Production Of Aromatic Amines Research Articles

Rapid Access to Fluorinated Anilides via DAST-Mediated Deoxyfluorination of Arylhydroxylamines.

A new strategy for the synthesis of fluorinated anilides in the absence of metals and oxidants has been developed. This deoxyfluorination of N-arylhydroxylamines with diethylaminosulfur trifluoride (DAST) proceeded smoothly under mild conditions, and the ortho- or para-fluorinated aromatic amine products were prepared in moderate to good yields. Structurally diverse fluorinated anilides, including heterocyclic and pharmaceutically relevant molecules, can be efficiently constructed by this protocol.

Production of aromatic amines via catalytic co-pyrolysis of lignin and phenol-formaldehyde resins with ammonia over commercial HZSM-5 zeolites

Aromatic amines could be produced from organic wastes via catalytic pyrolysis with ammonia that served not only as a carrier gas but also as a reactant. Aromatic amines of 14.2 C% with selectivity of 57.6% were obtained from phenol-formaldehyde resins via pyrolysis over commercial HZSM-5-3 zeolite (Si/Al ratio of 80) catalyst at 650 °C. Significant synergetic effects have been observed when lignin was added, which improved aromatic amines yield by 32.2% to 11.8 C% at the mixing weight ratio of lignin to PF resins of 1:1. HZSM-5-3 was slightly deactivated after 3 cycles with acid sites loss. Catalytic co-pyrolysis of plastics and biomass wastes is a fast and effective method to produce aromatic amines.

Simultaneous Determination of Harmful Aromatic Amine Products of Azo Dyes by Gas Chromatography–Mass Spectrometry

Azo dyes constitute about 66% of all colorants and they are widely used in industries such as textiles, plastics, ceramics, cosmetics and food. However, due to the reductive cleavage of some azo dyes into carcinogenic aromatic amines, many countries have set concentration limits or have banned the use of these azo dyes. Selected aromatic amines that pose health risk to consumers were simultaneously determined by gas chromatography mass spectrometry. A good linearity in calibration plot was obtained for the analytes and the low relative standard deviations indicated high instrumental precision. A recovery test was performed to validate the extraction method and the results obtained were between 92–114%. The method was applied to the analysis of real samples and the concentrations of aromatic amines detected were below the 30 mg/kg limit set by regulatory authorities.

Liquid phase microextraction based sensitive analytical strategy for the determination of 22 hazardous aromatic amine products of azo dyes in wastewater and tap water samples by GC-MS system

Dyes that consist of the azo functional group (RNNR′) are classified as azo dyes, which make up a large percentage of commercial dyes. Cleavage of the azo bond could lead to products including some aromatic amines that are harmful (carcinogen) to human beings and other organisms. This study presents a comprehensive optimization and validation of a dispersive liquid-liquid microextraction (DLLME) method for the preconcentration of 22 aromatic amines in gas chromatography spectrometry system. DLLME parameters including dispersive solvent, extraction solvent and salting-out effect were optimized in a univariate approach to obtain optimum conditions of the method. An isotopically labeled compound (bisphenol A D-16) was used as internal standard to enhance the precision (R2) of calibration plot from 0.9952 – 0.9994 to 0.9991 – 0.9999. The limits of detection calculated for the analytes were in the range of 0.17–8.5 μg/L, corresponding to enhancement in detection powers between 4.0 and 99 folds. Spike recovery experiments were used to validate the optimized method's accuracy and the results obtained for tap water and wastewater samples spiked at different concentrations were in the range of 91–109% and 91–110%, respectively. The recovery results established the method's accuracy and applicability to real samples.

Preparation of sub-microspherical Fe3O4@PDA-Pd NPs catalyst and application in catalytic hydroreduction reaction of halogenated aromatic nitro compounds to prepare halogenated aromatic amines

