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CATALYSTS, DESULFURIZATION, CARBON emissions, ORGANIC chemistry, CARBON disulfide, and INTERMEDIATES (Chemistry)

Hydrodesulfurization is well established in the industry while costly and environmentally unfriendly due to CO 2 emissions and H 2 S production. An alternative, cost-effective desulfurization process remains unreported. Here, we demonstrate a desulfurization process for dibenzothiophene, one of the most well-known and recalcitrant sulfur-containing model compounds against catalytic desulfurization, under the regulation of methane instead of hydrogen over a combination of two catalysts, generating a new sulfur-containing product, CS 2 , as an important intermediate in organic chemistry and non-polar solvent with lower environmental impact than H 2 S. A catalytic mechanism is proposed and supported by extensive experimental and computational evidence. It is discovered that methane acts as a critical initiator and intensifies the direct desulfurization pathway, where two catalysts must work cooperatively and a surface sulfur transfer process is indispensable. This study explores an alternative desulfurization route with unique reaction pathways towards CS 2 formation, whose practical potential is also supported by the desulfurization performance over a series of real-world crude samples. [Display omitted] • Methane-regulated catalytic desulfurization of dibenzothiophene is realized. • Methane initiates a direct desulfurization pathway and ends up in final products. • Carbon disulfide is observed as an environmentally benign sulfur-containing product. • A dual catalyst system is designed and the mechanism is proposed and verified. • Real-world sample desulfurization practices confirm the technical feasibility. [ABSTRACT FROM AUTHOR]

CATALYSTS, CYCLOHEXENE, ORGANIC chemistry, CHEMICAL reactions, CERIUM oxides, and CATALYTIC oxidation

• Ultrasonic impregnation of Co, Ce or Co-Pd active phase on γ-Al 2 O 3 is presented. • Ultrasounds influences higher metal distribution and smaller crystallites and grains. • Characterization methods indicate Co as Co 3 O 4 or CoAl 2 O 4 and Ce in the form of CeO 2. • The addition of Pd to Co/γ-Al 2 O 3 do not influence the status of cobalt. • Ultrasonic irradiation increases surface area and decreases pore size and pore volume. The oxidation of cyclohexene belongs to the most important reactions in organic chemistry and leads to the production of the precursors for surfactants, polymers, agrochemicals, and drugs. So far, however, due to a complex reaction mechanism, it was hard to find the catalyst of satisfactory properties. Attractive catalysts in this reaction could be sonochemically prepared Co, Ce, and Pd containing γ-Al 2 O 3 , which is the object of the undertaken research. What is more, this combination of metals in the oxide system has not been studied. The analysis of catalytic performance indicated that all studied catalysts were active in the catalytic oxidation of cyclohexene. For metal-containing alumina (Me=Co, Ce, Pd), the conversion of cyclohexene was 61–84%. The best catalyst was Co 5 Ce 5 /γ-Al 2 O 3 s , prepared via the sonochemically-assisted procedure. It was also shown that the application of ultrasonic irradiation during the preparation of samples enhanced metal distribution over alumina support, resulted in smaller crystallites of prepared materials, and caused higher surface area with simultaneous smaller both pore size and pore volume in comparison with counterparts prepared via the standard procedure. XRD, Ra, and DR..-UV–vis spectroscopies indicated the coexistence of Co as Co 3 O 4 and CoAl 2 O 4 spinel, however, Ce was found in the form of CeO 2. The addition of Pd to Co/γ-Al 2 O 3 did not influence the status of cobalt. [Display omitted] [ABSTRACT FROM AUTHOR]

MEASUREMENT of viscosity, DIFFUSION coefficients, STABILITY constants, AQUEOUS solutions, ORGANIC chemistry, TEMPERATURE measurements, CARBONATE minerals, and GLYCERIN

