Synthesis Of Benzenes Research Articles

Synthesis of Acetylene and Benzene in Controlled Methane-Plasma System

Synthesis of Acetylene and Benzene in Controlled Methane-Plasma System

Gold-Catalyzed Diyne-Ene Annulation for the Synthesis of Polysubstituted Benzenes through Formal [3+3] Approach with Amide as the Critical Co-Catalyst.

The one-step synthesis of tetra-substituted benzenes was accomplished via gold-catalyzed diyne-ene annulation. Distinguished from prior modification methods, this novel strategy undergoes formal [3+3] cyclization, producing polysubstituted benzenes with exceptional efficiency. The critical factor enabling this transformation was the introduction of amides, which were reported for the first time in gold catalysis as covalent nucleophilic co-catalysts. This interesting protocol not only offers a new strategy to achieve functional benzenes with high efficiency, but also enlightens potential new reaction pathways within gold-catalyzed alkyne activation processes.

Application of the CIEMAT/NIST method to 14C low-level measurements

Radiocarbon dating of samples from benzene synthesis by low-level Liquid Scintillation Counting (LSC) method requires the availability of 14C standards in benzene, which are difficult to obtain, or the use of an absolute measurement which is out of reach for most analytical laboratories. This paper describes how the CIEMAT/NIST method can help to solve this issue and presents the measurements of low activity concentrations performed in the LRI-D using two different benzene base scintillator cocktails.

Synthesis of benzenes from pyridines via N to C switch

Synthesis of benzenes from pyridines via N to C switch

Palladium-Copper-Catalyzed Oxidative Intermolecular [2 + 2 + 2] Coupling-Annulation: Regioselective Synthesis of Multiaryl-Substituted Benzenes.

A palladium-catalyzed intermolecular [2 + 2 + 2] oxidative coupling-annulation of terminal alkenes and alkynes using copper(II) as the oxidant has been developed through direct C-C bond formation. These reactions provide effective access to multiaryl-substituted benzenes with high regioselectivity in the absence of any ligands. The features of this protocol are broad substrate scope, and high atom and step economy. The aggregation-induced emission properties of selected products were further investigated. These synthesized multiaryl-substituted benzenes may be worth exploring for further applications in the fields of advanced functional materials or drugs.

Synthesis of Benzene and Phenol From the Irradiation of Benzonitrile: Water Ices by (<10 eV) Electrons: Application to the Planets and Meteorites Surface Chemistry

AbstractAromatic compounds are present in the interstellar space and on carbonaceous meteorites where they intriguingly represent the most important constituents along with the water ice. Exposed to the cosmic radiation, more complex species are generated via processes that are still far from being understood. The present study aims at studying the chemistry of benzonitrile in water ice environment when exposed to the ballistic low energy free electrons produced abundantly along the radiation tracks. Here we show that phenol and benzene are synthetized at the electron energy above but also below 6 eV via different routes, which can be selectively activated by tuning the electron energy. The reactivity presented in this work may contribute to a better understanding of the time evolution, via models and simulations, of species present in interstellar space ices and meteorites.

Copper catalysis the synthesis of functionalized glycine-based sulphonamides: In silico and in vitro antibacterial studies

The synthesis of functionalized glycine-based sulphonamides via copper catalyzed N-arylation reaction and the in silico, in vitro antibacterial studies is reported. The procedure involved the initial synthesis of substituted p-toluenesulphonamides and substituted benzenesulphonamides by the reaction of glycine with p-toluenesulphonyl chloride and benzenesulphonyl chloride respectively in aqueous basic medium. The syn[1]thesized compounds were acetylated by reacting them with acetic anhydride and sodium acetate followed by acylation and amidation to yield amidated p-toluenesulphonamides and benzenesulphonamides respectively. Copper catalyzed N-arylation of the amidated products with aryltriolborates resulted in the synthesis of benzene, and 2-chlorophenyl derivatives of the amidated products. The synthesized compounds were characterized using FTIR, 1HNMR and elemental analysis and the spectra were in agreement with the assigned structures. The in silico antibacterial studies revealed that the compounds possess significant antibacterial potency in the respective bacteria cells and could be further employed as potential anti-bacterial agents. The in vitro antimicrobial study revealed that most of the synthesized compounds possess antibacterial activities.

