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Thiocyanates form an important class of organic compounds commonly found in natural products that exhibit excellent antimicrobial activity. The electrophilic thiocyanation is one of the most effective methods of introducing a -SCN functional group to the parent organic molecule. In this work, we explored an eco-friendly and highly efficient method for thiocyanation of anilines and 1-(substituted benzylidene)-2-phenylhydrazines using commercially available N-bromoscuccinimide (NBS) and potassium thiocyanate (KSCN). The optimized protocol afforded thiocyanates with good regioselectivity and excellent yields in comparison to the available methods. [ABSTRACT FROM AUTHOR]

This paper presents the photophysical investigations of two organic compounds synthesised directly by the aminolysis depolymerisation of the waste poly(ethylene terephthalate) (rPET) with aromatic amines, i.e., aniline and 3-amino-N-hexyl-1,8-naphthalimide without use of a catalyst. The chemical structure was confirmed by 1H-NMR and 13C-NMR, as well as FT-IR. The thermal, electrochemical and optical studies of the obtained derivatives were performed. The presented compounds were thermally stable up to 360 °C, and the glass transition temperature (Tg) occurred for the compound with the 1,8-naphthalimide units. The electrochemical investigations of the synthesised compounds have revealed one oxidation process and two reduction processes for the compound with the 1,8-naphthalimide fragments. The tested derivatives were characterised by a low-lying highest occupied molecular orbital (HOMO) level (below –6.09 eV) and an energy-band gap (Eg) below 3.10 eV. The obtained molecules were absorbed in the range of 204 nm - 445 nm and emitted light from a purple to a green spectral region deepened on the used solvent with low quantum yields. The blends with poly(3-hexylthiophene-2,5-diyl) (P3HT), which is used as a donor in the bulk heterojunction solar cells (BHJ), and amide derivative with 1,8-naphthalimide fragments were made, and the emission quenching of poly(3-hexylthiophene-2,5-diyl) (P3HT) was recorded. The presented results of the photophysical investigations have opened new possibilities for obtaining functional materials from recycled poly(ethylene terephthalate) (rPET). [ABSTRACT FROM AUTHOR]

Diffusive hydrogel-based passive sampler (HPS) based on diffusive gradients in thin films (DGT) is designed for monitoring polar organic contaminants in the aquatic environment. DGT technique controls the compound's overall uptake rate by adding a hydrogel layer of known thickness, which minimizes the importance of the resistive water boundary layer in the compound uptake process. In this work, we investigated several factors which may influence the diffusion of a range of aquatic contaminants in 1.5% agarose hydrogel. Diffusion in hydrogel was tested using the sheet stacking method. We demonstrated that a thin nylon netting incorporated into the diffusive hydrogel for mechanical strengthening does not significantly affect the diffusion of 11 perfluoroalkyl compounds. Further, we investigated the effect of pH in the range from 3 to 11 on the diffusion of a range of 39 aromatic amines (AAs) —36 aromatic, 2 aliphatic, and azobenzene in hydrogel. AAs were chosen as representatives of compounds with pH-dependent dissociation in water. Analysis of variance showed no significant difference in mean diffusion coefficient log D value at five pH values. The demonstration that the diffusion coefficient D and thus the sampling rate Rs are independent on pH simplifies the interpretation of data from field studies because we can neglect the influence of pH on the Rs. log D values (m2 s−1) of tested AAs ranged from to − 9.77 for 3,3′-dimethylbenzidine to − 9.19 for azobenzene. A negative correlation of log D with molar mass (log M) and molecular volume (log Vm) was observed (R = − 0.57 and − 0.56, respectively). The diffusion coefficient presents a critical parameter for the sampling rate estimation of HPS. Theoretical sampling rates Rs of AAs were calculated for a HPS using the average D values. Theoretical Rs values calculated for AAs at 22°C ranged from 29 mL day−1 for 3,3′-dimethylbenzidine to 106 mL day−1 for 2-aminopyridine. Our calculated values of Rs are in the same range as those already published for a range of low-molecular polar organic contaminants, which supports the possibility of deriving sampler performance parameters in the field from laboratory-derived diffusivity of analytes in hydrogel. [ABSTRACT FROM AUTHOR]

Amines are abundant in natural product chemistry and are readily available chemical raw materials. The C-N bonds of amines are difficult to break due to the large C-N bond energy. In recent years, chemists have developed a variety of activation methods for amino groups of amines. Among these reported methods, to convert amines into quaternary ammonium salts is preferred, for quaternary ammonium salts are readily available and stable. In recent years, great progress has been achieved in the study of transition metal-catalyzed construction of various C-X bonds involving aromatic amines and benzyl amines-derived quaternary ammonium salts by cleavage of C-N bonds. This review describes the transition metal-catalyzed reaction of quaternary ammonium salts to construct C-X bonds by cleavage of C-N bond. Moreover, if chiral benzylamines-derived quaternary ammonium salts are used, a variety of highly enantiomeric pure chiral organic compounds can also be obtained. The chirality of quaternary ammonium salts remained good in the products and all reactions underwent SN2-type configuration inversion. [ABSTRACT FROM AUTHOR]

Aromatic tertiary amines are one of the most important classes of organic compounds in organic chemistry and drug discovery. It is difficult to efficiently construct tertiary amines from primary amines via classical nucleophilic substitution due to consecutive overalkylation. In this paper, we have developed a radical tandem C-N coupling strategy to efficiently construct aromatic tertiary amines from commercially available carboxylic acids and nitroarenes. A variety of aromatic tertiary amines can be furnished in good yields (up to 98%) with excellent functional group compatibility under mild reaction conditions. The use of two different carboxylic acids also allows for the concise synthesis of nonsymmetric aromatic tertiary amines in satisfactory yields. Mechanistic studies suggest the intermediacy of the arylamine–(TPP)Fe(III) species and might provide a possible evidence for an SH2 (bimolecular homolytic substitution) pathway in the critical C-N bond formation step. Aromatic tertiary amines are versatile building blocks in organic synthesis. In this article, the authors report on an iron-catalysed reaction for the decarboxylative C-N coupling from carboxylic acids and nitroarenes, leading to non-symmetric tertiary aromatic amines. [ABSTRACT FROM AUTHOR]

