Search

The study describes toluene ethylation using TsVM zeolite (SiO2/Al2O3 = 40) and a series of TsVM-based catalysts modified with rare-earth metals. To investigate the effects of the type and loading of rare-earth metals in the HTsVM catalyst on the selectivity towards total ethyltoluenes and p-ethyltoluene, the reaction was carried out in a continuous-flow fixed-bed reactor at atmospheric pressure and temperatures of 300–400°C. The HTsVM was modified with praseodymium, ytterbium, and holmium nitrates. The physicochemical and textural properties of the catalysts were characterized by XRD, FTIR spectroscopy, NH3-TPD, and low-temperature nitrogen adsorption. The specific surface area, acidity, total pore volume, and mesopore volume were found to decrease with an increase in the holmium loading of the catalyst. The zeolite catalysts loaded with 4.0–5.0 wt % Ho exhibited optimum stability and high p-ethyltoluene selectivity (79.5–81.4%) in combination with adequate toluene conversion (19.4–20.3%). [ABSTRACT FROM AUTHOR]

This research was designed to isolate pinostrobin from Kaempferia pandurata Roxb. rhizome using a chromatography method and to study its structural modification through ethylation and allylation reactions. Two compounds were afforded from the ethylation reaction that were 5-ethoxy-7-methoxyflavanone and 4′-ethoxy-6′-methoxychalcone and in the case of the allylation, 5-O-allylpinostrobin (5-allyloxy-7-methoxyflavanone) and 6-allylpinostrobin (6-allyl-5-hydroxy-7-methoxyflavanone) were obtained. [ABSTRACT FROM AUTHOR]

Chemical modification of small molecules is a key step for the development of pharmaceuticals. S‐adenosyl‐l‐methionine (SAM) analogues are used by methyltransferases (MTs) to transfer alkyl, allyl and benzyl moieties chemo‐, stereo‐ and regioselectively onto nucleophilic substrates, enabling an enzymatic way for specific derivatisation of a wide range of molecules. l‐Methionine analogues are required for the synthesis of SAM analogues. Most of these are not commercially available. In nature, O‐acetyl‐l‐homoserine sulfhydrolases (OAHS) catalyse the synthesis of l‐methionine from O‐acetyl‐l‐homoserine or l‐homocysteine, and methyl mercaptan. Here, we investigated the substrate scope of ScOAHS from Saccharomyces cerevisiae for the production of l‐methionine analogues from l‐homocysteine and organic thiols. The promiscuous enzyme was used to synthesise nine different l‐methionine analogues with modifications on the thioether residue up to a conversion of 75 %. ScOAHS was combined with an established MT dependent three‐enzyme alkylation cascade, allowing transfer of in total seven moieties onto two MT substrates. For ethylation, conversion was nearly doubled with the new four‐enzyme cascade, indicating a beneficial effect of the in situ production of l‐methionine analogues with ScOAHS. [ABSTRACT FROM AUTHOR]

A KF/γ-Al2O3 solid base catalyst was prepared by wet impregnation and applied to the synthesis of eugenol ethyl ether (EEE) from eugenol and diethyl carbonate. By measuring the yield of eugenol ethyl ether, we investigated the effects of the catalyst active component, impregnation temperature, KF impregnation concentration, impregnation time, and calcination temperature on catalyst performance. The results showed that the KF/γ-Al2O3 catalyst can adequately facilitate the conversion of eugenol to EEE. The characterizations of the catalysts were examined by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The characterizations of EEE were examined by nuclear magnetic resonance spectrometry (H1-NMR), gas chromatography–mass spectrometer (GC-MS) and Fourier-transform infrared spectroscopy (FT-IR). It was found that the KF/Al2O3 catalyst (impregnation temperature 60 °C, KF impregnation concentration 40%, impregnation time 8 h, and calcination temperature 450 °C) showed the best effect. The yield of EEE remained 51.2% after recycling the supported catalyst three times. [ABSTRACT FROM AUTHOR]

In organic synthesis, formamides are the most abundant class of compounds owing to their importance as the building blocks in synthetic and industrial organic chemistry. Formamides are also one of the most valuable intermediates produced in drug synthesis and act as precursors for the synthesis of therapeutically‐relevant molecules. Here, we developed a simple, practical, and catalytic methodology for the N‐formylation of a wide variety of amines by using iron as a catalyst. This protocol features an inexpensive iron catalyst, short reaction time, mild reaction conditions, good yields, easy workup, and tolerance of a wide variety of functional groups. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Methods for regioselective N‐methylation and ‐alkylation of unsaturated heterocycles with "off the shelf" reagents are highly sought‐after. This reaction could drastically simplify synthesis of privileged bioactive molecules. Here we report engineered and natural methyltransferases for challenging N‐(m)ethylation of heterocycles, including benzimidazoles, benzotriazoles, imidazoles and indazoles. The reactions are performed through a cyclic enzyme cascade that consists of two methyltransferases using only iodoalkanes or methyl tosylate as simple reagents. This method enables the selective synthesis of important molecules that are otherwise difficult to access, proceeds with high regioselectivity (r.r. up to >99 %), yield (up to 99 %), on a preparative scale, and with nearly equimolar concentrations of simple starting materials. [ABSTRACT FROM AUTHOR]

