- Silica-supported perchloric acid and potassium bisulfate as reusable green catalysts for nitration of aromatics under solvent-free microwave conditions
-
Silica-supported perchloric acid and bisulfate (SiO2/HClO4 and SiO2/KHSO4) have been developed as reusable green catalysts for nitration of aromatic compounds using NaNO2 in acetonitrile medium under conventional and solvent-free microwave conditions. The reaction times under microwave irradiation are significantly shorter than conventional method even though the yields obtained in microwave-assisted reactions are comparable with those obtained under reflux conditions.
- Kumar, M. Satish,Sriram, Y. Hemanth,Venkateswarlu,Rajanna,Sudhakar, M. Sai,Venkanna, Purugula,Saiprakash
-
supporting information
p. 59 - 67
(2017/12/26)
-
- Potassium Periodate/NaNO2/KHSO4-Mediated Nitration of Aromatic Compounds and Kinetic Study of Nitration of Phenols in Aqueous Acetonitrile
-
Synthesis and kinetics of potassium periodate(KIO4)/NaNO2/KHSO4)-initiated nitration of aromatic compounds have been studied in aqueous acetonitrile medium. Synthesis of nitroaromatic compounds is achieved under conventional and solvent-free microwave conditions. Reaction times in microwave-assisted reaction are comparatively less than in conventional reaction. The reaction kinetics for the nitration of phenols in aqueous bisulfate and acetonitrile medium indicated first-order dependence on [phenol], [NaNO2], and [KIO4]. An increase in [KHSO4] accelerated the rate of nitration under otherwise similar conditions. The rate of nitration increased in the solvent of high dielectric media (solvents with high dielectric constant (D)). Observed results were in accordance with Amis and Kirkwood plots [log k′ vs. (1/D) and [(D ? 1)/(2D + 1)]. These observations probably indicate the participation of anionic species and molecular or (dipolar) species in the rate-determining step. In addition, the plots of (log k′) versus volume% of organic solvent were also linear, which probably indicate the importance of both electrostatic and nonelectrostatic forces, solvent–solute interactions during nitration of phenols. Reaction rates accelerated with the introduction of electron-donating groups and retarded with electron-withdrawing groups, but results could not be quantitatively correlated with Hammett's equation and depicted deviations from linearity. These deviations could probably be attributed to cumulative effects arising inductive, resonance, and steric effects. Leffler's plot (ΔH# vs. ΔS#) was found linear indicating the compensation (cumulative) effect of both enthalpy and entropy parameters in controlling the mechanism of nitration.
- Sriram, Y. Hemanth,Fatima, Touheeth,Rajanna,Kumar, M. Satish,Raju, R. Madhusudan
-
supporting information
p. 622 - 632
(2017/06/30)
-
- Ultrasonically Assisted Rate Enhancements in Trichloroisocyanuric Acid/DMF/NaNO2 Triggered Nitration of Aromatic Compounds and Decarboxylative Nitration of α,β-Unsaturated Acids
-
An efficient and safe method for nitration of aromatic compounds and decarboxylative nitration of α,β-unsaturated acids was developed using trichloroisocyanuric acid (TCICA)/dimethylformamide (DMF) in the presence of NaNO2. The reaction times of conventional protocol reduced from 8-10 h to 1.0-1.5 h (60-90 min) under sonication, even though the yields are comparable under both the conditions.
- Kumar, Mukka Satish,Rajanna, Kamatala Chinna,Venkateswarlu, Marri,Venkanna, Purugula,Saiprakash, Pondichery Kuppuswamy
-
p. 2251 - 2258
(2015/09/22)
-
- Oxalylchloride/DMF as an efficient reagent for nitration of aromatic compounds and nitro decarboxylation of cinnamic acids in presence of KNO 3 or NaNO2 under conventional and nonconventional conditions
-
Nitration of aromatic compounds and cinnamic acids with oxalylchloride/DMF afforded the corresponding nitro derivatives in the presence of KNO3 or NaNO2 under conventional and nonconventional (ultrasonic and microwave) conditions. The present methodology offers several benefits such as excellent yields, simple work-up procedure, and short reaction times. The yields obtained under present methodology are comparable with those obtained from (POCl3/DMF/KNO3 or NaNO2) and (SOCl 2/DMF/KNO3 or NaNO2) systems followed by shorter reaction times. The reaction times of sonication and microwave conditions are very shorter than those of the conventional conditions.
- Kumar, M. Satish,Reddy, K. Rajendar,Rajanna,Venkanna,Krishnaiah
-
p. 977 - 983
(2013/06/05)
-
- Studies on the biological activity of some nitrothiophenes
-
The biological activity of nineteen substituted thiophenes (3) have been assessed by evaluating the minimum inhibitory concentration required to inhibit the growth of E. coli, M. luteus and A. niger. The series displays a wide range of activities with 2-chloro-3,5-dinitrothiophene (3a) or 2-bromo-3,5- dinitrothiophene (3c) showing the highest activity against all three organisms, while the simplest compound of the series, 2-nitrothiophene (3s) shows the smallest activity in each case. The mode of action of 3a and 3c is thought to involve nucleophilic attack by intracellular thiols at the 2-position of the heterocyclic ring leading to displacement of halogen, but other active derivatives, such as 2,4-dinitrothiophene (3h) and 5-nitrothiophene-2- carbaldehyde (3d) which have no displaceable halogen or leaving group are thought to act by forming Meisenheimer complexes. The Royal Society of Chemistry 2006.