Water-soluble organic nitrogen (WSON) is ubiquitous in fine particulate matter (PM 2.5) and poses health and environmental risks. However, there is limited knowledge regarding its comprehensive speciation and source-specific contributions. Here, we conducted chemical characterization and source apportionment of WSON in 65 PM 2.5 samples collected in Hong Kong during a 1-yr period. Using various mass-spectrometry-based techniques, we quantified 22 nitrogen-containing organic compounds (NOCs), including 17 nitroaromatics (NACs), four amines, and urea. The most abundant amine and NACs were dimethylamine and 4-nitrocatechol, respectively. Two secondary (i.e., secondary formation and secondary nitrate) and five primary sources (i.e., sea salt, fugitive dust, marine vessels, vehicle exhaust, and biomass burning) of WSON and these three categories of NOCs were identified. Throughout the year, secondary sources dominated WSON formation (69.0%), while primary emissions had significant contributions to NACs (77.1%), amines (75.9%), and urea (83.7%). Fugitive dust was the leading source of amines and urea, while biomass burning was the main source of NACs. Our multi-linear regression analysis revealed the significant role of sulfate, NO 3 , nitrate, liquid water content, and particle pH on WSON formation, highlighting the importance of nighttime NO 3 processing and heterogeneous and aqueous-phase formation of NOCs in the Hong Kong atmosphere. [Display omitted] • Aerosol phase WSON is mainly secondarily formed (69.0%) in Hong Kong. • Heterogeneous and aqueous-phase reactions and nighttime NO 3 oxidation are major formation pathways of WSON. • Sulfate and NO 3 played key roles in WSON formation. • Nitroaromatic compounds were predominantly from biomass-burning. • Amines and urea were primarily from dust and crustal origin. [ABSTRACT FROM AUTHOR]

This review would like to show the state of the art regarding the coupling of High-Performance Liquid Chromatography (HPLC) with Electrochemical Detection (ED). Since a universal detector for HPLC is not available, the electrochemical detection methods, thanks to their versatility and specificity, are competitive with respect to the detectors currently used. The papers present in literature on HPLC-ED technique are analyzed and discussed: for example, they regard the development of analytical determinations of resveratrol, rosmarinic acid, aromatic heterocyclic amines and glyphosate in food matrices such as meat, aromatic plants, vegetables, fruit and tomato juices. These papers show that electrochemical sensors used as detectors for HPLC can offer better sensitivity values than other detectors. Furthermore, the use of specific working potentials allows avoid matrix interferences to be avoided by almost exclusively determining the analytes of interest. It should be underlined that HPLC-ED methods have a selectivity that allows for limitation of the sample preparation and clean-up procedures to a minimum, making them quick and easy to apply. In addition, these methods offer advantages such as the possibility of direct analysis, that derivatization is often not necessary, the cost-effectiveness of the instrumentation and the possibility of regenerating the electrodes which allows numerous analyses in succession. [ABSTRACT FROM AUTHOR]

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Ammonia and nitric acid are two key platform chemicals to introduce nitrogen atoms into organic molecules in chemical industry. Indeed, nitric acid is mostly produced through the oxidation of ammonia. The ideal nitrogenation would involve direct use of dinitrogen (N2) as a N source to construct N-containing organic molecules. Herein, we report an example of direct catalytic nitrogenation to afford valuable diarylamines, triarylamines, and N-heterocycles from easily available organohalides using dinitrogen (N2) as the nitrogen source in a one-pot/two-step protocol. With this method, 15N atoms are easily incorporated into organic molecules. Structurally diversified polyanilines are also generated in one pot, showing great potential for materials chemistry. In this protocol, lithium nitride, generated in situ with the use of lithium as a reductant, is confirmed as a key intermediate. This chemistry provides an alternative pathway for catalytic nitrogenation to synthesize highly valuable N-containing chemicals from dinitrogen. Ammonia and nitric acid are key platform chemicals to introduce nitrogen into organic molecules, however gaseous N2 would be a more direct and available source of nitrogen. Here, the authors report a direct catalytic nitrogenation to afford valuable arylamines and N-heterocycles from organohalides using dinitrogen (N2) as the nitrogen source. [ABSTRACT FROM AUTHOR]

Synthesis of some new mono azo organic compounds, based on 1‐arylazo‐2‐naphthol nucleus is performed by diazo‐coupling strategy of β‐naphthol with different 1ry aromatic amines. Interestingly, the monoazo products undergo functionalized reactions to obtain the target azo naphthol derivatives (3–14). The synthesized dyes are conjugated with gold and/ or silver nanoparticles by electrostatic interaction. Photodynamic therapeutic efficiencies of the synthesized naphthol azo dyes and their conjugates have been evaluated against promyelocytic leukemia cell lines (HL‐60) in dark and light conditions. Dye‐Nanometal conjugates act as photosensitizers (PSs) exhibiting an enhancement of the optical properties as well as in photodynamic therapeutic efficiencies in variable degrees depending on dye structure. [ABSTRACT FROM AUTHOR]

Electroactive organic compounds could bring new chemical opportunities to further improve existing electrochemical energy‐storage technologies as they can be prepared from less‐limited resources and potentially at low environmental footprint. Among the current explored research fields, the anion–ion cell configuration appears poorly investigated although quite promising to promote the fabrication of molecular (metal‐free) rechargeable batteries. Herein, we report the synthesis and the electrochemical behavior of both Mg/Li salts of 2,5‐(dianilino)terephthalate (MgDAnT and Li2DAnT) and cross‐linked polyviologen (c‐PV2+) that can reversibly uptake/extract anions at different working potentials, enabling the assembly of full anionic organic batteries. The reversible anion ingress in MgDAnT is however accompanied by solvent co‐insertion from the electrolyte that provokes an overpotential effect during the first charge. Full anionic batteries pairing Li2DAnT with c‐PV2+ were assembled giving rise to 0.7 V as output voltage with a specific capacity of 50 mAh per gram of Li2DAnT. [ABSTRACT FROM AUTHOR]

