Oxidation of aniline and some para-substituted anilines by benzimidazolium fluorochromate in aqueous acetic acid medium – A kinetic and mechanistic study

The oxidation kinetics of some para-substituted anilines by benzimidazolium fluorochromate (BIFC) have been studied in aqueous acetic acid media in the presence of perchloric acid. The reaction is first order with respect to both aniline and BIFC and is catalysed by a hydrogen ion. The rate data obey Hammett relationship. The products of oxidation are the corresponding azo benzenes. Based on the kinetic results and product analysis, a suitable mechanism has been proposed for the reaction of BIFC with anilines.     

Reaction of the carbonate radical with substituted anilines

Rate constants for the reaction of carbonate radical with aniline and some parasubstituted anilines have been determined by the flash photolysis technique. Using σ⁺ para values the rate constants at pH 8.5 correlate very well with the Hammett equation yielding ρ= − 1. The carbonate radical oxidises aniline giving the anilino radical. The products so formed have been identified through studies under conditions of continuous irradiation.     

Experimental and Computational Studies on the CH Amination Mechanism of Tetrahydrocarbazoles via Hydroperoxides

The acid‐catalyzed reactions of photochemically generated tetrahydrocarbazole peroxides with anilines have been studied experimentally and computationally to identify the underlying reaction mechanism. The kinetic data indicate a reaction order of one in the hydroperoxide and zero in the aniline. Computational investigations using density functional theory support the experimental findings and predict an initial tautomerization between an imine and enamine substructure of the primarily generated tetrahydrocarbazole peroxide to be the rate controlling step. The enamine tautomer then loses hydrogen peroxide upon protonation, generating a stabilized allylic carbocation that is reversibly trapped by solvent or aniline to form the isolated products.     

Selective Para-C−H Alkynylation of Aniline Derivatives by Pd/S,O-Ligand Catalysis

Herein, we report a nondirected para-selective C−H alkynylation of aniline derivatives by a Pd/S,O-ligand-based catalyst. The reaction proceeds under mild conditions and is compatible with a variety of substituted anilines. The scalability and further derivatizations of the alkynylated products have been also demonstrated.     

Copper-Mediated monochlorination of anilines and nitrogen-containing heterocycles

A simple and selective copper(II) chloride-mediated monochlorination of anilines and nitrogen-containing heterocycles has been developed. Stirring a mixture of aniline, copper(II) chloride, lithium chloride in EtOH under reflux condition produced 4-chloroaniline with high yield. Eighteen substrates including substituted anilines, N-substituted anilines, N,N-disubstituted anilines, 5-nitroindole and carbazole were all reactive and afforded desired products in moderate to excellent yields (52%–98%).     

Adsorption and oxidation of aniline and anisidine by chromium ferrocyanide

The interaction of aniline and p-anisidine with chromium ferrocyanide has been studied. Maximum uptake of both anilines was observed around pH 7. The adsorption data obtained at neutral pH were found to follow Langmuir adsorption. Anisidine was a better adsorbate because of its higher basicity. In alkaline medium (pH>8) both aniline and anisidine reacted with chromium ferrocyanide to give colored products. Analysis of the products by GC-MS showed benzoquinone and azobenzene as the reaction products of aniline while p-anisidine afforded a dimer. IR analysis of the amine-chromium ferrocyanide adduct suggests that the outer metal ion of chromium ferrocyanide and amino group of amines are responsible for the interaction. A possible reaction mechanism for the product formation in alkaline medium has been proposed. The present study suggests that metal ferrocyanides might have played an important role in the stabilization of organic molecules through their surface activity in the prebiotic condensation reactions.     

