Simple Aromatic Compounds Research Articles

ChemInform Abstract: Direct Access to Acylated Azobenzenes via Pd‐Catalyzed C—H Functionalization and Further Transformation into an Indazole Backbone.

Azobenzenes were readily acylated at the 2-position through a Pd-catalyzed C–H functionalization from simple aromatic azo compounds and aldehydes in good yields. The obtained acylated azobenzenes could be efficiently converted into the corresponding indazole derivatives in nearly quantitative yields.

Direct Access to Acylated Azobenzenes via Pd-Catalyzed C–H Functionalization and Further Transformation into an Indazole Backbone

Azobenzenes were readily acylated at the 2-position through a Pd-catalyzed C-H functionalization from simple aromatic azo compounds and aldehydes in good yields. The obtained acylated azobenzenes could be efficiently converted into the corresponding indazole derivatives in nearly quantitative yields.

Phenolic Compounds of Sponge-associated Fungi (Lecanicillium evansii)

This study was chiefly aimed at pursuing new biologically active secondary metabolites of microfungus species, Lecanicillium evansii , isolated from sponge Callyspongia sp collected from West Bali Sea, Indonesia. Sponges were collected by scuba diving. A tiny piece of sponge was inoculated on the surface of malt agar plates and incubated at 27 oC. In order to get a pure mono-culture of the fungus, repeated sub-culturing onto fresh malt agar plates were performed. The collected fungi were maintained on malt agar plates using the Wickerham medium. Mass cultivation of the fungus L. evansii (10 L) was carried out in 30 erlenmeyer flasks in Wickerham medium. After 10 days incubation, without shaking under constant room temperature (20 oC), fungal mycelium were separated from the culture broth. The mycelia were extracted with methanol and ethyl acetate was added to the media. Both methanol-added mycelia and ethyl acetate-added media were left overnight. Seven compounds were isolated from L. evansii . Those compounds comprised phenolic compounds (terphenylin, deoxyterphenylin, terprenin 2, terprenin epoxide), bipeptide (cyclo-tyrosylprolyl), and simple aromatic compounds (acetyl hydroxybenzamide, 4-hydroxybenzaldehyde). Detailed analysis by NMR and mass spectrometry enabled their identification to be new deoxyterphenylin, new terprenin 2, and new terprenin epoxide.

Catalysts with noble metals based on super-cross-linked polystyrene for the hydrogenation of aromatic hydrocarbons

A series of catalysts containing noble metals on a super-cross-linked polystyrene (SCP) support with a developed specific surface area (>1000 m2/g) and high thermal stability are prepared and studied to develop an effective catalyst for the low-temperature hydrogenation of aromatic hydrocarbons. A study of Pt- and Pd-containing catalysts based on SCP, carbon supports, and alumina in the hydrogenation of simple (benzene, toluene), branched (n-butylbenzene) and polycyclic (terphenyl) aromatic compounds is conducted. In the hydrogenation of aromatic hydrocarbons, the activity of the catalysts on SCP is comparable to or surpasses analogous catalysts based on Al2O3 and Sibunit in the content of noble metals; it is established that catalysts on SCP have greater selectivity in the hydrogenation of benzene in a benzene-toluene mixture. The electronic state of metals in the Pt(Pd)/SCP catalysts is studied by the IR spectroscopy of adsorbed CO. In testing the catalysts in the hydrogenation of terphenyl, it is found that Pt-containing catalyst on the SCP can operate in reversible hydrogenation-dehydrogenation cycles (terphenyl-tercyclohexane); this is promising for the use of such catalyst systems in creating composite materials for hydrogen storage.