Nowadays one of the great challenges is to design new bimetallic catalysts with enhanced catalytic activity, selectivity and recycling properties. In this work, the preparation of new Co/Cu bimetallic Zeolitic Imidazolate Framework (Co‐Cu/ZIF) as an efficient catalyst for the reduction of nitro compounds and organic dyes is described. Co‐Cu/ZIF was characterized with different techniques such as SEM, TEM, XRD, XPS, TGA, FT‐IR and UV–vis absorption indicating formation of entirely uniform cubic particles. Using this catalyst, structurally different aromatic nitro compounds were reduced efficiently to corresponding amines in excellent yields. Kinetic studies revealed that the reduction rates of nitrophenol isomers follow 3‐NP > 4‐NP > 2‐NP order. The catalytic activity of Co‐Cu/ZIF was further investigated in the reduction of organic dyes such as methyl orange (MO) and rhodamine B (RhB). This catalyst was recycled for at least ten runs in the reduction of 4‐nitrophenol without a noticeable decrease in activity and reused catalyst was characterized. [ABSTRACT FROM AUTHOR]

The comparison of D index with HOMHED gave a good correlation (R2= 0.8221). However, a modification of D index, namely D', where the number of cycles involved in the tested molecule is substituted by the ratio between the number of atoms involved in π orbitals in the tested molecule and in reference molecule, gave a better correlation with a larger number of compounds (R2=0.8819), The correlation of D' with calculated HOMHED for pentatomic heterocyclic compounds did not give a unique correlation but a series of possible correlations. This behavior depends on the parameters used for the calculation of HOMHED that allow some negative values. In fact, the comparison of D' with NICS for selected pentatomic heterocycles gave good correlation. Good correlations were observed also in the comparison of D' with HOMHED and NICS for antiaromatic compounds. [ABSTRACT FROM AUTHOR]

A detailed study has been carried out on monohydroxycucurbit[7]uril-based stir-bar sorptive extraction (SBSE). A polydimethylsiloxane coating was produced by a sol–gel technique and doped with monohydroxycucurbit[7]uril ((HO)1Q [7]) as a selective sorbent phase. (HO)1Q [7] was chemically bound to the sol–gel silica substrate through hydrolysis and polycondensation. The coating possesses a porous surface, shows strong solvent resistance and good thermal stability, and has a long lifespan. Four groups of compounds, with polarities ranging from apolar polycyclic aromatic hydrocarbons to polar ketones, aromatic amines and phenols, were selected as test analytes. They were extracted with the coated stir bar, then desorbed with methanol and quantified by high-performance liquid chromatography with ultraviolet detection. The limits of detection range between 1.3 and 15 μg L−1, the linear ranges extend from 5 to 10,000 μg L−1, and the relative recoveries from spiked samples range between 76.4 and 97.9%. The intraday relative standard deviations range from 2.3 to 8.6% (for n = 3, at 500 μg L−1). Compared with a commercial PDMS-coated stir bar and a polyether sulfone-coated stir bar, the new stir bar shows wider applicability and better extraction efficiency for each group of compounds. In addition, the stir bar can simultaneously extract mixtures of chemicals of different polarities. This endows it with the potential for recovering a broad group of polar organic compounds. [ABSTRACT FROM AUTHOR]

Photolysis is one of the main transformation pathways for 2,4,6-trinitrotoluene (TNT) released into the environment. Upon exposure to sunlight, TNT is known to undergo both oxidation and reduction reactions with release of nitrite, nitrate, and ammonium ions, followed by condensation reactions of the oxidation and reduction products. In this study, compound classes of transformation products from the aqueous and solid phase photodegradation of 2,4,6-trinitrotoluene (TNT) have been identified by liquid and solid state 13C and 15N NMR. Aqueous phase experiments were performed on saturated solutions of T15NT in deionized water, natural pond water (pH = 8.3, DOC = 3.0 mg/L), pH 8.0 buffer solution, and in the presence of Suwannee River Natural Organic Matter (SRNOM; pH = 3.7), using a Pyrex-filtered medium pressure mercury lamp. Natural sunlight irradiations were performed on TNT in the solid phase and dissolved in the pond water. In deionized water, carboxylic acid, aldehyde, aromatic amine, primary amide, azoxy, nitrosophenol, and azo compounds were formed. 15N NMR spectra exhibited major peaks centered at 128 to 138 ppm, which are in the range of phenylhydroxylamine and secondary amide nitrogens. The secondary amides are proposed to represent benzanilides, which would arise from photochemical rearrangement of nitrones formed from the condensation of benzaldehyde and phenylhydroxylamine derivatives of TNT. The same compound classes were formed from sunlight irradiation of TNT in the solid phase. Whereas carboxylic acids, aldehydes, aromatic amines, phenylhydroxylamines, and amides were also formed from irradiation of TNT in pond water and in pH 8 buffer solution, azoxy and azo compound formation was inhibited. Solid state 15N NMR spectra of photolysates from the lamp irradiation of unlabeled 2,6-dinitrotoluene in deionized water also demonstrated the formation of aromatic amine, phenylhydroxylamine/ 2° amide, azoxy, and azo nitrogens. [ABSTRACT FROM AUTHOR]