Germacrone and curdione are germacrane-type sesquiterpenoids that are widely distributed and have extensive pharmacological activities; they are the main constituents of 'Xing-Nao-Jing Injection' (XNJ). Studies on the metabolic features of germacrane-type sesquiterpenoids are limited. In this study, the metabolites of germacrone and curdione were characterized by UHPLC-Q-Exactive Oribitrap mass spectrometry after they were orally administered to rats. In total, 60 and 76 metabolites were found and preliminarily identified in rats administered germacrone and curdione, respectively, among which at least 123 potential new compounds were included. New metabolic reactions of germacrane-type sesquiterpenoids were identified, which included oxidation (+4 O and +5 O), ethylation, methyl-sulfinylation, vitamin C conjugation, and cysteine conjugation reactions. Among the 136 metabolites (including 113 oxidation metabolites, two glucuronidation, two methylation, nine methyl-sulfinylation, three ethylation, six cysteine conjugation, and one Vitamin C conjugation metabolites), 32 metabolites were detected in nine organs, and the stomach, intestine, liver, kidneys, and small intestine were the main organs for the distribution of these metabolites. All 136 metabolites were detected in urine and 64 of them were found in feces. The results of this study not only contribute to research on in vivo processes related to germacrane-type sesquiterpenoids but also provide a strong foundation for a better understanding of in vivo processes and the effective forms of germacrone, curdione, and XNJ. [Display omitted] • Distribution of the metabolites of germacrane-type sesquiterpenes were studied. • ESI MS fragmentation rules of germacrane-type sesquiterpenes were summarized. • 60 and 76 metabolites of germacrone and curdione were identified in rats. • Among 136 metabolites, 123 were potential new compounds. • 5 metabolic reactions of germacrane-type sesquiterpenes were discovered in rats. [ABSTRACT FROM AUTHOR]

An efficient ethylation reaction of phenols was accomplished by using boron triflouride diethyletherate solution as alkyl source at elevated temperatures. The reaction furnished a repertoire of aryl ethyl ethers in decent yields and tolerated a range of functional groups. The method is robust and therefore provides a convenient procedure to protect phenols expeditiously. [ABSTRACT FROM AUTHOR]

Taking advantage of the opposite chirality of two privileged starting materials, l‐cysteine and d‐penicillamine, a wide range of thiazolidine‐based amino alcohols was synthesized. l‐Cysteine derivatives were more efficient chiral inductors than the d‐penicillamine ones, with ee up to 92% in the enantioselective ethylation of benzaldehyde. The scope of the best catalyst was evaluated using several aromatic, heteroaromatic, and aliphatic aldehydes, providing excellent (S)‐enantioselectivities. Given the opposite chirality of the l‐cysteine and d‐penicillamine thiazolidines, it was expected that the use of one or the other type of derivative as ligand would allow the formation of opposite configurations of the alkylated product. However, whereas the l‐cysteine thiazolidines predominantly gave the (S) form of the alkylated product, the d‐penicillamine ones led to both configurations. The significant difference in the stereochemical outcome of this reaction when catalyzed by the two types of ligands prompted us to investigate the reasons behind such results. Extensive quantum chemical calculations were performed in order to identify the transition state structures by which the enantioselective ethylation of benzaldehyde in the presence of these type of amino alcohols can proceed. An alternative path for the rate‐determining step was also explored and found decisive for the rationalization of the experimental outcomes. It was observed that the type of ligand dictates the accessible reaction paths for the formation of the chiral product, which ultimately determine the balance between the two possible configurations. [ABSTRACT FROM AUTHOR]

The use of electricity over traditional stoichiometric oxidants is a promising strategy for sustainable molecular assembly. Herein, we describe the rhoda‐electrocatalyzed C−H activation/alkylation of several N‐heteroarenes. This catalytic approach has been successfully applied to several arenes, including biologically relevant purines, diazepam, and amino acids. The versatile C−H alkylation featured water as a co‐solvent and user‐friendly trifluoroborates as alkylating agents. Finally, the rhoda‐electrocatalysis with unsaturated organotrifluoroborates proceeded by paired electrolysis. [ABSTRACT FROM AUTHOR]

The effects of the zeolite structure and acidic property on the activity and selectivity in gas‐phase alkylation of benzene with ethylene were investigated using TUN, IMF, *SFV and MFI with different structures and Si/Al2 ratios. The channels of TUN and IMF provide both higher selectivity to ethylation (ethylbenzene and di‐ethylbenzene) and lower xylene selectivity compared to MFI with slightly smaller pore diameter in which the pore diffusion limitations are suffered. The activity is mainly controlled by zeolite channel architecture. The higher activity and selectivity are obtained using modified TUN and modified IMF with suitable density of Brønsted acidity in a well‐defined channel structure sterically constrained for heavy by‐products. It is shown that the activity and selectivity increase with increasing pore diameter of three‐dimensional 10 ring channel structure, while the rule is not valid for *SFV. [ABSTRACT FROM AUTHOR]

Benzene ethylation over zeolites has a long-standing controversy on two different possible reaction pathways, i.e., stepwise and concerted mechanisms. To solve this doubt and further find out the suitable zeolite to catalyze benzene ethylation with ethylene, we employed density functional theory (DFT) and molecular dynamic (MD) methods to insight the reaction mechanisms of benzene ethylation over five widely-applied zeolites, i.e., ZSM-5, ZSM-22, ZSM-12, Y and MOR. ZSM-5 is the optimal framework than the other zeolites in both stepwise and concerted mechanisms, and the host–guest interaction between the intersection pore and reacted species drives to the lower maximum free energy span (viz. 23.41 and 20.96 kcal/mol for stepwise and concerted mechanisms) thermodynamically, and stepwise mechanism was confirmed as the superior pathway to catalyze benzene ethylation kinetically. Moreover, the faster diffusion rate of ethylene (50 times) than that of benzene in ZSM-5 indicates that the ethylation is diffusion limited and ethylene could preferentially occupy the Bronsted acid site to form surface ethyoxyl. Furthermore, the quantitative Mulliken population analysis and qualitative reduced density gradient (RDG) analysis reveal that the pore confinement effect drives the priority of ZSM-5 to catalyze benzene ethylation. [ABSTRACT FROM AUTHOR]

A diastereoselective synthesis of donor-acceptor bicyclopropyl, 8-phenyldispiro[2.3.2.0]-nonane-1,1-dicarboxylate, was carried out, which treated with Lewis acids acts as a synthetic equivalent of cis-1,6-zwitterionic intermediates. In the presence of GaCl3, the main direction is 1,6-cyclization to the substituted 1,2,3,4,6,7-hexahydro-5H-indene, while the action of EtAlCl2 triggers the three-membered rings opening, leading to the ethylation at the carbocation center. The reaction of 8-phenyldispiro[2.3.2.0]nonane-1,1-dicarboxylate with 4-phenyl-1,2,4-triazoline-3,5-dione in the presence of 10 mol.% of Yb(OTf)3 proceeds through the ionic [6+2] cycloaddition of 1,6-zwitterion to the N=N bond with the formation of an eight-membered heterocycle. [ABSTRACT FROM AUTHOR]

