Conversion Of Aniline Research Articles

Catalytic conversion of soluble aniline into insoluble N-phenylphenazine for wastewater treatments

Aniline, a common pollutant in industrial wastewater, requires an effective treatment method with minimal chemical usage. In this study, a two-stage catalytic oligomerization process has been developed to address this issue by converting soluble aniline into insoluble oligomers for wastewater treatment. In the first stage, aniline is oxidized using hydrogen peroxide (H2O2) and a green catalyst, iron tetraamido macrocyclic ligand (Fe-TAML) to form aniline tetramers or pentamers. In the second stage, these oligoanilines undergo further oxidation with H2O2 alone at a higher temperature, resulting in the formation of N-phenylphenazine or its derivatives. These macrocyclic compounds precipitate from the wastewater due to π− π stacking, allowing easy separation through decantation or gravity filtration. After process optimization, only 3 mg/L of Fe-TAML and 2 g/L of H2O2 are required to treat 1 g/L of aniline, achieving a remarkable 96.8% aniline removal efficiency and a 62.5% precipitate yield. This two-stage oxidation approach shows promise for treating aniline and similar aromatic compounds in real industrial wastewater.

Phenyl-bridged N,N,N'N'-Tetrasubstituted bis(2-amino-5-thiazolyl) diamine: Synthesis and applications in electrochromism and photocatalytic nitrobenzene reduction

A novel type of triphenylamine derivatives, phenyl-bridged N,N,N′,N′-tetrasubstituted bis(2-amino-5-thiazolyl) diamine (4) and its cationic form (5) were synthesized via the Hantzsch reaction. The UV–Vis spectroscopy, cyclic voltammetry (CV) and density functional theory (DFT) calculation results showed that the diamine possesses excellent redox properties and a narrow optical energy gap (∼1.85 eV). As an electrochromic material, compound 4 exhibits a notable color change from colorless to blue. It maintains stable cycling performance for up to 175 cycles, even within a higher voltage range of −2.4 to 2.4 V. In addition, as a catalyst, compound 5 exhibits good substrate compatibility and an aniline conversion rate of up to 89 % during the photocatalytic reduction of nitrobenzene. These results would contribute to understand the synthesis of triphenylamine electrochromic materials and expand their applications in the field of photocatalysis.

Rb‐Promoted Au/CeO2 Nanocatalyst for Remarkably‐Enhanced Aniline Conversion to Azoxybenzene with Ultrahigh Selectivity

Aromatic azo compounds have proven to be a relevant class of building blocks in chemical synthesis. However, uncontrollable selectivity towards azo compounds and low reactant conversion in traditional synthetic methods seriously impede their applications. Herein, Rb‐doped Au/CeO2 nanocatalyst (Rb‐Au/CeO2) was prepared and utilized as a highly efficient supported metal catalyst for the selective oxidation of anilines to azocompounds using hydrogen peroxide as an oxidant, which reached ultrahigh selectivity (92%) towards azoxybenzene and complete aniline conversion (100%). The addition of Rb+ accelerates the electron transformation of Au to produce Au+, which is ready for catalysis. This research presents a promising Rb‐doped strategy for achieving complete aniline conversion and high selectivity towards azoxybenzene, opening up new possibilities for the application of aromatic azo compounds in chemical synthesis.

Enhanced removal of nitrobenzene with lignosulfonate modified zero valent iron: removal kinetic, reaction mechanism, and application feasibility