Photoinduced electron transfer (ET) between coumarin dyes and aromatic amine has been investigated in two cationic micelles, namely, cetyltrimethyl ammonium bromide (CTAB) and dodecyltrimethyl ammonium bromide (DTAB), and the results have been compared with those observed earlier in sodium dodecyl sulphate (SDS) and triton-X-100 (TX-100) micelles for similar donor-acceptor pairs. Due to a reasonably high effective concentration of the amines in the micellar Stern layer, the steady-state fluorescence results show significant static quenching. In the time-resolved (TR) measurements with subnanosecond time resolution, contribution from static quenching is avoided. Correlations of the dynamic quenching constants (kqTR), as estimated from the TR measurements, show the typical bell-shaped curves with the free-energy changes (ΔG0) of the ET reactions, as predicted by the Marcus outersphere ET theory. Comparing present results with those obtained earlier for similar coumarin-amine systems in SDS and TX-100 micelles, it is seen that the inversion in the present micelles occurs at an exergonicity (-ΔG0>∼1.2–1.3 eV) much higher than that observed in SDS and TX-100 micelles (-ΔG0>∼0.7 eV), which has been rationalized based on the relative propensities of the ET and solvation rates in different micelles. In CTAB and DTAB micelles, the kqTR values are lower than the solvation rates, which result in the full contribution of the solvent reorganization energy (λs) towards the activation barrier for the ET reaction. Contrary to this, in SDS and TX-100 micelles, kqTR values are either higher or comparable with the solvation rates, causing only a partial contribution of λs in these cases. Thus, Marcus inversion in present cationic micelles is inferred to be the true inversion, whereas that in the anionic SDS and neutral TX-100 micelles are understood to be the apparent inversion, as envisaged from two-dimensional ET theory. [ABSTRACT FROM AUTHOR]

The glass-former m-toluidine displays the characteristic properties of a fragile supercooled liquid, which suggest the existence of a slow secondary relaxation process. In view of the recently realized importance of such a secondary relaxation feature, we have conducted a dielectric search for the secondary process in viscous and glassy m-toluidine. Based on high-resolution experiments on the distilled liquid, a secondary process can be identified which has the properties typical of a Johari–Goldstein β relaxation. As a result, the previous hypothesis that the methyl group might be responsible for suppressing the secondary dynamics in glassy m-toluidine no longer holds. [ABSTRACT FROM AUTHOR]

Photoinduced electron transfer (ET) reactions between anthraquinone derivatives and aromatic amines have been investigated in sodium dodecyl sulphate (SDS) micellar solutions. Significant static quenching of the quinone fluorescence due to high amine concentration in the micellar phase has been observed in steady-state measurements. The bimolecular rate constants for the dynamic quenching in the present systems kqTR, as estimated from the time-resolved measurements, have been correlated with the free energy changes ΔG0 for the ET reactions. Interestingly it is seen that the kqTR vs ΔG0 plot displays an inversion behavior with maximum kqTR at around 0.7 eV, a trend similar to that predicted in Marcus ET theory. Like the present results, Marcus inversion in the kqTR values was also observed earlier in coumarin-amine systems in SDS and TX-100 micellar solutions, with maximum kqTR at around the same exergonicity. These results thus suggest that Marcus inversion in bimolecular ET reaction is a general phenomenon in micellar media. Present observations have been rationalized on the basis of the two-dimensional ET (2DET) theory, which seems to be more suitable for micellar ET reactions than the conventional ET theory. For the quinone-amine systems, it is interestingly seen that kqTR vs ΔG0 plot is somewhat wider in comparison to that of the coumarin-amine systems, even though the maxima in the kqTR vs ΔG0 plots appear at almost similar exergonicity for both the acceptor-donor systems. These observations have been rationalized on the basis of the differences in the reaction windows along the solvation axis, as envisaged within the framework of the 2DET theory, and arise due to the differences in the locations of the quinones and coumarin dyes in the micellar phase. [ABSTRACT FROM AUTHOR]

The impact of black cumin usage on some qualitative properties and formation of heterocyclic aromatic amines (HAAs) in meatball production was investigated. It was found that black cumin usage rate, cooking process and temperature had a significant effect (p<0,01) on the water content, pH, and thiobarbituric acid reactive substances (TBARS) values of meatballs. On the other hand, black cumin usage significantly (p<0,01) reduced the water content and cooking loss. The water content and cooking loss of the meatballs decreased with increases in the usage rate. While IQx, IQ, MeIQ, 7,8-DiMeIQx, 4,8-DiMeIQx, AαC, and MeAαC could not be detected in meatballs, varying amounts of MeIQx (up to 1,53 ng/g) and PhIP (up to 1,22 ng/g) were determined. The total amounts of HAAs ranged between non-detected (nd) to 2,75 ng/g. Both the usage rate and cooking temperature had a very significant effect (p<0,01) on the total contents of HAAs. The total amounts of HAAs were decreased in correlation with the increases in the usage rate; the proportion which is increased when the cooking temperature increased as well. Results of the present study suggested that addition of black cumin may have a substantial role in decreasing the TBARS value, cooking loss, and HAA contents during meatball production. Therefore, using of black cumin in meatball production has been suggested. [ABSTRACT FROM AUTHOR]

Quorum sensing (QS), a mechanism of microbial communication dependent on cell density, governs developmental decisions in many bacteria and in some pathogenic and non-pathogenic fungi including yeasts. In these simple eukaryotes this response is mediated by the release into the growth medium of quorum-sensing molecules (QSMs) whose concentration increases proportionally to the population density. To date the occurrence of QS is restricted to a few yeast species. We show that a QS mediated by the aromatic alcohols phenylethanol and tryptophol represses the dimorphic yeast to hypha differentiation in the fission yeast S. japonicus in response to an increased population density. In addition, the stress activated MAPK pathway (SAPK), which controls cell cycle progression and adaptation to environmental changes in this organism, constitutively represses yeast to hypha differentiation both at transcriptional and post-translational levels. Moreover, deletion of its main effectors Sty1 MAPK and Atf1 transcription factor partially suppressed the QS-dependent block of hyphal development under inducing conditions. RNAseq analysis showed that the expression of nrg1+, which encodes a putative ortholog of the transcription factor Nrg1 that represses yeast to hypha dimorphism in C. albicans, is downregulated both by QS and the SAPK pathway. Remarkably, Nrg1 may act in S. japonicus as an activator of hyphal differentiation instead of being a repressor. S. japonicus emerges as an attractive and amenable model organism to explore the QS mechanisms that regulate cellular differentiation in fungi. [ABSTRACT FROM AUTHOR]

