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Additives for Crankcase Lubricant Applications
Published in Leslie R. Rudnick, Lubricant Additives, 2017
Ewa A. Bardasz, Gordon D. Lamb
Modern compounds of this type contain mostly tert-butyl radicals besides methyl groups, such as 4,4′-thio-bis-(2-tert-butyl)-5-methylphenol. Sulfur–nitrogen compounds are also suited as oxidation inhibitors to lubricating oils (2-mercaptobenzimidazole, mercaptotriazines, reaction products of benzotriazole–alkylvinyl ethers or esters, and phenothiazine and its alkyl derivatives). Among sulfur-containing carboxylic acid esters, 3, 3′-thio-bis-(propionic-acid dodecyl ester) and bis-(3,5-di-tert-butyl-4-hydroxybenzyl)-malonicaid-bis-(3-thia-pentadecyl) esters have been applied with success. These compounds have been replaced by the dialkyldithiophosphates due to their broad application spectrum. Sulfoxides, sometimes in combination with aromatic amines, have also been utilized.
Theory of Radiation-Induced Cracking Reactions in Hydrocarbons
Published in Yuriy Zaikin, Raissa Zaikina, Petroleum Radiation Processing, 2013
Thus, ozonolysis of the straight-run diesel fractions provides deep fuel desulfurization without application of catalysts, hydrogen-containing gases, or high temperatures. It also provides concomitant production of sulfoxide and/or sulfone concentrates used in industry as efficient agents for extraction of metals, flotators, and other valuable materials. However, the substantial factors that hinder the fullscale industrial realization of oil ozonolysis are the high consumption of expensive ozone and limited productivity of the industrially produced ozone generators (primarily, for water purification).
Microcrystalline Cellulose: An Overview
Published in Chin Hua Chia, Chin Han Chan, Sabu Thomas, Functional Polymeric Composites, 2017
Srimanta Sarkar, Celine Valeria Liew, Josephine Lay Peng Soh, Paul Wan Sia Heng, Tin Wui Wong
Mascia et al. introduced dimethyl sulfoxide as a non-aqueous moistening liquid for pelletization by extrusion–spheronization.52 Dimethyl sulfoxide is a polar solvent and it is used in a number of finished pharmaceutical products. However, it is not currently permitted for use in oral solid dosage forms, although it is a class III solvent (International Conference on Harmonisation, ICH, Guidelines) along with ethyl alcohol and acetone. In the study by Mascia et al.,52 the functionality of dimethyl sulfoxide as moistening liquid was compared with water and ethyl alcohol for MCC-based pellet formation. MCC-moistened mass, prepared using dimethyl sulfoxide as moistening liquid, was successfully processed to produce highly spherical pellets. The mechanical strength of pellets prepared using dimethyl sulfoxide was comparable to those prepared using water. The authors pointed out that polarity, surface tension, and viscosity of the moistening liquid were the critical properties of the solvent to be used as moistening liquid for successful pelletization by extrusion–spheronization. On the basis of the similar microstructure of pellets formulated using dimethyl sulfoxide and water as moistening liquids, it was postulated that dimethyl sulfoxide interacts with MCC in a similar fashion to water. Ethyl alcohol, on the other hand, could not solvate the MCC polar group unlike dimethyl sulfoxide and water as a result of its low polarity and surface tension attributes. Ethyl alcohol was retained in the large inter-particular void spaces and was not penetrated into the small micropores in MCC. Ethyl alcohol could not form hydrogen bonds with the microfibrils and did not promote microcrystal rearrangement. The microstructure of pellets formed was different from those of water and dimethyl sulfoxide.
