Aromatic Olefins Research Articles

Cu-Catalyzed Regioselective C-H Alkylation of Benzimidazoles with Aromatic Alkenes.

Herein we report a novel Cu-catalyzed regioselective C2-H alkylation of benzimidazoles with aromatic alkenes. The reaction features exclusive regioselectivity and broad substrate scope in the intermolecular alkylation of benzimidazoles with terminal and internal aromatic alkenes, constituting a modular access toward benzimidazole-containing 1,1-di(hetero)aryl alkanes. The intramolecular C2-H alkylation of benzimidazoles with aromatic alkenes has been achieved in an endo-selective manner. The enantioselective C2 alkylation of benzimidazoles has also been realized with moderate to good stereocontrol.

Agarwood Oil Quality Classification based on Aromatic Alkane using Portable FTIR Spectroscopy Technique

Agarwood Oil Quality Classification based on Aromatic Alkane using Portable FTIR Spectroscopy Technique

Electrophilic fluorination using PhIO/HF·THF reagent

New electrophilic fluorination reagent HF·THF/PhIO was introduced and tested on three general classes of compounds. Compared with the literature data reported for basic reagents, such as HF/TEA/PhIO and HF/Py/PhIO, the new reagent showed superior performance in fluorination of aromatic alkenes, subpar reactivity with ketones and malonates, while in the reactions with 1,3-unsaturated carbonyl compounds the results were much the same as the literature data.

Chelating Group Enabled Palladium-Catalyzed Regiodivergent Carbonylative Synthesis of 2,3-Dihydroquinolin-4(1H)-ones.

A new procedure on palladium-catalyzed carbonylative cyclization of N-(2-pyridyl)sulfonyl (N-SO2 Py)-2-iodoanilines with terminal alkenes has been developed for the rapid construction of dihydroquinolin-4(1H)-one scaffolds. Enabled by the chelating group and using benzene-1,3,5-triyl triformate (TFBen) as the CO source, both aromatic and aliphatic alkenes were smoothly transformed into the corresponding 2,3-dihydroquinolin-4(1H)-ones in good yields with excellent regioselectivities. Notably, the reaction of aromatic alkenes produces 2-aryl-2,3-dihydroquinolin-4(1H)-ones, while 3-alkyl-2,3-dihydroquinolin-4(1H)-ones were obtained when aliphatic alkenes were used. This protocol has been applied in the synthesis of antitumor agent A as well.

Chlorination and bromination of olefins: Kinetic and mechanistic aspects

Hypochlorous acid (HOCl) is typically assumed to be the primary reactive species in free available chlorine (FAC) solutions. Lately, it has been shown that less abundant chlorine species such as chlorine monoxide (Cl2O) and chlorine (Cl2) can also influence the kinetics of the abatement of certain organic compounds during chlorination. In this study, the chlorination as well as bromination kinetics and mechanisms of 12 olefins (including 3 aliphatic and 9 aromatic olefins) with different structures were explored. HOCl shows a low reactivity towards the selected olefins with species-specific second-order rate constants <1.0 M−1s−1, about 4-6 orders of magnitude lower than those of Cl2O and Cl2. HOCl is the dominant chlorine species during chlorination of olefins under typical drinking water conditions, while Cl2O and Cl2 are likely to play important roles at high FAC concentration near circum-neutral pH (for Cl2O) or at high Cl− concentration under acidic conditions (for Cl2). Bromination of the 12 olefins suggests that HOBr and Br2O are the major reactive species at pH 7.5 with species-specific second-order rate constants of Br2O nearly 3-4 orders of magnitude higher than of HOBr (ranging from <0.01 to >103 M−1s−1). The reactivities of chlorine and bromine species towards olefins follow the order of HOCl < HOBr < Br2O < Cl2O ≈ Cl2. Generally, electron-donating groups (e.g., CH2OH- and CH3-) enhances the reactivities of olefins towards chlorine and bromine species by a factor of 3-102, while electron-withdrawing groups (e.g., Cl-, Br-, NO2-, COOH-, CHO-, -COOR, and CN-) reduce the reactivities by a factor of 3-104. A reasonable linear free energy relationship (LFER) between the species-specific second-order rate constants of Br2O or Cl2O reactions with aromatic olefins and their Hammett σ+ was established with a more negative ρ value for Br2O than for Cl2O, indicating that Br2O is more sensitive to substitution effects. Chlorinated products including HOCl-adducts and decarboxylated Cl-adduct were identified during chlorination of cinnamic acid by high-performance liquid chromatography/high resolution mass spectrometry (HPLC/HRMS).