[Display omitted] • Diffusivity, density and viscosity for GC in H 2 O were measured at 283.15 K–313.15 K. • The activation energy and the hydrodynamic parameters were calculated. • Data analysis suggests the formation of hydrogen bonded GC-GC dimers. • Formation constant, diffusivity and hydrodynamic radius were calculated for the dimer. Glycerol Carbonate (4-hydroxymethyl-2-oxo-1,3-dioxolane, GC) is an emerging green reactant for many organic chemistry applications. GC popularity stems from its high reactivity, which makes it attractive for many chemical transformations and for its easy synthesis from glycerol, a byproduct of biodiesel production. While extensive literature covers the synthesis and chemical reactivity of GC, its transport properties are poorly studied, especially in water. Here, we measured for the first time the diffusion coefficient of GC in water in the temperature range 283.15–313.15 K and for concentrations up to 0.1 M. By taking advantage of the Taylor Dispersion Analysis (TDA) we found D 0 = 9.53 ± 0.06 × 10 - 10 m2/s at 298.15 K and an activation energy for the diffusion process E a = 3.74 ± 0.09 kcal/mol. Density and dynamic viscosity were also measured in the same temperature interval to calculate the hydrodynamic radius of GC. Experimental data helped in assessing the structure of GC aggregates formed in aqueous solutions and provided an estimation of the equilibrium constant for the dimer formation. Our findings can be useful for studying the fate of GC in the environment and to improve its use for applications in aqueous media. [ABSTRACT FROM AUTHOR]

FATTY acids, ORGANIC chemistry, OLEIC acid, DIFFRACTION patterns, INDUSTRIAL capacity, INORGANIC compounds, and X-ray diffraction

The preparation of a novel crystalline fatty lambda-zirconium phosphate oleate, λ- ZrPO 4 (OH) 0.18 (C 18 H 33 O 2) 0 · 82 (CH 3) 2 SO, is reported in this research work. The material is characterized and formulated on the basis of its elemental, TGA, FT-IR and X-ray analyses. The X-ray diffraction pattern reveals that the interlayer distance of our new fatty material is heavily increased (2.96 nm) in comparison with that of the pristine λ-ZrP (1.02 nm). Therefore, this material could have potential applications in the field of intercalation chemistry of large organic and inorganic guests. • Chloride ligand of pure λ-ZrP can be easily exchanged with fatty acids. • Oleic acid leading to the formation of novel λ-type fatty solid material. • λ-ZrP materials could be functionalized with other aliphatic and aromatic fatty acids. • λ-ZrP and these fatty solid materials could have potential industrial applications. [ABSTRACT FROM AUTHOR]

ONLINE education, DISTILLATION, LEARNING strategies, PEERS, and ORGANIC chemistry

Model distillation is an effective way to let a less-parameterized student model learn the knowledge of a large teacher model. It requires a well-trained and high-performance model in advance, which limits the application of the deep model in some multimedia devices. However, the powerful teacher is not always available. Given this, some researchers propose a strategy of learning from each student model to replace the traditional teacher–student learning paradigm. Although this way has achieved good results recently, the simple mutual learning between student networks is easy to reach saturation earlier. In this work, we propose a smarter mutual learning method called Smarter Peer Learning (SPL) for online knowledge distillation, which puts forward a weight evaluation mechanism to build a virtual teacher and a novel online distillation framework. The ensemble teacher is constructed by combining the output of student networks through the calculated weight so that students will learn more from the better performance peers in the next stage of the learning. The experiments show that our SPL can train more efficient students than some existing advanced methods by applying various backbone networks to CIFAR-10, CIFAR-100, and Tiny-ImageNet datasets. [ABSTRACT FROM AUTHOR]

PRECIOUS metals, PERICYCLIC reactions, ORGANIC chemistry, DERACEMIZATION, ORGANOCATALYSIS, ASYMMETRIC synthesis, and CRUST of the earth

"Cheap but efficient". Magnesium-catalyzed enantioselective transformations can be efficiently used for the synthesis of diverse organic molecules of a complex structure. Therefore, catalysis by Earth-abundant main group metals might be considered the third way in the development of asymmetric catalysis, combining the advantages of catalysis with noble metals and organocatalysis. [Display omitted] Magnesium (Mg) constitutes one of the most abundant metal elements in the Earth's crust. The spectacular career of magnesium in organic chemistry has been initiated at the beginning of XX century and has still been lasting today. The discovery of organomagnesium compounds by Philippe A. Barbier and Victor Grignard is commonly recognized as one of the milestones in development of (organic) chemistry. The subsequent applications of Grignard reagents as relatively easy generated synthons in enantioselective reactions have opened new possibilities for acquiring enantiomerically enriched compounds. On the other hand, asymmetric reactions in which magnesium plays a role of catalyst can be considered still limited, especially when their number is compared to the number of contributions aimed at transition metal-catalyzed or organocatalyzed stereoselective transformations. However, taking into account the current trends of replacing expensive metals with their cheaper counterparts and making catalysis more environmentally (and user) friendly, the development of new and modification of known methods, which employ Earth-abundant metals, is very advisable. In this study we intend to emphasize the role of magnesium in organic chemistry, mainly in catalytic asymmetric synthesis. Among the already reported catalytic procedures, we have discussed the most recent examples, however, we also mentioned some, the groundbreaking previous ones. An exception for the pericyclic reactions has been made, as these reactions constitute the first examples of the use of magnesium catalysis in asymmetric synthesis. An attention has been drawn to some structural aspects, associated with either experimentally-determined geometry of the catalytic species or the calculated transition state(s) for a given asymmetric transformation. [ABSTRACT FROM AUTHOR]