Solvent and substituent effects on the reaction of 2‐ and 4‐chloro‐3,5‐dinitrobenzotrifluorides with substituted anilines

The solvent effect on a nucleophilic substitution reaction of 2‐ and 4‐chloro‐3,5‐dinitrobenzotrifluoride with substituted anilines was studied in methanol, acetonitrile, and toluene at 25°C. This reaction is of second order, except 2‐chloro‐3,5‐dinitrobenzotrifluoride in toluene shows third order. The k_A values are found to be dependent on the substituent in aniline and give good Hammett correlations. The obtained ρ values are ?4.07 and ?4.62, for the reaction of anilines with 2‐chloro‐3,5‐dinitrobenzotrifluoride in methanol and acetonitrile, respectively. The ρ values for the reaction of the anilines with 4‐chloro‐3,5‐dinitrobenzotrifluoride are ?3.38, ?4.11, and ?4.34 in methanol, acetonitrile, and toluene, respectively. The reaction of the former compound with anilines in toluene shows a second order in aniline. The dependence of the reaction on the external base such as DABCO suggests a proton transfer controlling step. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 777–786, 2009     

One‐Pot Cascade Transformation of Glucal into Structurally Diverse Drug‐Like Scaffolds

A diversity‐oriented synthesis strategy to produce three types of structurally drug‐like N‐heterocyclic‐fused rings has been developed from abundant biomass‐derived d ‐glucal, aniline and water in a stereoselective manner. The overall transformation which entails a cascade of Ferrier reaction and 4π conrotatory imino‐Nazarov cyclization was performed in one‐pot allowing convenient preparation of scaffolds of high molecular complexity from relatively simple starting materials. While indoline‐fused products were readily accessible using ortho‐unsubstituted secondary anilines as substrates, reactions with ortho‐hydroxyl‐anilines furnished fused 1,4‐benzoxazines instead. In both cases, InBr₃ acted as the Lewis acid catalyst. By altering InBr₃ to Ln(OTf)₃, the indoline‐fused products could be further converted into tetrahydroquinoline‐fused cyclopentenones via ensuing retro‐ene rearrangement.     

Chemoselective anti-Markovnikov hydroamination of α,β-ethylenic compounds with amines using montmorillonite clay

The catalytic activity of montmorillonite clays as a catalyst for the hydroamination of α,β-ethylenic compounds with amines was tested. Aniline and substituted anilines reacted with α,β-ethylenic compounds in the presence of catalytic amount of commercially available clay to afford exclusively anti-Markovnikov adduct in excellent yields. Aniline reacted with ethyl acrylate to yield only anti-Markovnikov adduct N-[2-(ethoxycarbonyl)ethyl]aniline (mono-addition product). No Markovnikov adduct (N-[1-(ethoxycarbonyl)ethyl]aniline and double addition product N,N-bis[2-(ethoxycarbonyl)ethyl]aniline were formed under selected reaction conditions. For a better exploitation of the catalytic activity in terms of increased activity and improved selectivity for the mono-addition product, the reaction parameters were optimized in terms of temperature, solvent, reactant mole ratio. Under optimized reaction conditions, montmorillonite clay K-10 showed a superior catalytic performance in the hydroamination of ethyl acrylate with aniline with a conversion of aniline to mono-addition product (almost 100% chemoselectivity) with a high rate constant 0.3414 min⁻¹ compared to the reported protocols. The dependence of conversion of aniline over different types of montmorillonite clays (K-10, K-20, K-30, Al-Pillared clay and untreated clay) has also been discussed. The activities of clay for the hydroamination of different aromatic and aliphatic amines have also been investigated. Under harsh reaction conditions (increased temperature and long reaction time) small amounts of di-addition products were observed. The kinetics data has been interpreted using the initial rate approach model.     

Correlations between the Basicity and Proton Affinity of Substituted Anilines

The enthalpies and free energies of gas-phase proton affinity (PA) of aniline and 62 derivatives with different electron donor and electron acceptor substituents in the aromatic ring and at the nitrogen atom were calculated by the PM3 technique. Linear correlations between the shapes of pK_a and PA have been found. The deviation of data from the above dependences for ortho-substituted anilines are discussed in the light of possible hydrophobic hydration of molecular fragments near the protonation reaction center.     

