- Preparation method of 4-amino-1, 3-dihydro-benzimidazole-2-one
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The invention provides a preparation method of 4-amino-1, 3-dihydro-benzimidazole-2-one, which comprises the following steps: Q1, preparation of 2, 6-dinitrochlorobenzene, Q2, preparation of 2, 6-dinitroaniline, Q3, preparation of 3-nitro-o-phenylenediamine, Q4, preparation of 4-nitro-1H-benzo[d]imidazole-2(3H)-one and Q5, preparation of 4-amino-1, 3-dihydro-benzimidazole-2-one. According to the preparation method, 3, 5-dinitro-4-chlorobenzoic acid which is low in price is used as a raw material, and the high-yield 4-amino-1, 3-dihydro-benzimidazole-2-one is obtained through reactions such asdecarboxylation and ammoniation. The whole reaction process is easy to control, the product yield is high, good social benefits and economic benefits can be brought, and the economic value potential is large.
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Paragraph 0039
(2020/07/15)
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- Gold(I)-catalyzed protodecarboxylation of (Hetero)aromatic carboxylic acids
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Readily available, inexpensive and easy to handle, carboxylic acids have been shown to be very effective, greener coupling partners compared to costly organometallic reagents for the formation of C-C bonds. The use of well-defined gold complexes furnished 3 in slightly better yield with butyric acid, and in quantitative yield with adamantane-1-carboxylic acid. All reactions reached completion within 16 h. As with silver systems, this reactivity trend highlights, as previously observed, the benefits of potential coordinating groups in the ortho position to the gold binding site, which possibly facilitate the decarboxylation step. Additional reaction time and increased temperatures were necessary to afford the gold aryl products in satisfactory yields. Yet, some substrates such as 2-nitrobenzoic acids reacted poorly and could only be transformed in 50% yield.
- Dupuy, Stéphanie,Nolan, Steven P.
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supporting information
p. 14034 - 14038
(2013/11/19)
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- Unusual behaviour during the route of a Japp-Klingemann reaction
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Performing a standard Japp-Klingemann synthesis that involved diazotation of 2,6-dinitroaniline and reaction with pentane-2,4-dione in aqueous hydrochloric acid medium surprisingly yielded a mixture of the expected 2,6-dinitro-and the unexpected 2-chloro-6-nitro-substituted hydrazones. This mixture was isolated as solid-solution crystals containing the components in an approximate ratio of 1 to 2. Based on both, selected compounds of comparison that show the aromatic ring substituents changed in position and intermediate diazonium salts, potential causal connections of the unusual behaviour during the route of the particular Japp-Klingemann reaction were studied. X-Ray crystal structures of the relevant compounds have been determined to support the discussion.
- Marten, Jan,Seichter, Wilhelm,Wagler, Joerg,Weber, Edwin
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experimental part
p. 745 - 752
(2011/01/09)
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- Highly efficient dinitration of aromatic compounds in fluorous media using ytterbium perfluorooctanesulfonate and perfluorooctanesulfonic acid as catalysts
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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
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p. 2957 - 2961
(2007/10/03)
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- Synthesis of 2-N-alkyl(aryl)amino-7-nitrobenzothiazoles
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A highly efficient synthesis of 2-N-alkyl(aryl)amino-7-nitrobenzothiazoles has been developed. The key step involves intramolecular cyclization of a thiourea facilitated by the nitro group. A highly efficient synthesis of 2-N-alkyl(aryl)amino-7-nitrobenzothiazoles has been developed. The key step involves intramolecular cyclization of a thiourea facilitated by the nitro group.
- Huang, Shenlin,Connolly, Peter J.
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p. 9373 - 9375
(2007/10/03)
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- Regioselective double Kyodai nitration of toluene and chlorobenzene over zeolites. High preference for the 2,4-dinitro isomer at the second nitration stage
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(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
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p. 3431 - 3434
(2007/10/03)
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- Faujasite catalysis of aromatic nitrations with dinitrogen pentoxide. The effect of aluminium content on catalytic activity and regioselectivity: The nitration of pyrazole
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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.
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p. 197 - 200
(2007/10/03)
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- Preparation and NMR analysis of 2,6-heterodifunctional halobenzenes as precursors for substituted biphenyls
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Preparation and complete characterization of 16 2,6-disubstituted halobenzenes, including nine new compounds, from two common starting materials is described. Seven of the new compounds contain one or two propylthio groups, which have been introduced in two ways. Direct reaction of arenediazonium salts with 1-propanethiolate gives yields comparable to those obtained in a three-step method through sulfonyl chlorides. The 1H- and 13C NMR chemical shifts of 17 1,2,3-trisubstituted benzenes have been correlated with the predicted values and the observed trends explained using commonly available modeling packages.
- Sienkowska, Monika,Benin, Vladimir,Kaszynski, Piotr
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p. 165 - 173
(2007/10/03)
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- Zeolite catalysis of aromatic nitrations with dinitrogen pentoxide
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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.
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p. 1815 - 1818
(2007/10/03)
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- Synthesis of nitropolychlorinated dibenzo-p-dioxins (NPCDDs) and their photochemical reaction with nucleophiles
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A series nitropolychlorodibenzo-p-dioxins (NPCDDs) was synthesized by condensation between catechols and 2,6-dinitrochalobenzene derivatives.In the presence of sodium ethoxide in anhydrous ethanol, these underwent photochemical SN2Ar* substitutions meta to the nitro group in high chemical yield and moderate quantum yield.Both ring-opening and chloride replacement reactions were observed.The reactions involved the triplet excited state of the NPCDD, and showed a linear relationship between Φ-1 and -1.Analogous reactions with KCN in methanol showed similar behaviour, but the products could not be isolated.Key words: photosubstitution, SN2Ar*, dibenzo-p-dioxins.
- Merica, Simona G.,Bunce, Nigel J.
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p. 826 - 834
(2007/10/03)
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- Mechanism of reaction of hydroxide ion with dinitrochlorobenzenes
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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
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p. 238 - 246
(2007/10/02)
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- 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
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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.
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p. 667 - 674
(2007/10/02)
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