O-substituted Anilines Research Articles

ChemInform Abstract: Homogeneous Catalytic Oxidation of O-Substituted Anilines with Dioxygen in the Presence of Cobalt and Manganese Complexes.

Homogeneous catalytic oxidation of o-substituted aniline derivatives by dioxygen under ambient conditions has been studied. Systems exemplifying two fundamental mechanisms are described. Molecular oxygen may enter the catalytic cycle via either dioxygen complex formation, or the generation of RO' radicals via oxidation by metal salts. 2-Aminophenol is 2catalytically converted to 2-amino- phenoxazin-3-one (APX) via a series of H-abstraction and addition steps in the presence of triphenylphosphine- cobaloxime(II), which readily forms dioxygen complexes. A methyl-substituted 1,5-benzodiazepine (13) derived from o-phenylenediamine undergoes a methyl to formyl group oxidation catalyzed by manganese(II1) salts via a free-radical process of remarkable selectivity.

Steric hindrance as a key factor on proton transfer in the σ-adduct forming reactions of o-substituted anilines with 1,3,5-trinitrobenzene in dimethylsulfoxide

Kinetic and equilibrium studies are reported of the reactions of 1,3,5-trinitrobenzene (TNB) with a series of o-substituted anilines in dimethyl sulfoxide (DMSO) in the presence of 1,4-diazabicyclo[2.2.2.]octane (DABCO). The pKa values in DMSO for the aniline derivatives were measured using the proton-transfer equilibrium with 2,4-dinitrophenol. Kinetic studies are compatible with a two-step process involving initial nucleophilic attack on TNB by amine to give a zwitterionic intermediate which may transfer an acidic proton to DABCO to yield the anionic product. The results indicate steric hindrance to proton transfer in reactions involving 2,6-disubstituted anilines.

Corrosion inhibitors part 31 : quantum chemical studies on the efficiencies of some aromatic hydrazides and Schiff bases as corrosion inhibitors of steel in acidic medium

A quantum chemical study of the efficiency of some o-, m-, and p-substituted benzohydrazides, cinnamohydrazide, and Schiff bases derived from salcylaldehyde with o-substituted anilines, psubstituted benzaldehydes with 2-aminopyridine and 2-aminopyrimidine, benzaldehyde and cinnamaldehyde with p-phenylenediamine as corrosion inhibitors of steel in the presence of 1M HCl is presented. The AM1, PM3, MINDO/3 and MNDO semi-empirical SCF molecular orbital methods were used. A possible correlation between corrosion inhibition efficiencies and structural properties was searched to reduce the number of compounds to be selected for testing from a library of compounds. Quantum parameters, total negative charge (TNC) on the molecule, energy of highest occupied molecular orbital (EHOMO), energy of lowest unoccupied molecular orbital (ELUMO), dipole moment (μ), total energy (TE), and linear solvation energy terms, molecular volume (Vi) and dipolar-polarization (π*) were correlated to corrosion inhibition efficiency of the studied compounds. The results were used to predict the corrosion inhibition of some related aromatic hydrazide derivatives with correlation coefficient r > 0.96.

Recovery of free oligosaccharides from derivatives labeled by reductive amination

This study examined chemical regeneration of free oligosaccharides from their fluorescent derivatives prepared by reductive amination with various aromatic amines. Maltose derivatives of ethyl 4-aminobenzoate ( p-ABEE), 2-aminobenzonitrile ( o-ABN), 4-aminobenzonitrile ( p-ABN), 7-amino-4-methylcoumarin (AMC), 2-aminobenzoic acid ( o-ABA), 2-aminobenzamide ( o-ABAD), 2-aminopyridine (AP), and 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) were incubated at 30 °C with an aqueous solution of hydrogen peroxide/acetic acid. Recoveries of maltose from p-ABEE, p-ABN, and AMC derivatives were fairly good and gave approximately 90% of maltose. Recoveries of maltose from its o-substituted aniline ( o-ABA, o-ABAD, and o-ABN) derivatives were 5–40%, but maltose was unrecoverable from AP and ANTS derivatives. Nevertheless, prior treatment of an AP derivative with cyanogen bromide enabled the regeneration of maltose in high yields. As an application, p-ABEE-labeled N-glycans from some glycoproteins separated on an amide column were identified by converting peak components to their AP derivatives via free saccharides and following mapping by reversed-phase chromatography.