Bioprospecting of potential petroleum hydrocarbon degraders using bacterial strains isolated from soils around transformer installation areas

ABSTRACT The study assessed the contamination levels of the soils around transformer installation areas in Ile-Ife, which were contaminated with transformer oil. Contamination levels are determined by using some soil physicochemical properties (pH, electrical conductivity, and organic matter) and also identifying some hydrocarbon utilizing bacteria in the oil-contaminated soils. Soil samples were collected from transformer oil-contaminated and uncontaminated soils at 5−15-cm depth. Soil physicochemical properties were determined using standard methods. The soil samples were screened for hydrocarbon-degrading bacteria; the isolates were duly identified using the matrix-assisted laser desorption/ionization-time of flight/mass spectrometry technique. The growth rate of the bacterial isolates in the hydrocarbon medium was monitored. Thereafter, the residual oil was analyzed quantitatively and qualitatively using gravimetric and gas chromatography–mass spectrometry techniques, respectively. The results of the physiochemical parameters of the oil-contaminated soils showed that the soils had mean values of pH (5.01 ± 0.22), electrical conductivity (574.45 ± 63.35 µs/cm), and soil organic matter (50.53 ± 5.67 g/kg). The chromatogram of the residual oils from the biodegradation process showed the efficacy of Providencia stuartii and Bacillus pseudomycoides in degrading alkyl polycyclic aromatic hydrocarbons (PAHs), cycloalkanes, unsaturated alkanes, and unsaturated-branched alkanes, while Providencia rettgeri could adequately degrade cycloalkenes, cycloalkanes, unsaturated alkanes, and unsaturated-branched alkanes. In this study, novel hydrocarbon-degrading bacterial isolates were identified, and the extent of their hydrocarbon and complex organic compound utilization was shown, it suggests the need for further studies to explore their potentials in bioremediation programs.

Radical-Dual-Difunctionalization and Trifluoromethylative Decarboxylation of Two Different Alkenes.

From a single alkene to two different alkenes! A convenient Fe-catalyzed A-D-A-T-type radical-dual-difunctionalization and cross-coupling of two different alkenes to provide chain elongated and trifluoromethylated aromatic alkenes has been developed.

Generalized Chemoselective Transfer Hydrogenation/Hydrodeuteration

AbstractA generalized, simple and efficient transfer hydrogenation of unsaturated bonds has been developed using HBPin and various proton reagents as hydrogen sources. The substrates, including alkenes, alkynes, aromatic heterocycles, aldehydes, ketones, imines, azo, nitro, epoxy and nitrile compounds, are all applied to this catalytic system. Various groups, which cannot survive under the Pd/C/H2 combination, are tolerated. The activity of the reactants was studied and the trends are as follows: styrene&gt;diphenylmethanimine&gt;benzaldehyde&gt;azobenzene&gt;nitrobenzene&gt;quinoline&gt;acetophenone&gt;benzonitrile. Substrates bearing two or more different unsaturated bonds were also investigated and transfer hydrogenation occurred with excellent chemoselectivity. Nano‐palladium catalyst in situ generated from Pd(OAc)2 and HBPin extremely improved the TH efficiency. Furthermore, chemoselective anti‐Markovnikov hydrodeuteration of terminal aromatic olefins was achieved using D2O and HBPin via in situ HD generation and discrimination.magnified image

Source Composition Spectrum of Volatile Organic Compounds in Typical Industries in Sichuan

