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]
Kuterasiński, Ł., Kurowski, G., Jeleń, P., Sitarz, M., and Jodłowski, P.J.
Journal of Molecular Structure. Aug2022, Vol. 1261, pN.PAG-N.PAG. 1p.
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]
Valletti, Nadia, Acar, Mert, Cucciniello, Raffaele, Magrini, Claudia, Budroni, Marcello A., Tatini, Duccio, Proto, Antonio, Marchettini, Nadia, Lo Nostro, Pierandrea, and Rossi, Federico
Journal of Molecular Liquids. Jul2022, Vol. 357, pN.PAG-N.PAG. 1p.
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]
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]
Czombik, Anna M., Gajewy, Jadwiga, Czapik, Agnieszka, and Kwit, Marcin
Polyhedron. Jun2022, Vol. 219, pN.PAG-N.PAG. 1p.
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]
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]
Ma, Jiao‐Li, Zhou, Xu‐Ming, Guo, Peng‐Hu, Cheng, Hui‐Cheng, and Ji, Hong‐bing
Chinese Journal of Chemistry. May2022, Vol. 40 Issue 10, p1204-1223. 20p.
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]