One-pot conversion of aromatic bromides and aromatics into aromatic nitriles via aryllithiums and their DMF adduct

Various aromatic bromides and iodides were smoothly converted into the corresponding aromatic nitriles in good to moderate yields by the treatment with n-butyllithium and subsequently DMF, followed by treatment with molecular iodine in aq NH₃. The same treatment of typical aromatics and heteroaromatics with n-butyllithium and subsequently DMF, followed by treatment with molecular iodine in aq NH₃ also provided the corresponding aromatic nitriles in good yields. Moreover, the same treatment of aromatic bromides and aromatics with half amount of DIH (1,3-diiodo-5,5-dimethylhydantoin) instead of molecular iodine worked effectively to give the corresponding aromatic nitriles, respectively, in good yields. These reactions are novel and environmentally benign one-pot methods for the preparation of aromatic nitriles from aromatic bromides and aromatics, respectively, through the formation of aryllithiums and their DMF adducts.     

Aromatic Complexes of silver(I) triflate

The silver salt of trifluoromethanesulfonic acid (silver(I) triflate) forms complexes with aromatics whose solid state stoichiometries involve two salt units per organic, as does the copper analog. Both show a similar preference for p-xylene among the eight carbon aromatic isomers, indicative of isomorphic structures. The two Ib systems are contrasted in their behavior as slurries with aromatics.     

Distorted aryl homochirality controlled by β-sheet folding

Distortion of planar aromatics occurs in the fused rings conjugated with bulky substituents, which generates racemic enantiomers with high transformation energy barriers. However, direct synthesis of homochiral distorted aryl compounds is a very challenging task. Here, we presented a molecular folding strategy to control distorted aryl homochirality. Amino acids and their derivatives conjugated on the polycyclic aromatic hydrocarbons including benzenes, naphthalenes and triphenylenes, which formed parallel β-sheet arrays through intramolecular hydrogen bonds. The folding behavior enabled distorted or twisted geometry of aromatics, of which the handedness was associated with the absolute chirality of amino acids. X-ray crystallography, theoretical calculations and circular dichroism spectroscopy verified the distorted homochirality in the solid and solution phase. The relatively small rotational barrier between the enantiomers made the molecule sensitive to the environment and thus realized the solvent-controlled chiral inversion. The β-sheet folding strategy can be widely used in polycyclic aromatic hydrocarbons with various functions, which provided a promising strategy to control inherent chirality of aromatics with adaptive chiroptical responses.     

Effective synthesis of diiodinated picene and dibenzo[a,h]anthracene by AuCl-catalyzed double cyclization

6,13-Diiododibenzo[a,h]anthracene and 5,8-diiodopicene were synthesized by AuCl-catalyzed double cyclization. The highly selective reaction yielded a new class of peri-halogenated fused aromatics.     

Practical one-pot transformation of electron-rich aromatics into aromatic nitriles with molecular iodine and aq NH3 using Vilsmeier–Haack reaction

Various electron-rich aromatics could be efficiently transformed into the corresponding aromatic nitriles in good to moderate yields by treatment with DMF and POCl₃, followed by the reaction with molecular iodine or 1,3-diiodo-5,5-dimethylhydantoin (DIH) in aq NH₃. Some of less reactive aromatics, such as anisole, 1,2-dimethoxybenzene, 1,4-dimethoxybenzene, and mesityrene, could be also transformed into the corresponding aromatic nitriles in good to moderate yields using N-methylformanilide and O(POCl₂)₂, followed by the reaction with molecular iodine in aq NH₃. Moreover, propiophenone derivatives could be successfully transformed into the corresponding β-chlorocinnamonitriles by the reaction with DMF and POCl₃, followed by the reaction with molecular iodine and aq NH₃. These reactions are novel metal-free one-pot methods for the preparation of aromatic nitriles from electron-rich aromatics and β-chlorocinnamonitriles from propiophenones.     

Hydroxylation of ionized aromatics including carboxylic acid or amine using recombinant Streptomyces lividans cells expressing modified biphenyl dioxygenase genes

The bphA1(2072)A2A3A4 gene cluster codes for a shuffled biphenyl dioxygenase holoenzyme with broad substrate specificity. These bphA1(2072)A2A3A4 genes were expressed in the actinomycetes Streptomyces lividans using a thiostrepton-inducible promoter P_tipA. Biotransformation experiments of various aromatics including carboxylic acid or amine in their molecular structure, such as 1-naphthoic acid, 2-(1-naphthyl)acetic acid, diphenylamine, and 1-benzyl-4-piperidone, were performed using the recombinant S. lividans cells. These ionized aromatics were converted to the corresponding 1,2-dihydrodiol, mono- or tri-hydroxy forms in 48 h. The structure of the converted products was determined by their EI-MS, ¹H- and ¹³C NMR analysis, and several products were found to be novel compounds.     