Unexpectedly strong anion–π interactions on the graphene flakes

Interactions of anions with simple aromatic compounds have received growing attention due to their relevancy in various fields. Yet, the anion-π interactions are generally very weak, for example, there is no favorable anion-π interaction for the halide anion F(-) on the simplest benzene surface unless the H-atoms are substituted by the highly negatively charged F. In this article, we report a type of particularly strong anion-π interactions by investigating the adsorptions of three halide anions, that is, F(-), Cl(-), and Br(-), on the hydrogenated-graphene flake using the density functional theory. The anion-π interactions on the graphene flake are shown to be unexpectedly strong compared to those on simple aromatic compounds, for example, the F(-)-adsorption energy is as large as 17.5 kcal/mol on a graphene flake (C(84) H(24)) and 23.5 kcal/mol in the periodic boundary condition model calculations on a graphene flake C(113) (the supercell containing a F(-) ion and 113 carbon atoms). The unexpectedly large adsorption energies of the halide anions on the graphene flake are ascribed to the effective donor-acceptor interactions between the halide anions and the graphene flake. These findings on the presence of very strong anion-π interactions between halide ions and the graphene flake, which are disclosed for the first time, are hoped to strengthen scientific understanding of the chemical and physical characteristics of the graphene in an electrolyte solution. These favorable interactions of anions with electron-deficient graphene flakes may be applicable to the design of a new family of neutral anion receptors and detectors.

Synthesis and Crystal Structure of 3-(3-Methylthiophen-2-yl)-1,5-diphenyl-1<i>H</i>-pyrazole

The title compound, C20H16N2S, was synthesized, and the structure was investigated by X-ray crystallography and characterised by NMR and IR spectroscopy. The compound crystallizes in the orthorhombic crystal class in the space group F2dd with cell parameters a = 6.1830(5)A, b = 27.797(5)A, c = 38.234(7) and Z = 16. Pyrazole refers both to the class of simple aromatic ring organic compounds of the heterocyclic diazole series, characterized by a 5-membered ring structure composed of three carbon atoms and two nitrogen atoms in adjacent positions, and to the unsubstituted parent compound. Being so composed and having pharmacological effects on humans, they are classified as alkaloids, although they are rare in nature. The pyrazole ring is widely found as the core structure in a large variety of compounds that possess important agrochemical and pharmaceutical activities.1,2 Pyrazole derivatives are well known for analgesic, and antidiabetic activities.3-5 Numerous compounds containing the pyrazole moiety exhibit a wide range of biological activities, such as anti-inflammatory,6 antimicrobial,7 and antiviral8 properities. In this context, and as a part of our ongoing research on pyrazoles and their crystal structures, herein we report on the synthesis and crystal structure of the title compound.

Regioselectivity nitration of aromatics with N2O5 in PEG-based dicationic ionic liquid

Regioselective mononitration of simple aromatic compounds has been investigated with N2O5 as nitrating agent and a new PEG200-based dicationic acidic ionic liquid (PEG200-DAIL) as catalyst. The results of experiments show that this nitration system can significantly improve the para-selectivity of alkyl-benzenes and the ortho-selectivity of halogenated-benzenes. The PEG200-DAIL exhibits recyclable temperature-dependant phase behavior in CCl4 solvent, and it can be recycled without apparent loss of catalytic activity, and only 5% loss of weight is observed after six times recycling.

Fermentation, Isolation, Structure, and Antidiabetic Activity of NFAT-133 produced by Streptomyces strain PM0324667

Type-2 diabetes is mediated by defects in either insulin secretion or insulin action. In an effort to identify extracts that may stimulate glucose uptake, similar to insulin, a high throughput-screening assay for measuring glucose uptake in skeletal muscle cells was established. During the screening studies to discover novel antidiabetic compounds from microbial resources a Streptomyces strain PM0324667 (MTCC 5543, the Strain accession number at Institute of Microbial Technology, Chandigarh, India), an isolate from arid soil was identified which expressed a secondary metabolite that induced glucose uptake in L6 skeletal muscle cells. By employing bioactivity guided fractionation techniques, a tri-substituted simple aromatic compound with anti-diabetic potential was isolated. It was characterized based on MS and 2D NMR spectral data and identified as NFAT-133 which is a known immunosuppressive agent that inhibits NFAT-dependent transcription in vitro. Our investigations revealed the antidiabetic potential of NFAT-133. The compound induced glucose uptake in differentiated L6 myotubes with an EC50 of 6.3 ± 1.8 μM without activating the peroxisome proliferator-activated receptor-γ. Further, NFAT-133 was also efficacious in vivo in diabetic animals and reduced systemic glucose levels. Thus it is a potential lead compound which can be considered for development as a therapeutic for the treatment of type-2 diabetes. We have reported herewith the isolation of the producer microbe, fermentation, purification, in vitro, and in vivo antidiabetic activity of the compound.

