (SO42 -/M1xO y-M2xOy) using pollen grain templates
-
Porous micro-sized particles of binary metal oxide (SO4 2 -/M1xOy-M2xOy) shell were prepared by template-directed synthesis method employing HCl-treated pollen grains. With 150 m2/g high surface area, these solid acids could provide more acid sites and thus obtain better catalytic activity. Using aromatic nitration as the typical reaction, their catalytic performances were evaluated and showed a significant improvement in both conversion and regioselectivity. Then, with chlorobenzene as substrate, theoretical studies were performed to investigate the interaction between transition metals and chlorobenzene. The results showed that the excellent para-selectivity was closely relative to the metal ion in these solid acids.
- Wang, Peng Cheng,Yao, Kai,Zhu, Jie,Liu, Xiang,Lu, Ting Ting,Lu, Ming
-
-
- Synthesis, single crystal structure and performance of N-substituted derivatives of dinitroimidazole
-
The N-substituted derivatives of dinitroimidazoles have been synthesized for application as energetic materials. The synthesized compounds were fully characterized by 1H 13C NMR spectroscopy and elemental analysis. Most of them were determined by single crystal X-ray diffraction. The calculated densities of the compounds range between 1.89 and 1.91 g cm -3 and the experimental densities between 1.75 and 1.84 g cm -3, as obtained by X-ray crystallographic analysis. Notably, densities of the N-substituted derivatives of dinitroimidazoles are increased when two amino groups are introduced but decreased when one amino group is introduced.
- Hou, Kehui,Ma, Congming,Liu, Zuliang
-
p. 2837 - 2844
(2013/09/12)
-
- Quinolinium-based fluorescent probes for the detection of thiophenols in environmental samples and living cells
-
A new type of fluorescent probes for thiophenols, 6HQM-DNP and 7HQM-DNP, containing 6- or 7-hydroxy quinonlinium as fluorophore and 2,4-dinitrophenoxy (DNP) as nucleophilic recognition unit were constructed. As ethers, these non-fluorescent probe molecules can release the corresponding fluorescent quinolinium (6HQM and 7HQM) through aromatic nucleophilic substitution (S NAr) by thiolate anions from thiophenols. The sensing reaction is highly sensitive (detection limit of 8 nM for 7HQM-DNP) and highly selective to thiophenols over aliphatic thiols and other nucleophiles under neutral conditions (pH 7.3). The probes respond rapidly to thiophenols, with second-order rate constants k=45 M-1 s-1 for 7HQM-DNP and 24 M-1 s-1 for 6HQM-DNP. Furthermore, the selective detection of thiophenols in living cells by 7HQM-DNP was demonstrated by confocal fluorescence imaging. In addition, these quinolinium salts show excellent chemical and thermal stability. In conclusion, this type of probes may find use in the detection of thiophenols in environmental samples and biosystems. Copyright
- Liu, Xiu-Ling,Duan, Xue-You,Song, Qin-Hua,Du, Xiao-Jiao
-
p. 2696 - 2702,7
(2020/09/02)
-
- Ethylammonium nitrate (EAN)/Tf2O and EAN/TFAA: Ionic liquid based systems for aromatic nitration
-
Acting as in situ sources of triflyl nitrate (TfONO2) and trifluoroacetyl nitrate (CF3COONO2), the EAN/Tf 2O and EAN/TFAA systems, generated via metathesis in the readily available ethylammonium nitrate (EAN) ionic liquid as solvent, are powerful electrophilic nitrating reagents for a wide variety of aromatic and heteroaromatic compounds. Comparative nitration experiments indicate that EAN/Tf2O is superior to EAN/TFAA for nitration of strongly deactivated systems. Both systems exhibit low substrate selectivity (K T/KB = 5-10) in (Figure presented) between values reported for covalent nitrates and preformed nitronium salts.
- Aridoss, Gopalakrishnan,Laali, Kenneth K.