Highly structure-controlled B 4 C ceramics were prepared via strong magnetic field-assisted slip casting of a slurry, containing B 4 C base particles and pore-forming agents with a fiber shape. To achieve gas release at a lower porosity for maintaining its mechanical strength, these B 4 C ceramics had a structure in which a large number of oriented tubal pores were dispersed in a crystallographically-aligned and dense B 4 C matrix phase. The B 4 C microstructure, such as structuration and orientation degree distributions of the B 4 C grains and tubal pores, was characterized by SEM observation, EBSD analysis, and X-ray CT. Among the investigations, it was found that the oxidic impurities, as an inhibitor of sintering, which existed on the B 4 C surface, can be removed by ethylation and azeotropy due to an ethanol treatment followed by vacuum drying. Thus, an ethanol treatment of a green compact before sintering was significantly effective for the fabrication of the B 4 C ceramics, including the microstructure that coexisted with a dense matrix phase with tubal pores. The resultant ceramic specimens showed the remarkable three-point bending strength of 459−554 MPa, which is two times higher when compared to conventional B 4 C pellets with a similar porosity. [ABSTRACT FROM AUTHOR]

Selective alkylation of pyrazoles could solve a challenge in chemistry and streamline synthesis of important molecules. Here we report catalyst‐controlled pyrazole alkylation by a cyclic two‐enzyme cascade. In this enzymatic system, a promiscuous enzyme uses haloalkanes as precursors to generate non‐natural analogs of the common cosubstrate S‐adenosyl‐l‐methionine. A second engineered enzyme transfers the alkyl group in highly selective C−N bond formations to the pyrazole substrate. The cosubstrate is recycled and only used in catalytic amounts. Key is a computational enzyme‐library design tool that converted a promiscuous methyltransferase into a small enzyme family of pyrazole‐alkylating enzymes in one round of mutagenesis and screening. With this enzymatic system, pyrazole alkylation (methylation, ethylation, propylation) was achieved with unprecedented regioselectivity (>99 %), regiodivergence, and in a first example on preparative scale. [ABSTRACT FROM AUTHOR]

Installation of a carbanionic substituent, that is strongly stabilized by two (trifluoromethyl)sulfonyl (Tf=SO2CF3) groups, into several fluorescence dyes including boron‐dipyrromethenes (BODIPYs), fluoresceins, and aminocoumarins has been achieved by the 2,2‐bis(triflyl)ethylation reaction of the dye frameworks with highly electrophilic Tf2C=CH2, followed by neutralization with NaHCO3. Despite the contradiction between water solubility and lipophilicity, the carbanion‐decorated dyes thus obtained showed significant enhancement of not only water solubility but also lipophilicity. This work clearly demonstrates that the fluorinated, highly stabilized carbanionic substituent is a new option for controlling the macroscopic property of chemical materials. [ABSTRACT FROM AUTHOR]

Biocatalytic alkylations are important reactions to obtain chemo‐, regio‐ and stereoselectively alkylated compounds. This can be achieved using S‐adenosyl‐l‐methionine (SAM)‐dependent methyltransferases and SAM analogs. It was recently shown that a halide methyltransferase (HMT) from Chloracidobacterium thermophilum can synthesize SAM from SAH and methyl iodide. We developed an iodide‐based assay for the directed evolution of an HMT from Arabidopsis thaliana and used it to identify a V140T variant that can also accept ethyl‐, propyl‐, and allyl iodide to produce the corresponding SAM analogs (90, 50, and 70 % conversion of 15 mg SAH). The V140T AtHMT was used in one‐pot cascades with O‐methyltransferases (IeOMT or COMT) to achieve the regioselective ethylation of luteolin and allylation of 3,4‐dihydroxybenzaldehyde. While a cascade for the propylation of 3,4‐dihydroxybenzaldehyde gave low conversion, the propyl‐SAH intermediate could be confirmed by NMR spectroscopy. [ABSTRACT FROM AUTHOR]

A cobalt-catalyzed decarboxylative methylation of aliphatic redox-active esters [ N -(acyloxy)phthalimides; RAEs] with trimethylaluminum under mild conditions was developed, providing a method for transforming a carboxylate group into a methyl group without redox fluctuation. Primary and secondary RAEs were both amenable substrates, whereas a tertiary RAE delivered an elimination product. Triethylaluminum was also used to deliver a decarboxylative ethylation product. [ABSTRACT FROM AUTHOR]

Carbazoles possessing Tf2CHCH2 groups were obtained by the reaction of 1-(indol-2-yl)but-3-yn-1-ols with in situ-generated Tf2C＝CH2 through vicinal difunctionalisation of the alkyne moiety, where the vinyl-type carbocation intermediate was selectively attacked by the indole moiety and not by the carbanion moiety. [ABSTRACT FROM AUTHOR]

Understanding and optimizing structure of active sites is of significance in zeolite catalysis. Benzene ethylation is an industrially important process catalyzed by H-MCM-22 zeolite; while the active sites still remain elusive. In this work, density functional theory (DFT) calculations were employed to investigate the benzene ethylation at two different types of Brønsted acid sites (BAS) in H-MCM-22 zeolite, namely the internal cavity (IC) acid site and the external surface (ES) acid site. Both the stepwise and concerted pathways were addressed. The comparison of the calculated energetics of two pathways indicates that the benzene ethylation reaction primarily proceeds via the concerted pathway at both the IC and ES acid sites of H-MCM-22. The calculated overall Gibbs free energies at reaction condition (473 K and 3.5 MPa) on the IC and ES acid sites are 90 and 86 kJ/mol, with the rate constants of 1.20 × 10³ and 2.92 × 10³ s-1, respectively. It indicates that benzene ethylation could occur both on the IC and ES acid sites, with the catalytic activity of IC acid site being slightly lower than that of ES acid site. Furthermore, we theoretically reveal that the acid strength at the ES site is slightly weaker than that at the IC site via the frequency shift after the adsorption of CO. The differences in dispersion interaction between ES and IC sites are also quantified by the adsorption of base molecules with different sizes. The calculated results in this work demonstrate that the acid sites at the external surface of H-MCM-22 zeolites are suitable for benzene ethylation to produce ethylbenzene, providing theoretical implications for tailoring the distribution of active sites in H-MCM-22 zeolite. [ABSTRACT FROM AUTHOR]