Facile preparation of aromatic ketones from aromatic bromides and arenes with aldehydes

Aromatic ketones were efficiently prepared in good yields by the reactions of aryl bromides with n-BuLi, followed by the reactions with aromatic aldehydes or aliphatic aldehydes and the subsequent treatment with molecular iodine and K₂CO₃, in a one-pot method. The same treatment of arenes, instead of aromatic bromides, also provided the corresponding aromatic ketones in good yields. Using these methods, various diaryl ketones and alkyl aryl ketones bearing electron-rich aromatics and electron-deficient aromatics could be prepared efficiently by a simple, transition-metal-free, and therefore environmentally benign experimental procedure.     

Boosting the synthesis of value-added aromatics directly from syngas via a Cr2O3 and Ga doped zeolite capsule catalyst

Even though the transformation of syngas into aromatics has been realized via a methanol-mediated tandem process, the low product yield is still the bottleneck, limiting the industrial application of this technology. Herein, a tailor-made zeolite capsule catalyst with Ga doping and SiO₂ coating was combined with the methanol synthesis catalyst Cr₂O₃ to boost the synthesis of value-added aromatics, especially para-xylene, from syngas. Multiple characterization studies, control experiments, and density functional theory (DFT) calculation results clarified that Ga doped zeolites with strong CO adsorption capability facilitated the transformation of the reaction intermediate methanol by optimizing the first C–C coupling step under a high-pressure CO atmosphere, thereby driving the reaction forward for aromatics synthesis. This work not only reveals the synergistic catalytic network in the tandem process but also sheds new light on principles for the rational design of a catalyst in terms of oriented conversion of syngas.

The single-pass conversion of syngas into para-xylene was realized using a bifunctional catalyst Cr₂O₃/Ga-ZSM-5@SiO₂. The Ga species facilitates the methanol consumption process by C–C coupling optimization, enhancing the yield of the target aromatics.     

Synthesis of zwitterionic 4-hydroxy-2(1H)-quinolinone derivatives

Zwitterionic 4-hydroxy-2(1H)-quinolinone derivatives were synthesized through a unique reaction of 4-hydroxy-2(1H)-quinolinone with p-benzoquinone and N-heterocyclic aromatics. The zwitterions possessed astropisomeric nature. A possible mechanism of the reaction was presented.     

Role of biochar surface characteristics in the adsorption of aromatic compounds: Pore structure and functional groups

Biochar (BC) are widely used as highly efficient adsorbents to alleviate aromatics-based contaminants due to their ease of preparation, wide availability, and high sustainability. The surface properties of BCs usually vary greatly due to their complex chemical constituents and different preparation processes and are reflected in the values of parameters such as the specific surface area (SSA), pore volume/size, and surface functional groups (SFGs). The effects of SSA and pore volume/size on the adsorption of aromatics have been widely reported. However, the corresponding mechanisms of BC SFGs towards aromatics adsorption remains unclear as the compositions of the SFGs are usually complex and hard to determine. To address in this gap in the literature, this review introduces a new perspective on the adsorption mechanisms of aromatics. Through collecting previously-reported results, the parameters logP (logarithm of the K_ow), polar surface area, and the positive/negative charges were carefully calculated using ChemDraw 3D, which allowed the hydrophobicity/hydrophilicity properties, electron donor-acceptor interactions, H-bonding, and electrostatic interactions between SFGs and aromatics-based contaminates to be inferred intuitively. These predictions were consistent with the reported results and showed that tailor-made BCs can be designed according to the molecular weights, chemical structures, and polarities of the target aromatics. Overall, this review provides new insight into predicting the physicochemical properties of BCs through revealing the relationship between SFGs and adsorbates, which may provide useful guidance for the preparing of highly-efficient, functional BCs for the adsorption of aromatics.     

Facile preparation of aromatic esters from aromatic bromides with ethyl formate or DMF and molecular iodine via aryllithium

Various aromatic bromides were treated with n-BuLi and subsequently with ethyl formate, followed by the reaction with ethanol and molecular iodine in the presence of K₂CO₃ to provide the corresponding aromatic ethyl esters in good yields. Moreover, aromatic bromides could be transformed into the corresponding aromatic methyl esters in good yields by the treatment with n-BuLi and subsequently with DMF, followed by the reaction with methanol, molecular iodine, and K₂CO₃. Some aromatics could be also converted into the corresponding aromatic esters in good yields by the treatment with n-BuLi, and subsequently with ethyl formate or DMF, followed by the reaction with molecular iodine and K₂CO₃. The present reactions offer a novel route for the transition-metal-free, carbon-monoxide-free, and therefore environmentally benign one-pot conversion of aromatic bromides and aromatics into aromatic esters.     

A two-step method for the preparation of homochiral cathinones

A simple method for the preparation of homochiral ring-substituted 1-aryl-2-aminopropanones 2 (‘cathinones’) is described, involving initial Friedel–Crafts acylation of aromatics with (S)- or (R)-N-trifluoroacetylalanyl chloride, followed by acid hydrolysis of the intermediate trifluoroacetamido intermediates 1, for which X-ray diffraction analysis confirmed the structures.     

