Condensation Of Anilines Research Articles

Enhancing Aniline Condensation Reaction Efficiency Using Alkali and Rare Earth Element Modified USY Zeolite Catalyst: Synergistic Effects and Mechanistic Insights

Enhancing Aniline Condensation Reaction Efficiency Using Alkali and Rare Earth Element Modified USY Zeolite Catalyst: Synergistic Effects and Mechanistic Insights

C–H bond activation over chitosan based Fe(III) and Ni(II) catalysts

Chitosan (Cs) supported heterogeneous catalysts of Fe(III) and Ni(II) is developed by the equimolar reaction of two schiff base ligands, L1 [Cs-HACP] and L2 [ANI-HACP] and Metal salts {where Metal = Fe(III) and Ni(II)}with chitosan. The L1 ligand is prepared by the reaction of chitosan (Cs) and ortho hydroxyl (HACP) acetophenone in methanol and L2 ligand is prepared by the condensation of aniline (ANI) and ortho hydroxyl acetophenone (HACP) in solvent free condition. The prepared catalysts {M-[Cs-L1-L2]Cl2} are characterized by different analytical techniques viz. scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), powder X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), Raman, UV-VIS-NIR, X-ray photoelectron spectroscopy (XPS) and computational studies. The catalytic behavior of newly synthesized catalysts are tested for the C–H activation using 70 % tert-butyl hydroperoxide (TBHP). The best results are obtained for tetralin oxidation. The order of catalytic reactivity of {M-[Cs-L1-L2]Cl2}catalyst is in decreasing order: {Fe(III)-[Cs-L1-L2]Cl2} > {Ni(II)-[Cs-L1-L2]Cl2}. The {Fe(III)-[Cs-L1-L2]Cl2} gives maximum conversion 81.99 % of tetralin with 84.50 % selectivity of tetralone (T-lone) and 6.47 % selectivity of tetralol (T-lol) after 5 h of reaction at 80 °C temperature. The chitosan based heterogeneous catalyst is easy to separate and recover. It can be recycled seven times.

Synthesis, immobilization and acid‑catalyzed application of binary and ternary deep eutectic solvent: Synthesis of diphenylamine by condensation of aniline

Binary and ternary acidic deep eutectic solvents (ADES) were synthesized by using choline chloride as hydrogen bond acceptor, trifluoromethanesulfonic acid and glycerol as hydrogen bond donors, respectively. They were immobilized on β zeolite. The structure and surface morphology were characterized by FTIR, 1H NMR, XRD and SEM, which proved the successful preparation and immobilization of ADES. The catalytic performance of the materials was investigated by the reaction of aniline condensation to prepare diphenylamine. Both ADES and immobilized ADES showed extremely high catalytic activity. Among them, immobilized ADES as a new heterogeneous catalytic material, breaks through the limitation of difficult separation of homogeneous catalysts, and has high economy, high activity and environmental protection. The hydrogen bonding interaction and catalytic mechanism between the components were further discussed in combination with the reaction mechanism.

One-pot synthesis of secondary amines from aldehydes and primary amines over trifunctional Au-TiO2 as a water adsorbent, acid catalyst and photocatalyst without the use of hydrogen gas

We succeeded in one-pot synthesis of N-phenylbenzylamine (PBA) from benzaldehyde (BAD) and aniline (AN) over titanium(IV) oxide having a gold (Au) cocatalyst (Au-TiO2) without the use of hydrogen gas. This process consists of two steps: 1) formation of benzylideneaniline (BAN) and water by condensation of AN and BAD, a step that is a thermal reaction and results in an equilibrium being reached, and 2) photocatalytic hydrogenation of BAN to PBA through a hydrogen transfer reaction from alcohol. Reactions under various conditions revealed that TiO2 showed bifunctionality in the condensation process as an acid catalyst and an adsorbent of water. Among the cocatalysts examined in this study, Au showed the highest performance for PBA production. Photoirradiation to the system in equilibrium containing Au-TiO2 produced PBA in a yield of about 92%. We found that TiO2 having a gold (Au) cocatalyst (Au-TiO2) works as a trifunctional catalytic material, i.e., an acid catalyst and water adsorbent for the first step and a photocatalyst for the second step. Expandability of this reaction system in production of halogen-substituted PBA and selection of alcohol was investigated.