BackgroundThe side reactions of dehalogenation or C–N coupling tend to occur when halogenated aromatic amines are prepared by catalytic hydrogenation reduction of halogenated aromatic nitro compounds. In this paper, we prepared the sub-microspherical Fe3O4@PDA-Pd NPs catalyst apply it efficiently in the hydrogenation reduction of halogenated aromatic nitro compounds to prepare the halogenated aromatic amines under atmospheric pressure. The catalyst shows a high selectivity of greater than 96% and can effectively inhibit the occurrence of the side reactions of dehalogenation and C–N coupling.ResultsThe optimum condition of the hydroreduction reaction is when tetrahydrofuran is used as solvent and the reaction happens at 50 °C for 5 h. The selectivity of the chlorinated aromatic amine and the fluorinated aromatic amine products exceed 99% and the yield exceeds 90%. Only a small amount of dehalogenated products and C–N coupling by-products were produced in the brominated aromatic compound and the iodinated aromatic compound.ConclusionWe developed a promising method for preparing the superparamagnetic and strongly magnetic Fe3O4@PDA core–shell sub-microsphere-supported nano-palladium catalyst for catalyzing the hydrogenation reduction of halogenated aromatic nitro compounds. The halogenated aromatic amines were efficiently and highly selectively prepared under atmospheric pressure, with the side reactions of dehalogenation and C–N coupling effectively inhabited simultaneously.

Integrated production of aromatic amines, aromatic hydrocarbon and N-heterocyclic bio-char from catalytic pyrolysis of biomass impregnated with ammonia sources over Zn/HZSM-5 catalyst

By introducing exogenous nitrogen during biomass pyrolysis under nitrogen-rich conditions, high-value nitrogen-containing products, i.e., nitrogen-rich char and oil may be produced. Based on the cogeneration of high-value nitrogen products from biomass, biomass nitrogen-enriched pyrolysis was performed in a fixed bed with different sources and contents of ammonia. The yields, composition and characteristics of the products were investigated. Moreover, the formation mechanism of N-containing species was explored in depth for the pyrolysis and catalytic pyrolysis with HZSM-5 and Zn/HZSM-5 catalysts via elemental analysis, XPS, FTIR and BET. The results showed that ammonia impregnation could promote a Maillard reaction, reduce the content of small aldehydes and ketones, and produce a nitrogen-enriched bio-oil. The contents of N-containing species and phenolic substances in the pyrolysis oil of biomass impregnated with 10% urea reached 15.66% and 56.69%, respectively. Moreover, the nitrogen on the coke surface after pretreatment was mainly composed of CN, CN and NCOO functional groups. The bio-char generated abundant pyridinic-N, pyrrolic-N, quaternary-N, and pyridone-N oxides. The presence of urea introduced many alkaline N-containing functional groups on the surface of the bio-char and promoted the transformation of nitrogen from amides and imides to heterocyclic nitrogen with higher thermal stability. Furthermore, Zn was an excellent catalyst for the Maillard reaction, and the Zn/HZSM-5 catalyst had a higher selectivity for aromatic hydrocarbons (96.98% for biomass and 86.48% for urea/biomass) and N-containing heterocyclic compounds, such as indoles (6.16% for biomass and 13.51% for urea/biomass). Additionally, the coke content decreased, and the catalyst deactivation decreased.

Accurate and sensitive determination of harmful aromatic amine products of azo dyes in wastewater and textile samples by GC–MS after multivariate optimization of binary solvent dispersive liquid-liquid microextraction

In this study, eight hazardous aromatic amine products of azo dyes were simultaneously determined by GC–MS in wastewater and textile samples after preconcentration with an accurate and sensitive binary solvent dispersive liquid-liquid microextraction method. A univariate optimization procedure was used to determine the most influential experimental parameters and a multivariate optimization was used to determine optimum amounts of each parameter. A model developed from experimented results was used to ascertain the effects of main parameters and their interaction effects with each other. The optimum parameters obtained from the model were chloroform (100 μL), 1,2‑dichloroethane (100 μL), ethanol (2.0 mL) and vortex (15 s). The limits of detection (LOD) and quantification (LOQ) of the analytes determined under optimum conditions ranged between 0.16–1.4 μg/L and 0.53–4.6 μg/L, respectively. The calibration plots of the analytes were linear (R2 > 0.9991) over a broad range and the %RSDs were below 10%. The method was applied to wastewater and textile samples as a test of the method's applicability and accuracy. The percent recovery obtained for wastewater by the standard calibration method was appreciable (85–109%), but procedural matrix matching was used to improve the percent recovery for the textile sample (85–103%).

