4667-99-6Relevant academic research and scientific papers
Semisynthetic Antimycobacterial C-3 Silicate and C-3/C-21 Ester Derivatives of Fusidic Acid: Pharmacological Evaluation and Stability Studies in Liver Microsomes, Rat Plasma, and Mycobacterium tuberculosis culture
Njoroge, Mathew,Kaur, Gurminder,Espinoza-Moraga, Marlene,Wasuna, Antonina,Dziwornu, Godwin Akpeko,Seldon, Ronnett,Taylor, Dale,Okombo, John,Warner, Digby F.,Chibale, Kelly
, p. 1634 - 1644 (2019)
Fusidic acid (FA), a natural product fusidane triterpene-based antibiotic with unique structural features, is active in vitro against Mycobacterium tuberculosis, the causative agent of tuberculosis (TB). While possessing good pharmacokinetics in man, FA is rapidly metabolized in rodents, thus complicating proof-of-concept studies in this model. Toward the repositioning of FA as an anti-TB agent, we herein describe the synthesis, activity, and metabolism of FA and semisynthesized ester derivatives in rat liver microsomes, rat plasma, and mycobacterial cell culture. FA and derivative molecules with a free C-3 OH underwent species-specific metabolism to the corresponding 3-OH epimer, 3-epifusidic acid (3-epiFA). FA was also metabolized in rat plasma to form FA lactone. These additional routes of metabolism may contribute to the more rapid clearance of FA observed in rodents. C-3 alkyl and aryl esters functioned as classic prodrugs of FA, being hydrolyzed to FA in microsomes, plasma, and Mycobacterium tuberculosis culture. In contrast, C-3 silicate esters and C-21 esters were inert to hydrolysis and so did not act as prodrugs. The antimycobacterial activity of the C-3 silicate esters was comparable to that of FA, and these compounds were stable in microsomes and plasma, identifying them as potential candidates for evaluation in a rodent model of tuberculosis.
Synthesis of a 12-membered cyclic siloxane possessing alkoxysilyl groups as a nanobuilding block and its use for preparation of gas permeable membranes
Yoshikawa, Masashi,Shiba, Hiroya,Kanezashi, Masakoto,Wada, Hiroaki,Shimojima, Atsushi,Tsuru, Toshinori,Kuroda, Kazuyuki
, p. 48683 - 48691 (2017)
A 12-membered cyclic siloxane possessing alkoxysilyl groups was synthesized as a nanobuilding block for siloxane-based materials by the alkoxysilylation of organometallasiloxane containing a 12-membered ring with Si-Me and Si-O- groups as the side groups. The cyclic structure was retained not only in the hydrolysis and condensation reactions (sol-gel process) of the alkoxysilyl groups but also in the xerogel and membrane preparation processes. The degree of condensation of the xerogel derived from the 12-membered ring siloxane was higher than that derived from alkoxysilane monomers, indicating that the alkoxysilylated cyclic oligosiloxane is useful for controlling siloxane networks. A membrane composed of the cyclic siloxane was prepared by coating the hydrolyzed solution onto a porous alumina tube for evaluating the gas permeation properties. The membrane showed a molecular sieving effect for H2/SF6.
Synthesis of triethoxysilanol
Kazakova,Gorbatsevich,Skvortsova,Demchenko,Muzafarov
, p. 1350 - 1351 (2005)
Triethoxysilanol was isolated for the first time by hydrolysis of chloro(triethoxy)silane in an organic solvent in the presence of a heterogeneous base and identified as an individual compound. The synthesis of this compound made it possible to study its physicochemical properties and substantially extended its potentialities for the synthesis of hyperbranched polyethoxysiloxanes and functional oligomers.
Industrial synthesis method of triethoxychlorosilane
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Paragraph 0040-0077, (2021/05/05)
The invention relates to the field of organic synthesis, aims to overcome the defects of high content of byproducts, low selectivity of triethoxychlorosilane and the like in preparation of triethoxychlorosilane by using triethoxysilane as a raw material and adopting a chlorination reaction, and provides a method for converting the triethoxysilane into the triethoxychlorosilane by using trichloroisocyanuric acid as a chlorination reagent and halogenated metal salt as an additive. The method for converting the triethoxysilane into the triethoxychlorosilane has the advantages of high conversion rate of the triethoxysilane, low content of byproducts, high selectivity of the triethoxychlorosilane and small separation load, and is particularly suitable for industrial preparation of the triethoxychlorosilane.
Method for removing methyldichlorosilane and silicon tetrachloride impurities in trimethyl chlorosilane
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Paragraph 0037-0038; 0042-0044; 0049; 0051-0052; 0063; ..., (2021/08/25)
The invention relates to a method for removing methyldichlorosilane and silicon tetrachloride impurities in trimethyl chlorosilane, which comprises a hydrosilylation reaction, a partial esterification reaction and a complete esterification reaction. Firstly, a mixture of trimethylsilyl chloride containing methyldichlorosilane and silicon tetrachloride impurities is added to a reactor for hydrosilylation reaction, and the reaction product enters a separation system. The silicon tetrachloride in the mixture is partially esterified and reacted by adding the low-carbon alcohol as an esterifying agent, and the reaction product enters a separation system. Finally, the partially esterified product is further fully esterified to valuable tetraalkoxy silicon products. The high-efficiency recycling of trimethylchlorosilane is realized, and high-value utilization is also realized.
