6526-74-5Relevant academic research and scientific papers
Regioselective mononitration of aromatic compounds with N2O5 by acidic ionic liquids via continuous flow microreactor
Liu, Jianhua,Li, Bindong,Wang, Huan
, p. 513 - 516 (2016/01/20)
We employed N2O5 as highly active nitrating reagents and a host of acidic ionic liquid as catalysts in these reactions which were conducted in a continuous flow microreactor. When we utilized PEG400-DAIL as catalysts, the conversion of toluene was increased to 95.5 % and the yield of mononitration product (o/p ratio reached 1.10) significantly improved to 99 %, meanwhile the reaction time was drastically shortened to 1/120 of the conventional reactor. Nitration in ionic liquids was surveyed using a host of aromatic substrates with similar reactivity. The ionic liquid recycling procedures had also been devised.
Reusable and efficient polystryrene-supported acidic ionic liquid catalyst for mononitration of aromatic compounds
Li, Li Xia,Ling, Qi Long,Liu, Zu Liang,Xing, Xiao Dong,Zhu, Xiao Qin,Meng, Xiao
, p. 3373 - 3377 (2013/01/15)
A series of polystyrene-supported 1-(propyl-3-sulfonate)-3-methyl- imidazolium hydrosulfate acidic ionic liquid (PS-[SO3H-PMIM][HSO 4]) catalysts were prepared and tested for mononitration of simple aromatics compounds with nitric acid. It was found that the reactivity of the catalysts increased with increasing [SO3HPMIM][ HSO4] content. The para-selectivity was not only related to the [SO 3H-PMIM][HSO4] content but also the substituent groups in aromatics. A reaction mechanism of nitration over this new catalyst was proposed. The catalytic activity of this catalyst decreased slightly after fifth runs in the synthesis of nitrotoluene.
Structurally simple inhibitors of lanosterol 14α-demethylase are efficacious in a rodent model of acute Chagas disease
Suryadevara, Praveen Kumar,Olepu, Srinivas,Lockman, Jeffrey W.,Ohkanda, Junko,Karimi, Mandana,Verlinde, Christophe L. M. J.,Kraus, James M.,Schoepe, Jan,Van Voorhis, Wesley C.,Hamilton, Andrew D.,Buckner, Frederick S.,Gelb, Michael H.
experimental part, p. 3703 - 3715 (2010/04/24)
We report structure-activity studies of a large number of dialkyl imidazoles as inhibitors of Trypanosoma cruzi lanosterol-14α-demethylase (L14DM). The compounds have a simple structure compared to posaconazole, another L14DM inhibitor that is an anti-Chagas drug candidate. Several compounds display potency for killing T. cruzi amastigotes in vitro with values of EC 50 in the 0.4-10 nM range. Two compounds were selected for efficacy studies in a mouse model of acute Chagas disease. At oral doses of 20-50 mg/kg given after establishment of parasite infection, the compounds reduced parasitemia in the blood to undetectable levels, and analysis of remaining parasites by PCR revealed a lack of parasites in the majority of animals. These dialkyl imidazoles are substantially less expensive to produce than posaconazole and are appropriate for further development toward an anti-Chagas disease clinical candidate.
Nitration of alkylbenzenes in acid medium: Regioselectivity of the reaction and acidity of the medium
Krylov
, p. 1413 - 1418 (2007/10/03)
Isomer distribution in the nitration of toluene and its homologs with nitric acid in acid media (trifluoroacetic acid and solutions of sulfuric acid in acetic acid) is determined by the acidity of the medium, the degree of para substitution changing in parallel with the acidity. The ortholpara regioselectivity is governed by the polarity of the transition state. The sensitivity of the ortholpara ratio to variation of the acidity of the medium and reaction temperature is directly related to steric effects of the alkyl groups.
Regioselectivity of the mononitration of alkylbenzenes by immobilized acyl nitrates
Augusto,Rodrigues,Pedro Oliveira Filho,Moran, Paulo J. S.
, p. 2169 - 2174 (2007/10/03)
Mononitration of alkylbenzenes was studied using acyl nitrates and trimethylsilyl nitrate supported on clay-minerals. Chrysotile gave higher performance than other materials. High para-selectivity was obtained with the supported reagents. Nitration of tol
A novel method for the nitration of simple aromatic compounds
Smith, Keith,Musson, Adam,DeBoos, Gareth A.