- Morley, John O.,Matthews, Thomas P.
-
p. 359 - 366
(2008/01/27)
-
- A mild and efficient method for the mononitration of aromatic compounds by cerium (III) ammonium nitrate in acetic anhydride
-
A mild and efficient method for the mononitration of aromatic and olefinic compounds is described. This method is especially useful for active substrates.
- Tanemura, Kiyoshi,Suzuki, Tsuneo,Nishida, Yoko,Satsumabayashi, Koko,Horaguchi, Takaaki
-
p. 497 - 499
(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)
-
- The synthesis of highly active thiophene ring-containing chromophore components for photonic polymers based on a newly designed route
-
2-Aminothiophene derivatives are the key intermediates for the present synthesis. It is known that the synthesis of 2-aminothiophene is troublesome although it is a rather simple heterocycle. In this work, an early report was newly developed as a basis for the efficient synthesis of thiophene-ring-containing chromophore components for photonic polymers. 2-Amino-5-nitrothiophene and 2-amino-3,5-dinitrothiophene were synthesized in excellent yield. After diazotization, the 2-aminothiophene derivatives were directly treated with N-phenyldiethanolamine to afford two-electron push-pull compounds. A similar styryl compound was also prepared. All of these chromophore molecules have further polymerizable hydroxy groups on one end of the molecule. These compounds are currently showing interesting potential in making highly sensitive, nonlinear optical polymeric materials. The Royal Society of Chemistry 1999.
- Yuquan, Shen,Yuxia, Zhao,Zao, Li,Jianghong, Wang,Ling, Qiu,Shixiong, Liu,Jianfeng, Zhai,Jiayun, Zhou
-
p. 3691 - 3695
(2007/10/03)
-
- A convenient catalytic route to symmetrical functionalized bithiophenes
-
A series of symmetrical functionalized bithiophenes has been synthesized in good to excellent yields via homocoupling of thiophene halides in the presence of Pd(OAc)2 as a catalyst.
- Hassan, Jwanro,Lavenot, Laurence,Gozzi, Christel,Lemaire, Marc
-
p. 857 - 858
(2007/10/03)
-
- A novel method for the nitration of simple aromatic compounds
-
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.
- Smith, Keith,Musson, Adam,DeBoos, Gareth A.
-
p. 8448 - 8454
(2007/10/03)
-
- Five membered ring analogues of nifedipine - Part 1: 2-Nitro-3-furanecarbaldehyde and 2-nitro-3-thiophenecarbaldehyde in the Hantzsch pyridine synthesis
-
The heterocyclic aldehydes 4 in the Hantzsch pyridine synthesis afforded dependent on the choosen variation, either the 1,4-dihydropyridines (DHP) 5, the 1,2-DHP 6 or the 1,2,3,4-tetrahydropyrimidines (THPM) 7 as main products. 5-7 were dehydrogenated to the corresponding heteroaromatics 8-10 by cerium(IV). The lactames 11 and 12 were isolated by appropiate reduction of the nitro group from 8 and 9 by neighbour group participation of an ester function. The synthesis of 12 represents for the second time the evidence of an 2-aminofurane compound. 11 and 12 were converted with phosphorous oxychloride to form the annulated chloronaphthyridines 13 and 14 which were cyclized with sodium azide to yield the tetrazoles 15 and 16. The half wave potentials E1/2 of the DHP and THPM 5-7 were determined by anodic oxidation with the rotating platinum electrode using difference pulse voltammetry (DPV). These are comparable with those of the 2-nitrophenyl analogues.
- Goerlitzer,Dobberkau
-
p. 386 - 391
(2007/10/03)
-
- INVESTIGATION OF THE KINETICS OF THE NITRATION OF THIOPHENE DERIVATIVES
-
The kinetics of the nitration of thiophene derivatives with nitric acid in acetic anhydride were investigated.The nitration of 2-substituted thiophenes is a second-order reaction.The rate constants and activation parameters of the reaction were calculated.The possibility of the Hammett and Yukawa-Tsuno equations for this reaction series is demonstrated.An isokinetic dependence is observed.
- Freidlin, G. N.,Glushkova, A. A.,Solop, K. A.