Synthesis, antiproliferative and antifungal activities of some 2-(2,4-dihydroxyphenyl)-4 H-3,1-benzothiazines

A new method for the synthesis of 4 H-3,1-benzothiazine skeleton is described. The compounds were obtained by the reaction of sulfinylbis(2,4-dihydroxythiobenzoyl) with o-substituted anilines bearing an activated methylene group (–CH 2OH, –CH 2NR 1R 2), o-aminobenzanilides or 2-aminobenzophenones. The reaction proceeded through thiobenzanilide intermediates, which were converted to the 4 H-3,1-benzothiazine fused ring by an endocyclization process. The compounds were tested for their antiproliferative properties against the cells of a human breast cancer T47D line. The activity of some compounds was comparable to that of cisplatin, studied as a control. A strong antifungal effect against the strains of moulds, yeasts and dermatophytes was also found.

New Routes to 1,2‐Dithiole‐3‐thiones and 3‐Imines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Selective palladium-catalyzed amination of β-chloroacroleins by substituted anilines

β-Chloroacroleins can undergo a selective amination on their chloro position under palladium catalysis; in those conditions, no imine formation was observed. Their coupling with anilines carrying electron-donating or electron-withdrawing substituents proceeds in moderate to good yields and steric hindrance does not seem to be a limitation as o-substituted anilines react readily.

Synthesis of Azulen‐3‐ylheterocyclic Compounds Using 2‐(3‐Methoxycarbonylazulen‐1‐yl)ethynyltriphenylphosphonium Bromide.

AbstractFor Abstract see ChemInform Abstract in Full Text.

New routes to 1,2-dithiole-3-thiones and 3-imines

The reaction of readily available 3,4,5-trichloro-1,2-dithiolium chloride 1 and 4,5-dichloro-1,2-dithiole-3-thione 2 with o-substituted anilines provides a simple route to 1,2-dithiole-3-thiones and 3-imines, which can be cyclised to give new, more complex heterocyclic systems such as 1,2-dithiolo[4,3-b][1,4]benzoxazine of potential value in cancer chemotherapy

Synthesis of Azulen-3-ylheterocyclic Compounds Using 2-(3-Methoxycarbonylazulen-1-yl)ethynyltriphenylphosphonium Bromide

3-(3-methoxycarbonylazulen-1-yl)ethynyltriphenylphosphonium bromide was prepared from methyl 3-formylazulenecarboxylate. Its resonance structures were discussed on the basis of the 'H and 1 3 C NMR spectroscopy. Furthermore, its reactivity with o-substituted aniline was examined. We found that 2-(1-methoxycarbonyl-azulen-3-yl)ethynyltriphenylphosphonium bromide reacted with o-substituted aniline except 2-aminophenol to give corresponding methyl 3-(benzazol-2-yl)azulene-1-carboxylate.

Investigation of the inhibitive effect of ortho-substituted anilines on corrosion of iron in 0.5 M H 2SO 4 solutions

The inhibiting action of six o-substituted anilines against the corrosion of iron (99.9999%) in solutions of sulphuric acid has been studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). At inhibitor concentration range (10 −3 to 10 −2 M) in 0.5 M acid, the efficiency of the inhibitors increases in the order o-toluidine < 2-chloroaniline < 2-ethylaniline < 2-fluoroaniline < o-aminoanisole < 2-amiophenetole. Comparable results were obtained by the different electrochemical methods used. Adsorption of these compounds on the iron surface was found to obey a Langmuir adsorption isotherm. An equivalent circuit is suggested based on analysis of EIS data.

Investigation of the inhibitive effect of ortho-substituted anilines on corrosion of iron in 1 M HCl solutions

The inhibitory activity of some o-substituted anilines on iron corrosion in hydrochloric acid (HCl) was studied in relation to inhibitor concentration using potentiodynamic and electrochemical impedance spectroscopy (EIS) measurements. O-substituted anilines were found to act as mixed type inhibitors. The results showed that o-substituted anilines suppressed both cathodic and anodic processes of iron corrosion in 1 M HCl by its adsorption on the iron surface according to Langmuir adsorption isotherm. Potentiodynamic and EIS measurements reveal that these compounds inhibit the iron corrosion in 1 M HCl and that the efficiency increases with increasing of the inhibitor concentration. Data obtained from EIS are analyzed to model the corrosion inhibition process through equivalent circuit.