, p. 8448 - 8454 (2007/10/03)
Simple aromatic compounds such as benzene, alkylbenzenes, halogenobenzenes, and some disubstituted benzenes are nitrated in excellent yields with high regioselectivity under mild conditions using zeolite β as a catalyst and a stoichiometric quantity of nitric acid and acetic anhydride. The zeolite can be recycled, and the only byproduct is acetic acid, which can be separated easily from the nitration product by distillation; the process is inexpensive and represents an attractive method for the clean synthesis of a range of nitroaromatic compounds. For example, nitration of toluene gives a quantitative yield of mononitrotoluenes, of which 79% is 4-nitrotoluene; fluorobenzene gives a quantitative yield of mononitro compounds, of which 94% is 4-nitrofluorobenzene; and 2-fluorotoluene gives a 96% yield of mononitro products, of which 90% is the 5-nitro isomer and 10% is the 4-nitro isomer.
Synthesis of functionalized carbamates through a palladium-catalyzed reductive carbonylation of substituted nitrobenzenes
Wchman, Petra,Borst, Leo,Kamer, Paul C. J.,Van Leeuwen, Piet W. N. M.
, p. 13 - 21 (2007/10/03)
The palladium-catalyzed reductive carbonylation of ortho and para-substituted nitrobenzenes has proven to be an attractive route for the synthesis of functionalized carbamates. For the Pd(1,10-phenanthroline)2(triilate}2 catalyst system, the scope of the reaction has been studied. Substrates with electron-donating substituents at the para position were found to decrease the catalytic activity, most probably as a result of their relatively low oxidizing capacity. The selectivity towards the desired carbamate, however, was increased for these substrates. Under the influence of electron-withdrawing substituents the azoxybenzene and azobenzene derivatives became important side products. Introduction of large steric hindrance at the ortho position of the nitro substrates gave rise to an interesting side reaction, viz. methoxylation of the aromatic ring. The methoxylation reaction appeared to occur on an intermediate species in the catalytic cycle. Several functionalities have shown to be resistant to the reaction conditions required for the conversion of the nitro group. Especially with 4-nitrobenzoic acid, an extremely high activity and selectivity was found, thus yielding a very convenient synthesis for N-protected amines containing carboxylic acid functions. VCH Verlagsgesellschaft mbH.
Nitration of Alkylbenzenes in Trifluoroacetic Acid
Krylov,Gvozdareva
, p. 1618 - 1623 (2007/10/03)
The substrate selectivity of alkylbenzene nitration with nitric acid in trifluoroacetic acid is controlled either by electronic or by steric effects of the substituents, depending the medium composition and temperature. The positional selectivity of this reaction is sterically controlled, even under electronic control of substrate selectivity.
Substituent Effect in C-Isopropylation of Benzene Derivatives in the Nitrobenzene-Methanesulfonic Acid-Isopropyl Methanesulfonate System
Zaraiskaya, N. A.,Kachurin, O. I.
, p. 641 - 644 (2007/10/03)
Relative reactivities of chlorobenzene, o-dichlorobenzene, and nitrobenzene in C-isopropylation in the system nitrobenzene-methanesulfonic acid-isopropyl methanesulfonate at 298 K and the initial regioselectivity of the reaction were studied.Correlation analysis shows that sensitivity of the reaction to mesomeric effects of the substituents increses with decreasing activity of the substrate.
Ozone-mediated Nitration of Alkylbenzenes and Related Compounds with Nitrogen Dioxide
Suzuki, Hitomi,Murashima, Takashi,Kozai, Iku,Mori, Tadashi
, p. 1591 - 1598 (2007/10/02)
In the presence of ozone, nitrogen dioxide exhibits a strong nitrating ability for alkylbenzenes at low temperatures, converting them into the corresponding nitro derivatives in high yield.The addition of a protonic acid as catalyst enhances considerably the ability of this nitrating system and leads to a good yield of polynitro compounds.The reaction is clean and proceeds rapidly without any accompanying side-chain substitution or aryl-aryl coupling.It shows no kinetic dependence on the concentration of substrates and, as far as can be judged from relative reactivities and isomer distributions of products, it gives the appearance of being an electrophilic aromatic process.A possible role for nitrogen trioxide has been suggested as the initial electrophilic agent for the nitration of alkylbenzenes.