LLE data for the ionic liquid 3-methyl-N-butyl pyridinium dicyanamide with several aromatic and aliphatic hydrocarbons

(Liquid + liquid) equilibrium data for ternary systems of several aromatic and aliphatic hydrocarbons with the ionic liquid 3-methyl-N-butylpyridinium dicyanamide were determined at T = 303.15 K and 328.15 K and atmospheric pressure. As aromatics benzene, cumene and p-xylene have been chosen, as paraffins n-hexane and n-nonane were used. The experimental data were regressed and could be adequately correlated with the NRTL model. A logical order in the extraction capacity of 3-methyl-N-butylpyridinium dicyanamide for the different aromatics is obtained: benzene > p-xylene > cumene.     

Reactions of coordinated compounds. Chelate-induced acceleration of methyl-proton dissociation from acetophenones

Rate constants of acetyl-proton exchange of alkali acetylphenolates and related acetyl aromatics were measured and compared in D₂0 and in CD₃OD. The results exhibited chelate-induced activation of acetyl C-H bonds. A palladium complex with N,N,N′,N′-tetramethylethylenediamine turned out to catalyze the acetyl proton exchange of o-hydroxyacetophenone due to chelation.     

Number ofKekulé structures of single-chain aromatics

The number ofKekulé structures is derived for an arbitrary single-chain aromatic. This class of molecules consists of condensed aromatics where the line through the centers of the fused benzene rings is a single (unbranched) line.     

黏土负载镍的纳米片高效芳烃加氢催化剂

以天然层状黏土蒙脱石（MMT）为前体,通过液相沉积-沉淀将镍物种引入水溶液中剥离为MMT纳米片表面的简易方法制得Ni/MMT纳米片。该Ni/MMT纳米片由于是二维（2D）结构,利于芳烃及其加氢产物的传质扩散,相比Ni/SBA-15和Ni/γ-Al₂O₃催化剂,具有更为高效的芳烃加氢性能,且在镍负载量高达18.5%时,其四氢萘加氢的转化频率（TOF）达到最高值。     

Supramolecular assembly in a polymer/ low-molar-mass system

Thermal analysis and infra-red spectroscopy have been used to study the interactions between poly (N-vinylpyrrolidone) and low-molar-mass, hydrogen-bonding-active aromatics. A remarkably strong interaction is observed between the polymer and 3,5-dihydroxybenzoic acid, which is consistent with the crosslinking of the polymer by acid dimers.     

Multilayered catalysts for fatty acid ester hydrotreatment into fuel range hydrocarbons

This study aims to investigate Ni–Mo/γAl₂O₃ and Ni–La/Zn-ZSM-5–γAl₂O₃ catalysts, which convert methyl esters into various compounds with a similar composition to those found in diesel fuels. The catalysts were synthesized by impregnation using two different routes and characterized by atomic absorption spectrometry, Brunauer–Emmett–Teller, and scanning electron microscopy. The acid strength distribution indicates a relatively high concentration of weak acid centers for both materials. The disposal of the catalysts into the reactor system is an important factor for driving the process toward the desired reaction products. The hydrodeoxygenation becomes important and paraffins are formed as intermediaries when Ni–Mo/γAl₂O₃ is first disposed into the reactor, whereas hydrocracking is poor and the dehydrocyclization does not occur in the case of Ni–La/Zn-ZSM-5–γAl₂O₃ as first layer. Triple-layered catalytic systems enhance the production of n-paraffins with high carbon number, mainly C17 and C18, which are important as diesel component. The effect of temperature was also studied and it was found that aromatics are mainly formed over double-layered catalytic systems by varying the temperature. In the case of triple-layered catalysts, the change in the product composition from saturated hydrocarbons with 12–18 carbon atoms to aromatics was observed by increasing the temperature from 420 to 445 °C. An interesting finding by the addition of n-octane in the feed was observed and the considerable increase in C8 aromatics involved the dehydrocyclization that occurred faster than hydrocracking.     

A novel effective electrophile: β-trifluoroacetylketene diphenyldithioacetal S,S-tetroxide

A synthesis of a novel electrophilic reagent--β-trifluoroacetylketene diphenyldithioacetal S,S-tetroxide 3 is described. The reaction of 3 with various electron-rich aromatics such as 1,3-dimethoxybenzene, 2-methylthiophene, N-methylpyrrole, and 2-methylindole was investigated. In the course of these reactions an unusual migration of a phenylsulfonyl group takes place. An easy and ready for scale-up procedure for the synthesis of previously unknown β-aryl, α-phenylsulphonyl substituted α,β-unsaturated trifluoromethyl ketones is reported.     

Torsions in conjugated aromatics: substituted styrenes

The low frequency torsional overtone (Δ v = 2) of the vinyl group has been observed in the gas phase Raman spectra of m- and p-fluorostyrene, m- and p-chlorostyrene and p-methylstyrene. The calculated barriers to internal rotation are all slightly smaller than that forstyrene itself. It appears that canonical structures, consistent with the conventional resonance arguments used to explain the reactions of para-substituted aromatics, play little or no role in the ground electronic states of these substituted styrenes. The slight downward trend in the barrier heights may be explained in terms of a small increase in the steric forces at the planar conformation.