Occurrences and distributions of branched alkylbenzenes in the Dongsheng sedimentary uranium ore deposits, China

A series of branched alkylbenzene ranging from C 15 to C 19 with several isomers (2–5) at each carbon number were identified in sediments from the Dongsheng sedimentary uranium ore deposits, Ordos Basin, China. The distribution patterns of the branched alkylbenzenes show significant differences in the sample extracts. The branched alkylbenzenes from organic-rich argillites and coals range from C 15 to C 19 homologues, in which the C 17 or C 18 dominated. On the other hand, the C 19 branched alkylbenzenes dominated in the sandstone/siltstone extracts. The obvious differences of the branched alkylbenzene distributions between the uranium-host sandstones/siltstones and the interbedded barren organic-rich mudstones/coals probably indicate their potential use as biological markers associated with particular depositional environments and/or maturity diagenetic processes. Possible origins for these branched alkylbenzenes include interaction of simple aromatic compounds with, or cyclization and aromatization reactions of, these linear lipid precursors such as fatty acids, methyl alkanoates, wax esters or alkanes/alkenes that occur naturally in carbonaceous sediments. The possible simple aromatic compounds may include substituted benzenes, functionalized compounds such as phenols that are bound to kerogen at the benzyl position, and phenols that are decomposition products derived from aquatic and terrestrial sources. The distributions of methyl alkanoates and n-alkanes were found to be different between organic-rich mudstone/coal and sandstone/siltstone. From this result, it can be concluded that such differences of the alkylbenzene distributions were mainly resulting from the differences of organic precursors, although maturity effect and radiolytic alteration cannot be completely excluded.

Formation of oxidized products from the reaction of gaseous phenanthrene with the OH radical in a reaction chamber

The reaction of gas phase phenanthrene (Phen) with the OH radical in the presence of NO x was studied in a reaction chamber. A number of oxidation products were identified by two dimensional gas chromatography–time of flight mass spectrometry (GC × GC–TOFMS). Identified products included 9-fluorenone, 1,2-naphthalic anhydride, 2,2′-diformylbiphenyl, dibenzopyranone, 1, 2, 3, 4 and 9-phenanthrols, 2, 3, 4 and 9-nitrophenanthrenes, 1,4-phenanthrenequinone, 9,10-phenanthrenequinone, and 2- and 4-nitrodibenzopyranones. This is the first study to identify 1,2-naphthalic anhydride and 1,4-phenanthrenequinone as products of the gas phase reaction of Phen with the OH radical. Eight more products were tentatively identified by their mass spectral fragmentation patterns and based on the typical OH radical initiated photochemical reaction mechanisms of simple aromatic compounds and naphthalene. In the reaction chamber, particle formation of products as a function of irradiation time was measured. Phenanthrenequinones, phenanthrol, nitrophenanthrene and nitrobenzopyranone were observed predominantly in the particle phase. This implies that these oxidized products formed from the reaction of Phen with the OH radical in the chamber would be associated with particles in the atmosphere and may, therefore, have an impact on human health. Possible pathways for the formation of these products are suggested and discussed.

Multifunctional Silver‐Embedded Magnetic Nanoparticles as SERS Nanoprobes and Their Applications

In this study, surface-enhanced Raman spectroscopy (SERS)-encoded magnetic nanoparticles (NPs) are prepared and utilized as a multifunctional tagging material for cancer-cell targeting and separation. First, silver-embedded magnetic NPs are prepared, composed of an 18-nm magnetic core and a 16-nm-thick silica shell with silver NPs formed on the surface. After simple aromatic compounds are adsorbed on the silver-embedded magnetic NPs, they are coated with silica to provide them with chemical and physical stability. The resulting silica-encapsulated magnetic NPs (M-SERS dots) produce strong SERS signals and have magnetic properties. In a model application as a tagging material, the M-SERS dots are successfully utilized for targeting breast-cancer cells (SKBR3) and floating leukemia cells (SP2/O). The targeted cancer cells can be easily separated from the untargeted cells using an external magnetic field. The separated targeted cancer cells exhibit a Raman signal originating from the M-SERS dots. This system proves to be an efficient tool for separating targeted cells. Additionally, the magnetic-field-induced hot spots, which can provide a 1000-times-stronger SERS intensity due to aggregation of the NPs, are studied.