The reductive capacity of zero valent iron (ZVI) is extremely restricted by the surface passivation. To address this issue, ball-milling lignosulfonate modified ZVI (LS-ZVI) was prepared and used to determine the reactivity, electron utilization efficiency and application feasibility towards nitrobenzene (ArNO2) removal. The results showed that LS-ZVI could completely remove ArNO2 within 40 min with aniline conversion percentage of ∼95%, while ArNO2 reduction by ZVI was negligible within 180 min. Electrochemical evidence, H2 production, and characterization analysis collectively illuminated that the enhanced ArNO2 reduction by LS-ZVI was attributed to the increased Fe0 exposure that endowed it with excellent electron transfer ability. The inhibited H2 production indicated that the electron utilization efficiency of LS-ZVI towards ArNO2 was close to 100%. Moreover, ArNO2 removal was slightly inhibited under higher solution pH. Except for the obvious inhibitory effect of high concentration NO3−, the effects of co-existing ions (Cl−, NO3−, SO42−, Ca2+, and Mg2+) were little. The presence of Ni(II) had a negligible effect on ArNO2 removal, while high concentration of Cd(II) and Cr(VI) could obviously inhibit ArNO2 reduction. In addition, the excellent reusability of LS-ZVI and the complete ArNO2 removal in groundwater suggested the feasibility of LS-ZVI in practical field remediation.

Selective N-monomethylation of amines using CO2/H2 catalyzed by high-activity Cu–ZrOx interface on SBA-15

N-methylation of amines using CO2 and H2 addresses the problems of expensive raw materials and harsh reaction conditions. However, designing a high-active and stable interface for the efficient preparation of monomethyl amine compounds in this tandem reaction remains a challenge to be overcome. Here, Cu–ZrOx composites are dispersed on SBA-15, silicalite-1, and ZSM-5 through the oxalic acid precipitation method for the N-methylation of amines using CO2 and H2. Results show that the dispersion of Cu–ZrOx on the surface of SBA-15 is superior to the other two molecular sieves and effectively prevents the sintering of active metals. A 20 wt% Cu–ZrOx/SBA-15 catalyst proves to be optimal for the N-methylation of aniline (AN) using CO2 and H2 to methylaniline (MA) and the catalyst performance remains stable after 5 cycle runs. The optimal catalyst exhibits an AN conversion of 97.6% and a selectivity of 96.5% for MA under the conditions of 180 °C, 4.0 MPa (H2/CO2/N2 = 72/24/4, molar ratio), and 8 h. Spectroscopic investigation and controlled experiments indicated that the preferential adsorbed AN on the catalyst surface reacts with CO2 to generate C–N bond, thereby avoiding the self-coupling side reaction of AN and achieving a high yield of 94.2% for MA.

Untangling the catalytic importance of the Se oxidation state in organoselenium-mediated oxygen-transfer reactions: the conversion of aniline to nitrobenzene.

Seleninic acids and their precursors are well-known oxygen-transfer agents that can catalyze several oxidations with H2O2 as the final oxidant. Until very recently, the Se(iv) "peroxyseleninic" acid species has been considered the only plausible catalytic oxidant. Conversely, in 2020, the involvement of Se(vi) "peroxyselenonic" acid has been proposed for the selenium mediated epoxidation of alkenes. In this work, we theoretically probe different mechanisms of H2O2 activation and of Se(iv) to Se(vi) interconversion. In addition, we investigate through a combined theoretical (DFT) and experimental approach the mechanistic steps leading to the oxidation of aniline to nitrobenzene, when Se(iv) seleninic acid or Se(vi) selenonic acids are used as catalysts and H2O2 as the oxidant. This process encompasses three subsequent organoselenium mediated oxidations by H2O2. These results provide a mechanistic explanation of the advantages and disadvantages of both oxidation states (iv and vi) in the different stages of catalytic oxygen-transfer reactions: hydrogen peroxide activation and actual substrate oxidation. While the Se(vi) "peroxyselenonic" acid is found to be a better oxidant, the privileged role of "peroxyseleninic" acid as the main active species is assessed and its origin is identified in the lower catalyst-distortion that seleninic acid undergoes when activating H2O2. Conversely, the higher catalyst-distortion that characterizes the reaction of selenonic acid with H2O2 supports an inactivating role of Se(iv) to Se(vi) interconversion.