The effect of shear flow on microreactor clogging

Solid handling is a key issue in microreactors where clogging problems can be severe due to confined flow conditions. Here, microreactor clogging is investigated in a Buchwald–Hartwig C–N cross-coupling reaction of amines with organohalides important in the pharmaceutical and fine chemicals industries for the production of aromatic amines. The reaction takes place in a tubular stainless steel continuous-flow reactor and generates solid particles by precipitation of potassium bromide in the continuous phase. The reactor output is fed to a glass microchannel where the flowing particles are imaged by on-line high-speed video microscopy. It is found that KBr particles adhere to the channel wall and aggregate into clusters, eventually leading to channel clogging. The effect of flow is studied by setting the Reynold number (Re) at 1.5 and 15. At Re = 1.5 cluster growth is faster and less dense, dendritic structures made of needle-like crystals are observed. At Re = 15, cluster growth is slower and more compact structures of spherical shape are found. Clogging time is faster at Re = 15. These results can be explained by the interplay between flow-induced interactions and particle-wall and particle-particle attractive forces. Since cluster formation starts at the wall, the insight provided by this work, although obtained in a microfluidic geometry, can be applied more generally to the problem of fouling in continuous flow reacting systems.

Efficient degradation of Azo dyes by a newly isolated fungus Trichoderma tomentosum under non-sterile conditions

A fast-growing fungus with remarkable ability to degrade several azo dyes under non-sterile conditions was isolated and identified. This fungus was identified as Trichoderma tomentosum. Textile effluent of ten-fold dilution could be decolorized by 94.9% within 72h before optimization. Acid Red 3R model wastewater with a concentration of 85.5mgL−1 could be decolorized by 99.2% within the same time after optimization. High-level of manganese peroxidase and low-level of lignin peroxidase activities were detected during the process of decolorization from the culture supernatant, indicating the possible involvement of two enzymes in azo dye decolorization. No aromatic amine products were detected from the degradation products of Acid Red 3R by gas chromatography–mass spectrometry (GC/MS) analysis, indicating the possible involvement of a special symmetrical oxidative degradation pathway. Phytotoxicity assay confirmed the lower toxicity toward the test plant seeds of the degradation products when compared to the original dye.

Catalytic reduction of aromatic nitro compounds: general questions, equipment, enlarged laboratory tests

The article is devoted to issues of amines production from nitro compounds. The processes of catalytic reduction of aromatic nitrocompounds by hydrogen to amines have practically superseded all other methods for the production of aromatic amines in large-tonnage plants. Aromatic mono-, di- and polyamines, due to their high reactivity, are widely used in the production of various compounds (photochemicals, fuel stabilizers and additives lubricating oils, in the paint and varnish industry, for painting natural and synthetic fibers). Authors compare methods of nitro compounds reduction and show different variants of apparature design. The article also describes the results of enlarged laboratory examinations of the deposited catalysts synthesized by authors in reactions of p-phenylenediamine, p-amino-diethylaniline, o- and p-aminophenols production. By using relatively small amounts of catalysts (0.48-0.6 g of catalyst by hydrogenating 50 g of an aromatic nitro compound) were obtained high amine yields of 90-98.7%.

Synthesis and properties of alkali-clearable azo disperse dyes containing a carboxylic ethyl ester group

Three alkali-clearable azo disperse dyes containing a carboxylic ethyl ester group (D1-D3) were readily synthesized using three different synthetic strategies. D1 was prepared from a carboxylic acid-containing dye by esterification with ethanol. D2 was prepared from a carboxylic ester-containing dye by transesterification with ethanol. D3 was prepared from a cyano group-containing dye by alcoholysis with ethanol and water. The molecular structures of the dyes were characterized by FTIR, mass spectrometry, 1H NMR, 13C NMR, and elemental analysis. The synthesized dyes and the control dyes were used to dye poly(ethylene terephthalate) fabric, and their washing and rubbing fastness properties following different after-treatment methods (reduction clearing and alkali clearing) were examined and compared. The carboxylic ethyl ester-containing disperse dyes show good alkali clearing ability on poly(ethylene terephthalate) fabric and cause fewer environmental issues due to the absence of reductants, no production of aromatic amines with high toxicity and carcinogenicity, as well as the low toxicity of the dye hydrolysate ethanol.

Integrated Production of Aromatic Amines and N-Doped Carbon from Lignin via ex Situ Catalytic Fast Pyrolysis in the Presence of Ammonia over Zeolites

Due to the irregular polymeric structure and carbon based inactive property, lignin valorization is very difficult. In this study we proposed a new route for lignin valorization by which aromatic amines can be directly produced from lignin by ex situ catalytic fast pyrolysis with ammonia over zeolite catalysts. Meanwhile, the obtained pyrolytic biochar can be activated to produce high surface area N-doped carbon for electrochemical application. Wheat straw lignin served as feed to optimize the pyrolysis conditions. MCM-41, β-zeolite, HZSM-5, HY, ZnO/HZSM-5, and ZnO/HY were screened, and ZnO/HZSM-5 (2 wt % Zn, Si/Al = 50) showed the optimal reactivity for producing aromatic amines due to the desired pore structure and acidity. Temperature, residence time, and ammonia content in the carrier gas displayed significant effects on the product distribution. The maximum yield of aromatic amines was obtained at moderate temperatures around 600 °C, 0.57 s, and 75% ammonia in the carrier gas. Under the optimized con...