Methylmercury (MeHg) speciation in urine requires a robust, reproducible and sensitive technique that enables reliable measurements in limited sample volumes. Conventional MeHg extraction by acid digestion allows for processing of only small amounts of urine digest, making accurate MeHg determination in low-concentration samples virtually impossible. Distillation has been proven as an efficient isolation method with very low detection limits for measuring MeHg in water samples; therefore, in this study, it was optimised for urine samples. Combined with aqueous phase ethylation, purging with nitrogen, preconcentration on Tenax trap, isothermal gas chromatography and cold vapour atomic fluorescence detection, distillation achieved high and repeatable urine spike recoveries of 94% ± 7%. Larger measured aliquot volume led to a significantly lower limit of detection (LOD) for distillation compared with acid digestion (1.1 versus 5.5 pg g−1 urine). Thirty-two general population urine samples were analysed using both methods, and the results were compared. Distillation led to better separation of MeHg from inorganic Hg and the matrix. Good correlation was observed between the results obtained by the two methods for samples with MeHg concentrations above 10 pg g−1 urine (slope = 0.9492, R2 = 0.9879). For samples below this MeHg concentration, distillation was superior, enabling the measurement of MeHg in 9 out of 12 urine samples that were below the LOD of acid digestion. Distillation had significantly lower measurement uncertainty, particularly in the low-concentration samples, where the expanded combined standard uncertainty of the acid digestion method reached as high as 43.2% (k = 2), predominantly owing to poor sample repeatability. [Display omitted] • Distillation was used for methylmercury speciation in urine samples. • Distillation had lower limit of detection (LOD) compared to acid leaching. • Distillation had smaller measurement uncertainty. • It enabled MeHg measurement in samples that were

Mercury (Hg) is a highly toxic element, which is frequently enriched in flooded soils due to its anthropogenic release. The mobilization of Hg and its species is of ultimate importance since it controls the transfer into the groundwater and plants and finally ends in the food chain, which has large implications on human health. Therefore, the remediation of those contaminated sites is an urgent need to protect humans and the environment. Often, the stabilization of Hg using amendments is a reliable option and biochar is considered a candidate to fulfill this purpose. We tested two different pine cone biochars pyrolyzed at 200 °C or 500 °C, respectively, with a view to decrease the mobilization of total Hg (Hg t), methylmercury (MeHg), and ethylmercury (EtHg) and/or the formation of MeHg and EtHg in a contaminated floodplain soil (Hg t : 41 mg/kg). We used a highly sophisticated automated biogeochemical microcosm setup to systematically alter the redox conditions from ~−150 to 300 mV. We continuously monitored the redox potential (E H) along with pH and determined dissolved organic carbon (DOC), SUVA 254 , chloride (Cl−), sulfate (SO 4 2−), iron (Fe), and manganese (Mn) to be able to explain the mobilization of Hg and its species. However, the impact of biochar addition on Hg mobilization was limited. We did not observe a significant decrease of Hg t , MeHg, and EtHg concentrations after treating the soil with the different biochars, presumably because potential binding sites for Hg were occupied by other ions and/or blocked by biofilm. Solubilization of Hg bound to DOC upon flooding of the soils might have occurred which could be an indirect impact of E H on Hg mobilization. Nevertheless, Hg t , MeHg, and EtHg in the slurry fluctuated between 0.9 and 52.0 μg/l, 11.1 to 406.0 ng/l, and 2.3 to 20.8 ng/l, respectively, under dynamic redox conditions. Total Hg concentrations were inversely related to the E H ; however, ethylation of Hg was favored at an E H around 0 mV while methylation was enhanced between −50 and 100 mV. Phospholipid fatty acid profiles suggest that sulfate-reducing bacteria may have been the principal methylators in our experiment. In future, various biochars should be tested to evaluate their potential in decreasing the mobilization of Hg and to impede the formation of MeHg and EtHg under dynamic redox conditions in frequently flooded soils. Unlabelled Image • Biochars had little influence on total Hg (Hg t) release, methylation, & ethylation. • Biochars likely curtailed Hg t release at redox potential (E H) around −110 mV. • Concentrations of EtHg and MeHg were highest at E H s 0 mV and 100 mV, respectively. • Phospholipid fatty acid profiles suggest sulfate-reducing bacteria as methylators. [ABSTRACT FROM AUTHOR]

The structure of 6-polyfluoroalkyl-2-thiouracils and reactivity of nucleophilic centers in their molecules were analyzed by quantum chemical calculations. According to the experimental data, methylation of 6-polyfluoroalkyl-2-thiouracils with methyl iodide initially gives 2-methylsulfanyl-substituted pyrimidin-4-one and then S,N3- and S,O-dimethyl derivatives. The optimal conditions for the selective formation of the S, N3- isomer were heating in tert-butyl alcohol in the presence of cesium carbonate as a base. Ethylation of 6-polyfluoroalkyl-2-thiouracils afforded approximately equal amounts of S,N3- and S,O-dimethyl derivatives. S,N3-Dimethyl-substituted pyrimidines in boiling ethanol in the presence of potassium carbonate were converted into uracil potassium salts as a result of nucleophilic substitution of the methylsulfanyl group by ethoxy and subsequent dealkylation of the latter. [ABSTRACT FROM AUTHOR]