-
p. 8088 - 8094
(2011/11/13)
-
- CAN-mediated oxidation of electron-deficient aryl and heteroaryl hydrazines and hydrazides
-
Aryl and heteroaryl hydrazines and hydrazides were successfully oxidised using CAN, deriving dehydrazinated products. The reaction pathway strongly depends on the nature of the substrate, resulting in the formation of hydrocarbons or alkoxy derivatives. When deuterated solvents such as methanol-d4 or acetonitrile-d3 were used, a regiospecific incorporation of deuterium was achieved. Georg Thieme Verlag Stuttgart.
- ?tefane, Bogdan,Polanc, Slovenko
-
experimental part
p. 1279 - 1282
(2009/04/06)
-
- Highly efficient dinitration of aromatic compounds in fluorous media using ytterbium perfluorooctanesulfonate and perfluorooctanesulfonic acid as catalysts
-
Ytterbium perfluorooctanesulfonate [Yb(OPf)3] and perfluorooctanesulfonic acid [PfOH] catalyze the highly efficient dinitration of toluene, benzene, benzyl chloride, and chlorobenzene in fluorous media. Notably the process produces almost no waste acid, as opposed to the traditional case. The fluorous phase-containing catalyst could be easily and efficiently recovered for reuse by simple phase separation. Copyright Taylor & Francis Group, LLC.
- Yi, Wen-Bin,Cai, Chun
-
p. 2957 - 2961
(2007/10/03)
-
- Regioselective double Kyodai nitration of toluene and chlorobenzene over zeolites. High preference for the 2,4-dinitro isomer at the second nitration stage
-
(matrix presented) The Kyodai nitration of toluene and chlorobenzene has been examined in the presence of a solid inorganic catalyst (montmorillonite K10, zeolite HZSM-5, or HBEA-25). Regioselection was quite low at the mononitration stage, but a considerably high preference for the 2,4-isomer was observed at the dinitration stage.
- Peng, Xinhua,Suzuki, Hitomi
-
p. 3431 - 3434
(2007/10/03)
-
- Dual-parameter correlations on rate of an aromatic nucleophilic substitution reaction in aqueous solutions of methanol, ethanol, and propan-2-ol
-
Reaction kinetics of 1-chloro-2,4-dinitrobenzene with piperidine was studied spectrophotometrically in aqueous solutions of methanol, ethanol, and propan-2-ol at 25 °C. The reaction in these solutions is not catalyzed by piperidine. The plots of second-order rate constants of the reaction vs. mole fraction of water show maxima in the all-aqueous solutions. Single-parameter correlations of log k2 vs. π* (dipolarity/polarizability), α (hydrogen-bond donor acidity), and ETN (normalized polarity parameter) are very poor in the all solutions (for example, in aqueous solutions of ethanol, regression coefficients are 0.814, 0.113, and 0.486, respectively). Dual-parameter correlations of log k2 vs. π* and α in all cases represent significant improvement with regard to the single-parameter models (in aqueous solutions of ethanol: n = 11, r = 0.980, and s = 0.034). Dipolarity/polarizability and hydrogen-bond donor acidity (HBD) of media have opposite effects on the reaction rate. The activated complex leading to the zwitterionic intermediate is expected to be favored by increasing the solvent dipolarity/polarizability parameter. Increasing the hydrogen-bond donor acidity of solvent stabilizes piperidine and hence the reaction rate decreases. A dual-parameter equation of log k2 vs. π* and α was obtained in the all-aqueous solutions (n = 31, r = 0.956, s = 0.055) in which π* and α have approximately equal and opposite effects on the reaction rate.