Efficient aerobic oxidation of alcohols and sulfides using an M-doped (M: Mn and Ni) zinc oxide nanostructure
Published in Inorganic and Nano-Metal Chemistry, 2023
Gholam Reza Najafi, Mahboubeh A. Sharif, Mahdi Taghvay Nakhjiri, Ensieh Kazemi-Habib
Selective oxidation of sulfides and alcohols to their corresponding sulfoxides and aldehydes is the most important organic transformation because of their wide usage in beverages, pharmaceutical industries, foods, etc.[25–27] The oxidation of alcohols (especially benzyl alcohols) is proven more challenging than the other organic compounds owing to the Cα-H bond relative inertness next to an Oxygen atom.[28–36] Traditionally, stoichiometric amounts of toxic oxidizing agents such as MnO2, K2Cr2O7, etc.) have been used in oxidation procedures under harsh conditions (high or temperatures or pressure, strong mineral acids etc.). Consequently, a mass of harmful toxic salts is usually formed from these chemical transformations. As a result, design and fabrication of an effective green oxidative catalytic platform is still a serious challenge. On the other hand, sulfoxides play key role as important intermediates in organic reactions or as pharmaceutically active compounds in industry. So, there is an intense demand for mild and green methods of sulfide oxidations forming sulfoxides without overoxidation (generation of sulfones). Shan-Shui Meng et.al, reported an efficient and practical protocol for the oxidation of alcohols using a simple Mn catalyst under air.[37] They proved the generation of highly active radicals when the (Mn2(CO)10) was heated with a small amount of oxygen without additives.
New oxovanadium and dioxomolybdenum complexes as catalysts for sulfoxidation: experimental and theoretical investigations of E and Z isomers of ONO tridentate Schiff base ligand
Published in Journal of Sulfur Chemistry, 2022
Hadi Kargar, Atefeh Moghimi, Mehdi Fallah-Mehrjardi, Reza Behjatmanesh-Ardakani, Hadi Amiri Rudbari, Khurram Shahzad Munawar
Sulfoxides are of prime importance due to their contribution in biological along with industrial asymmetric synthetic procedures. Sulfoxides are served as intermediates in formulations and processing of drugs, Swern oxidation [26,27] coupling reactions for the formation of C–C bond [28,29] and in the Diels–Alder reaction [30]. Numerous kinds of transition metals were employed in the literature for the sulfoxidation reactions such as iron, cobalt, titanium and manganese [31,32]. But oxovanadium complexes got an advantage over the rest of the metals because their cyclic voltammetry curves are capable of being reversed [33]. On the other hand, sulfoxidation by dioxomolybdenum complexes has the advantages like excellent results under mild reaction conditions and the ability to interact with various kinds of substrates having diverse functional groups [34].
Efficient, selective and mild oxidation of sulfides and oxidative coupling of thiols catalyzed by Pd(II)-isatin Schiff base complex immobilized into three-dimensional mesoporous silica KIT-6
Published in Journal of Sulfur Chemistry, 2020
Saeedeh Pakvojoud, Mehdi Hatefi Ardakani, Samira Saeednia, Esmaeil Heydari-Bafrooei
The environmentally friendly catalytic oxidation of sulfides to sulfoxides with high performance has been the subject of numerous studies over the last two decades [1–4]. Sulfoxides have been applied in the synthesis of chemically useful materials such as drugs, flavors, germicides, and biologically active molecules like catabolism regulators [5]. On the other hand, the oxidation of organic sulfides such as dibenzothiophene (DBT) as an impurity in crude oil, is a major challenge in the petroleum industry and its removal is a necessary action in the petrochemical processes. Recently, Doustkhah and co-workers have prepared a green and recyclable catalyst by supporting copper(II) ions onto the internal pore surface of the thiourea-bridged periodic mesoporous organo-aluminosilica material. This catalyst (Cu@Al/Si-PMO-TU) was successfully applied for deep oxidation of dibenzothiophene to dibenzothiophen dioxide with hydrogen peroxide under aqueous conditions at room temperature [6]. Likewise, the conversion of thiols to the corresponding disulfides is a main transformation in both chemical and biological processes [7,8]. Disulfides are used in the sulfonylation of anions such as enolates, preparation of the sulfinyl and sulfenyl compounds as well as the vulcanizing agents for rubber and elastomers [9,10]. In addition, the thiol group can be protected as a disulfide, because disulfides are relatively more stable than the corresponding free thiols in the oxidation, alkylation and acylation reactions [11].