China
Africa
Explore chapters and articles related to this topic
Photocatalysts Based on Covalent Organic Frameworks
Published in Tuan Anh Nguyen, Ram K. Gupta, Covalent Organic Frameworks, 2023
Nazanin Mokhtari, Mohammad Dinari
Phthalocyanines, porphyrins, and triazines are nitrogen-rich skeletons used to prepare COFs. However, using other heteroatoms could also be helpful. The electron-donor ability of the sulfur-containing heterocycles was approved in different studies. Thiophene derivatives have been put at the center of attention due to their excellent electronic properties. They also used electron-withdrawing materials to prepare D-A systems. SBA-15 is mesoporous silica with hexagonal channels used as a substrate for different materials. In 2017, Zhang and co-workers [43] trimerized 2,5-dicyanothiophene on the SBA-15 to prepare a thiophene-based CTF (CTF-Th@SBA-15). The formation of triazine units, besides the thiophene moieties, developed a D-A system. The levels of HUMO and LUMO of the prepared material were found to be at +1.75 V and -0.72 V (vs. SCE) respectively. It led to a visible-light absorption at around 520 nm. Comparing the CTF-Th@SBA-15 and pure CTF-Th, represent a marked increase in the surface area and photocatalytic activity of CTF-Th@SBA-15 in benzyl alcohol oxidation to benzaldehyde. The higher photocatalytic activities might be due to the mesoporous structure of the support, making nanoreactors for reactions.
Desulfurization of Diesel Fuels
Published in Ozcan Konur, Petrodiesel Fuels, 2021
Lauritsen et al. (2004) synthesized single-layer MoS2 nanoclusters on an Au substrate as a model system for the hydrotreating catalyst and studied them by atomically resolved scanning tunneling microscopy (STM) in order to achieve atomic-scale insight into the interactions with hydrogen and thiophene (C4H4S) in a paper with 238 citations. Surprisingly, they observed that thiophene molecules could adsorb and react on the fully sulfided edges of triangular single-layer MoS2 nanoclusters. They associate this unusual behavior with the presence of special brim sites exhibiting a metallic character. These sites existed only at the regions immediately adjacent to the edges of the MoS2 nanoclusters, and from density-functional theory such sites were associated with one-dimensional electronic edge states. The full sulfur-saturated sites were capable of adsorbing thiophene, and when thiophene and hydrogen reactants were coadsorbed here, a reaction path was revealed which led to partial hydrogenation of the thiophene followed by C-S bond activation and ring opening of thiophene molecules. These might be regarded as important first steps in the HDS of thiophene. The metallic brim sites were important for other hydrotreating reactions over MoS2-based catalysts, and the properties of the brim sites directly explain why hydrogenation reactions of aromatics were not severely inhibited by H2S. The presence of brim sites in MoS nanoclusters also explains previous structure-activity relations and observations regarding steric effects and the influence of stacking of MoS2 on the reactivity and selectivity.
Crude Properties
Published in Mark J. Kaiser, Arno de Klerk, James H. Gary, Glenn E. Hwerk, Petroleum Refining, 2019
Mark J. Kaiser, Arno de Klerk, James H. Gary, Glenn E. Hwerk
Mercaptans are made of an alkyl chain with the –SH group at the end (R–SH). In sulfides, sulfur atoms occur in the chain and are often present in light fractions. Sulfides and disulfides may also be cyclic or aromatic. Thiophenes are polynuclear aromatic compounds in which the sulfur atom replaces one or more carbon atoms in the aromatic ring. Thiophenes are normally present in heavy fractions.
Recyclization of 3-formylchromone with phenacyl thiocyanate: fast and efficient access to thiophenes and 2-aminothiophenes bearing o-acylphenol moiety
Published in Journal of Sulfur Chemistry, 2022
Abdolali Alizadeh, Reza Rezaiyehraad
Thiophenes are commonly obtained via the reaction between thiation agents and 1,4-dicarbonyl compounds or hydrocarbons, especially their unsaturated derivatives. For example, the Paal–Knorr thiophene synthesis reported in 1885 is the reaction of 1,4-dicarbonyl compounds such as diketones, diesters, or dicarboxylates with phosphorus pentasulfide [20]. In 1885, the Volhard–Erdmann cyclization is used to synthesize alkyl and aryl thiophenes via cyclization of disodium succinate with P4S7 [21]. Moreover, the Gewald reaction in 1966 is described as an efficient method for the preparation of a fully substituted 2-aminothiophene via the condensation reaction between a carbonyl compound containing acidic α-hydrogen with α-cyanoesters, and S8 in the presence of a base [20,24]. In industry, thiophene is typically produced via the gas-phase reaction of CS2 and butanol fuzing an oxide catalyst in 500–550°C [21,22].
Synthesis, X-ray analysis and computational studies of two novel thiophene derivatives
Published in Journal of Sulfur Chemistry, 2020
Abdullatif Bin Muhsinah, Abdulrhman Alsayari, H. Algarni, Saied M. Soliman, Nabila A. Kheder, Hazem A. Ghabbour, Yahya I. Asiri, Kumar Venkatesan, Yahia N. Mabkhot
Thiophene is a sulfur-containing five-membered heterocyclic compound and a core structure in several biologically active, natural compounds [1,2]. Thiophene and its derivatives are scaffold compounds in heterocyclic chemistry due to their pharmacological and biological activities, as well as their applications in other fields [1–3]. Thiophene derivatives are reported to have a wide range of interesting biological and pharmacological activities, including antimicrobial [2–4], antiamoebic [5], analgesic and anti-inflammatory [6,7], antimetabolite and anticancer [8,9], antiviral [10], antipsychotic [11], antidiabetic [12], anticonvulsant [13], antidepressant [14], antihistaminic [15], antiallergic [16], antioxidant [17], antifungal [18] and antihypertensive [19]. In addition, thiophene derivatives are important in fields such as dye chemistry [20], electronic and optoelectronic devices [21] and self-assembled superstructures [22]. These compounds are used as a corrosion inhibitors for metals [23] and in the fabrication of light-emitting diodes [24]. In light of the aforementioned facts and as a continuation of our ongoing research in the synthesis of novel thiophene derivatives [2,25–29], we describe herein the synthesis, characterization, X-ray analysis and computational studies of two new thiophene derivatives.
Synthesis, characterization, and photocatalytic activity of Co(II) and Cu(II) phthalocyanines linked with thiophene–Schiff base substituents for 4-nitrophenol oxidation
Published in Journal of Coordination Chemistry, 2019
Ayse Aktas Kamiloglu, Ece Tugba Saka, Irfan Acar, Kader Tekintas
Thiophenes are important heterocyclic compounds, widely used as building blocks in many agrochemicals and pharmaceuticals. Thiophenes are strong donors [9, 10]. Sulfur-bearing compounds, such as thiophene, alkali sulfides, alkali thiosulfates, and mercaptans, are byproducts of industrial operations. Phthalocyanine compounds are powerful catalysts and photocatalysts for oxidation of sulfur-containing compounds by oxygen [11–15]. Metallophthalocyanines (especially CoPc) can reversibly coordinate and activate oxygen in the dark, which is the basis of the redox mechanism of catalytic oxidation of some sulfur-containing compounds [13]. According to these features, sulfur-containing Pcs are very useful for applications such as photooxidation and oxidation, and as gas sensors [11–16]. Additionally, Schiff base metal complexes show excellent catalytic activities in Jacobsen–Katsuki epoxidation [17, 18], oxidation [19], reduction [20], and polymerization reactions [21, 22]. They also serve as photoactive materials [23], electroluminescent materials [24], and nonlinear optical materials [25, 26].