In this paper, a novel strategy integrating ultrasound (US) with a Fenton-like (zero-valent iron/EDTA/air, ZEA) process was proposed for the removal of the refractory and carcinogenic aromatic amines (AAs) in textile dyeing sludge for the first time. The operating condition was optimized as 1.08 W/cm3 ultrasonic density, 15 g/L ZVI, and 1.0 mM EDTA, which could reach degradation efficiencies of 51.79% in US, 72.88% in ZEA, and 92.40% in US/ZEA system after 90-min reaction. Quenching experiments showed that electron transfer reactions generated by the iron ligands in ZEA brought about various reactive oxidative species (ROS), in which Fe (IV), O2˙−, and ˙OH dominated the degradation. US induced sludge disintegration by ultrasonic shear, proven by particle size decrease and supernatant organic matter upsurge, which helps ROS contact with those pollutants in the sludge cavities. Besides, US facilitated the iron redox cycle for oxygen activation by promoting the corrosion of ZVI and stripping considerable ferric ions from sludge iron oxides which were verified by SEM, XRF, and XPS. Graphical abstract [ABSTRACT FROM AUTHOR]

A 1,1'-binaphthyl-based ladder polymer containing fused polyaromatic rings and aldehyde groups in its repeating units has been synthesized. In the presence of primary aliphatic amines, this polymer shows fluorescence enhancement at λ = 655 nm with a significant red shift from its original emission wavelength at λ = 585 nm. However, neither fluorescence enhancement nor shift of the emitting wavelength was observed when the polymer was treated with secondary and tertiary amines as well as with an aromatic amine. Thus, this ladder polymer can be used to selectively recognize primary aliphatic amines with ratiometric detection. The fluorescence response of the ladder polymer is also very different from its precursor polymer as well as its monomeric analogue, which do not show fluorescence enhancement towards primary amines. [ABSTRACT FROM AUTHOR]

Rapid, on-site analysis was achieved through significantly simplified operation procedures for a wide variety of toy samples (crayon, temporary tattoo sticker, finger paint, modeling clay, and bubble solution) using a miniature mass spectrometry system with ambient ionization capability. The labor-intensive analytical protocols involving sample workup and chemical separation, traditionally required for MS-based analysis, were replaced by direct sampling analysis using ambient ionization methods. A Mini β ion trap miniature mass spectrometer was coupled with versatile ambient ionization methods, e.g. paper spray, extraction spray and slug-flow microextraction nanoESI for direct identification of prohibited colorants, carcinogenic primary aromatic amines, allergenic fragrances, preservatives and plasticizers from raw toy samples. The use of paper substrates coated with Co 3 O 4 nanoparticles allowed a great increase in sensitivity for paper spray. Limits of detection as low as 5 μg kg -1 were obtained for target analytes. The methods being developed based on the integration of ambient ionization with miniature mass spectrometer represent alternatives to current in-lab MS analysis operation, and would enable fast, outside-the-lab screening of toy products to ensure children's safety and health. [ABSTRACT FROM AUTHOR]

Abstract: The chromatographic separation of several isomeric anilines is a challenging issue. Herein, a simple method for the simultaneous determination of four groups of isomeric primary aromatic amines, including chloroanilines, methylanilines, methoxylanilines, and dimethylanilines, was presented. In this method, all of the 15 primary aromatic amines were easily transformed into the corresponding imine derivative by treatment with benzaldehyde under mild conditions. The formed isomeric imine derivatives were completely separated on a commercial capillary gas chromatography column. The effects of several derivatization parameters were investigated and optimized. Linearity in the optimized method ranged from 0.050 to 50 μg/mL with the squared correlation coefficients (R2) between 0.9981 and 0.9999. Reasonable reproducibility was obtained, with the intraday relative standard deviation (N = 5) ranging from 0.89 to 4.57% and interday relative standard deviation ranging from 2.26 to 7.69% at the concentration of 5.0 μg/mL. The developed method has been successfully applied to determine these isomeric aromatic amines in real samples. [ABSTRACT FROM AUTHOR]

Chemicals safety control and eco-properties have become a priority for the textile industry to avoid the negative effects on humans and environment. The European regulations limit the presence of 24 listed carcinogenic aromatic amines by 30 mg/kg of textile material. The paper aims to present a comparison between different parameters of procedures for the extraction, reduction and purification of the amines obtained by the reductive cleavage of azo dyes in order to choose the optimal method. In order to test the amine extracts obtained, the 8-point calibration curve was performed for the mixture of the 24 standard amines and the solutions obtained from the extraction of the dyestuffs from the textile samples were analysed. Their testing was performed by liquid chromatography and the results were confirmed by the gas chromatography method. [ABSTRACT FROM AUTHOR]

A highly sensitive o-phenylenediamine (OPD) sensor based on a Fe 3 O 4 doped with functionalized multi-walled carbon nanotubes (Fe 3 O 4 @ f -MWCNTs) composite fabricated glassy carbon electrode (GCE) was developed. The modified Fe 3 O 4 @ f -MWCNTs/GCE showed an enhanced current ( I pa ) response toward OPD relative to that of a Fe 3 O 4 /GCE, f -MWCNTs/GCE, and a bare GCE. Under optimum conditions, the Fe 3 O 4 @ f -MWCNTs/GCE showed a wide linear range remove at OPD concentrations of 0.6–80 µM. The limit of detection and sensitivity of the f -MWCNTs/GCE, Fe 3 O 4 /GCE sensor were found to be 50 µM, and 2.8002 mA mM −1 cm −2 , respectively. The developed sensor showed excellent accumulation time, good repeatability, and operational stability. The obtained results suggest that the development of composite could be an effective electro-catalyst and it can play a vital role in biomedical, pharmaceutical, and hazardous free environmental applications. [ABSTRACT FROM AUTHOR]