Studies on the kinetics of imidazolium fluorochromate oxidation of some meta‐ and para‐substituted anilines in nonaqueous media

The imidazolium fluorochromate (IFC) oxidation of meta‐ and para‐substituted anilines, in seven organic solvents, in the presence of p‐toluenesulfonic acid (TsOH) is first order in IFC and TsOH and is zero order with respect to substrate. The IFC oxidation of 15 meta‐ and para‐substituted anilines at 299–322 K complies with the isokinetic relationship but not to any of the linear free energy relationships; the isokinetic temperature lies within the experimental range. The specific rate of oxidizing species‐anilines reaction (k₂) correlates with substituent constants affording negative reaction constants. The rate data failed to correlate with macroscopic solvent parameters such as ε_r and E^N_T. A correlation of rate data with Kamlet–Taft solvatochromic parameters (α, β, π*) suggests that the specific solute–solvent interactions play a major role in governing the reactivity, and the observed solvent effects have been explained on the basis of solute–solvent complexation. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 166–175, 2006     

Liquid chromatographic determination of aniline and derivatives in environmental waters at nanogram per litre levels using fluorescamine pre-column derivatization

Summary Fluorescamine (fluram) has been used as a fluorogenic compound for pre-column derivatization of aniline and some derivatives. Anilines were derivatized with fluram in citrate buffer media (pH 5.5) to form pyrrolinones. The highly fluorescence pyrrolinones were isolated and pre-concentrated by solid phase extraction. A reversed phase, Spherisorb RP-8 column and tetrahydrofuran: water:formic acid (42:56:2) mobile phase was used for separation. Detection method was by a sensitive fluorimetric method and quantitation was at 395 and 495 nm. The various parameters such as reaction conditions between anilines and fluram, solid phase extraction and chromatographic separation were optimized. Calibrations were linear over the range considered with excellent correlation coefficients (r>0.999). Relative standard deviations are less than 2.5 % and detection limits for aniline,p-toluidine, 4-chloroaniline and 4-bromoaniline were 6, 30, 6 and 8 ng L⁻¹, respectively. This method has been used successfully for the determination of anilines in environmental waters.     

Solvent and substituent effects on the electrochemical oxidation of para‐ and meta‐substituted anilines

Electrochemical oxidation of 15 para‐ and meta‐substituted anilines in different mole fractions of water in 2‐methylpropan‐2‐ol has been investigated in the presence of 0.1 M sulfuric acid as a supporting electrolyte. The oxidation potential data of anilines correlate well with the Brown–Okamoto's substituent constants affording a negative reaction constant. The effect of para‐ and meta‐substituents on the oxidation potential confirms to Swain's F and R, affording negative reaction constants. The oxidation potential values also correlate satisfactorily with macroscopic solvent parameter such as relative permittivity, ε_r. The results of Kamlet–Taft multiple correlation analysis show that specific solute–solvent interactions play a dominant role in governing the reactivity. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 289–297, 2007     

2,4,6‐trichloropyrimidine. Reaction with anilines

The reaction of 2,4,6‐trichloropyrimidine 1 with a variety of 4‐substituted anilines 2 has been investigated. Monosubstitution occurs readily for all anilines except those containing strongly electron‐withdrawing groups. The yields of the isomeric products 3 and 4 parallel the Hammet constants of the ring substituents. The main product when ethanol was used as the solvent was the 4‐substituted‐2,6‐dichloropyrimidine 3. Spectral and X‐ray data confirmed this assignment. However, a solvent dependence on the 3:4 ratio was demonstrated. In some cases, excess aniline under forcing conditions led to 2,4‐disubstituted products.     