In this study, typical industries that act as sources of volatile organic compound (VOCs) emission in Sichuan, including automobile manufacturing, wooden furniture, wood-based panel manufacturing, and paint production, were selected and GC-MS national standard analysis to study the organized emission VOC components of every procedure. The spectra of VOCs in the automobile industry were obtained by means of total emission normalization. The results showed that the VOC components of automobile manufacturing, wooden furniture, and oil paint manufacturing enterprises were mainly aromatic hydrocarbons and oxygen-containing compounds, accounting for more than 70% of total VOCs; the emissions from automobile part manufacturing enterprises were mainly aromatic hydrocarbons, with a ratio of over 90%. The proportion of oxygen-containing compounds in the wood-based panel manufacturing industry was found to be up to 97%, mainly caused by the emission of formaldehyde, which accounts for 75%, followed by isopropanol, acetone, and other substances. The proportion of aromatic hydrocarbon and olefin in synthetic resin enterprises is relatively high at over 80%. The olefin species are mainly 1,3-butadiene and 1-butene. Although there are some differences in emission species between different industries, they are mainly composed of aromatic hydrocarbons and oxygenates. Therefore, it is necessary to improve the identification and control of components with high concentration, activity, and toxicity for aromatic hydrocarbons and oxygenates. The source, process, and end process control should be monitored to achieve the effect of total emission reduction.

Iodobenzene-catalyzed oxidative cleavage of olefins to carbonyl compounds

A metal-free approach for the oxidative cleavage of carbon–carbon double bonds of olefins to carbonyl compounds was established by using oxidant m-CPBA and non-metallic organocatalyst PhI in toluene/H2O. A broad scope of aromatic olefins was used. All the reactions proceeded smoothly at 35 °C in short reaction time to furnish the respective mono- and double carbonyl compounds selectively in moderate to good yields.

An overview on disulfide-catalyzed and -cocatalyzed photoreactions.

Disulfides are versatile catalysts. They can be photocatalysts, hydrogen atom transfer (HAT) catalysts, cocatalysts, or initiators in photocatalytic reactions. Under photoirradiation, organic disulfides can be easily cleaved into free thiyl radicals (RS•) and can reversibly add to unsaturated multiple bonds to catalyze a variety of functionalization reactions under mild conditions. In photoredox catalysis reactions, an excellent electron transfer ability and excellent radical properties also made these thiyl radicals powerful HAT catalysts. They have increasingly been proven useful in various types of organic photoreactions, such as cyclizations, anti-Markovnikov additions, aromatic olefin carbonylations, isomerizations, etc. They are a class of green, economic, mild, and chemoselective radical catalysts that deserve more attention. The present review highlights the recent progress in the field of disulfide-catalyzed and -cocatalyzed photocatalytic reactions for different reaction types.

&lt;sup&gt;13&lt;/sup&gt;C-NMR spectroscopy of humic substances isolated from the agricultural soils of Puchuncavi (El Melón and Puchuncavi areas), central Chile

Chile is a well-developed agricultural country, which is faced with the problem of agricultural soil contamination with metals, such as Cu, Cd, Pb and Zn, and metalloids (As). These elements can be retained by soils through different mechanisms, i.e., complex-forming with organic matter or occlusion within organic matter. That is why studying soil contamination should also be accompanied by detailed investigations of the soil organic matter composition. Soil organic matter is crucial for plant growth since its decomposition releases nitrogen, phosphorus and other nutrients available for the plants. &lt;sup&gt;13&lt;/sup&gt;C nuclear magnetic resonance spectroscopy, providing crucial data on carbon functional structures diversity, can also be used to study changes in the soil organic matter (SOM) during decomposition and humification. This study is aimed at investigating the molecular composition of the soil organic matter in the agricultural soils of urbanised areas of central Chile using &lt;sup&gt;13&lt;/sup&gt;C nuclear magnetic resonance (NMR) spectroscopy. The studied soils were characterised by almost neutral pH values and organic carbon contents from 1.7% to 5.2%. The results showed that soils with an increased content of the total organic matter demonstrated an increased portion of aromaticity and a decreased portion of aliphaticity. Most of the investigated humic acids show the highest peaks centred at 125 ppm, which can be tentatively assigned to aromatic alkene structures. The relatively high stabilisation rate of the organic matter in the studied soils can be explained by the mineralisation of its peripheral part, which, in turn, is explained by the decreasing C/N ratio values. The humic substances of the studied agricultural soils of central Chile showed a high average content of aromatic carbon, which is also typical for subboreal soils.