Synthesis and Spectral, Thermal and Antimicrobial Investigation of Mixed Ligand Metal Complexes of N-Salicylidene Aniline and 1,10-Phenanthroline

Coordination compounds of Co(II), Cu(II), Y(III), Zr(IV) and La(III) ions were synthesized from the N-salicylidene aniline (L) derived from the condensation of aniline with salicylaldhyde and 1,10-phenanthroline (phen) as a secondary mixed ligand. L, phen and their complexes were characterized using various physiochemical methods, such as elemental analyses (CHN), Fourier-transform infrared spectroscopy (FT-IR), molar conductance (Λ), magnetic susceptibility (μeff), proton nuclear magnetic resonance (1H NMR), ultraviolet–visible spectroscopy (UV–Vis) and thermogravimetric analysis (TG/DTG). The analytical and spectroscopic data supporting the chemical formulas of the metal complexes and chelation of L and phen with the metal ions forming octahedral complexes. FT-IR spectra demonstrated that L chelated with metal ions as a bidentate ligand via the oxygen atom of the phenolic group with a band in the range 3378–3437 cm−1 and the nitrogen atom of the azomethine group at 1612 cm−1. In addition, phen chelated through two nitrogen atoms in the range 1525–1565 cm−1. The 1H NMR results confirmed the IR assumption that the ligand connected to the metal ions via the phenolic’s oxygen atom. The molar conductance measurements of the complexes revealed high values of the electrolytic nature of these complexes in the range of 90.40–125.80 S cm2 mol−1. Thermal analysis (TG/DTG) was used to differentiate between coordinated and hydrated water molecules and the thermal stability of the complexes. Finally, the anti-microbial activities of the complexes were investigated against fungi (Candida albicans), Gram-negative bacteria (Escherichia coli and Salmonella typhimurium) and Gram-positive bacteria (Staphylococcus aureus and Micrococcus sp.) using the disc diffusion method. The La(III) complex was significant against C. albicans compared with all other compounds and reference standard control.

NH4F modified β zeolite for aniline condensation to diphenylamine and its catalytic mechanism

The main factors affecting the performance of solid acid catalyzed liquid-phase condensation of aniline to diphenylamine are acidity and pore structure. Fluorine has strong electron affinity due to its special electronic structure, which can adjust the acidity and pore structure of zeolite. β zeolite was modified with different concentrations of NH4F solution. The aluminum in the framework of aluminosilicate zeolite was removed to a certain extent, and the acidity and pore size of β zeolite were controlled. Combined with XRD, Py-IR, Al MAS NMR and DRIFTS the active center and reaction mechanism of the catalytic reaction were discussed.

Synthesis of diphenylamine by condensation of aniline catalyzed by microporous-mesoporous composite solid acid nanoreactor

Microporous zeolite has regular pores, good surface properties and strong thermal and hydrothermal stability, but the adsorption and diffusion of macromolecules are limited by small and narrow pores, and the active sites of pores are difficult to use effectively. Mesoporous materials have good pore structure, but poor thermal and hydrothermal stability and weak acidity. In order to overcome the structural defects of single channel catalyst, a series of β zeolite and activated clay composite solid acid catalysts were prepared in this paper. X-ray diffraction and N2 physical adsorption-desorption showed that the composite catalyst has a microporous-mesoporous composite structure. The synthesis of diphenylamine by aniline condensation proved that the composite catalyst can be used as nanoreactor to promote the reaction. Combined with pyridine adsorption infrared spectroscopy, thermogravimetry, scanning electron microscope and kinetic analysis, the catalytic mechanism of microporous-msoporous composite solid acid nanoreactor was explored.

β Zeolite/bentonite composite as a novel catalyst for condensation of aniline to diphenylamine

β Zeolite/bentonite composite as a novel catalyst for condensation of aniline to diphenylamine

Dehydrogenative Condensation of Anilines with Dioles on Platinum/Alumina

Key words platinum catalysis - alumina - indoles - quinolines - dioles

Synthesis of 2,2,4-trimethyl-1,2-dihydroquinolines over metal-modified 12-tungstophosphoric acid-supported γ-Al2O3 catalyst

In spite of having significant pharmacological importance, scalable synthesis of 2,2,4-trimethyl-1,2-H-dihydroquinoline (TMQ) is always being cumbersome due to harmful solvents, drastic reaction conditions, and high recovery cost of homogeneous catalysts. Heterogeneous catalytic condensation of aniline with acetone was employed here to synthesize TMQ. As efficient materials, Zn2+-, Sn2+-, and Cu2+-exchanged tungstophosphoric acid (TPA) supported on γ-Al2O3 was synthesized by microwave-assisted hydrothermal method. The synthesized catalysts were thoroughly characterized by XRD, Raman, FE-SEM, etc. and were screened for condensation reaction. Among the metal-exchanged catalysts, Zn0.5TPA/Al2O3 showed highest aniline conversion with the highest yield of TMQ up to three consecutive cycles. The acidic sites over the catalysts were probed by pyridine-adsorbed FT-IR spectra and NH3-TPD studies. The reaction conditions were optimized, and plausible reaction mechanistic pathway was derived from FT-IR and GC–MS data.