An Important Photocatalysis Oxidation: Selective Oxidation of Aniline to Azobenzene over a {P4Mo6}-based Crystalline Catalyst Under Visible-light Irradiation at Room Temperature.

Selective oxidation of aniline to azobenzene with a higher economic value is significant for modern industrial production. However, the high reaction temperature and undefined catalytic reaction center always limit the promotion of this reaction. Here, we designed and synthesized a new [P4MoV6O31]12--based cobalt-containing complex (Hbiz)5{Co(H2O)3[Co(H2O)2]2}{Co[Mo6O12(OH)3(PO4)(HPO4)3][Mo6O12(OH)3(PO4)2(HPO4)2]}·3H2O (1; biz = benzimidazole) under solvothermal conditions. Using 1 as the photocatalyst, the visible-light-driven conversion of aniline to azobenzene at room temperature was realized for the first time (conversion rate 97%, selectivity 96% of azobenzene, reaction time of 12 h). Additionally, real sunlight irradiation can produce a comparable outcome in 48 h. The mechanism investigation manifested that the Mo and Co centers in 1 acted as Brönsted and Lewis acid centers, synergistically promoting the aniline oxidation reaction. This research advances the application of polyoxometalate-based photocatalysts while also offering a sustainable and effective method for producing azobenzene.

Trimetallic Oxide Foam as an Efficient Catalyst for Fixation of CO2 into Oxazolidinone: An Experimental and Theoretical Approach

The excess anthropogenic CO2 depletion via the catalytic approach to produce valuable chemicals is an industrially challenging, demanding, and encouraging strategy for CO2 fixation. Herein, we demonstrate a selective one-pot strategy for CO2 fixation into "oxazolidinone" by employing stable porous trimetallic oxide foam (PTOF) as a new catalyst. The PTOF catalyst was synthesized by a solution combustion method using transition metals Cu, Co, and Ni and systematically characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), N2 sorption, temperature-programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS) analysis. Due to the distinctive synthesis method and unique combination of metal oxides and their percentage, the PTOF catalyst displayed highly interconnected porous channels along with uniformly distributed active sites on its surface. Well ahead, the PTOF catalyst was screened for the fixation of CO2 into oxazolidinone. The screened and optimized reaction parameters revealed that the PTOF catalyst showed highly efficient and selective activity with 100% conversion of aniline along with 96% selectivity and yield toward the oxazolidinone product at mild and solvent-free reaction conditions. The superiority of the catalytic performance could be due to the presence of surface active sites and acid-base cooperative synergistic properties of the mixed metal oxides. A doubly synergistic plausible reaction mechanism was proposed for the oxazolidinone synthesis experimentally with the support of DFT calculations along with bond lengths, bond angles, and binding energies. In addition, stepwise intermediate formations with the free energy profile were also proposed. Also, the PTOF catalyst displayed good tolerance toward substituted aromatic amines and terminal epoxides for the fixation of CO2 into oxazolidinones. Very interestingly, the PTOF catalyst could be significantly reused for up to 15 consecutive cycles with stable activity and retention in physicochemical properties.

Synthesis and characterization of novel binuclear zinc complex, immobilization in nano-porous support, and its catalytic application