-
p. 127 - 130
(2007/10/02)
-
- PROTIODESILYLATION OF SUBSTITUTED 2-TRIMETHYLSILYLTHIOPHENS
-
First-order rate constats at 50 deg C have been determined for cleavage of the thiophen compounds XC4H2SSiMe3-2 in mixtures of (a) MeOH (5 vol.) with aqueous HClO4 (2 vol.) and (b) CH3CO2H (4 vol.) with aqueous H2SO4 (3 vol.) Relative rates krel, in the first medium are (X =) 5-OMe, 7 200; 5-Me, 36; H, 1.00; 5-Cl, 1.08E-1; 5-Br, 9.0E-2; 3-Br, 5.0E-2; 4-Br, 4.9E-3, and in the second medium 5-Me, 36; H, 1.00; 5-Cl, 1.28E-1; 5-Br, 9.8E-2; 3-Br, 5.5E-2; 4-Br, 6.5E-3; 5-NO2, 9.1E-7; 3-NO2, 7.1E-7.Except for the nitro-compounds, the two sets of log krel values show excellent linear correlations with values for the corresponding XC6H4SiMe3 compounds, with 3-, 4-, and 5-X in the thiophen ring being taken as equivalent to o-, m-, and p-X groups, respectively, in the benzene ring, the effects of substituents being a litle larger in the thiophen than the benzene system; 3- and 5-O2NC4H2SSiMe3 are less reactive than would be expected from the correlations.Again with the exception of the data for the nitro-compound, the krel values for the 4- and 5- substituted thiophens show very good correlation with ?m+ and ?p+ constants.
- Seconi, Giancarlo,Eaborn, Colin
-
p. 931 - 934
(2007/10/02)
-
- THE RATES OF BASE CLEAVAGE OF SUBSTITUTED 2-THIENYLTRIMETHYLSILANES. AB INITIO CALCULATIONS OF THE ACIDITIES OF MONOSUBSTITUTED THIOPHENS
-
Rates of cleavage in NaOMe-MeOH at 50 deg C have been determined for the mono-substituted 2-trimethylsilylthiophens X*C4H2S*SiMe3-2 with X = H, 3-NO2, 3-Br, 4-Br-, and 5-NO2, -CN, -COPh, -Me, -OMe and -NMe2, and for one disubstituted compound, 4,5-Br2*C4HS*SiMe3-2.For several compounds the rate and product isotope effects have also been determined.The energies involved in the process X*C4H3S X*C4H2S- for deprotonation at the 2-position have been calculated by an ab initio method (STO-3G), and the results used in analysis of the substituent effects in the cleavage of the XC4H2S*SiMe3-2 compounds.The results are consistent with the view the aryl anions separate in the rate-determining step of the cleavage.The isotope effects are all close to unity, whereas by comparison with results for XC6H4CH2SiMe3 and related species of similar reactivity, values in the region of 10 would be expected for the 3- and 5-NO2 compounds if the product isotope effect for a carbanion R depended only in the pKa of RH.The difference between the thienyl- and benzyl-type anions is attributed to the absence of conjugative delocalization of the charge in the former. Approximate pKa values are derived for the 2-positions of the X*C4H3S compounds.
- Seconi, Giancarlo,Eaborn, Colin,Stamper, John G.
-
p. 153 - 168
(2007/10/02)
-
- MECHANISM OF THE ELECTROCHEMICAL REDUCTION OF 2-HALO-5-NITROTHIOPHENES IN DIMETHYLFORMAMIDE
-
The reduction of 2-bromo-5-nitrothiophene and 2-iodo-5-nitrothiophene in dimethylformamide (DMF) was studied by means of classical and commutated polarography, EPR spectroscopy, a rotating platinum disk electrode with a ring, and preparative electrolysis.It was established that, depending on the nature of the halogen, their anion radicals may undergo further reduction to 2-nitrothiophene anion radicals or decomposition with splitting out of a halide anion and conversion to nitrothienyl radicals, which were identified on the ring electrode.The latter are capable of undergoing dimerization to 2,2'-dinitro-5,5'-dithienyl.The spectra of the anion radicals of 2-nitrothiophene and 2,2'-dinitro-5,5'dithienyl were recorded by means of EPR.A mechanism for the reduction of halonitrothiophenes is proposed.
- Sosonkin, I. M.,Strogov, G. N.,Ponomareva, T. K.,Domarev, A. N.,Glushkova, A. A.,Freidlin, G. N.
-
p. 137 - 140
(2007/10/02)
-
- Sulfonation of aromatic compounds in the presence of solvents
-
A process for the sulfonation of aromatic compounds wherein an aromatic substance consisting of one or more aromatic compounds susceptible to the action of sulfur trioxide is formed into a reactant by admixture with one or more organic liquids, substantially inert to sulfur trioxide under the conditions of the process, which reactant is brought to boiling at a temperature not greater than 100° C under a pressure of from 0.1 mm Hg to atmospheric pressure, gaseous sulfur trioxide is introduced thereinto thereby causing it to continue to boil, the component or components of the reactant thus volatilized is or are reconverted to liquid in a heat-exchanger and recycled to the reaction chamber, and the pressure in the reaction chamber and the rate at which the gaseous sulfur trioxide is introduced into the reactant are controlled so as to ensure that there is always present in the reaction chamber an amount of volatilizable matter exceeding that amount volatilizable by the heat of reaction of the aromatic substance present in the reaction chamber with the gaseous sulfur trioxide in contact with said aromatic substance and that the temperature of the reaction mixture is a temperature of 100° C or below.
- -
-
-