Synthesis of Polycyclic and Cage Siloxanes by Hydrolysis and Intramolecular Condensation of Alkoxysilylated Cyclosiloxanes
Sugiyama, Tomoaki,Shiba, Hiroya,Yoshikawa, Masashi,Wada, Hiroaki,Shimojima, Atsushi,Kuroda, Kazuyuki
, p. 2764 - 2772 (2019/02/01)
The controlled synthesis of oligosiloxanes with well-defined structures is important for the bottom-up design of siloxane-based nanomaterials. This work reports the synthesis of various polycyclic and cage siloxanes by the hydrolysis and intramolecular condensation of monocyclic tetra- and hexasiloxanes functionalized with various alkoxysilyl groups. An investigation of monoalkoxysilylated cyclosiloxanes revealed that intramolecular condensation occurred preferentially between adjacent alkoxysilyl groups to form new tetrasiloxane rings. The study of dialkoxy- and trialkoxysilylated cyclotetrasiloxanes revealed multistep intramolecular condensation reactions to form cubic octasiloxanes in relatively high yields. Unlike conventional methods starting from organosilane monomers, intramolecular condensation enables the introduction of different organic substituents in controlled arrangements. So-called Janus cubes have been successfully obtained, that is, Ph4R4Si8O12, in which R=Me, OSiMe3, and OSiMe2Vi (Vi=vinyl). These findings will enable the creation of siloxane-based materials with diverse functions.
Selective Formation of Alkoxychlorosilanes and Organotrialkoxysilane with Four Different Substituents by Intermolecular Exchange Reaction
Komata, Yuma,Yoshikawa, Masashi,Tamura, Yasuhiro,Wada, Hiroaki,Shimojima, Atsushi,Kuroda, Kazuyuki
, p. 3225 - 3233 (2016/11/29)
Alkoxychlorosilanes are scientifically and industrially important toward preparing silicone and silica as well as preparation of siloxane-based nanomaterials by stepwise reactions of Si?OR (R=alkyl) and Si?Cl groups. Intermolecular exchange of alkoxy and chloro groups between alkoxysilanes and chlorosilanes (functional group exchange reaction) provides an efficient and environmentally benign route to alkoxychlorosilanes. BiCl3 as a Lewis acid catalyst can promote the functional group exchange reactions more efficiently than conventional acid catalysts. Higher reactivity has been observed for chlorosilanes with smaller numbers of Si?CH3 groups and for alkoxysilanes with larger numbers of Si?CH3 groups. The reaction mechanism is proposed and selective syntheses of alkoxychlorosilanes are demonstrated. These findings also enable us to synthesize an organotrialkoxysilane with four different substituents.
Method of producing arylhalosilane alkoxyphthalocyanine (by machine translation)
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Paragraph 0015; 0021-0022; 0027, (2016/10/09)
PROBLEM TO BE SOLVED: alkoxyphthalocyanine arylhalosilane compd. alkoxy halo silane can be efficiently manufactured to provide a novel method of producing and purpose. SOLUTION: arylhalosilane compd. alkylalkoxysilane compound having a functional group and in exchange reaction, by utilizing a bismuth halide (III), alkoxyphthalocyanine arylhalosilane compd. can be efficiently manufactured. Selected drawing: no (by machine translation)
Mechanistic insights into the hydrosilylation of allyl compounds - Evidence for different coexisting reaction pathways
Gigler, Peter,Drees, Markus,Riener, Korbinian,Bechlars, Bettina,Herrmann, Wolfgang A.,Kuehn, Fritz E.
, p. 1 - 14 (2013/01/14)
The hydrosilylation of allyl compounds is often accompanied by the formation of high amounts of byproducts. The formation processes have not been fully understood so far. In this work, the allyl hydrosilylation mechanism is investigated in detail and experimental and theoretical evidence for multiple, coexisting reaction pathways is provided. Based on earlier reports and the observations during an extensive catalytic study, different pathways, leading to the observed byproducts, were identified and proven by labeling experiments and DFT calculations. Oxidative addition of the silane and the insertion of the allyl compound into the Pt-H bond turned out to be the crucial, selectivity-determining steps within the catalytic cycle. Based on these findings, it should be possible to systematically influence these steps and pave the way to a rational and straightforward design of more selective catalysts.
Ethylene polymerization reactions with multicenter Ziegler-Natta catalysts-manipulation of active center distribution
Kissin, Yury V.,Mink, Robert I.
scheme or table, p. 4219 - 4229 (2011/12/15)
This article describes ethylene/1-hexene copolymerization reactions with a supported titanium-based, multicenter Ziegler-Natta catalyst. The catalyst was modified by pretreating its solid precursor with AlEt2Cl and with similar organoaluminum chlorides, Al2Et3Cl3, AlEtCl2, and AlMe2Cl. Testing of the untreated and the pretreated catalysts in copolymerization reactions under standard reaction conditions demonstrated that the modifying agents produce two changes in the catalyst. First, the pretreatment significantly reduces the reactivity of active centers that produce high molecular weight, highly crystalline copolymer components with a low 1-hexene content. Second, the pretreatment noticeably increases the reactivity of active centers that produce low molecular weight copolymer components with a high 1-hexene content. The first effect is caused by Lewis acidbase interactions of the modifiers with the active centers, whereas the second (activating) effect is due to the removal of catalyst poisons (organosilicon compounds generated in the process of the catalyst synthesis) by AlEt2Cl.