- Gholami,Yangjeh, A. Habibi
-
p. 118 - 123
(2007/10/03)
-
- 1-Aryl-3,3-dialkyltriazenes: A convenient synthesis from dry arenediazonium o-benzenedisulfonimides - A high yield break down to the starting dry salts and efficient conversions to aryl iodides, bromides and chlorides
-
This research comprises three parts. The first part regards the synthesis of 1-aryl-3,3-dialkyltriazenes 3 by reaction of dry arenediazonium o-benzenedisulfonimides 1, also coming from weakly basic aromatic amines with dimethylamine or diethylamine in aqueous solution at 0-5 °C. Yields were usually greater than 90% and there was the possibility of recovering the o-benzenedisulfonimide (5), which could be reused to prepare the salts 1. In the second part it was demonstrated that there is the possibility of reconverting the triazenes 3 into the starting stable dry salts 1 by using 5 as acid. The reactions were carried out in glacial acetic acid at 50-55 °C and normally afforded salts 1 in yields of around 90-99%. The third part concerns the setting up of two procedures for the conversion of 3 to aryl iodides 9, bromides 10 and chlorides 11. Procedure A used the corresponding aqueous hydrogen halides in acetonitrile at r.t. or 60 °C, sometimes in the presence of aqueous HBF4, sometimes Cu powder (25 examples, yields 65%-88%). Procedure B usually used anhydrous methanesulfonic acid and tetraalkylammonium halides in anhydrous acetonitrile at temperatures varying from r.t. to 80 °C, sometimes in the presence of Cu (16 examples, yields 65-88%).
- Barbero,Degani,Diulgheroff,Dughera,Fochi
-
p. 2180 - 2190
(2007/10/03)
-
- Faujasite catalysis of aromatic nitrations with dinitrogen pentoxide. The effect of aluminium content on catalytic activity and regioselectivity: The nitration of pyrazole
-
The reaction of 1-chloro-2-nitrobenzene with dinitrogen pentoxide in dichloromethane catalysed by H-faujasite zeolites F-712, F-720, F-780 and F-901, giving 1-chloro-2,4-dinitro- and 1-chloro-2,6-dinitrobenzene in approximately 30:1 ratio, is a kinetically first-order process. First-order rate constants are independent of the concentration of N2O5 and proportional to the mass of catalyst used. Specific rate constants, obtained by dividing the first-order rate constant by the mass of faujasite, are constant for a given faujasite. Amongst the faujasites, they increase in approximate proportion to the aluminium content. A mechanism is proposed in which the protons in the faujasite, near aluminium in the faujasite framework, are replaced by nitronium ions derived from N2O5 in a fast pre-equilibrium process. This produces active sites for transfer of nitronium ion from faujasite to aromatic in the rate-determining step. The similar reactions of 2-nitrotoluene, too fast for kinetic study, reveal that the ratio of 2,4- to 2,6-dinitrotoluene in the product increases with the aluminium content of the faujasite. Nitration of nitrobenzene is also catalysed by faujasite. Relative reactivities of nitrobenzene, 1-chloro-2-nitro- and 1-chloro-4-nitrobenzene are compared to those found in mixed-acid nitration. Pyrazole can be nitrated readily with N2O5 over faujasites, yielding 1,4-dinitropyrazole in 80% yield under mild conditions.
- Claridge, Robert P.,Lancaster, N. Llewellyn,Millar, Ross W.,Moodie, Roy B.,Sandall, John P.B.
-
p. 197 - 200
(2007/10/03)
-
- Regioselective nitration of arylboronic acids
-
A convenient and simple regioselective ipso-nitration of arylboronic acids to nitroarenes has been developed. Under certain conditions even dinitro products were isolated.
- Salzbrunn,Simon,Prakash,Petasis,Olah
-
p. 1485 - 1487
(2007/10/03)
-
- Zeolite catalysis of aromatic nitrations with dinitrogen pentoxide
-
The reactions of 2-nitrotoluene. 1-chloro-2-nitrobenzene, and 1-chloro-4-nitrobenzene with dinitrogen pentoxide in dichloromethane at 0 °C are strongly catalysed by some zeolites notably H-Faujasite-720, catalysis by which is investigated in detail. Yields of the nitrated aromatics are near-quantitative. In the first two substrates nitration occurs more regioselectively at the 4-position compared to the uncatalysed reaction. The reaction of 1-chloro-2-nitrobenzene shows a kinetic form which is close to first-order with a rate-constant independent of the concentration Of N2O5 and proportional to the mass of zeolite. Initial addition of the major product, 1-chloro-2,4-dinitrobenzene, causes rate-inhibition. Mechanisms are discussed.