Influence of steric hindrance on the 1,4- versus 1,6-Michael addition: synthesis of furans and pentasubstituted benzenes.

We described the influence of steric hindrance on the 1,4- versus 1,6-Michael addition reaction on 2-(3,3-bis(methylthio)-1-arylallylidene)malononitriles. An efficient and direct synthesis of trisubstituted furans was achieved through the reaction of 2-(3,3-bis(methylthio)-1-arylallylidene)malononitriles and acetone under mild conditions in good to moderate yield by the 1,4-Michael addition. Further exploration of the reaction with a sterically hindered aryl group containing 2-(3,3-bis(methylthio)-1-arylallylidene)malononitriles afforded biaryls by an in situ generated nucleophile through the 1,6-Michael addition. The synthetic utility of furan is further explored. These precursors are easily accessible from aryl methyl ketones. Various functional groups like alkyl, aryl, nitrile, amine, aroyl, and thiomethyl can be directly installed in the benzene and furan rings. A one-pot approach for the construction of a benzene nucleus was also developed. The structure of two compounds was confirmed by X-ray crystallography.

Methane dehydroaromatization process in a carbon-neutral strategy

Methane dehydroaromatization (MDA) process is a “non-oxidative” technology for CH4 utilization, esteemed as a propitious substitution for fossil fuel-based counterparts in the synthesis of benzene, toluene, and xylene (BTX). However, the MDA process is less cost-effective than both commercial BTX production and “oxidative” CH4 conversion technologies, primarily due to its inherently low BTX yield and CH4 conversion rate. As the focus on attaining net-zero emissions escalates and concerns regarding the usage of abundant CH4 arise, the MDA process has emerged as an environmentally efficient alternative that can generate high-value products while decreasing direct CO2 emissions. In this study, we evaluate various MDA reaction systems, including MDA utilizing only pure CH4, additive co-feeding MDA, and hydrocarbons co-feeding MDA, employing a Mo/HZSM-5 catalyst. The proposed process design comprehensively analyzes the impact of MDA reaction systems on product distribution and energy consumption. Furthermore, we confirm the feasibility of the proposed MDA processes through an exhaustive environmental and economic assessment of “oxidative” CH4 conversion methods and commercial BTX production processes. By decentralizing some of the immense direct CO2 emissions from existing CH4 utilization to controllable indirect CO2 emissions, the MDA processes prove to be more advantageous under the net-zero strategy. The results of this analysis reinforce the potential of MDA reaction processes as a carbon-neutral technology that can effectively replace oxidative CH4 conversion while producing high-value products.

Léon Prunier

Léon Prunier (1846-1906), a French pharmacist and physician, who studied the synthesis of polypropylene hydrocarbons by the reaction of propylene bromide with nascent hydrogen prepared by different means, and the synthesis of ethylene acetylene; proving that the latter was identical with crotonylene. Together with R. David they synthesized a variety of high melting point unsaturated hydrocarbons by the pyrolysis of American petroleum. His main contribution was the study of quercitol, its preparation by means of lead acetate, its physical and chemical properties, as well as its reaction with a wide range of chemicals. He proved that the thermal decomposition of quercitol at high temperatures led to synthesis of aromatic compounds, among them, hydroquinone, quinhydrone, and benzene.

Exciting catalysts for borylation and benzene synthesis

Exciting catalysts for borylation and benzene synthesis

Synthesis and Characterization of Benzene- and Triazine-Based Azo-Bridged Porous Organic Polymers.