A Regioselective and Convergent Paired Electrochemical Synthesis of N,N′-Diphenyl-3-sulfonyl-[1,1′-biphenyl]-4,4′-diamines

A regioselective synthesis of N,N′-diphenyl-3-sulfonyl-[1,1′-biphenyl]-4,4′-diamine derivatives is carried out by anodic oxidation of N,N′-diphenylbenzidine in the presence of sulfinic acids as nucleophiles via a convergent paired electrochemical process. The sulfonylated aromatic amine products are obtained under mild reaction conditions with high yields, high current efficiency and atom economy.

Solvent‐Free Selective Hydrogenation of Nitroarenes Using Nanoclusters of Palladium Supported on Nitrogen‐Doped Ordered Mesoporous Carbon

AbstractThe selective hydrogenation of nitroarenes is a key transformation for the production of aromatic amines, which are primary intermediates in the synthesis of pharmaceuticals, agrochemicals, and dyes. However, most reaction processes require toxic organic solvents and suffer from poor selectivity in the presence of other reducible groups. Herein, we report a successful example of nanoclusters of ultrafine Pd supported on N‐modified ordered mesoporous CMK‐3 carbon (Pd/N‐CMK‐3) prepared by a facile two‐step impregnation route with aqueous solutions of 1,10‐phenanthroline and H2PdCl4 that hydrogenated various nitroarenes highly efficiently and selectively to the corresponding aromatic amines with hydrogen in the absence of solvent. The Pd/N‐CMK‐3 catalyst could be recovered easily for multiple recycling reactions without a loss of catalytic performance.

New Technologies in Intensification of Biological Removal of Aniline from Wastewater

Microbiological and hydrogeological analysis of active sludge of biological treatment facilities of the enterprise for production of aromatic amines is performed. It is shown that traditional purification methods of industrial wastewater do not make it possible to attain the required purification quality of wastewater. It is proposed to improve the design of biological treatment facilities at enterprises of organic synthesis by means of their replacement for a new in principle complex of continuous biological purification of industrial wastewater developed at OJSC “NIPIEP” (Orenburg). The operating principle of proposed apparatuses for biological purification of wastewater is based on the methods of continuous cultivation of active sludge microorganisms both in anaerobic and aerobic conditions. Sectioning the process of biological purification and the use of microbubble aerators made of sintered titanium powder and biotechnologies with rapidly growing aboriginal microorganisms immobilized on an inert biological carrier makes it possible to attain almost complete aniline destruction.

Chemical coagulation and sonolysis for total aromatic amines removal from anaerobically pre-treated textile wastewater: A comparative study

The present study primarily focuses on the evaluation of the comparative effect of chemical coagulation and ultrasonication for elimination of aromatic amines (AAs) present in anaerobically pretreated textile wastewater containing different types of dyes including azo dyes. Color and COD reduction was also monitored at the optimized conditions. The production of AAs was measured spectrophotometrically in the form of total aromatic amines (TAAs) and also verified with high performance liquid chromatography (HPLC) selectively. A composite coagulant, magnesium chloride (MC) aided with aluminium chlorohydrate (ACH) in an equal ratio (MC + ACH) was utilized during the coagulation process, which yielded 31% of TAAs removal along with 85% of color and 52% of COD reduction. At optimized power (200 W) and sonication time (5 h), an appreciable TAAs degradation efficiency (85%) was observed along with 51% color reduction and 62% COD removal using ultrasonication. The chromatographic data indicate that sulphanilic acid and benzidine types of aromatic amines were produced after the reductive cleavage of utilized textile dyes, which were effectively mineralized after ultrasonication. The degradation followed the first order kinetics with a correlation coefficient (R 2 ) of 0.89 and a first-order kinetic constant (k) of 0.0073 min -1 .