The selective catalytic reduction of nitroaromatics towards aromatic amines under mild reaction condition is an important approach to reduce the toxicity of waste effluents from industry and afterwards utilize the product as important fine organic chemical raw materials. P-nitrophenol (PNP) is chosen as the probe molecule of nitroaromatics in this study. A Fe-embedded N-doped Carbon (Fe-N-C) catalyst prepared using ZIF-8 has been identified as a highly active, selective and stable catalyst in the selective catalytic reduction of PNP. The Fe-N-C catalyst is for the first time applied in PNP reduction and found to present 100% conversion and 100% product selectivity. A mechanism investigation has been carried out to conclude that in the PNP reduction on Fe-N-C, water acts as the main hydrogen provider and sodium borohydride is the electron donator. Furthermore, the Fe-N-C catalyst works well when it is applied in PNP degradation in real water samples, which further indicates its applicability in industrial wastewater treatment. This work offers a simple and useful strategy to design robust catalysts for the selective catalytic reduction of nitroaromatics. [Display omitted] • Fe-N-C is highly active, selective, and stable in p-nitrophenol reduction. • An isotope experiment has been designed to reveal the reaction mechanism. • Fe-N-C is still robust for p-nitrophenol degradation in real water treatment. [ABSTRACT FROM AUTHOR]

Over the past decades, electrospray ionization for mass spectrometry (ESI-MS) has become one of the most commonly employed techniques in analytical chemistry, mainly due to its broad applicability to polar and semipolar compounds and the superior selectivity which is achieved in combination with high resolution separation techniques. However, responsiveness of an analytical method also determines its suitability for the quantitation of chemical compounds; and in electrospray ionization for mass spectrometry, it can vary significantly among different analytes with identical solution concentrations. Therefore, we investigated the ESI-response behavior of 56 nitrogen-containing compounds including aromatic amines and pyridines, two compound classes of high importance to both, synthetic organic chemistry as well as to pharmaceutical sciences. These compounds are increasingly analyzed employing ESI mass spectrometry detection due to their polar, basic character. Signal intensities of the peaks from the protonated molecular ion (MH+) were acquired under different conditions and related to compound properties such as basicity, polarity, volatility and molecular size exploring their quantitative impact on ionization efficiency. As a result, we found that though solution basicity of a compound is the main factor initially determining the ESI response of the protonated molecular ion, other factors such as polarity and vaporability become more important under acidic solvent conditions and may nearly outweigh the importance of basicity under these conditions. Moreover, we show that different molecular descriptors may become important when using different types of instruments for such investigations, a fact not detailed so far in the available literature. [ABSTRACT FROM AUTHOR]

The conversion of commercially available anilines into biaryl and biarylacetylene products was realized by using a telescoped, three-reactor flow diazotization/iododediazotization/cross-coupling process. The segmented flow stream created by off-gassing during the Sandmeyer sequence was restored to a continuous column of reaction solution by using a specially designed continuous-flow unit controlled by custom software created in-house. The resultant aryl iodide was then combined with a stream of cross-coupling solution that fed into the final reactor. The system proved versatile as modifications to the diazotization/iododediazotization sequence could be made rapidly to account for any substrate specificity (e.g., solubility problems), leading to a wide substrate scope of Suzuki-Miyaura and Sonogashira cross-coupled products. [ABSTRACT FROM AUTHOR]

Epoxy resin nanocomposites containing graphite nanosheets (GNS) and unsaturated polyester resin (UPR) were prepared by incorporating GNS in semi interpenetrating network (semi-IPN) of epoxy resin and unsaturated polyester resin (E-UPR). GNS are prepared by thermal shock treatment of sulphuric acid-graphite intercalation compound (GIC) followed by ultra-sonication. The E-UPR-GNS semi-IPNs were further modified with aromatic amines such as benzidine (Bz) and diphenyl amine (DPA). All the samples were prepared by mixing Triethylenetetramine (TETA) as the curing agent at two different temperatures viz. room temperature (RT) and low temperature (LT; 5 °C). A transition is observed in the conducting properties of the samples: from an electrical insulator to an electrical semiconductor in case of nanocomposites especially on addition of GNS to E-UPR semi-IPNs. A sharp improvement is observed in conductivity after modification with diphenyl amine (DPA) cured at LT. The nanocomposites obtained at LT exhibit homogeneity with minimum anisotropy in conductivity. The morphology, mechanical, thermal and electrical properties were evaluated using various analytical techniques. Positron annihilation spectroscopy was carried out to correlate the measured properties with the free volume and free volume hole size distribution. The results are consistent with the reported studies. [ABSTRACT FROM AUTHOR]

A method of synthesis of maleopimaric acid N-aryl(aralkyl)imidoamides by reaction of the corresponding aromatic amides of maleopimaric acid and amines in p-xylene at reflux was developed. Thermal stability of the synthesized compounds was evaluated by derivatography. [ABSTRACT FROM AUTHOR]

Meat products are sources of protein with high biological value and an essential source of other nutrients, such as vitamins and minerals. Heating processes cause food to become more appetizing with changes in texture, appearance, flavor, and chemical properties by the altering of protein structure and other ingredients. During heat treatment, heterocyclic aromatic amines (HAAs), potent mutagens/carcinogens, are formed due to the Maillard reaction. The HAAs are classified in at least 2 groups: thermic HAAs (100 to 300 °C) and pyrolytic HAAs (>300 °C). This review focuses on the parameters and precursors which affect the formation of HAAs: preparation, such as the marinating of meat, and cooking methods, including temperature, duration, and heat transfer, as well as levels of precursors. Additionally, factors are described subject to pH, and the type of meat and ingredients, such as added antioxidants, types of carbohydrates and amino acids, ions, fat, and other substances inhibiting or enhancing the formation of HAAs. An overview of the different analytical methods available is shown to determine the HAAs, including their preparation to clean up the sample prior to extraction. Epidemiological results and human daily intake of HAAs obtained from questionnaires show a relationship between the preference for very well-done meat products with increased HAA levels and an enhanced risk of the incidence of cancer, besides other carcinogens in the diet. The metabolic pathway of HAAs is governed by the activity of several enzymes leading to the formation of DNA adducts or HAA excretion and genetic sensitivity of individuals to the impact of HAAs on human cancer risk. [ABSTRACT FROM AUTHOR]