Porous organic polymers incorporating nitrogen-rich functionalities have recently emerged as promising materials for efficient and highly selective CO2 capture and separation. Herein, we report synthesis and characterization of new two-dimensional (2D) benzene- and triazine-based azo-bridged porous organic polymers. Different synthetic approaches towards the porous azo-bridged polymers were tested, including reductive homocoupling of aromatic nitro monomers, oxidative homocoupling of aromatic amino monomers and heterocoupling of aromatic nitro monomers and a series of aromatic diamines of different lengths and rigidity. IR spectroscopy, 13C CP/MAS NMR spectroscopy, powder X-ray diffraction, elemental analysis, thermogravimetric analysis, nitrogen adsorption-desorption experiments and computational study were used to characterize structures and properties of the resulting polymers. The synthesized azo-bridged polymers are all amorphous solids of good thermal stability, exhibiting various surface areas (up to 351 m2 g-1). The obtained results indicated that the synthetic methods and building units have a pronounced effect on the porosity of the final materials. Reductive and oxidative homocoupling of aromatic nitro and amino building units, respectively, lead to 2D azo-bridged polymers of substantially higher porosity when compared to those produced by heterocoupling reactions. Periodic DFT calculations and Grand-canonical Monte Carlo (GCMC) simulations suggested that, within the used approximations, linear linkers of different lengths do not significantly affect CO2 adsorption properties of model azo-bridged polymers.

Validation of carbonization as a part of benzene synthesis for radiocarbon measurement

Carbonization, i.e., turning organic sample to carbon, was validated for the benzene synthesis for the radiocarbon liquid scintillation measurement. Tests of sample preparation by combustion, carbonization followed by combustion and carbonization followed by a direct reaction with lithium were performed. Wood and charcoal samples were good for carbonization followed by direct reaction with lithium, while collagen obtained from bones had to be combusted. Direct reaction of carbonized sample with lithium required three times less amount of lithium than the combusted sample.

Synthesis and AIE properties of benzene fused cyclooctetrathiophenes

We have synthesized a series of benzene fused cyclooctetrathiophenes (COThs), including BCOTh, 2BCOTh, 3BCOTh, and 4BCOTh with rotor-free molecular structures, which are similar to the luminogens with the aggregation-induced emission (AIE) property based on the mechanism of restriction of intramolecular vibration (RIV). Investigation on the photophysical properties in THF-H2O mixture solvent showed that 4BCOTh exhibits the aggregation-caused quenching (ACQ) properties, while the others exhibit AIE effect. With increasing the number of the fused benzene rings, the emission behaviors of COThs showed hypsochromic shift in both rigid solution (77 K) and AIE state, which are attributed to the gradually weakened intramolecular through-space conjugation (ITSC). Theoretical calculations and crystal packing analysis indicated that the emission difference in solid between 2BCOTh and 4BCOTh is mainly affected by the factors of molecular conjugation and rigidity. In addition, the model compound COThMe, bearing two methylene groups locking the thiophene rings of COTh, was employed for the experimental investigation of RIV mechanism in the AIE case of COThs.

N-Heterocyclic Carbene Catalyzed Three-Component Reaction for the Synthesis of Multi-substituted Benzenes.

An N-heterocyclic carbene-catalyzed three-component reaction of ketone, acetylenedicarboxylate, and enal for the synthesis of multisubstituted benzenes has been developed. The key features of this reaction are mild reaction conditions and high efficiency and chemoselectivity. The corresponding pentasubstituted benzenes are obtained in good to high yields.

RUDJER BOŠKOVIĆ INSTITUTE RADIOCARBON MEASUREMENTS XVIII

ABSTRACTIn this paper we present dating of archaeological samples from Croatia only performed since our last reports (Obelić et al. 2011; Horvatinčić et al. 2012). Liquid scintillation radiometric measurement technique with benzene synthesis (LSC-B) and accelerator mass spectrometry (AMS) technique were applied.