- Claridge, Robert P.,Lancaster, N. Llewellyn,Millar, Ross W.,Moodie, Roy B.,Sandall, John P. B.
-
p. 1815 - 1818
(2007/10/03)
-
- Halodediazoniations of dry arenediazonium o-benzenedisulfonimides in the presence or absence of an electron transfer catalyst. Easy general procedures to prepare aryl chlorides, bromides, and iodides
-
The paper reports the results of a wide study aimed at preparing aryl chlorides 3 (19 examples), bromides 4 (19 examples), and iodides 5 (9 examples) by halodediazoniation of dry arenediazonium o-benzenedisulfonimides 1 with tetraalkylammonium halides 2. The reactions were carried out in anhydrous acetonitrile at room temperature (~20 °C) in the presence of copper powder and at 60 °C or room temperature without the catalyst. In optimal conditions the yields were from good to excellent (60 reactions, 61- 94% yield), with only a few exceptions (8 reactions, 51-55% yield). A good amount of the o-benzenedisulfonimide (7) was always recovered from the reactions and could then be reused to prepare salts 1. An interesting aspect of this research is the surprising role of the anion of o- benzenedisulfonimide (9) as an electron transfer agent.
- Barbero,Degani,Dughera,Fochi
-
p. 3448 - 3453
(2007/10/03)
-
- Synthesis of 3-demethylphenylsilyl-substituted pyrido[1,2-a]benzimidazoles
-
Reductive cyclization of 1-(2,4-dinitrophenyl)-3-methyl-4-dimethylphenylsilylpyridinium chloride by the action of phenylhydrazine or hydrogen in the presence of Pd/C gave, for the first time, 7-nitro(amino)-3-dimethylphenylsilylpyrido[1,2-a]benzimidazoles. 1996 Plenum Publishing Corporation.
- Krapivko,Savitkina,Antares, Kuanu A.,Astakhov,Varlamov
-
p. 290 - 293
(2007/10/03)
-
- Catalysis in Nucleophilic Aromatic Substitution Reactions. The Presence of Molecular Complexes on the Pathway of Reactions between 1-Fluoro- and 1-Chloro-2,4-dinitrobenzene and Aliphatic Amines
-
The kinetics of reactions between 1-halogeno-2,4-dinitrobenzene (halogen = F, Cl) and butylamine and piperidine were re-investigated in cyclohexane.The kobs values (s-1 mol-1 dm3) increased with increases in the initial concentration of the reacting amine.Investigation of the reaction mixtures at zero reaction time, indicated the presence of an interaction between the substrate and the amine which occurred in a rapidly established equilibrium and which preceded the substitution process.The nature of the molecular complexes observed is discussed.Present and previous data indicate that the kobs increase was difficult to explain with the traditional hypotesis of proton and leaving group departure as a rate determining step.A better rationalisation of the experimental data may be obtained by involving the molecular complexes on the substitution reaction pathway.
- Forlani, Luciano
-
p. 1525 - 1530
(2007/10/02)
-
- ONE STEP CONVERSION OF ANILINES TO ARYL HALIDES USING SODIUM NITRITE AND HALOTRIMETHYLSILANE
-
Anilines were easily diazotized and efficiently converted to aryl halides in an one-pot reaction using sodium nitrite and halotrimethylsilane in carbon tetrachloride.Halotrimethylsilanes are used for both generating nitrosonium donor from sodium nitrite, and the halogen substitution of diazonium group.