Ethylmercury (EtHg) has been widely observed in the environment due to anthropogenic contamination and/or environmental ethylation of inorganic mercury. Herein, the acute and sublethal effect of EtHg chloride on Chinese rare minnow (Gobiocypris rarus) as a fish model was studied. EtHg chloride showed an obvious toxicity to 4-month-old Chinese rare minnow (LC50 24.8 µg L−1 (as Hg) at 24 h). Histological analysis revealed that acute EtHg exposure can induce necrosis, telangiectasis and exfoliation of epithelial cells in the gill, as well as edema, vacuoles, and pyknotic nuclei in hepatocytes. Sublethal dose exposure revealed a very high accumulation of EtHg in fish, which is subsequently metabolized to inorganic mercury and eliminated after depuration. A new mercury species, possibly diethylmercury, was also observed as the metabolite of EtHg in rare minnow. The present study provides useful information for assessing the risks of EtHg and understanding its bioaccumulation in aquatic organisms. [ABSTRACT FROM AUTHOR]

The activity of zeolite MCM‐22 and modified MCM‐22 catalyst were tested in the vapor phase alkylation of toluene and ethylbenzene by ethanol to investigate the influence of thermodynamic parameters, reaction temperature, and the molar ratio of toluene and ethylbenzene to ethanol. The reactions were evaluated with experimental and theoretical approaches. The catalysts were characterized by XRD, FE‐SEM, TGA, N2‐adsorption, and NH3 & Py‐TPD analyses. The superior catalytic performance of modified MCM‐22 was observed in ethylation of ethylbenzene and ethylation of toluene. The catalytic performance indicates that zeolite MCM‐22 retained shape selectivity resulting into para‐selectivity, while modified MCM‐22 possessed more mesopores and increased accessibility to the acid sites thereby increasing conversion of ethylbenzene. The catalytic vapor phase alkylation reaction of toluene and ethylbenzene with ethanol was carried out in a continuous fixed‐bed down‐flow reactor at atmospheric pressure and at various temperature range to investigate activity and desired product distribution over MCM‐22 and modified MCM‐22. The experimental flow of desired products further was predicted with thermodynamic results from Gaussian09 computational study. Experimental results of alkylation reaction are compared with computational data to correlate selectivity of isomers over MCM‐22 and modified‐MCM‐22. [ABSTRACT FROM AUTHOR]

The separation of dihalobenzene isomers, such as dichlorobenzene isomers and difluorobenzene isomers, has a high practical value in both synthetic chemistry and industrial production. Herein we provide a simple to operate and energy‐efficient adsorptive separation method using nonporous adaptive crystals of perbromoethylated pillar[5]arene (BrP5) and pillar[6]arene (BrP6). BrP6 crystals show a preference towards the ortho isomer of dichlorobenzene in isomer mixtures, but cannot discriminate difluorobenzene isomers. Single‐crystal structures reveal that this selectivity is derived from the stability of the new host–guest crystal structure of BrP6 after uptake of the preferred guest and the binding strength of the host–guest interactions. Furthermore, because of the reversible transition between guest‐free and guest‐loaded structures, BrP6 crystals are recyclable. [ABSTRACT FROM AUTHOR]

Abstract A library of new chiral thiazolidines was prepared starting from l -cysteine and d -penicillamine in a simple, one-step procedure. 2-Arylthiazolidines were obtained, as diastereoisomeric mixtures, with good yields and in short reaction times, through a new and greener procedure, using microwave irradiation. Their use as chiral ligands in the enantioselective ethylation of aromatic aldehydes was studied and optimized, originating good to excellent conversions and ee up to 94% in 6 h. A series of heteroaromatic and aliphatic substrates were also enantioselectively ethylated with success, with ee up to 77%. The distinct opposite chirality in l -cysteine and d -penicillamine makes the use of these ligands an interesting approach for obtaining both the (S) and (R) enantiomers of the chiral alcohols, compounds with potential applications in the area of fine chemistry. NMR studies were carried out using a diastereoisomeric mixture of thiazolidines, allowing the identification of the most stable structure. Computational studies confirmed this result and also gave important insight into the species involved in the catalytic cycle of the enantioselective alkylation. Graphical abstract d -Penicillamine and l -cysteine derived thiazolidines were obtained through a simple microwave procedure and used in the enantioselective alkylation of aldehydes with diethylzinc, giving (S) and (R) enantiomers of the product alcohols with ee up to 94%. NMR and computational studies gave important insight into the species involved in the catalytic cycle. Image 1 Highlights • Chiral thiazolidines prepared from l -cysteine/ d -penicillamine with MW irradiation. • Enantioselective ethylation of aromatic aldehydes gave ee up to 94%. • Enantioselective ethylation of heteroaromatic/aliphatic substrates gave ee up to 77%. • Interesting approach for obtaining both the (S) and (R) chiral alcohols. • NMR and Computational studies gave insight into catalytic species. [ABSTRACT FROM AUTHOR]

Natural spider silk is one of the world’s toughest proteinaceous materials, yet a truly biomimetic spider silk is elusive even after several decades of intense focus. In this study, Next-Generation Sequencing was utilised to produce transcriptomes of the major ampullate gland of two Australian golden orb-weavers, Nephila plumipes and Nephila pilipes, in order to identify highly expressed predicted proteins that may co-factor in the construction of the final polymer. Furthermore, proteomics was performed by liquid chromatography tandem-mass spectroscopy to analyse the natural solid silk fibre of each species to confirm highly expressed predicted proteins within the silk gland are present in the final silk product. We assembled the silk gland transcriptomes of N. plumipes and N. pilipes into 69,812 and 70,123 contigs, respectively. Gene expression analysis revealed that silk gene sequences were among the most highly expressed and we were able to procure silk sequences from both species in excess of 1,300 amino acids. However, some of the genes with the highest expression values were not able to be identified from our proteomic analysis. Proteome analysis of “reeled” silk fibres of N. plumipes and N. pilipes revealed 29 and 18 proteins, respectively, most of which were identified as silk fibre proteins. This study is the first silk gland specific transcriptome and proteome analysis for these species and will assist in the future development of a biomimetic spider silk. [ABSTRACT FROM AUTHOR]