Establishment and verification of a metering scheme for biomass-coal blending ratios based on 14C determination

The lack of reliable schemes for measuring biomass-coal blending ratios hinders the development of biomass-coal co-combustion. In this study, the accuracy and sensitivity of the 14C method were verified on a free-fall reactor with blending ratios of 0.99 ∼ 10.93%. Comparison between accelerator mass spectrometry (AMS)-graphitization and liquid scintillation counting (LSC)-benzene synthesis was performed in terms of accuracy, precision and costs. Based on these, a complete scheme for measuring the blending ratios in industrial power plants was established and applied in a power plant for verification. The results on the free-fall reactor perfectly agreed with actual ratios (less than 0.43%, 5.69% of absolute and relative errors); LSC with higher cost-effectiveness was capable of measuring the blending ratios accurately. Blending ratios less than 3% in the power plant were accurately measured with the established scheme (less than 0.22%, 10.68% of absolute and relative errors). Factors affecting the accuracy, especially the 14CO2 contamination, should be considered for improvement of the accuracy.

Synthesis of Multisubstituted Benzenes from Phenols via Multisubstituted Benzynes

AbstractA new method to synthesize multifunctionalized arenes from simple phenols through aryne intermediates is described. Multisubstituted aryne precursors were prepared from phenols by Ir-catalyzed C–H borylation, deborylthiolation, O-triflylation, S-oxidation, and further modification through ortho-deprotonation directed by the sulfoxide moiety. Various multisubstituted arenes were synthesized by transformations of highly functionalized aryne intermediates generated from the o-sulfinylaryl triflates.

TESTING THE METHODS FOR DETERMINATION OF RADIOCARBON CONTENT IN LIQUID FUELS IN THE GLIWICE RADIOCARBON AND MASS SPECTROMETRY LABORATORY

ABSTRACTDetermining the biocomponents in liquid fuels using radiocarbon radioisotope (14C) dating requires sample preparation adaptations to the conditions of the Gliwice Radiocarbon and Mass Spectrometry Laboratory. Liquid scintillation counting (LSC), and accelerator mass spectrometry (AMS) were investigated using six samples, including one 14C-free fuel and modern hydrotreated vegetable oil (HVO). For AMS, samples were prepared using tin capsules for liquids for EA combustion and graphitization in an AGE system. For LSC, liquid fuels were prepared by mixing with purified preheated sand and a benzene synthesis line. Benzene resublimation was also tested. IRMS measurements were also conducted for benzene to account for isotopic fractionation. Sample background measurements using both methods showed good performances by both AMS and LSC without resublimation. Comparable results were also obtained for HVO.

Synthesis of Long-Chain Alkanoyl Benzenes by an Aluminum(III) Chloride-Catalyzed Destannylative Acylation Reaction.

This paper describes the facile synthesis of haloaryl compounds with long-chain alkanoyl substituents by the destannylative acylation of haloaryls bearing tri-n-butyltin (Bu3Sn) substituents. The method allows the synthesis of many important synthons for novel functional materials in a highly efficient manner. The halo-tri-n-butyltin benzenes are obtained by the lithium-halogen exchange of commercially available bis-haloarenes and the subsequent reaction with Bu3SnCl. Under typical Friedel-Crafts conditions, i.e., the presence of an acid chloride and AlCl3, the haloaryls are acylated through destannylation. The reactions proceed fast (<5 min) at low temperatures and thus are compatible with aromatic halogen substituents. Furthermore, the method is applicable to para-, meta-, and ortho-substitution and larger systems, as demonstrated for biphenyls. The generated tin byproducts were efficiently removed by trapping with silica/KF filtration, and most long-chain haloaryls were obtained chromatography-free. Molecular structures of several products were determined by X-ray single-crystal diffraction, and the crystal packing was investigated by mapping Hirshfeld surfaces onto individual molecules. A feasible reaction mechanism for the destannylative acylation reaction is proposed and supported through density functional theory (DFT) calculations. DFT results in combination with NMR-scale control experiments unambiguously demonstrate the importance of the tin substituent as a leaving group, which enables the acylation.