- Lee, Jong Gun,Cha, Hee Tae
-
p. 3167 - 3168
(2007/10/02)
-
- Mechanism of reaction of hydroxide ion with dinitrochlorobenzenes
-
Formation of dinitrophenoxide ion from 2,4- and 2,6-dinitrochlorobenzene (2,4- and 2,6-DNCB) and OH- (OD-) in 70:30 and 80:20 (v/v) DMSO-H2O (D2O) is accompanied by extensive 1H NMR line broadening of unreacted substrate and exchange of arene hydrogen with D2O, which is quantitative at the 3-position of 2,4-DNCB. Unproductive Meisenheimer complexes are detected spectrophotometrically in the course of reaction. For reaction of 2,4-DNCB, the Meisenheimer 3-complex is formed first and then the more stable 5-complex can be detected and characterized by NMR spectrometry. There is no hydrogen exchange of Meisenheimer complexes or dinitrophenoxide ions and their 1H NMR signals are not broadened. These results do not fit the classical mechanism of single-step nucleophilic addition, but they, and the kinetic results, are fitted by a reaction scheme involving single-electron transfer from OH- to give a charge-transfer complex of OH? and a radical anion which collapses to give Meisenheimer complexes and aryl oxide ion. This scheme is consistent with MO calculations by the AM1 method.
- Bacaloglu, Radu,Blaskó, Andrei,Bunton, Clifford,Dorwin, Ellen,Ortega, Francisco,Zucco, César
-
p. 238 - 246
(2007/10/02)
-
- Electrophilic Aromatic Substitution. Part 37. Products of Aromatic Nitrations of some Chloronitrobenzenes and Substituted Benzoic Acids in Solutions of Dinitrogen Pentaoxide and of Nitronium Salts in Nitric Acid
-
Yields of aromatic products of nitration in nitric acid solutions containing dinitrogen pentaoxide or nitronium salt have been determined.Evidence for the intrusion of a mechanism other than the normal nitronium ion one comes from comparison of products in the two media and from the observation of 15N NMR CIDPN effects.The additional mechanism operative with some substrates in concentrated solutions of dinitrogen pentaoxide is postulated to be one in which reversible addition of the NO3 radical is followed by combination with NO2.Dienes produced in this way can give aromatic nitroproducts by elimination of nitric acid.Nitrodecarboxylation of substituted benzoic acids occurs by a radical process.
- Moodie, Roy B.,Sanderson, Andrew J.,Willmer, Richard
-
p. 645 - 650
(2007/10/02)
-
- Electrophilic Aromatic Substitution. Part 35. Chlorination of 1,3-Dinitrobenzene, 1-Chloro-2,4-dinitrobenzene, and 2,4-Dinitrotoluene with Nitric Acid and Hydrogen Chloride or Chlorine in Sulphuric Acid or Oleum
-
Solutions of sulphuric acid or oleum containing HCl or Cl2 and nitric acid have been found both to chlorinate and nitrate deactivated aromatic compounds.The kinetics and products of the chlorination of 1,3-dinitrobenzene and 1-chloro-2,4-dinitrobenzene in sulphuric acid or oleum containing HCl and nitric acid at 130 deg C, and the kinetics and products of the chlorination of 2,4-dinitrotoluene at 90 deg C in sulphuric acid or oleum containing Cl2 and nitric acid, are reported. 1,3-Dinitrobenzene and 1-chloro-2,4-dinitrobenzene were predominantly chlorinated. 2,4-Dinitrotoluene gave approximately equal amounts of 6-chloro-2,4-dinitrotoluene and 2,4,6-trinitrotoluene.The results show that under these conditions, chlorination and nitration are competing electrophilic reactions, and that chlorination is less selective than nitration.Possible mechanisms for chlorination are discussed.
- Melhuish, Martin W.,Moodie, Roy B.
-
p. 667 - 674
(2007/10/02)
-
- Electrophilic Aromatic Substitution. Part 34. Nitration of 1-Chloro-4-nitrobenzene, 1,3-Dichloro-2-nitrobenzene, 1,3-Dinitrobenzene, 1-Chloro-2,4-dinitrobenzene, and 2-Chloro-1,3-dinitrobenzene in Sulphuric Acid and Oleum
-
Yields of the expected nitro products from 1-chloro-4-nitrobenzene and 1,3-dichloro-2-nitrobenzene nitrated at 25 deg C in sulphuric acid or oleum containing 1 mol dm-3 nitric acid were quantitative.The rate profile for nitration of 1,3-dichloro-2-nitrobenzene is normal, but sulphonation is a competing process when the concentration of nitric acid is low.Kinetics of nitration of 1,3-dinitrobenzene at 150 deg C are reported; yields of 1,3,5-trinitrobenzene, the only detected aromatic product, are low.The title chlorodinitrobenzenes each give, on nitration at 130 deg C, a dichlorodinitrobenzene as well as a chlorotrinitrobenzene.The kinetics and yields of the two products from 1-chloro-2,4-dinitrobenzene under a variety of conditions are reported and discussed in relation to a previously proposed mechanism.