Abstract A two new series of ferrocene containing quinolinones – 1-allyl-2-ferrocenyl-2,3-dihydroquinolin-4(1 H )-ones and 1-allyl-2-ferrocenylquinolin-4(1 H )-ones – were prepared and characterized by standard spectroscopic techniques and cyclic voltammetry. The in vitro antitumor activity of all synthesized compounds was investigated against Human Cervix Carcinoma (HeLa), Chronic Myelogenous Leukemia (K562) and normal endothelial (HUVEC) cell lines using the MTT method. Quinolone derivative 5c exhibited the highest cytotoxic activity in the cell growth inhibition of HeLa cell line while 5f was the most toxic against K562 cells. Graphical abstract Image 1 Highlights • Two novel series of ferrocene containing quinolinones were synthesized and characterized. • Their electrochemical behavior was examined using cyclic voltammetry. • Cytotoxicity of all synthesized quinolinones was measured against HeLa, K562 and HUVEC cell lines. • All tested ferrocene compounds displayed the better activity against K562 cell lines. [ABSTRACT FROM AUTHOR]

Abstract The novel optically active zinc(II) phthalocyanine having four (1 R ,2 R )-1,2-di(naphthalen-1-yl)ethane-1,2-diol 1 at non-peripheral positions has been synthesized in a condensation using optically active phthalonitrile 2 , and characterized by 1H NMR, IR, UV–Vis, Circular Dichroism (CD) and HRMS-TOF spectral data. The spectral and aggregation properties of novel optically active zinc(II) phthalocyanine 3 were investigated. The aggregation behavior of phthalocyanine 3 was investigated at different concentrations in N,N -dimethylformamide and tetrahydrofuran. No aggregation behavior was observed in both solvents at concentrations between 10 × 10−6 and 2 × 10−6 mol dm−3. The applicability of these chiral ligands 1–3 was evaluated in the enantioselective diethyl zinc addition of aldehydes. The addition of diethylzinc to 2-methoxybenzaldehyde was achieved with excellent enantioselectivity (87% ee , 80% yield) under catalysis with (1 R ,2 R )-1,2-di(naphthalen-1-yl)ethane-1,2-diol 1. At the same condition, optically active zinc(II) phthalocyanine 3 afforded the corresponding chiral secondary alcohol with the enantiomeric excess of 11%. Graphical abstract Image 1 Highlights • Novel optically active phthalocyanine derivative was synthesized. • Aggregation properties of phthalocyanine were investigated. • ZnPc derivative was tested as catalysts in asymmetric catalysis. [ABSTRACT FROM AUTHOR]

Abstract: A reaction of nitrones with 1,2‐dibromotetrafluoroethane affording bromodifluoroethyl‐substituted hydroxylamines is described. The process is performed in the presence of a ruthenium photocatalyst and ascorbic acid as a stoichiometric reducing agent and is mediated by blue light irradiation. The fluroalkylation products can undergo chemoselective transformations involving either N−O or C−Br bonds furnishing various tetrafluorinated compounds. [ABSTRACT FROM AUTHOR]

Abstract: A highly efficient copper‐mediated aromatic pentafluoroethylation method using TMSCF3 as the sole fluoroalkyl source is described. The reaction proceeds by a key C1 to C2 process, that is, the generation of CuCF3 from TMSCF3, followed by a subsequent spontaneous transformation into CuC2F5. Various aryl iodides were pentafluoroethylated with the TMSCF3‐derived CuC2F5. This method represents the first practical and efficient method for pentafluoroethylation of aryl iodides using commercially available TMSCF3 as a pentafluoroethyl precursor. [ABSTRACT FROM AUTHOR]

The ethylation of aryl alcohols by an ethyl moiety of boron trifluoride etherate is described. The reaction proceeded cleanly and afforded good yields of the corresponding aryl ethyl ethers. It tolerated the presence of functional groups such as aryl, alkyl, halogens, nitro, nitrile, and amino. However, the presence of amino or nitro groups ortho to a hydroxyl group of an aryl compound drastically reduced the yields of the anticipated products due to the chelation of the aforementioned functional groups with boron trifluoride etherate. A nitrogen atom in the aromatic ring system, as exemplified by hydroxypyridine and 8-hydroxyquinoline, completely inhibited the reaction. Resorcinol, hydroquinone, and aryl alcohols with aldehyde functions decomposed under the reaction conditions.

Abstract: Lignosulfonate is a byproduct of the sulfite pulping process and has limited use in industry. The main objective of this study was to investigate the carboxyethylation of lignosulfonate to increase its charge density to broaden its applications. The carboxyethylation of lignosulfonate was optimized under the conditions of 30 wt % NaOH, 2.0 mol mol−1 2‐chloropropinic acid/lignosulfonate, 90 °C, 0.5 h, and 0.03 mol 2‐chloropropinic acid, which produced carboxyethylated lignosulfonate with a charge density and molecular weight of −3.51 meq g−1 and 46 493 g mol−1, respectively. The mechanism of the carboxyethylation reaction using 2‐chloropropinic acid by an SN1 pathway in an alkaline solution was discussed. Methylation was also used to mask the phenolic hydroxide groups of lignosulfonate to investigate if carboxyethylation occurred on aliphatic hydroxide groups of lignosulfonate. The produced carboxyethylated lignosulfonate was characterized by using FTIR spectroscopy, NMR spectroscopy, gel permeation chromatography, and elemental and functional group analyses. Basic 1H‐1H 2 D COSY NMR spectroscopy was used to record the coupled spins of the carboxyethyl group on carboxyethylated lignosulfonate. The information from 1 D 1H NMR and 2 D NMR COSY spectroscopy provided evidence for the existence of a 1‐carboxyethyl group on the carboxyethylated lignosulfonate structure. [ABSTRACT FROM AUTHOR]

3,4-Substituted-(4 H)-1,2,4-triazole-5-thiols were synthesized and used for S-alkylation, cyanoethylation, and aminomethylation to produce a series of new 1,2,4-triazole derivatives of interest as biologically active compounds. The antitumor properties of several of the 1,2,4-triazole derivatives were studied. [ABSTRACT FROM AUTHOR]