A New and Convenient Synthesis of Amino‐phthalimide (1H‐Isoindole‐1,3(2H)‐dione) Derivatives and Their Photoluminescent Properties

AbstractA new and convenient synthesis for amino‐phthalimide (1H‐isoindole‐1,3(2H)‐dione) derivatives has been developed starting from an α,β‐unsaturated ketone. The ketones were reacted with amines to give aromatic amine products. This is the first time that substituted amine groups have been incorporated in aromatic rings. The mechanism of the product formation is rationalized by the 1,2‐addition of amines to ketones. All aromatic compounds exhibited high fluorescence properties at the blue‐green region.

Understanding the Broad Substrate Repertoire of Nitroreductase Based on Its Kinetic Mechanism

The oxygen-insensitive nitroreductase from Enterobacter cloacae (NR) catalyzes two-electron reduction of nitroaromatics to the corresponding nitroso compounds and, subsequently, to hydroxylamine products. NR has an unusually broad substrate repertoire, which may be related to protein dynamics (flexibility) and/or a simple non-selective kinetic mechanism. To investigate the possible role of mechanism in the broad substrate repertoire of NR, the kinetics of oxidation of NR by para-nitrobenzoic acid (p-NBA) were investigated using stopped-flow techniques at 4 °C. The results revealed a hyperbolic dependence on the p-NBA concentration with a limiting rate of 1.90 ± 0.09 s(-1), indicating one-step binding before the flavin oxidation step. There is no evidence for a distinct binding step in which specificity might be enforced. The reduction of p-NBA is rate-limiting in steady-state turnover (1.7 ± 0.3 s(-1)). The pre-steady-state reduction kinetics of NR by NADH indicate that NADH reduces the enzyme with a rate constant of 700 ± 20 s(-1) and a dissociation constant of 0.51 ± 0.04 mM. Thus, we demonstrate simple transient kinetics in both the reductive and oxidative half-reactions that help to explain the broad substrate repertoire of NR. Finally, we tested the ability of NR to reduce para-hydroxylaminobenzoic acid, demonstrating that the corresponding amine does not accumulate to significant levels even under anaerobic conditions. Thus E. cloacae NR is not a good candidate for enzymatic production of aromatic amines.

Enhanced biodegradation and detoxification of disperse azo dye Rubine GFL and textile industry effluent by defined fungal-bacterial consortium

In this study, a defined consortium-AP of Aspergillus ochraceus NCIM-1146 fungi and Pseudomonas sp. SUK1 bacterium was studied to assess its potential for enhanced decolorization and detoxification of azo dye Rubine GFL and textile effluent. Developed consortium-AP showed enhanced decolorization of dye (95% in 30 h) and effluent (98% ADMI removal in 35 h) without formation of aromatic amines under microaerophilic conditions. Individual A. ochraceus NCIM-1146 showed only 46% and 5% decolorization of the dye and effluent. However, Pseudomonas sp. SUK1 showed 63% and 44% decolorization of the dye and effluent respectively with the production of aromatic amines. Induction of laccase, veratryl alcohol oxidase, azo reductase and NADH-DCIP reductase in the consortium-AP suggests synergetic reactions of fungal and bacterial cultures for enhanced decolorization process. Differential fate of metabolism of Rubine GFL by an individual and consortium-AP cultures were proposed on the basis of enzymatic status, FTIR and GC-MS analysis. Furthermore, consortium-AP also achieved a significant reduction in COD (96%), BOD (82%) and TOC (48%) of textile effluent. The results of toxicity studies suggest that this consortium may effectively be used for complete detoxification of dye and effluent and has potential environmental implication in cleaning up azo dyes containing effluents.

The effect of perspiration on photo-induced chemical reaction of azo dyes and the determination of aromatic amine products

In order to investigate the impact of perspiration on photo-induced chemical reaction of azo dyes and the carcinogenic aromatic amine products produced from the reaction, we have carried out experimental studies on the photochemical reaction of C.I. Reactive Red 2 mixed with American Association of Textile Chemists and Colorists（AATCC）standard artificial perspiration. UV–vis spectroscopic technique was employed to monitor the reaction processes, and the reaction products were analyzed by hollow fiber protected liquid-liquid-liquid phase micro-extraction with capillary electrophoresis（HF-LLLME-CE). The results showed that perspiration had remarkable influence on the photochemical reaction of azo dyes. Aromtic amines formed during the photochemical process as a result of reduction of azo dyes by organic components in perspiration. The HF-LLLME-CE methodology was validated in analyzing aromatic amines produced from the photochemical degradation of azo dye C.I. Reactive Red 2 and C.I. Acid Red 35 mixed with artificial perspiration.