A procedure for the formation of aryl amides through the palladium-catalyzed coupling of nitriles and aryl bromides, via the formation of intermediary silanoate derived imidate species is reported. Optimization was undertaken and examples of the process are described that furnish the products in up to 86% isolated yield. [ABSTRACT FROM AUTHOR]

A transamidation reaction of thioacetamide with primary and secondary amines is described. The use of catalytic amounts of SbCl 3 notably increases the yields and diminishes the reaction times. Typically, the amines should be aliphatic, but aromatic amines can be used as well, though with lower yields. This is one of the few examples where antimony has been used as a catalyst in organic reactions. [ABSTRACT FROM AUTHOR]

The interaction of molybdenum (VI) with o-hydroxythiophenol derivatives (HTPDs) and aromatic amines (AAs) was studied. The following three HTPDs, which contain different halogen atoms at position 5, were used: 2-hydroxy-5-chlorothiophenol(HCTP), 2-hydroxy-5-bromothiophenol (HBTP), 2-hydroxy-5-iodothiophenol (HITP)]. The examined AAs were aniline (An), Nmethylaniline (mAn) and N,N-dimethylaniline (dAn). The obtained ternary complexes have a composition of 1:2:2 {Mo(V):HBTP:AA}.Optimal conditions for their liquid-liquid extraction (LLE) were found: organic solvent (chloroform), pH (4-6), concentration of the reagents ((1.3- 1.5)×10-3moldm-3 (HTPD) and (1.2-1.5) ×10-3moldm-3 (AA)) and extraction time(colour develops almost immediately after the reagents addition). The absorbance of the extracts is stable for at least 48 hours. The optimum shaking time is 10 min.). Under the optimal conditions, the complexes have absorption maxima (λmax) at 515-538 nm and molar absorptivities (εmax) between 3.1×104dm3mol-1 cm-1. The degrees of extraction were ⩾98.4%. The results suggested that linear relationships exist between the spectral characteristics (λmax or λmax) and some fundamental properties of the halogen substituent in the HTPD (atomic mass and electronegativity). The effect of foreign ions on the LLE-spectrophotometric determination of molybdenum was examined and two sensitive, selective and precise procedures for molybdenum determination were proposed. The relative standard deviations for Mo content of (3-5)×10-4 % were 4% (HCTP-An procedure) and 3% (HBTP-An procedure). [ABSTRACT FROM AUTHOR]

Radical carboiodination of various aryl amines is reported. Aryl diazonium salts, generated in situ from the corresponding aryl amines, are reacted with Bu4NI to provide the corresponding aryl radicals which undergo 5-exo or 6-exo cyclization. Iodine abstraction eventually affords the carboiodinated products in good to excellent yields. If TEMPO is added, the cascade provides the cyclized carboaminoxylation products. Running the reaction in the presence of PhTeTePh affords the phenyltellurated cyclized products. [ABSTRACT FROM AUTHOR]

The highly efficient transamidation of several primary, secondary, and tertiary amides with aliphatic and aromatic amines (primary and secondary) is described. The reaction is performed in the presence of a 5 mol % concentration of different hydrated salts of Fe(III), and the results show that the presence of water is crucial. The methodology was also applied to urea and phthalimide to demonstrate its versatility and wide substrate scope. An example of its use is an intramolecular application in the synthesis of 2,3-dihydro-5H-benzo[b]-l,4-thiazepin-4-one, which is the bicyclic core of diltiazem and structurally related drugs (Budriesi, R.; Cosimelli, B.; Ioan. P.; Carosati, E.; Ugenti, M. P.; Spisani, R. Curr. Med. Chem. 2007, 14, 279-287). A plausible mechanism that explains the role or water is proposed on the basis of experimental observations and previous mechanistic suggestions for transamidation reactions catalyzed by transition metals such as copper and aluminum. This methodology represents a significant improvement over other existing methods; it can be performed in air and with wet or technical grade solvents. [ABSTRACT FROM AUTHOR]

Catalytic amination of 7-hydroxy-6-cyanocoumarin or 7-hydroxy-6-methoxycarbonylcoumarin triflates with substituted anilines, isoquinolin-5-amine, 1 H-pyrazol-3-amine, or amino acids of penicillin series affords the corresponding 7-( N-substituted) aminocoumarins. In the amination of the mentioned triflates and also of peuruthenicine tosilate with 2-(piperidin-1-yl)aniline the catalytic system Pd(OAc)-BINAP has been efficient. [ABSTRACT FROM AUTHOR]

DNA adducts are considered an integrate measure of carcinogen exposure and the initial step of carcinogenesis. Their levels in more accessible peripheral blood lymphocytes (PBLs) mirror that in the bladder tissue. In this study we explore whether the formation of PBL DNA adducts may be associated with bladder cancer (BC) risk, and how this relationship is modulated by genetic polymorphisms, environmental and occupational risk factors for BC. These complex interrelationships, including direct and indirect effects of each variable, were appraised using the structural equation modeling (SEM) analysis. Within the framework of a hospital-based case/control study, study population included 199 BC cases and 213 non-cancer controls, all Caucasian males. Data were collected on lifetime smoking, coffee drinking, dietary habits and lifetime occupation, with particular reference to exposure to aromatic amines (AAs) and polycyclic aromatic hydrocarbons (PAHs). No indirect paths were found, disproving hypothesis on association between PBL DNA adducts and BC risk. DNA adducts were instead positively associated with occupational cumulative exposure to AAs (p = 0.028), whereas XRCC1 Arg 399 (p<0.006) was related with a decreased adduct levels, but with no impact on BC risk. Previous findings on increased BC risk by packyears (p<0.001), coffee (p<0.001), cumulative AAs exposure (p = 0.041) and MnSOD (p = 0.009) and a decreased risk by MPO (p<0.008) were also confirmed by SEM analysis. Our results for the first time make evident an association between occupational cumulative exposure to AAs with DNA adducts and BC risk, strengthening the central role of AAs in bladder carcinogenesis. However the lack of an association between PBL DNA adducts and BC risk advises that these snapshot measurements are not representative of relevant exposures. This would envisage new scenarios for biomarker discovery and new challenges such as repeated measurements at different critical life stages. [ABSTRACT FROM AUTHOR]