N-cyanoethyl polyethylenimine (CN-PEI) is synthesized by modifying polyethylenimine (PEI) with acrylonitrile through a Michael addition reaction. Depending on cyanoethylation level, CN-PEI can be obtained as a form of solution, micro-emulsion or emulsion in water. CN-PEI micro-emulsion is investigated as water-soluble binder for the application of lithium iron phosphate (LFP) cathode in lithium-ion batteries. CN-PEI binder not only maintains the outstanding dispersion capability of PEI but also exhibits an excellent adhesion strength and higher ionic conductivity because of the introduction of polar cyano groups. As a result, CN-PEI binder can effectively maintain the mechanical integrity and decrease the polarization of LFP electrode during the operation of the battery. LFP electrode with CN-PEI binder exhibits good cycle stability and enhanced rate performance delivering a capacity of 99.6% at a rate of 0.5 C after 100 cycles and a high discharge capacity of 102.4 mAh g−1 at 5 C. [ABSTRACT FROM AUTHOR]

1. The in vitro metabolism of alectinib, a potent and highly selective oral anaplastic lymphoma kinase inhibitor, was investigated. 2. The main metabolite (M4) in primary human hepatocytes was identified, which is produced by deethylation at the morpholine ring. Three minor metabolites (M6, M1a, and M1b) were also identified, and a minor peak of hydroxylated alectinib (M5) was detected as a possible precursor of M4, M1a, and M1b. 3. M4, an important active major metabolite, was produced and further metabolized to M6 by CYP3A, indicating that CYP3A enzymes were the principal contributors to this route. M5 is possibly produced by CYP3A and other isoforms as the primary step in metabolism, followed by oxidation to M4 mainly by CYP3A. Alternatively, M5 could be oxidized to M1a and M1b via an NAD-dependent process. None of the non-CYP3A-mediated metabolism appeared to be major. 4. In conclusion, this study suggests that involvement of multiple enzymes in the metabolism of alectinib reduces its potential for drug-drug interactions. [ABSTRACT FROM AUTHOR]

Two analytical procedures based on the generation of volatile tributyltin derivatives, their separation by headspace solid-phase microextraction (HS SPME) and subsequent determination using plasma optical emission spectrometry (OES) have been developed for the selective determination of trace tributyltin (TBT) in the presence of other butyltins and inorganic tin in sediments without the use of chromatography. A microwave-assisted leaching of tin compounds from the sediment using 25%v/v acetic acid is applied for sample pretreatment. The first method takes advantage of TBT chloride releasing from the lecheate after adding 3 M hydrochloric acid, and subsequent separation of the analyte by HS SPME using Carboxen-poly(dimethylsiloxane) (CAR/PDMS). The second method involves the use of masking agents, namely ethylenediaminetetraacetic acid (EDTA) and diphenylcarbazone (DFC), which form stable chelates with monobutyltin (MBT) and dibutyltin (DBT), respectively, followed by the ethylation of tributyltin at pH 5 using sodium tetraethylborate (NaBEt4) solution. The final concentration of NaBEt4 is 0.05%w/v. The parameters affecting the TBT derivatisation and separation by HS SPME have been optimised including the selection of SPME fibre coating (PDMS, CAR/PDMS), the amount of masking agents and NaBEt4 added, sorption time (2-40 min) and sorption temperature (25-60°C). Higher sensitivity and robustness are attained with the method involving ethylation derivatisation, leading to the limit of detection (LOD) of 3 ng L-1. The selective release of TBT is observed from aqueous solutions, where the concentrations of MBT and DBT were in 2-50-fold excess to TBT. The SPME-TD-MIP-OES methods have been validated against several certified reference materials (CRMs), including SOPH-1 marine sediment, PACS-2 marine sediment and BCR 646 freshwater sediment. [ABSTRACT FROM AUTHOR]

Abstract: The borrowing hydrogen strategy has been applied to the ethylation of imines with an air‐stable iron complex as precatalyst. This approach opens new perspectives in this area as it enables the synthesis of unsymmetric tertiary amines from readily available substrates and ethanol as a C2 building block. A variety of imines bearing electron‐rich aryl or alkyl groups at the nitrogen atom could be efficiently reductively alkylated without the need for molecular hydrogen. The mechanism of this reaction, which shows complete selectivity for ethanol over other alcohols, has been studied experimentally and by means of DFT computations. [ABSTRACT FROM AUTHOR]

The hydrolysis of phosphonothioates with a binaphthyl group afforded the first example of O-(2'-hydroxy)binaphthyl phosphonothioic acids in good to high yields and >95:5 diastereoselectivity. The reaction proceeds via an axis-to-center chirality-transfer reaction. The ability of these acids to act as chiral molecular auxiliaries was demonstrated by using them as optically active ligands for the asymmetric ethylation of benzaldehyde and as a chiral discriminating agent for chiral aliphatic amines. [ABSTRACT FROM AUTHOR]

The mechanism of Pd(OAc) 2 -catalyzed trifluoroethylation of aromatic systems is explored using the density function theory (DFT) computations. The calculation results indicate that the whole catalytic cycle involves a coordinated process of catalyst Pd(OAc) 2 with acetanilide 1a , a C–H bond activation and a two-step migration of CF 3 CH 2 – group. The interesting role of additive (CF 3 COOH) is that it can react with substrate 2a (mesityl(trifluoroethyl)iodonium triflate) to form an active species mesityl(trifluoroethyl)iodonium trifluoroacetate 2a′ . 2a′ can assist the C–H activation to decrease the rate-limiting free energy barrier of the catalytic reaction by changing the rate-limiting step from the transferring process of CF 3 CH 2 – group to the C–H bond activation. [ABSTRACT FROM AUTHOR]