TERTIARY amines, IMINES, BIOACTIVE compounds, ORGANIC chemistry, AMINES, ENOLS, and NUCLEOPHILES

Chiral α-tertiary amines, a motif present in α,α-disubstituted α-amino acids, in a wide range of natural products, and many drugs and drug candidates, are important targets in organic chemistry. Among the possible strategies, 1,2-addition to chiral N -sulfinyl-ketimines is one of the best routes to form chiral α-tertiary amines with a high level of stereoselectivity. In this review, we focus first on the addition of organometallic reagents or other nucleophiles as enols or ylides to chiral N -sulfinylketimines. Then secondly we cover a selection of applications of these additions in the synthesis of valuable biologically active compounds. 1 Introduction 2 1,2-Addition Reaction Methodologies 2.1 Organolithium Reagent Additions 2.2 Grignard Additions 2.3 Organozinc Reagent Additions 2.4 Organoindium Reagent Additions 2.5 Organoboron Reagent Additions 2.6 Strecker Reactions 2.7 Palladium-Catalyzed Reactions 2.8 Enols, Enolates, and Other Deprotonated Reagent Additions 2.9 Ylide Additions 2.10 Heteroatom Nucleophiles 2.11 Miscellaneous Reactions 3 Applications to the Synthesis of Biologically Active Molecules 4 Conclusions [ABSTRACT FROM AUTHOR]

ORGANIC chemistry, RADICAL anions, ACENES, MATERIALS science, and X-ray diffraction

Boron‐embedded heteroacenes (boraacenes) have attracted enormous interest in organic chemistry and materials science. However, extending the skeleton of boraacenes to higher acenes (N≥6) is synthetically challenging because of their limited stability under ambient conditions. Herein, we report the synthesis of boron‐embedded heptacene (DBH) and nonacene (DBN) as the hitherto longest boraacenes. The former is highly stable (even after 240 h in tetrahydrofuran), while the latter is air‐sensitive with the half‐life (t1/2) of 11.8 min. The structures of both compounds are verified by single‐crystal X‐ray diffraction, revealing a linear backbone with an antiaromatic C4B2 core. Photophysical characterizations associated with theoretical calculations indicate that both compounds exhibit highly efficient anti‐Kasha emissions. Remarkably, the air‐stable DBH manifests an ultrahigh photoluminescence quantum yield (PLQY) of 98±2 % and can be chemically reduced to its radical anion and dianion states, implying the value of boron‐doped higher acenes as novel functional materials. [ABSTRACT FROM AUTHOR]

CHELATION, AMINATION, CATALYSTS, ORGANIC chemistry, PHARMACEUTICAL chemistry, and OXIDATION states

Comprehensive Summary: Nitrogen‐containing compounds are ubiquitously found in the fields of organic chemistry, pharmaceuticals, agrochemicals, medicinal chemistry and functional materials. The C—H bond amination reaction is one of the most straightforward protocols in the C—N bond formation, showing "step" and "atomic" economy. As a catalyst for C—H amination reaction, copper exhibits its unique catalytic properties due to easily accessible oxidation states. The research progress of copper‐catalyzed C—H amination in recent years is summarized. At the same time, reaction mechanisms are also briefly described in representative aminations to provide insights for the development prospects of highly practical and more environmentally benign processes. [ABSTRACT FROM AUTHOR]

CHEMICAL warfare agents, LIQUID chromatography-mass spectrometry, NERVE gases, and ORGANIC chemistry