Lipophilic constituents from aerial and root parts of Mercurialis perennis L.

Dog's mercury (Mercurialis perennis L.) is a perennial herb used in remedies for medicinal purposes. The plant is supposed to contain potentially active substances but its constituents have only been rarely studied. Detailed studies on the phytochemical composition are of great interest to broaden the knowledge on the chemotaxonomy and pharmacognosy of M. perennis. Chloroform and hexane extracts from roots and aerial parts were investigated using GC/MS and LC/MS. The whole plant exhihited a broad spectrum of structurally diverse constituents, mainly alkaloids, terpenes, sterols and simple aromatic compounds. Closer inspection of the piperidine alkaloid hermidin revealed its inherent instability towards air oxygen. To obtain quantitative data on these alkaloids the synthesis of the more stable reference compound 4-methoxy-1-methylpyridine-2,6(1H,3H)-dione (MMPD) was required. In this study, MMPD was detected for the first time as a genuine compound in Mercurialis. Hermidine quinone and hermidin dimers originating from hermidin via a free anionic radical reaction were also confirmed by GC/MS. Moreover, volatile compounds such as benzylalcohol, 2-phenylethanol, 4-methoxy- and 3,4-dimethoxyphenol, (-)-cis- and (+)-trans-myrtanol, (-)-cis-myrtanal as well as squalene were predominantely present in Mercurialis roots. In contrast, aerial parts mainly contained phytol derivatives, sterols and tocopherols. By changing solvent polarity, lipid and wax-containing fractions were obtained. LC/MS-studies on hexane extracts showed the presence of several mixed triglycerides constituted by linolenic, linoleic, oleic, stearic and palmitic acids, as well as lutein, carotenes and pheophytins. The phytochemical data presented complement our knowledge on the rarely studied plant M. perennis and may broaden its use in future phytotherapy.

Surface‐Treated Activated Carbon for Removal of Aromatic Compounds from Water

AbstractModifications of commercial activated carbons by chemical treatment with HNO3 or HCl and HF and the adsorption behavior of simple aromatic compounds (aniline, pyridine, phenol, and benzene) on activated carbon and modified activated carbon were investigated. The results show that the textural properties change a little after these modifications, but the surface acidity (mainly oxygen‐containing groups) of activated carbon modified with HNO3 increases greatly. The effect of ash of activated carbon on adsorption of the organic compounds mentioned above is insignificant. However, addition of surface acidity (mainly surface oxygen‐containing groups) decreases the adsorption capacity of compounds significantly. The adsorption uptake of compounds on activated carbon with oxidation of HNO3 is low possibly due to dispersive interaction, water cluster blocking, or competition between water and compounds adsorbed on activated carbon's surface because of hydrophilic increase of the activated carbon surface. The solubility of aromatic compounds in water has an important effect on the adsorption capacity of activated carbon. qm and KL (Langmuir adsorption parameters) for the aromatic compounds vary similarly.

Solar photocatalytic degradation of real textile effluents by associated titanium dioxide and hydrogen peroxide

The present work investigated the photodegradation of real textile effluents by advanced oxidative process (AOP) using TiO 2/H 2O 2/sunlight system. The procedures were carried out at ambient conditions in March 2005. The results were evaluated by COD reduction concomitant to the increase in inorganic ion concentration (mineralization) and the analysis of the effluent characteristic spectral wavelengths: 228, 254, and 284 nm (simple aromatic compounds), 310 nm (conjugated aromatic compounds), and 390, 450, and 530 (color). As this study is not restricted to the decolorization process, it allows a more reliable evaluation of effluent mineralization. The results indicate that solar radiation is as efficient as or even more efficient than artificial radiation was in previous studies and that it also allows a reduction in effluent treatment operational costs.