Reaction of [ArICH 2 CF 3 ][OTf] with structurally diversified 1,3-dicarbonyls and an appropriate base at room temperature gave O -trifluoroethylated products, C -trifluoroethylated products, or a mixture of O - and C -trifluoroethylated products in good yields. The product type was dramatically dependent upon the structure of the starting 1,3-dicarbonyls in this reaction. The cyclic 1,3-diketones exclusively afforded the O -trifluoroethylated products, whereas the acyclic 1,3-diketones, β -keto esters, and malonates selectively or specifically formed the C -trifluoroethylated products. Li 2 CO 3 facilitated the C -trifluoroethylation of acyclic 1,3-diketones and β -keto esters. The reaction proceeded under mild conditions, without pre-activation of 1,3-dicarbonyls and use of strong base, and demonstrated a catalyst-free structure-dependent regioselective trifluoroethylation of 1,3-dicarbonyls by mesityl(2,2,2-trifluoroethyl)iodonium triflate. [ABSTRACT FROM AUTHOR]

The meso-macropore network of a hierarchically structured zeolite catalyst is numerically optimized to maximize the volume-integrated reaction yield in the ethylation of benzene to produce ethylbenzene over zeolite H-ZSM-5. A hierarchical approach is used at multiple length scales to determine the optimal pore network properties. The maximum volume-integrated reaction yield of the hierarchically structured zeolite catalyst containing meso- and macropores is nearly twice the yield of a zeolite pellet containing only macropores, at the same macroporosity. To bridge the gap between modeling and experiments, a series of physical mixtures of ZSM-5 crystals and mesoporous silica, containing different weight fractions of zeolite is synthesized and used in fixed bed reactor experiments to determine the optimal pellet structure to maximize the conversion of ethylene. Comparison with reactor simulations of the zeolite composites shows that the performance of the zeolite composites might be limited by surface barriers at the external surface of the zeolite crystals, rather than by diffusion limitations within the meso-macropore network of the pellets. [ABSTRACT FROM AUTHOR]

Hericium erinaceus polysaccharide (HEP) has been shown to possess a variety of biological activities. In present study, HEP was successfully modified to obtain its hydroxyethylated derivative hHEP. Its potential immunomodulatory activities on RAW264.7 macrophages were investigated. Results showed that the hHEP were significantly stronger than that of the corresponding unmodified polysaccharide, HEP. Meanwhile, the NO, IL-6 and TNF-α production activities of macrophages were enhanced in the RAW264.7 macrophages by stimulation of hHEP. In addition, the hHEP increase significantly higher iNOS expression than HEP. These results indicated that the hydroxyethylated derivative hHEP could enhance the activation of peritoneal macrophages, and hydroxyethylation modification can enhance the immunomodulation function of HEP. [ABSTRACT FROM AUTHOR]

It was found that oligo(hexamethylene guanidine) (OHMG) reacted very slowly with unactivated high-molecular-mass alkyl halides (dodecyl chloride), possibly due to steric hindrance and the low nucleophilicity of the guanidine moiety. Therefore, this alkyl halide could not be used to modify OHMG under conventional conditions. Ethylation of OHMG was much more facile. However, the substitution in the derivatives was broadly scattered (under ordinary conditions and reagent ratios). It was shown simultaneously that the antibacterial activity of the alkylated derivatives was less than that of the starting OHMG hydrochloride. Benzyl chloride reacted readily with OHMG to produce derivatives with the desired degree of substitution. It was found that benzyl derivatives with 0.2 degree of substitution were more active against mycobacteria than the starting hydrochloride with the activity gradually diminishing if the degree of substitution was increased further. The increased activity may have been related to the optimum increase of OHMG hydrophobicity and/or steric structure. The rather high antibacterial activities of the benzyl derivatives against Mycobacterium smegmatis strain ATCC 607 made them promising for further development and studies of the properties of alkylated OHMG derivatives to discover more active derivatives, including against M. smegmatis. The most obvious candidates could become the methylcarboxy-substituted OHMG derivatives. [ABSTRACT FROM AUTHOR]

The study describes the development of a simple and effective method for 18 F-fluoroethylation -omitting the azeotropic drying step- by elution of a [ 18 F]fluoride loaded QMA column with a K 2 CO 3 /K 222 /acetonitrile solution containing 2–3% (v/v) water directly to the 1,2-ethylene glycol-bis-tosylate precursor. In acetonitrile containing 2–3% (v/v) water the labeling agent 2-[ 18 F]fluoroethyl tosylate ([ 18 F]FETs) was formed in 76–96% non-isolated radiochemical yield. The method was exemplified on the 18 F-fluoroethylation of three COX-2 inhibitors with different core structures. The superiority of the so called “hydrous 18 F-fluoroethylation” is characterized by a minimum loss of [ 18 F]fluoride, by fivefold increased radiochemical yield of isolated final radiotracers and by shortened overall reaction time, in comparison to conventional approach. [ABSTRACT FROM AUTHOR]

Iron based metal organic frameworks as novel catalysts were developed for ethylbenzene synthesis by alkylation of benzene with ethanol in low temperature gas phase conditions employing MIL-101 (Fe) and MIL-88 (Fe) catalysts. Both of catalysts were synthesized with solvothermal method. Catalysts characterization were performed using X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), and Field Emission Scanning Electron Microscope (FE-SEM). Nitrogen adsorption measurements were done to determining the catalyst surface area and pore volume and pore size distribution. Also the acidity of catalysts was measured using NH 3 -TPD. The catalysts activity and product selectivity for ethylbenzene production have been investigated in a specially designed flow microreactor in gas phase. Effects of temperature and space velocity at constant benzene to ethanol ratio (3:1 volumetric ratio) have been studied for catalyst performance and ethylbenzene selectivity and yield. In comparison of two synthesized catalysts, MIL-88 showed a higher performance (100% ethanol conversion, 72% benzene conversion and 76% ethylbenzene selectivity at 175 °C). The main byproduct was recognized as toluene. Long reaction time for both catalysts showed no decline in conversion and selectivity of desired product. The BET measurement and the FTIR spectra of used catalysts revealed these Fe-based metal organic frameworks are stable catalysts for alkylation of benzene by ethanol. [ABSTRACT FROM AUTHOR]