Characteristics and Source Apportionment of Atmospheric VOCs in the Nanjing Industrial Area in Autumn

Atmospheric volatile organic compounds (VOCs) were continuously monitored via an online GC-FID/MS system in Nanjing during the autumn of 2018 to analyze the chemical characteristics, ozone formation potential (OFP), and potential sources of VOCs in this industrial region. During the sampling period, the average concentration of atmospheric total VOCs (TVOCs) was (64.3±45.6)×10-9. Alkanes were the most predominant VOC compound, accounting for 33.1% of the TVOC mass, followed by oxygenated volatile organic compounds (OVOCs, 22.3%) and halogenated hydrocarbons (21.8%). The diurnal cycles of VOCs revealed "bimodal" distributions. The higher concentrations of VOCs observed at 06:00-07:00 and 18:00-20:00 were attributed to the intense traffic emissions and meteorological conditions. Furthermore, maximum incremental reaction (MIR) analysis was used to estimate OFP of VOCs. The results showed that the calculated OFP in Nanjing was 267.1 μg·m-3. Aromatic hydrocarbons and alkenes were the dominant contributors to OFPs, which accounted for 55.2% and 20.8% to the total OFPs, respectively. Finally, five potential sources of VOCs were quantified by the positive matrix factorization model, including traffic emissions (34%), industrial emissions (19%), liquefied petroleum gas (LPG) emissions (17%), usage of paints and solvents (16%), coal combustion, and biomass burning (14%). These findings suggested that control of vehicle emissions and industrial sources would be an important way to reduce VOC concentrations and improve air quality in Nanjing.

Spectral observation of agarwood by infrared spectroscopy: The differences of infected and normal Aquilaria microcarpa

Abstract. Adi DS, Hwang SW, Pramasari DA, Amin Y, Widyaningrum BA, Darmawan T, Septiana E, Dwianto W, Sugiyama J. 2020. Spectral observation of agarwood by infrared spectroscopy: The differences of infected and normal Aquilaria microcarpa. Biodiversitas 21: 2893-2899. This study was conducted to evaluate and to determine the potential spectral band assignments that influenced the differentiation of normal and infected agarwood of Aquilaria microcarpa using Fourier Transform Infrared Spectroscopy (FTIR) and Fourier Transform Near-Infrared Spectroscopy (FTNIR). The results showed that the differences in band intensity on FTIR were identified as C=O stretching (lignin), COO-stretching (hemicellulose), aromatic skeletal vibration (lignin), and C-H bending vibration. The increasing absorbances of infected agarwood were supposed as the change on the wood tissues due to the releasing resinous compound. The C-O bond (aromatic alkane) and stretching (ether), C-C stretching (aromatic alkane), and C-H bond (aromatic ring) which related to the scented fragrance of agarwood have appeared on the FTIR spectra. Multivariate analysis with principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) of the second derivative NIR spectra at the wavenumber 8,000-4,000 cm-1 showed that normal and infected agarwood was successful to be separated. Discriminant model one-on-one classification exhibited good performances as the R2 performance (R2P) values was 0.99. There were eight major wood components which contributed to the separation based on NIR spectra, where lignin, hemicellulose, and xylans were the most valuable chemical compound.

Structural, Optical Absorption and Conductivity of PIn/Co3O4 Composites

This article presents the results obtained from structural, optical absorption and dc conductivity studies of pure polyindole (PIn) and its Co3O4 doped composites. Polyindole has been prepared by chemical oxidation method at room temperature using APS as an oxidant. The composites with varied concentrations of Co3O4 were prepared by in situ polymerization method. The obtained powder XRD patterns of both PIn and its composites indicated amorphous nature. Shifting of aromatic alkene peaks in FTIR reveals interaction between PIn and Co3O4. DC electrical conductivity has been measured in the temperature range 303–393 K and its observed variation inferred semiconducting nature of both pure PIn and the composites. Optical absorption studies have carried out and the band gap for both direct and indirect allowed transitions has been determined to be in the range from 1.79 to 2.34 eV and 2.38 to 3.19 eV respectively. These sizes of band gap values make them to be suitable for opto electronic applications. Activation energy for dc conduction has been determined using Arrhenius expression and it is found to be in the range of 0.3252–0.3806 eV. Conductivity increased and activation energy for conduction decreased with increase of Co3O4 concentration. This is interpreted to be due to decrease of hopping distance of charge carriers with increase of Co3O4 in the composites.