Volatiles of myrmecophytic Piper plants signal stem tissue damage to inhabiting Pheidole ant‐partners

Summary The major aim of this paper was to explore the mechanistic basis of induced defensive ant response in myrmecophytic Piper species and their ant‐partner Pheidole bicornis by combining experimental trials and chemical analysis. In field experiments, the response of Pheidole ants to simulated stem‐damage of their host plant was documented. Their reaction to other myrmecophytic and non‐myrmecophytic Piper species was explored by fixing respective stem sections onto inhabited Piper fimbriulatum individuals. After artificial damage to stems of P. fimbriulatum and stem sections from other myrmecophytic Piper, the number of ants increased to a maximum of 63 individuals on the damaged internode within the first 10 min. By contrast, no or only a poor reaction was elicited by stem sections from the selected non‐myrmecophytic Piper species. Solid‐phase microextraction/gas chromatography–mass spectrometry identified 68 volatile organic compounds (VOCs) which were emitted from wounded stem bark of three myrmecophytic (P. fimbriulatum, P. obliquum, P. sagittifolium) and two non‐myrmecophytic (P. hispidum, P. riparense) Piper species, comprising monoterpenes, sesquiterpenes, simple aromatic compounds, and green leaf volatiles (GLVs, oxylipins). Despite considerable variation in the VOC profiles, an analysis of similarities (anosim) classified the accumulation of the sesquiterpenes β‐caryophyllene, germacrene D and emission of the oxylipin reactive electrophilic species (RES) compounds hexanal, cis‐3‐hexene‐1‐ol, 2‐hexenal, 2‐undecanone and 1‐hexanol as characteristic of the myrmecophytic species. Synthesis. Field experiments showed that mechanical disturbance of myrmecophytic Piper stems is not sufficient to elicit recruitment and alertness of the ant‐partner Ph. bicornis, but that specific volatiles released from the host plant are responsible. Analyses of the VOCs identified after simulated stem damage of three myrmecophytic and two non‐myrmecophytic Piper species revealed differences in their VOC emission profiles: Only in the myrmecophytic species were induced stress compounds found, such as various oxylipin RES or the sesquiterpene β‐caryophyllene, which are typically emitted after plant damage for interplant signalling. Some of these compounds (e.g. hexanal, 1‐hexanol) are known to induce alerting and alarm behaviours in several ant species. Our study provides evidence that the VOCs of the Piper host plant may signal stem damage and induce recruitment and alert behaviour of associated Pheidole ants.

The cooperative effect of the surface heterogeneity and of the lateral interactions between adsorbed molecules on adsorption of simple aromatic compounds from dilute aqueous solutions on activated carbons

Abstract The cooperative effect of the surface heterogeneity and of the interactions between adsorbed molecules on adsorption of simple aromatic compounds from aqueous solutions is presented. The phenomenon is investigated on the basis of adsorption isotherms of phenol and aniline from dilute aqueous solutions at various pH values on activated carbons prepared from different precursors. The literature experimental data concerning phenol adsorption from aqueous solutions on APET carbon prepared from polyethyleneterephthalate (PET) as well as the data of aniline adsorption on commercial ACP carbon prepared from peat have been utilized. The lateral interactions in the adsorbed phase are taken into account by use of the Fowler–Guggenheim (FG) isotherm, and by use of isotherms based on vacancy solution model (VSM) in conjunction with the Flory–Huggins (FH) and Wilson (W) activity coefficient equations. By assuming the definite form of the local isotherm of adsorption in the integral equation (IE) and quasi-Gaussian distribution of adsorption energy, the condensation approximation (CA) approach led to new isotherm equations for single-solute adsorption from dilute solutions.

Rigidanthrin, a new dimeric phenanthrene derivative of the orchid Bulbophyllum rigidum

: Rigidanthrin, a new dimeric phenanthrene derivative, was isolated from the orchid Bulbophyllum rigidum which also afforded the known monomeric phenanthrenes nudol and gymnopusin and the simple aromatic compound ethyl 4-hydroxy-3-methoxycinnamate. The structure of rigidanthrin was established as 2,2',7,7'-tetrahydroxy-3,3',4,4'-tetramethoxy-1,1'-biphenanthryl from various spectral and chemical evidence. The structure of rigidanthrin was finally confirmed by regio- as well as regio- and enantio-selective biomimetic synthesis from its monomeric congener nudol (2,7-dihydroxy-3,4-dimethoxyphenanthrene) by oxidative phenol-coupling reaction with phosphomolybdic acid (PMA) on silica gel surface and CuCl(OH).(-)-(S)-proline methyl ester, respectively, in very good yields. The optical purity of (-)-rigidanthrin obtained in the latter case was found to be 95.79%. The co-occurrence of rigidanthrin with its monomer nudol in the same orchid Bulbophyllum rigidum provides a strong circumstantial evidence in support of the proposed biogenesis of the naturally occurring biphenanthryl derivatives which are assumed to have been formed from their corresponding monomers by enzymatic oxidative phenol-coupling reaction.