Binuclear zinc complex, [Zn2(L)(I)2(CH3CN)] (I) (LH2 = 1,2-phenylenebis(azaneylylidene))bis(methaneylylidene))bis(2-methoxyphenol)) was prepared and single-crystal X-ray diffraction was used to establish the structure of complex assembly. Organic acid and base were used to functionalize the nano-porous material and then binuclear Zn complex was grafted into the modified materials. Brunauer-Emmett-Teller isotherm (BET), Nuclear Magnetic Resonance (NMR), Inductively Coupled Plasma analysis (ICP), X-ray Diffraction (XRD), Fourier transform infrared spectra (FT-IR), thermogravimetric analysis (TG), Scanning electron microscope (SEM), etc., were used to characterized the synthesized nano-catalysts to check for existence of guest moiety, structural stability of the parent and modified catalysts. Catalytic performance was noticeably enhanced post modification; without catalyst, acid/base functionalized, Zn2 immobilized catalyst. Binuclear zinc immobilized on acid/base silica catalyst exhibited a maximum 95%, 89% conversion of piperidine, and 87% and 86% conversion of aniline respectively. Prior to the theoretical investigation the bond parameters of the binuclear zinc complex were measured experimentally. Time-dependent Density Functional Theory (TD-DFT) and Density Functional Theory (DFT) methods were used to calculate the molecule's UV–Vis absorption spectra at B3LYP as well as LANL2DZ and 6–31G(d)). LUMOs and HOMOs energy gap were determined from the electronic transitions to determine electrophilicity index (ω), softness (S), electronegativity (χ), hardness value (Ƞ), and chemical potential (μ), etc.

A novel 2‐D accordion like Al‐BPED MOF as reusable and selective catalyst for N‐alkylation of amines with dialkylcarbonates

A novel 2‐D flakes like Al‐BPED ((N1,N2‐bis [pyridine‐2‐yl]methyl)ethane‐1,2‐diamine) metal–organic framework (MOF) have been explored for its catalytic potential in the N‐alkylation of amines with dialkyl carbonates. The Al‐BPED MOF catalyst has been synthesized by hydrothermal route. The X‐ray diffraction, Fourier Transform Infrared Spectroscope (FTIR), and High Resolution Transmission Electron Microscopy (HRTEM) images were used to analyze the morphology of the synthesized Al‐BPED MOF samples. With the use of Al‐BPED MOF, the primary and secondary aromatic amines were selectively and efficiently methylated with dimethyl carbonate. The effect of process conditions has been investigated toward N‐methylation, N‐ethylation, and N‐benzylation of aromatic amines. Under the optimal conditions with 10 mol% of the MOF catalyst, a maximum aniline conversion of 88% and a selectivity >90% toward N‐alkylation was achieved. The kinetic studies revealed the N‐alkylation reaction in presence of Al‐BPED MOF followed pseudo‐first order rate kinetics.

Synthesis and characterization of mononuclear Zn complex, immobilized on ordered mesoporous silica and their tunable catalytic properties

In this work, mononuclear zinc complex, [Zn(dmp)Cl2] (dmp = Neocuprine) was synthesized and characterized by quantum mechanical (QM) calculations using Density Functional Theory (DFT) and Time-dependent Density Functional Theory (TD-DFT) method. The UV–Vis absorption spectra of the molecule were calculated using the TD-DFT method at B3LYP functional and mix basis set (LANL2DZ and 6–31G(d)). The electronic transitions and their corresponding HOMOs and LUMOs were analysed. The characteristics such as chemical potential (μ), hardness value (Ƞ), softness (S), electronegativity (χ) and electrophilicity index (ω) were calculated from the HOMO-LUMO energy gap. After thorough characterization the Zn complex was incorporated to the sulfopropylsilylated ordered mesoporous silica materials via post-synthesis modification. The synthesized catalysts were characterized by powder XRD, BET, FT-IR, SEM, TGA, NMR, ICP etc., to confirm the structural integrity, presence of additional functionality, morphology of the materials and other vital parameters. After thorough characterization, all the materials were used in epoxide ring opening reaction with different amines to produce important intermediates β-amino alcohols. Gradual enhancement of catalytic activities in terms of conversion was observed from blank (without catalyst) to sulfopropylsilylated mesoporous material and finally to immobilized Zn complex incorporated hybrid ordered mesoporous materials. Zn complex incorporated MCM-48 was found to be most active in this reaction system and gave maximum 99%, 92% and 70% conversion of piperidine, morpholine and aniline respectively and 98% selectivity of the desired products.