This article describes the multistep synthesis and photophysical properties of three highly fluorescent dyes based on the 2-(2′-hydroxyphenyl)benzoxazole (HBO) scaffold and their resulting chelation to a BF2 fragment. These dyes possess functionalization at the 3,5-positions of the phenol ring with an ethynyl-extended fragment bearing TMS, p- tBuC6H4, or p-N nBu2C6H4 groups. All of the new compounds were characterized by NMR spectroscopy, mass spectrometry, and elemental analysis. The optical properties of the HBO dyes reveal the presence of enol and keto bands as a result of a strong excited-state intramolecular proton transfer (ESIPT). This ESIPT process is highly dependent on the nature of the electronic substituents and the polarity of the solvent. Upon coordination to a BF2 fragment, typical singlet emission is observed with λem ranging from 439 to 553 nm and quantum yields from 0.03 to 0.36. If aromatic amines are involved, strong aggregates are observed that could be dissociated upon protonation of the lone electron pair. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new multi-interaction sorbent based on polymeric ionic liquid was prepared. [•] The sorbent was used as extractive medium of stir cake sorptive extraction. [•] The sorbent could extract apolar, polar compounds and inorganic anions effectively. [•] The analytical methods for parabens and aromatic amines in samples were developed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Land-use change impacts on WEOM dynamics were assessed down to 1-m depth. • Agriculture under NT affected more WEOM composition than its concentration. • WEOM molecular weight and aromaticity decreased after LUC to agriculture under NT. • WEOM became N- and polysaccharide-rich after LUC. Most studies assessing land-use change (LUC) and management impacts on the soil organic carbon (SOC) budget mainly focused on total soil organic matter (SOM), neglecting its functional fractions such as water-extractable organic matter (WEOM). This may limit a better understanding of SOC dynamics along the soil profile as WEOM plays a key role in several soil and microbial processes. Here, we aimed to obtain a quantitative and qualitative assessment of WEOM dynamics to 1 m depth in areas after native vegetation conversion to long-term agriculture in Brazil. For this purpose, cropland areas under no-tillage (NT; ∼ 23 years old) and native vegetation (NV; i.e., Cerrado vegetation) were evaluated across a transect of 1000 km within Brazil's new agricultural frontier – the so-called MATOPIBA region. We combined spectroscopic analyses (UV–Vis and DRIFT spectroscopies), C and nitrogen (N) determination in different SOM pools (i.e., bulk SOM, WEOM, and microbial biomass), and microbial measurements [e.g., microbial biomass C (MBC) and N (MBN), and β-glucosidase activity] to better understand changes in WEOM dynamics induced by LUC. We observed that although SOC decreased along the soil profile after NV (4.2–20.7 g kg−1) conversion to NT (3.8–14.2 g kg−1), water-extractable organic C levels (3.6–79.3 mg L−1) were similar between land uses. On the other hand, an increase in water-extractable total N was observed after NV (0.4–4.6 mg L−1) conversion to NT (0.5–19.3 mg L−1). Although MBC and MBN levels decreased for most study sites, β-glucosidase activity increased after LUC indicating intensive microbial processing of SOM. As a result, WEOM had lower aromaticity and molecular weight (i.e., low values of SUVA254 and A2/A3) in NT than NV; and a relative decomposition of aliphatic and polysaccharides over aromatic and amine/amide was observed after LUC through DRIFT spectroscopy. Our study indicates that LUC had stronger impacts on WEOM quality than its quantity, with agricultural areas having more biochemical changes in WEOM than NV. [ABSTRACT FROM AUTHOR]

Oxidation of phenosafranin and an excess of aniline gave a novel hydroxylated derivative of pseudo-mauveine. N-Methyl-p-toluidine and bis(4-methylphenyl)amine are efficient building blocks for making mauveine-related chromophores. Their oxidation with K2Cr2O7 is believed to form nitrogen centred radicals which then couple with an aromatic amine by homolytic aromatic substitution of hydrogen. The N-methyl substituent and the p-methyl substituents are essential for the reaction to proceed. N-Methyl substituted chromophores were not demethylated in the reaction or by oxidation with K2Cr2O7 in dilute H2SO4. N-Nitroso-bis(4-methylphenyl)amine rearranges smoothly to the orange compound, (2-nitro-4-methylphenyl)-4-methylphenylamine, when a solution in CH2Cl2 is treated with montmorillonite at room temperature for 24 h. 2,4-Dimethylaniline has been used to make a mauveine homologue. The colour of silk dyed with mauveine chromophores has been compared to the colour of silk dyed with authentic 1862 mauveine. [ABSTRACT FROM AUTHOR]

Complexation of tungsten with 2-hydroxy-5-chlorothiophenol ( HCTP) and hydrophobic amines ( A) was studied by spectrophotometry. Aniline, N-methylaniline, and N,N-dimethylaniline were the examined hydrophobic amines. As was found, in weakly acidic media, optimal pH 4.2-5.4, a number of mixedligand complexes formed. The ratio of components in the complexes W(VI): HCTP: A was found to be 1: 2: 2. The maximum of absorbance was observed at λ = 465-475 nm, ɛ = (2.4-2.6) × 10. A number of methods for the quantification of tungsten in various types of steel were developed. They demonstrated high sensitivity and precision; the relative standard deviation did not exceed 5%. [ABSTRACT FROM AUTHOR]

Abstract: Various β-aminoalcohols were prepared by the ring opening reaction of epoxides with aromatic amines in the presence of Fe(III) substituted Wells–Dawson type polyoxometalate, α2-[(n-C4H9)4N]7P2W17FeO61·3H2O, as an efficient catalyst. The reaction was performed under neutral condition at room temperature and afforded the corresponding products in high to excellent yields. [Copyright &y& Elsevier]