Recently, the cases of Sergei and Yulia Skripal and of Alexei Navalny have attracted considerable public interest in acetylcholine esterase inhibitors in general, and Novichok agents in particular. The name "Novichok" is given to chemical warfare agents supposedly developed in the former Soviet Union between the 1970s and the 1990s, as a reaction to the British/American invention of VX agent. These three newcomer agents were synthesized much like VX, tabun, soman, and sarin, as unitary agents, meaning that the chemical structure is altered during production so that maximum potency occurs rapidly at the outset. In response, development of binary newcomer agents escalated at GosNIIOKhT, and in 1989 the first known binary newcomer agent, Novichok-5 was synthesized off the base structure of A-232 i " (for detailed references, see Chai et al. [2]). [Extracted from the article]

HYDROGENATION, ALKENES, DIOLEFINS, ORGANIC chemistry, SILYL enol ethers, LIGANDS, and CATALYSTS

Comprehensive Summary: Olefins are very easily accessible compounds which are both popular substrates in synthetic chemistry and good ligands in the organometallic complexes. This dual character makes olefins a rich source of chiral ligands and catalysts for asymmetric catalysis. Herein, we will briefly summarize our studies on the development of chiral diene ligands for transition‐metal catalyzed asymmetric reactions and chiral FLP catalysts for asymmetric metal‐free hydrogenations and hydrosilylations. Several acyclic chiral diene ligands as well as P/olefin and S/olefin hybrid ligands were developed for Rh or Pd‐catalyzed asymmetric reactions. With these ligands in hand, we further put forward a novel strategy for acquiring chiral FLP catalysts via the in situ hydroboration of chiral dienes with Piers' borane. These catalysts proved to be highly effective for asymmetric metal‐free hydrogenations and hydrosilylations of imines, silyl enol ethers, ketones, and aromatic N‐heterocycles. What is the most favorite and original chemistry developed in your research group? The development of acyclic dienes both as chiral ligands and as precursors of chiral FLP catalysts. How do you get into this specific field? Could you please share some experiences with our readers? When I started my independent research in 2008, chiral olefins belong to one novel ligand type. We got into the field with the thought of the simpler the better. This experience further led us to step into FLP catalysis. What is the most important personality for scientific research? Courage and persistence of doing something unique. What are your hobbies? Walking and playing cards. How do you keep balance between research and family? Life is not only research, but also family. You believe it, the balance is there. What is your favorite journal(s)? My favorite journal is Organic Letters, in which authors can publish their work rapidly and readers can browse the progress of organic chemistry comprehensively. [ABSTRACT FROM AUTHOR]

DIPHENYL, ENANTIOMERIC purity, DERACEMIZATION, ORGANIC chemistry, DIAMIDES, and NUCLEAR magnetic resonance spectroscopy

Chiral compounds with a 1,2‐diamine structure motif and their derivatives are of great interest in organic chemistry and are broadly used in asymmetric transformations, as chiral auxiliaries, (co)ligands, and ligand core structure. Here, we present a straightforward, diastereoselective synthesis for a diamide‐bridged biaryl ligand. The ring closing reaction of the racemic atropos biphenyl 6,6′‐dimethoxy‐[1,1′‐biphenyl]‐2,2′‐dicarboxylic acid with (R,R)‐diaminocyclohexane yields the diasteromerically and enantiomerically pure cyclic (Sax,R,R)‐BIPOL, which can be used as a versatile chiral ligand. By NMR spectroscopy, we observed the formation of intermolecular aggregates of the diamide‐bridged BIPOL with anhydrous DMSO‐d6. DFT calculations at the B3LYP/6‐31G* level of theory corroborate the high interconversion barrier for the biaryl axis of ΔGǂ = 148.7 kJ mol−1 and the favoured formation of (Sax,R,R)‐BIPOL as single stereoisomer. [ABSTRACT FROM AUTHOR]

QUINONE derivatives, MELTING points, INDOLE, THIN layer chromatography, and ORGANIC synthesis

12-Ethyl-6-methyliden-1,2,3,4,5,6-hexahydro-1,5-methanoazocino[4,3-b]indole-3-one (4) Methyllithium (10 mL, 3.0 M MeLi solution in THF) was added to a solution of compound B 3 b (1.5 g, 5.2 mmol) in 30 mL of anhydrous THF under a nitrogen atmosphere at 0 SP ° sp C and the mixture was stirred at 0 SP ° sp C for 1 h. The organic layer was dried over magnesium sulfate, filtered, and the solvent was evaporated to give an oil, which was purified by column chromatography (silica gel, ethyl acetate:acetone:triethylamine, 4:1:1). Finally, compound B 4 b was reduced with tris(triphenylphosphine)rhodium(I) carbonyl hydride in THF to give (±)-noruleine B 5 b in four steps, with an over-all yield of 41% and also obtained as yellow oil.[21],[22],[28] All of the component compounds in the preparative sequence were rigorously characterized (see Experimental section). The uleine alkaloids (Figure 1) have remarkable biological activities and have attracted much interest from synthetic organic chemists. [Extracted from the article]