Degradation of Bis(4-Hydroxyphenyl)methane (bisphenol F) by Sphingobium yanoikuyae strain FM-2 isolated from river water.

Three bacteria capable of utilizing bis(4-hydroxyphenyl)methane (bisphenol F [BPF]) as the sole carbon source were isolated from river water, and they all belonged to the family Sphingomonadaceae. One of the isolates, designated Sphingobium yanoikuyae strain FM-2, at an initial cell density of 0.01 (optical density at 600 nm) completely degraded 0.5 mM BPF within 9 h without any lag period under inductive conditions. Degradation assays of various bisphenols revealed that the BPF-metabolizing system of strain FM-2 was effective only on the limited range of bisphenols consisting of two phenolic rings joined together through a bridging carbon without any methyl substitution on the rings or on the bridging structure. A BPF biodegradation pathway was proposed on the basis of metabolite production patterns and identification of the metabolites. The initial step of BPF biodegradation involves hydroxylation of the bridging carbon to form bis(4-hydroxyphenyl)methanol, followed by oxidation to 4,4'-dihydroxybenzophenone. The 4,4'-dihydroxybenzophenone appears to be further oxidized by the Baeyer-Villiger reaction to 4-hydroxyphenyl 4-hydroxybenzoate, which is then cleaved by oxidation to form 4-hydroxybenzoate and 1,4-hydroquinone. Both of the resultant simple aromatic compounds are mineralized.

Temperature-Dependent Chemical-Specific Emission Rates of Aromatics and Polyaromatic Hydrocarbons (PAHs) in Bitumen Fume

Chemical-specific emission rates for simple aromatic and polycyclic aromatic hydrocarbon compounds (PAHs) from bitumens during hot mix asphalt (HMA) production and placement activities were evaluated using a headspace gas chromatography method. Temperature-dependent headspace concentrations of the EPA listed aromatic and polycyclic aromatic compounds were measured in the laboratory using headspace gas chromatographs equipped with a variety of detectors. The methodology has previously been calibrated and verified by a program of simultaneous laboratory and field tests, and is accurate in identifying field inhalation exposure potential to individual compounds in asphalt fumes. The results indicated that chemical-specific emission rates of aromatic and PAHs are strongly linked to both the performance grade of the asphalt binder and the binder temperature. Individual chemical compounds were quantified for 22 paving grade bitumen sources from throughout the United States. Chemical-specific emission rates from each binder were measured at a series of temperatures spanning the range, typically used for application of HMA, and at temperatures well in excess of those used for HMA applications in the United States. Emissions of all detected compounds increased with elevating temperature. The amount and composition of PAHs were markedly influenced by changes in temperature. At binder temperatures at or below 190°C, only very small amounts of mostly 2- and 3-ringed PAHs were emitted. Concentrations of individual two-ringed PAHs ranged from 0.5 to 11 μ g/m 3 at 150°C and ranged from 2.0 to 100 μ g/m 3 at 190°C. Concentrations of 3-ringed PAHs were below method detection level of 0.1 μ g/m 3 and ranged from 0.1 to 120 μ g/m 3 at 190°C. Larger ring number PAHs were below detection at 150°C and less than 10 μg/m 3 for 4-ringed PAHs at 190°C. As binder temperature increased above the typical limit for HMA production and application, several PAHs with greater ring numbers (4-, 5-, and 6-ringed PAHs) and more potent toxicity equivalency factors (carcinogenic potential) were detected.

Arene‐Sandwiched Silver(I) Pyrazolates

A silver filling: The π-acidic, trinuclear silver(I) pyrazolate [{[3,5-(CF3)2pz]Ag}3] readily reacts with simple electron-rich aromatic hydrocarbon compounds to form sandwich complexes. The type of complex formed depends on the solvent and the arene, and includes supramolecular stacks. Additionally, some of these complexes appear to have interesting luminescence properties. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2007/z604585_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.