Synthesis of Azulenylheterocyclic Compounds Using 2-(2-Azulenyl)ethynyltriphenylphosphonium Bromide

2-(2-Azulenyl)ethynyltriphenylphosphonium bromide was prepared from 2-formylazulene. Its NMR spectroscopic property was made clear. Furthermore, its reactivity with osubstituted aniline was examined. We found that 2-(2-azulenyl)ethynyltriphenylphosphonium bromide reacted with osubstituted aniline to give corresponding 2-(2-azulenyl)benzoazoles.

Carbon disulfide promoted reactions of 2-chloro-4,5-dihydro-imidazole with some N-nucleophiles.

The reactions of 2-chloro-4,5-dihydroimidazole 1 with o-substituted anilines and azoles promoted by carbon disulfide have been carried out. Ab initio MO calculations were used to elucidate the mechanism of the reaction of 1 with N-nucleophilic reagents. A facile synthesis of 2-(4,5-dihydroimidazol-2-yl)-1H-indazole 3e bearing structural resemblances to 2-BFI, a potent and selective agonist of imidazoline I2 receptors, is also described. Structure of 3e was confirmed by NMR spectroscopy and X-ray analysis.

Syntheses and electronic structures of benzannelated isoquinolinones and their photoinduced cycloaddition reactions with electron deficient alkenes †

Benzoxazolo[3,2-b]isoquinolin-11-ones 4, benzothiazolo[3,2-b]isoquinolin-11-one 5, benzimidazo[1,2-b]isoquinolin-11-ones 6 and isoquino[2,3-a][3,1]benzoxazine-5,12-dione 7 were synthesized by the reaction of homophthalic anhydride with the corresponding o-substituted anilines. Reaction mechanisms were investigated by isolation of the intermediate products under controlled reaction conditions. Electronic structures of 4a and 5 were investigated by ab initio calculations. Photoinduced [2+2] cycloaddition reactions of 4a and 5 with electron deficient alkenes (acrylonitrile, methyl acrylate, dimethyl fumarate and dimethyl maleate) gave cyclobutane products (36, 37 and 39–47 respectively). The regioselectivity in these photocycloadditions was examined by FMO interaction considerations. The mechanism of the cycloadditions was investigated by fluorescence quenching and triplet quenching experiments, solvent effect on the reaction and calculation of free energy change for electron transfer (SET) between the excited states of 4a (and 5) and the alkenes.

ChemInform Abstract: Synthesis of Heterocyclic Compounds from o‐Substituted Anilines under Microwave Irradiation.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Homogeneous catalytic oxidation of o-substituted anilines with dioxygen in the presence of cobalt and manganese complexes

Abstract

ChemInform Abstract: ACIDITY DEPENDENCE OF THE TAUTOMERIC EQUILIBRIUM BETWEEN THE FIRST CONJUGATED ACIDS OF 4‐AMINOAZOBENZENES

AbstractDie Aziditätsfunktionen für prim. Aniline, die keine o‐Substituenten haben, in 20% Ethanol/80% (H2SO4‐H2O) werden in Abhängigkeit von der H2SO4‐Konzentration bestimmt.

Acidity Dependence of the Tautomeric Equilibrium Between the First Conjugated Acids of 4-Aminoazobenzenes

Acidity functions based upon primary anilines which have no ortho substituents have been established in 20% ethanol-80% aqueous sulfuric acid solutions, and compared with those based upon o-substituted anilines and azobenzenes. It was found that the tautomeric equilibrium between azonium and anilinium forms in 4-aminoazobenzene derivatives invariably shifts to the azonium form with increase in acidity. This observation has been interpreted in terms of acidity functions.

Reaction of Dioxygen Complexes with Catechols

Abstract The square planar dioxygen complexes MO2(PPh3)2(M=Pt, Pd) reacted with catechols at low temperature to give H2O2 and the corresponding catecholato complexes, characterized by their physical properties, in high yields. A similar treatment of PtO2(PPh3)2 with o-substituted anilines afforded the corresponding adducts and H2O2 in moderate yields.