Viscosity and Thermodynamics of Viscous Flow of 1-propanol with Aniline,N-methylaniline and N,N-dimethylaniline

Abstract

Viscosities of the systems, 1-propanol + aniline, 1-propanol+N-methylaniline and 1-propanol+N,N-dimethylaniline have been measured in the temperature range 294.15 to 323.15K for the whole range of composition. The viscosities have been plotted against mole fraction of anilines. The viscosity-composition curves show minima, though not well-defined, in highly rich, moderately rich and moderately poor regions of 1-propanol respectively for 1-propanol + aniline, 1-propanol + N-methylaniline and 1-propanol +N,N-dimethylaniline systems. The excess viscosities have been found to be negative for all the systems throughout the whole composition and plotted against mole fraction of anilines. The thermodynamic activation parameters, such as, enthalpies, entropies and free energies and their excess values have been evaluated. The excess free energies have been found to be negative for all the systems and over the whole range of composition. The excess free energies have been plotted against the mole fraction of anilines. The viscosities, excess viscosities and excess free energies have been explained by assuming that the associated compounds, aniline, N-methylaniline and 1-propanol, are dissociated into smaller units in the solution systems by the rupture of H-bonds.     

Kinetik und Mechanismus der Aminaustauschreaktion anSchiff-Basen mit Essigsäureanhydrid

The reaction of N-benzylidene aniline withAc ₂O and aromatic amines yields substitutedSchiff bases, acetanilide and acetic acid. Kinetics and mechanism of the reaction of the intermediate N-(-acetoxybenzyl)-acetanilide formed from N-benzylidene aniline andAc ₂O with several anilines has been studied in toluene/acetic acid mixtures.

---

---

Mit 2 Abbildungen

---

10. Mitt.:O. S. Wolfbeis undE. Ziegler, Z. Naturforsch.31b, 1519 (1976).     

Au-doped TiO2 nanoparticles for selective photocatalytic synthesis of quinaldines from anilines in ethanol

A convenient eco-friendly photocatalytic synthesis of quinaldines has been developed by a simple one-pot reaction of anilines in ethanol solution with Au-loaded TiO₂ under UV irradiation. Upon irradiation in the presence of Au-TiO₂, aniline and oxidation products derived from ethanol undergo condensation-cyclization to afford quinaldines.     

N-芳基二茂铁丙烯酰胺的合成与表征

二茂铁丙烯酰氯;N-芳基二茂铁丙烯酰胺的合成与表征     

An unexpected reaction of 2-(cyclopent-2-enyl)aniline hydrochloride with dimethyldioxirane

An unusual direction of the reaction of 2-(cyclopent-2-enyl)aniline hydrochloride with dimethyldioxirane was found: the formation of two isomeric products,viz., 3- and 6-chloro-2-(cyclopent-2-enyl)anilines, was observed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1654–1655, August, 1998.     

Iron(III)–salen–H<Subscript>2</Subscript>O<Subscript>2</Subscript> as a peroxidase model: electron transfer reactions with anilines

Abstract  

Iron(III)–salen complexes catalyze the H₂O₂ oxidation of various ring-substituted anilines in MeCN have been studied, and [O=Fe^IV(salen)]^+· is proposed as the active species. Study of the kinetics of the reaction by spectrophotometry shows the emergence of a new peak at 445 nm in the spectrum which corresponds to azobenzene. Further oxidation of azobenzene by H₂O₂ leads to the formation of azoxybenzene. ESI–MS studies also support the formation of these products. The rate constants for the oxidation of meta- and para-substituted anilines were determined from the rate of decay of oxidant as well as the rate of formation of azobenzene, and the reaction follows Michaelis–Menten kinetics. The rate data show a linear relationship with the Hammett σ constants and yield a ρ value of −1.1 to −2.4 for substituent variation in the anilines. A reaction mechanism involving electron transfer from aniline to [O=Fe(salen)]^+· is proposed. The presence of axial ligands modulates the activity of the complex.