A Highly Efficient Heterogeneous Catalyst of Bimetal-Organic Frameworks for the Epoxidation of Olefin with H2O2.

A series of bimetel organic framework MnxCu1−x-MOF were prepared. The MOFs was characterized and analyzed by powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The catalytic activity of the developed catalyst was tested on various olefins by H2O2 as oxidant. The MOFs catalyst exhibits excellent catalytic activity for the epoxidations of various aromatic and cyclic olefins. Particularly, Mn0.1Cu0.9-MOF can achieve 90.2% conversion of styrene with 94.3% selectivity of styrene oxide at 0 °C after reaction 6 h. The MOF exhibited the catalytic activity of inverse temperature effect on epoxidation of styrene. The introduction of copper component can stabilize H2O2 and inhibit its decomposition to a certain extent. The catalyst can be reused at least five cycles without significant loss in activity towards epoxidation.

Visible-Light-Induced Palladium-Catalyzed Intermolecular Narasaka-Heck Reaction at Room Temperature.

A palladium-catalyzed Narasaka-Heck reaction by a domino cross-coupling reaction with aromatic alkenes under blue LED irradiation at room temperature was developed. The undesired β-hydride elimination of the hybrid alkyl palladium radical species was prohibited, enabling a broad range of oxime esters to undergo 5-exo cyclization and subsequent coupling with olefins. The practicality of the method was well illustrated by the construction of a nitrogen bridgehead tricycle as a core skeleton of alkaloids.

Visible-Light-Induced Difunctionalization of Styrenes: Synthesis of N-Hydroxybenzimidoyl Cyanides.

A visible-light-induced synthesis of N-hydroxybenzimidoyl cyanides from aromatic terminal alkenes is achieved by using Eosin Y as an organic photoredox catalyst. The process goes via a radical pathway with successive incorporation of two nitrogen atoms, one each from tert-butyl nitrite and ammonium acetate. The final product is achieved by the concomitant installation of an oxime and a nitrile group. DFT calculation supports a biradical pathway and all the proposed steps. A few useful synthetic transformations of N-hydroxybenzimidoyl cyanide are also illustrated.

Atomic Pt-Catalyzed Heterogeneous Anti-Markovnikov C-N Formation: Pt10 Activating N-H for Pt1δ+-Activated C═C Attack.

C-N formation is of great significance to synthetic chemistry, as N-containing products are widely used in chemistry, medicine, and biology. Addition of an amine to an unsaturated carbon-carbon bond is a simple yet effective route to produce new C-N bonds. But how to effectively conduct an anti-Markovnikov addition with high selectivity has been a great challenge. Here, we proposed a strategy for highly regioselective C-N addition via hydroamination by using supported Pt. It has been identified that atomic-scale Pt is the active site for C-N addition with Pt12+ for Markovnikov C-N formation and atomic Pt (Pt1δ+ and Pt10) contributing to anti-Markovnikov C-N formation. A selectivity of up to 92% to the anti-Markovnikov product has been achieved with atomic Pt in the addition of styrene and pyrrolidine. A cooperating catalysis for the anti-Markovnikov C-N formation between Pt1δ+ and Pt10 has been revealed. The reaction mechanism has been studied by EPR spectra and in situ FT-IR spectra of adsorption/desorption of styrene and/or pyrrolidine. It has been demonstrated that Pt10 activates amine to be electrophilic, while Pt1δ+ activates C═C by π-bonding to make β-C nucleophilic. The attack of nucleophilic β-C to electrophilic amine affords the anti-Markovnikov addition. This strategy proves highly effective to a variety of substrates in anti-Markovnikov C-N formation, including aromatic/aliphatic amines reacting with aromatic olefins, aromatic/aliphatic olefins with aromatic amines, and linear aliphatic olefins with secondary aliphatic amines. It is believed that the results provide evidence for the function of varied chemical states in monatomic catalysis.

Silver(I) catalyzed intermolecular alkene carbo-alkoxylation through cleavage of allylic ether C–O bond

All rights reserved. First example of allylic ether’s dimerization reaction was developed through olefin’s C–O bond insertion via Ag(I) catalysis. Other aromatic olefins, such as styrene and its electro-poor analogues could participate to provide the allylic ether’s C–O bond insertion products.