Benzoxazine Formation Mechanism Evaluation by Direct Observation of Reaction Intermediates.

Benzoxazine formation is a fundamental step in the preparation of polybenzoxazine resins, and a detailed description of the mechanism governing the formation of benzoxazine and side products is vital for improving the properties and performance of these resins. Determination of the nature and properties of reaction intermediates is not trivial. Therefore, a Mannich-type condensation of aniline, formaldehyde, and phenol was evaluated as a potential method to form benzoxazine. Coupling positive mode electrospray ionization mass spectrometry (ESI(+)-MS) with infrared multiple photon dissociation (IRMPD) spectroscopy allowed unambiguous determination of an iminium-based mechanism and the direct observation of iminium intermediates. The benzoxazine formation mechanism was indirectly confirmed by the observation of side products that are relevant to the polymerization step, and directly confirmed by the identification of four distinct reaction intermediates that were completely characterized by IRMPD spectroscopy. The benzoxazine monomer was also shown to undergo isomerization under standard ESI-MS analysis conditions, suggesting the presence of a mixture of three isomers during their usual ESI-MS analysis.

Hydrothermal synthesis of FeVO4 and the use of composites on their basis as the cathode materials for lithium power sources

The synthesis of finely divided FeVO 4 from aqueous solutions was carried out, iron vanadate particles were incorporated in the polyaniline matrix through the process of oxidative condensation of aniline in a suspension of FeVO 4 in the presence of graphite. In the first case, the content of sulfanilic acid in the initial mixture for the preparation of the composite was 2.0 g, in the second – 1.0 g. The obtained materials on the basis of FeVO 4 are used for making positive electrodes of lithium current sources. Two kinds of lithium batteries were constructed and investigated. The discharge characteristics of the first element are relatively low. This may be due to the relatively higher content of sulfanilic acid on FeVO 4 surface in an electrically active material, which makes it difficult for vanadate particles to participate in the electrochemical process. Probably, sulfanilic acid on FeVO 4 surface can interact with lithium ions with producing insoluble salt. In addition to this case, nitrate and sulfate ions can be ion-dopants of polyaniline. The latter also form with lithium ions insoluble salts in propylene carbonate-ethylene carbonate electrolyte. That leads to the electrode surface blocking and leads to a sharp increase in the internal resistance of element 1. In the case of element 2, a smaller amount of sulfanilic acid was used during the synthesis of the composite. The discharge characteristics of the second element are much higher. There is a small plateau on discharge voltage and current curves. It should be noted that the recharge of element 2 was difficult, as evidenced by small charging currents (1–1.5 mA). That is, the lithium ions slowly diffused from the electrically active material. After reloading the characteristics of element 2 significantly deteriorated. This indicates that not all lithium ions are capable of reversibly intercalating into synthesized electrically active material. Keywords: iron (III) vanadate, lithium power sources, charge-discharge properties.

Synthesis of 2,2,4-trimethyl-1,2-H-dihydroquinoline (TMQ) over selected organosulfonic acid silica catalysts: Selectivity aspects

This paper presents investigation on the synthesis of 2,2,4-trimethyl-1,2-H-dihydroquinoline (TMQ) as a result of the reaction of aniline and both acetone and mesityl oxide in the presence of selected sulfonic acid silica catalysts. Condensation of aniline with acetone is very complex process with the formation of significant number of side products, both desirable and undesirable considering the final product (TMQ). In acidic conditions and elevated reaction temperature the reactivity of main raw materials (aniline, acetone) is significantly high, what causes the formation of many side by-products lowering the selectivity of this reaction. In this paper the reaction of aniline with acetone in the presence of heterogeneous acidic silica catalysts were investigated in more detail and discussed. The results were confirmed by GC/MS analysis, that the presence of TMQ isomers and other by-products significantly affected the formation of final product. The formation of previously not described structural isomer of TMQ has been also demonstrated.

Novel Brønsted acidic ionic liquids catalyzed one-pot reaction of highly green regioselective thiocyanation of N-containing aromatic and heteroaromatic compounds at room temperature

ABSTRACTIn this method, a novel Brønsted acidic ionic liquid silica-supported pyridinium sulfonic acid thiocyanate {SiO2@[Pyridine-SO3H]SCN} and sulfonic acid-functionalized pyridinium chloride {[PSA]Cl} were easily synthesized and characterized. In the first method, {SiO2@[Pyridine-SO3H]SCN as a novel and environmentally friendly catalyst with one acidic functional group and one thiocyanation agent group was efficiently used for the synthesis of aryl and heteroaryl thiocyanates via the condensation of anilines, indoles, pyrroles, and their derivatives in the presence of H2O2 as a green oxidant in EtOH:H2O (1:1) at room temperature. In the second method, {[PSA]Cl} as a new ionic liquid and environmentally friendly catalyst with one acidic functional group was used for the simple and efficient synthesis of aryl and heteroaryl thiocyanates via the condensation of anilines, indoles, pyrroles, and their derivatives with NH4SCN in the presence of H2O2 as a green oxidant in EtOH:H2O (1:1) at room temperature. A simple experimental procedure, clean reaction profile, use of an inexpensive catalyst, and recyclability of the catalyst are some of the advantages of the procedure. Also, one of the advantages of the first method is the non-usage of NH4SCN or KSCN in the reaction.