Preparation of magnetic Au/MIL-101(Cr)@SiO2@Fe3O4 catalysts and N-methylation reaction mechanism of CO2 with aniline/H2

MIL-101(Cr)@SiO2@Fe3O4 magnetic catalytic supports were synthesized by the in-situ growth method, where a MIL-101(Cr) shell was deposited on the surface of the SiO2@Fe3O4 core. A series of Au/MIL-101(Cr)@SiO2@Fe3O4 magnetic core-shell catalysts with different Au contents were prepared and Au nanoparticles (Au NPs) were decorated on the magnetic supports by the impregnation-reduction method. The structure of the as-synthesized catalysts was characterized by XRD, FTIR, HRTEM, XPS, N2 adsorption-desorption, NH3-TPD, CO2-TPD, and VSM, etc. The N-methylation reaction performance and recyclability performance of the catalysts were evaluated in a high-pressure microreactor. The mechanism of the N-methylation reaction had been deeply studied. The results indicated that the thickness of the MIL-101(Cr) shell was about 120 nm, and the Au NPs (~3 nm) were dispersed on the surface and/or in the pores of MIL-101(Cr). The catalytic performance for N-methylation of CO2 and aniline/H2 to N-methylaniline and N,N-dimethylaniline was satisfactory. Moreover, the incredible recyclability performance (external magnet) and applicability of different amine substrates were achieved. Under the optimized conditions, the 2%Au/MIL-101(Cr)@SiO2 @Fe3O4 catalyst demonstrated the best performance, the aniline conversion nearly 44.0%, the selectivity of N-methylaniline and N,N-dimethylaniline were 71.8% and 27.6%, respectively. The reaction mechanism investigation indicated that, firstly, H2 was adsorbed and activated on the Au NPs, and CO2 was adsorbed and activated on the O2- Lewis base sites of MIL-101(Cr) cages. Later, the activated H-atoms reacted with the activated CO2 to generate the formic acid as an intermediate product. Finally, the formic acid reacted with the adsorbed aniline and activated on the Cr3+ Lewis acid sites to produce N-methylaniline and N,N-dimethylaniline. The enhanced selectivity of the reaction might be attributed to the core-shell architecture, high surface area, plentiful active sites, and synergistic interactions between Au NPs and acid-base sites of the MIL-101(Cr) catalyst.

Investigation on size and conductivity of polyaniline nanofiber synthesised by surfactant-free polymerization

An attempt has been made to combine interfacial polymerization with a fast mixing technique without the use of surfactant. Effects of mixing speed, reaction time, temperature, oxidant-to-monomer molar ratio and nitric-to-monomer molar ratio were tested for electrical conductivity and polyaniline nanofiber size. The findings demonstrate that the diameter of polyaniline nanofiber can be reduced by optimising the synthesising parameter, thereby increasing the electrical conductivity of polyaniline nanofiber. Infrared spectroscopy has shown increased amplitude of the main absorption peak of polyaniline nanofiber during the conversion of aniline to conductive polyaniline nanofiber. The crystalline nature of polyaniline nanofiber has been discovered by the X-ray diffraction spectra. Hall effects experiments have shown that the electrical conductivity of polyaniline nanofiber has improved from 5.2 to 17.5 Scm −1 with an increase in homogenizer speed. The morphological properties of polyaniline nanofiber through electron microscopy scanning have confirmed the decreasing size of polyaniline nanofiber from 50-60 nm to 20–30 nm by increasing the homogenizer speed to 30,000 rpm. These findings demonstrate that higher homogenization speed can split the solution to smaller molecules during polymerization contributing to the creation of smaller nanofiber sizes.