DISSOLVED organic matter, ION mobility spectroscopy, ION cyclotron resonance spectrometry, ORGANIC chemistry, TIME-of-flight mass spectrometry, and EUTROPHICATION

• Eutrophication shaped DOM chemistry to a more aliphatic signature with lower isomeric complexity. • Eutrophication induced production of a red-shifted humic-like fluorescence. • This red-shifted humic-like fluorescence carries an aliphatic molecular signature. • Reed marsh introduced unique highly aromatic compounds to connected rivers. • Optical and molecular techniques are complimentary for DOM cycling study in coastal environments. Dissolved organic matter (DOM) plays a crucial role in the coastal carbon cycle. However, eutrophication-induced algal blooms and lateral transport from connected tidal marshes may significantly affect DOM cycling, which remains poorly understood. By combining a suite of bulk and optical techniques, and the Fourier transform ion cyclotron resonance mass spectrometry and ion mobility quadrupole time-of-flight mass spectrometry, we determined DOM concentration and composition along two typical river-estuary transects (namely Liao and Daliao rivers), Northeast China, with contrasting eutrophic state and distribution of tidal marshes. The Daliao River is characterized by a higher eutrophication degree and is surrounded with lower reed coverage than the Liao River. Compared to the Liao River, significantly higher dissolved organic carbon concentrations were observed in the Daliao River, where higher stable carbon isotope (δ13C) values and protein-like fluorescent components, characterized relatively higher autochthonous DOM. Further molecular analysis revealed higher peptide and sugar-like compounds but lower isomeric percentages of several molecular formulas in the Daliao River, suggesting higher molecular lability but lower isomeric complexity than the Liao River. Associations between optical and molecular signatures among all DOM samples revealed that a red-shifted humic-like C3 component was significantly correlated with molecular formulas with lower molecular weight and aromaticity, and higher H/C, indicating that C3 was likely a result of phytoplankton production coupled with further heterotrophic processing. Moreover, we found that reed marshes could introduce to both rivers a series of carboxylic-rich alicyclic compounds, highly unsaturated compounds, and polyphenols with high molecular weight and low H/C. This study suggests that eutrophication and reed marsh affect the DOM quality and can be a potential source of recalcitrant DOM compounds to coastal rivers and estuaries, which warrants further investigations considering the increasing worldwide eutrophication and sea-level rise in coastal delta environments. [Display omitted] [ABSTRACT FROM AUTHOR]

DENSITY functionals, ORGANIC chemistry, and CHEMICAL reactions

In this Communication, we assess a panel of 18 double-hybrid density functionals for the modeling of the thermochemical and kinetic properties of an extended dataset of 449 organic chemistry reactions belonging to the BH9 database. We show that most of DHs provide a statistically robust performance to model barrier height and reaction energies in reaching the "chemical accuracy." In particular, we show that nonempirical DHs, such as PBE0-DH and PBE-QIDH, or minimally parameterized alternatives, such as ωB2PLYP and B2K-PLYP, succeed to accurately model both properties in a balanced fashion. We demonstrate, however, that parameterized approaches, such as ωB97X-2 or DSD-like DHs, are more biased to only one of both properties. [ABSTRACT FROM AUTHOR]

ORGANIC compounds, ORGANIC chemistry, COMPLEX compounds, PHOSPHINE oxides, ALDEHYDES, and PENTANE

[Display omitted] H-phosphonates, H-phosphinates and secondary phosphine oxides are versatile reagents for the construction of complex phosphoryl compounds. Their decade advances in three-component reactions were recorded in this article. Reactions with bicyclo[1.1.1]pentane, alkenes, alkynes, aldehydes, imines, S, Se, et al will be discussed. In this review, we systematically summarized the applications of these P(O)-H compounds in organic synthetic chemistry, and their mechanisms were also discussed. [ABSTRACT FROM AUTHOR]