- Melhuish, Martin W.,Moodie, Roy B.,Payne, Malcolm A.,Schofield, Kenneth
-
p. 1637 - 1642
(2007/10/02)
-
- Reactions of Nitrophenols with Phosphorus Oxychloride in Dimethylformamide
-
A rapid and simple method for the replacement of hydroxyl group of nitrophenols and related compounds by chlorine using phosphorus oxychloride in dimethylformamide at ambient temperature is described.
- Akhtar, Nahid,Munawar, M. A.,Siddiq, M.
-
-
- The Stabilities of Meisenheimer Complexes. Part 40. A Kinetic Study of the Reaction of 1-Chloro-2,4-dinitrobenzene with Sulphite Ions in Water-Dimethyl Sulphoxide Mixtures
-
Kinetic and equilibrium data are reported for the reactions of 1-chloro-2,4-dinitrobenzene with sulphite ions in dimethyl sulphoxide-water mixtures.Attack at the unsubstituted 5-position yields an observable ?-adduct and is shown to be more rapid by a factor of ca. 12 than attack at the 1-position.The latter process which yields the substitution product is likely to involve intermolecular attack of sulphite on the substrate rather than intramolecular re-arrangement of the 5-adduct.
- Crampton, Michael R.,Greenhalgh, Colin
-
p. 599 - 602
(2007/10/02)
-
- Process for the preparation of 2-amino-4-nitrophenol
-
The process of reducing 2,4-dinitrophenol to 2-amino-4-nitrophenol by reduction with a hydrosulfide in aqueous alkaline solution at temperatures from 20°-100° C. is improved by maintaining the pH at 7 to 9.5 during the reduction.
- -
-
-
- Process for the manufacture of substantially pure 3-amino-4-alkoxy-acylanilides from 2,4-dinitrochlorobenzene
-
A process for the manufacture of a substantially isomerically pure acylanilide of the structure STR1 where R is hydrogen, lower alkyl, hydroxy-lower alkyl or lower alkoxy-lower alkyl; R1 is lower alkyl, phenyl, lower alkylphenyl, lower alkoxy, lower alkoxyphenyl, chlorophenyl, nitrophenyl, dichlorophenyl, chloro-lower alkyl, cyano-lower alkyl, lower alkyl amino, sulfamoylphenyl, carbamoylphenyl or lower alkoxy-lower alkyl; and X is --CO-- or --SO2 --; comprising the step of treating an alcohol solution of a diamino compound of the structure STR2 with an acylating agent, to give an alcohol solution of the acylanilide, wherein substantially equivalent amounts of the acylating agent and the diamino compound are used and wherein the treatment is carried out by the slow, drop-wise addition of the acylating agent at a temperature in the range of about 0° to 5° C. The process is particularly advantageous when the alcohol solution of the diamino compound is produced by reduction of a suspension of the corresponding dinitro compound in the alcohol.
- -
-
-
- Selective weed control with m-dinitrobenzene
-
Weeds can be controlled by the application as a herbicide of m-dinitrobenzene. This compound is particularly effective for selectively controlling weeds in agronomic crops.
- -
-
-
- Process for the production of nitro derivatives of aromatic compounds
-
Nitroderivates of aromatic compounds which are difficult to nitrate, can readily be obtained by nitration providing that the aromatic compound is treated with nitric acid or another nitrating agent in the presence of aliphatic or cycloaliphatic hydrocarbons monosubstituted or polysubstituted by halogen, the nitro group or an alkyl sulphonyl group, and the nitro derivative formed subsequently isolated.
- -
-
-