Application of an enzymatic cascade reaction for the synthesis of the emeraldine salt form of polyaniline

The synthesis of the emeraldine salt form of polyaniline (PANI-ES) from aniline with Aspergillus sp. glucose oxidase (GOD), d-glucose, dissolved O2, and horseradish peroxidase isoenzyme C (HRPC) in the presence of large unilamellar vesicles of AOT (sodium bis-(2-ethylhexyl)sulfosuccinate) as templates at pH = 4.3 and T ~ 25 °C was investigated in a systematic way. In this cascade reaction mixture, the oxidation of aniline is catalyzed by HRPC with H2O2 that is formed in situ as byproduct of the GOD-catalyzed oxidation of d-glucose with O2. Under the elaborated experimental conditions which we considered ideal, the formation of PANI-ES products is evident, as judged by UV/Vis/NIR and EPR measurements. Comparison was made with a reference reaction, which was run under similar conditions with added H2O2 instead of GOD and d-glucose. Although the reference reaction was found to be superior, with the cascade reaction, PANI-ES products can still be obtained with high aniline conversion (> 90%) within 24 h as stable dark green PANI-ES/AOT vesicle dispersion. Our results show that the in situ formation of H2O2 does not prevent the inactivation of HRPC known to occur in the reference reaction. Moreover, the GOD used in the cascade reaction is inactivated as well by polymerization intermediates.

Easy and One‐Step Synthesis of Ir Single Atom Doped PPy Nanoparticles for Highly Active N‐Alkylation Reaction

AbstractSingle atoms are nowadays considered new catalysts offering a lot of advantages such as reduced cost and use of noble metals. Here, we report the catalytic activity towards N‐alkylation reactions of single atoms (SACs) of iridium doped polypyrrole (Ir−PPy nanoparticles). The new nanocatalyst exhibits excellent behavior due to the combination of highly active SACs catalyst and the organic conductive support providing strong binding of single atoms and thus improved reusability and easiness to handle. In the presence of a low amount of Ir and of a suitable base, excellent activity (yield >99 %) and selectivity (>99 %) were obtained. In the optimized Ir condition (3 wt.% of Ir) an aniline conversion of about 99 %, with excellent selectivity, just after 600 min, was obtained. Recyclability tests show that the catalyst can be successfully recycled six times without significant catalyst activity loss.

Photochemical fixation of carbon dioxide for N-formylation of amine using Cu(II) embedded BiVO4 nanocomposite under visible light

N-Formylation reactions of amines with carbon dioxide (CO2) are gaining tremendous importance in the chemical fixation of CO2 to high-value chemicals. However, the methods reported so far either use homogeneous transition metal-based catalysts or higher reaction temperatures. The use of visible light under the mild experimental condition for the N-formylation of amines with CO2 is a promising approach yet less explored. The present paper describes an efficient methodology for the N-formylation of various aliphatic and aromatic amines with CO2 using a heterostructured CuO/BiVO4 catalyst under visible illumination. The incorporation of CuO as a p-type semiconductor enhanced the transfer of electrons in excess at the surface of BiVO4 semiconductor and afforded the highest 85 % conversion of aniline to formanilide. The heterostructured photocatalyst was found to be robust without any detectable leaching even after the seventh recycling run.

Influencing factors for the Fenton-like of biological sponge iron system and its degradation mechanism of aniline

The application of zero-valent iron (ZVI) coupled with microorganisms, has gained considerable attention in recent years for eliminating recalcitrant organic matters from wastewater. Nevertheless, there are no general conclusions regarding the degradation mechanism and the operating variables. In this paper, sponge iron (SFe, a kind of ZVI) has been submerged to the activated sludge process to develop a biological sponge iron system (SFe-M). The treatment impact of SFe-M system on aniline (AN) wastewater under the optimal conditions was significantly better than that of the general activated sludge system. In the SFe-M system, the variation trends of hydroxyl radicals (•OH) production were consistent with those of Fe(II), and the hydrogen peroxide concentration was approximately twice as high as the sum of activated sludge system and the SFe system. Both SFe and microorganisms could induce Fenton-like reactions directly or indirectly. This contributed to the production of •OH that constantly attacked the benzene ring and the amino group. It resulted in some nitrogen in AN released in the form of ammonia ions. Moreover, microorganisms could also use the mass and electrons during the AN conversion process. The AN was eventually oxidized to carbon dioxide.