Synthesis and Biological Evaluation of Imines Structurally Related to Resveratrol as Dual Inhibitors of VEGF Protein Secretion and hTERT Gene Expression1

A group of 28 N-benzylidene aniline derivatives structurally related to the natural stilbene resveratrol has been prepared through condensation of anilines with the corresponding aldehydes. The ability of these imines to inhibit proliferation of two tumor cell lines (HT-29 and MCF-7) and one non-tumor cell line (HEK- 293) was first determined. Subsequently, we determined the ability of some of the most cytotoxic compounds to inhibit the secretion of the VEGF-A factor in HT-29 cells and to downregulate the expression of the VEGF and hTERT genes, the latter one being involved in the activation of telomerase.

Direct Synthesis of Pyrroles via Heterogeneous Catalytic Condensation of Anilines with Bioderived Furans

Given the wide applications of pyrroles in agriculture, pharmaceuticals, and supramolecular and materials chemistry, a mild and eco-friendly route to produce functionalized pyrroles from bioderived feedstocks is highly desirable. Described herein is a mild and convenient synthesis of pyrroles via direct condensation of an equimolar amount of structurally diverse anilines with biobased furans catalyzed by a simple and efficient solid acid H form zeolite Y catalyst. The protocol tolerates a large variety of functional groups and offers a general and versatile method for scale-up synthesis of a variety of N-substituted pyrrole compounds. Most importantly, the bioactive pyrrole-derived drug pyrvinium, which has lately been confirmed as highly effective in curing colon cancer, can be obtained by this method.

Resource-efficient technology to produce 4-aminodiphenylamine

A critical analysis of the existing and emerging methods for preparation of 4-aminodiphenylamine has been conducted. It is noted that, in economic and environmental terms, the promising methods are based on condensation of aniline with nitrobenzene in an alkaline medium, followed by hydrogenation of the resulting intermediates. Using the above method for industrial production of 4-ADPA will help eliminateprincipal shortcomings inherent in the existing industrial methods: reduce unit operations of the process, use more accessible, inexpensive raw materials, increase product yield, eliminate formation of carcinogenic substances, significantly decrease the formation of waste products and, most importantly, decrease the volume of waste water. The most promising methods for industrial production are recent discoveries that use heterogeneous catalysts during condensation of aniline with nitrobenzene, e.g., zeolite ZSM-5 treated with tetramethylammonium hydroxide or highly basic anions which considerably simplify production technology and process control, lower costs and comply with strict environmental requirements.

Resource-efficient technology to produce 4-aminodiphenylamine

Abstract A critical analysis of the existing and emerging methods for preparation of 4-aminodiphenylamine has been conducted. It is noted that, in economic and environmental terms, the promising methods are based on condensation of aniline with nitrobenzene in an alkaline medium, followed by hydrogenation of the resulting intermediates. Using the above method for industrial production of 4-ADPA will help eliminate principal shortcomings inherent in the existing industrial methods: reduce unit operations of the process, use more accessible, inexpensive raw materials, increase product yield, eliminate formation of carcinogenic substances, significantly decrease the formation of waste products and, most importantly, decrease the volume of waste water. The most promising methods for industrial production are recent discoveries that use heterogeneous catalysts during condensation of aniline with nitrobenzene, e.g., zeolite ZSM-5 treated with tetramethylammonium hydroxide or highly basic anions which considerably simplify production technology and process control, lower costs and comply with strict environmental requirements.

Dual Behavior of Iodine Species in Condensation of Anilines and Vinyl Ethers Affording 2-Methylquinolines.

A metal-free, mild and efficient method for the synthesis of 2-methylquinolines was successfully developed by condensation of anilines with vinyl ethers in the presence of catalytic amount of iodine. Modification of both pyridine and benzene moieties was easily achieved by changing only the vinyl ether and aniline. In this reaction, the iodine species was revealed to show dual behavior; molecular iodine serves as an oxidant, while its reduced form, hydrogen iodide, activates the vinyl ether. The redox reaction between these iodine species enables the use of a catalytic amount of iodine in this synthetic method.

ChemInform Abstract: Difunctionalization of Acrylamides Through C—H Oxidative Radical Coupling: New Approaches to Oxindoles

AbstractReview: [43 refs.