Biocatalytic Strategy for Grafting Natural Lignin with Aniline.

This paper presents an enzyme biocatalytic method for grafting lignin (grafting bioprocess) with aniline, leading to an amino-derivatized polymeric product with modified properties (e.g., conductivity, acidity/basicity, thermostability and amino-functionalization). Peroxidase enzyme was used as a biocatalyst and H2O2 was used as an oxidation reagent, while the oxidative insertion of aniline into the lignin structure followed a radical mechanism specific for the peroxidase enzyme. The grafting bioprocess was tested in different configurations by varying the source of peroxidase, enzyme concentration and type of lignin. Its performance was evaluated in terms of aniline conversion calculated based on UV-vis analysis. The insertion of amine groups was checked by 1H-NMR technique, where NH protons were detected in the range of 5.01–4.99 ppm. The FTIR spectra, collected before and after the grafting bioprocess, gave evidence for the lignin modification. Finally, the abundance of grafted amine groups was correlated with the decrease of the free –OH groups (from 0.030 to 0.009 –OH groups/L for initial and grafted lignin, respectively). Additionally, the grafted lignin was characterized using conductivity measurements, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), temperature-programmed desorption (TPD-NH3/CO2) and scanning electron microscopy (SEM) analyses. The investigated properties of the developed lignopolymer demonstrated its disposability for specific industrial applications of derivatized lignin.

An Efficient and Robust Method for Selective Conversion of Aniline to Azobenzene Using nano-TiO2 -P25-SO3 H, under Visible Light Irradiation.

Nano-TiO2 -P25-SO3 H as our previous report has successfully been utilized to synthesize azobenzene through the selective conversion of aniline under visible light irradiation. According to PL emission spectra, the immobilizing a solid Brønsted acid of -SO3 H groups on the pure-TiO2 -P25 surface with a close interface is an approach to amplify the nano-TiO2 -P25 response to visible light, which can productively hinder the recombination rate of photogenerated electrons and holes as carriers. Therefore, the photocatalytic activity of the semiconductor is highly likely to increase. Photooxidation of aniline to azobenzene was achieved by applying nano-TiO2 -P25-SO3 H (Eg =2.6eV) that activated by blue photons (λmax =460nm), green photons (λmax =510nm) and red photons (λmax =630nm) which is introducing as a sustainable procedure. Central composite design (CCD) was employed for evaluating the effects of photocatalyst amount, oxidant concentration and irradiation time on the synthesis of azobenzene by this approach. Easily synthesizing, recyclability of the photocatalyst, mild reaction condition and short reaction time could be considered as plus points of this process.

Reaction Mechanism of CO2 and Styrene Oxide Catalyzed by Ionic Liquids: A Combined DFT Calculation and Experimental Study.

Bioactive compound 3-aryl-2-oxazolidinone could be synthesized by a green method mixing carbon dioxide, aniline, and ethylene oxide. Our group previously proposed a parallel mechanism for this conversion catalyzed by ionic liquids. Recently, a new study on a similar reaction system of styrene oxide, carbon dioxide, and aniline under the catalysis of K3PO4 gave a different serial mechanism. In order to explore the mechanism of reaction, we conducted a combined theoretical and experimental study on a one-pot conversion of styrene oxide, carbon dioxide, and aniline. In experiments, two isomer products, 3,5-diphenyl-l,3-oxazolidin-2-one and 3,4-diphenyl-l,3-oxazolidin-2-one, were observed. The computational results show that the parallel mechanism is more favored in thermodynamics and in kinetics due to the instability of isocyanate and hardness of its generation. Hence, we believe the previous parallel mechanism is more reasonable under our catalysts and conditions.