- Terminal functionalization of polypropylene by radical-mediated thiol-ene addition
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The radical-mediated addition of alkanethiols to the terminal unsaturation of polypropylene (PP) is used to prepare functional polyolefin derivatives without altering the molecular weight of the parent material. The sulfide product of thiol-ene addition, as well as the internal olefin resulting from a remarkable thiyl radical-mediated olefin migration, is characterized using a model hydrocarbon, 2,4-dimethylhept-1-ene. The yield of 3- mercaptopropyltrimethoxysilane (MPTMS) addition to atactic-PP is examined in detail, and the functionalization of high molecular weight isotactic-PP is used to produce moisture-curing resins that bind to siliceous fillers. The limited unsaturation content of PP, along with the high temperatures needed to modify the resin in its melt state, is shown to impact negatively on the reaction conversion due to the reversibility of thiyl radical attack on olefin.
- Parent, J. Scott,Sengupta, Saurav S.
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- Design of heterogeneous catalysts via multiple active site positioning in organic-inorganic hybrid materials
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Catalytic materials bearing multiple sulfonic acid functional groups and positioned at varying distances from one another on the surface of mesoporous solids are prepared to explore the effects that the spatial arrangement of active sites have on catalytic activity and selectivity. A series of organosiloxane precursors containing either disulfide or sulfonate ester functionalities (synthons of the eventual sulfonic acid groups) are synthesized. From these molecular precursors, a variety of organic - inorganic hybrid, mesostructured SBA-15 silica materials are prepared using a postsynthetic grafting procedure that leads to disulfide and sulfonate ester modified silicas: [Si]CH2CH2CH2SS-pyridyl, 2·SBA, [Si]CH2CH2CH2SSCH2 CH2CH2[Si], 3·SBA, [Si]CH2CH2(C6H4) (SO2)OCH2CH3, 4·SBA, and [Si]CH2CH2(C6H4) (SO2)OC6H4O(SO2) (C6H4)CH2CH2[Si], 6·SBA ([Si] = (≡SiO)x(RO)3-xSi, where x = 1, 2). By subsequent chemical derivatization of the grafted species, thiol and sulfonic acid modified silicas are obtained. The materials are characterized by a variety of spectroscopic (13C and 29Si CP MAS NMR, X-ray diffraction) and quantitative (TGA/DTA, elemental analysis, acid capacity titration) techniques. In all cases, the organic fragment of the precursor molecule is grafted onto the solid without measurable decomposition, and the precursors are, in general, attached to the surface of the mesoporous oxide by multiple siloxane bridges. The disulfide species 2·SBA and 3·SBA are reduced to the corresponding thiols 7·SBA and 8·SBA, respectively, and 4·SBA and 6· SBA are transformed to the aryl sulfonic acids 11·SBA and 12·SBA, respectively. 7·SBA and 8·SBA differ only in terms of the level of control of the spatial arrangement of the thiol groups. Both 7·SBA and 8·SBA are further modified by oxidation with hydrogen peroxide to produce the alkyl sulfonic acid modified materials 9·SBA and 10·SBA, respectively. The performances of the sulfonic acid containing SBA-15 silica materials (with the exception of 12·SBA) are tested as catalysts for the condensation reaction of phenol and acetone to bisphenol A. The alkyl sulfonic acid modified material 10·SBA derived from the cleavage and oxidation of the dipropyl disulfide modified material 3·SBA is more active than not only its monosite analogue 9· SBA, but also the presumably stronger acid aryl sulfonic acid material 11·SBA. It appears that a cooperative effect between two proximal functional groups may be operating in this reaction.
- Dufaud, Veronique,Davis, Mark E.
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- SILANE COMPOUND, SILICA MASTERBATCH COMPRISING THE SAME AND METHOD FOR PREPARING THE SAME
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The present invention provides a silane compound represented by structural formula 1. The silane compound, a silica master batch comprising the same, and a method for comprising the same of the present invention comprises the silane compound which is a methoxy-based silane coupling agent having high hydrolytic reactivity and an excellent surface modification effect, thereby having an effect of excellent vulcanization characteristics and mechanical properties.COPYRIGHT KIPO 2020
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Paragraph 0165-0170
(2019/12/25)
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- Iridium-Catalyzed Hydrosilylation of Sulfur-Containing Olefins
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Hydrosilylation of various sulfur-containing olefins with (RO)3SiH has been achieved using iridium catalysts [IrX(cod)]2 (X = Cl, SPh). The catalysis is applicable to the chemoselective hydrosilylation of thioacetate, which enables the preparation of an industrially important silane coupling agent.
- Srinivas, Venu,Nakajima, Yumiko,Sato, Kazuhiko,Shimada, Shigeru
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supporting information
p. 12 - 15
(2018/01/12)
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- Photocatalytic transformation of organic and water-soluble thiols into disulfides and hydrogen under aerobic conditions using Mn(CO)5Br
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The photolysis of Mn(CO)5Br with thiols under aerobic conditions at room temperature produces the corresponding disulfides in high yields, accompanied by the evolution of hydrogen as the only other product. This transformation is a greener route toward the synthesis of disulfides and exhibits 100% atom economy. The catalytic system possesses high chemoselectivity, as evidenced by high disulfide yields even in the presence of numerous functional groups. A mechanism has been proposed to involve free radical species and is based on fac-Mn(CO)3(RSH)2Br being an important catalytic intermediate. Mn(CO)5Br is also able to catalyze the conversion of naturally occurring water-soluble thiols such as cysteine and glutathione. Coupled with suitable enzymes that regenerate thiols from disulfides using proton sources, it is possible to envisage a combined catalytic cycle that is able to reduce protons to hydrogen efficiently.
- Tan, Kheng Yee Desmond,Teng, Guan Foo,Fan, Wai Yip
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experimental part
p. 4136 - 4143
(2011/10/03)
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- CpMn(CO)3-catalyzed photoconversion of thiols into disulfides and dihydrogen
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The UV photolysis of CpMn(CO)3 with thiols at room temperature effected the following catalytic transformation: 2 RSH → R 2S2 + H2. This reaction is a cleaner and greener way toward making disulfides, as it produces dihydrogen as the only side-product. The manganese system exhibits high chemoselectivity as the transformation proceeds efficiently even in the presence of numerous functional groups. A manganese dicarbonyl complex, CpMn(CO)2RSH, and cyclopentadiene have also been detected using FTIR and NMR spectroscopic techniques, respectively. Based on our experimental data, a mechanism has been proposed to account for the catalysis.
- Tan, Kheng Yee Desmond,Kee, Jun Wei,Fan, Wai Yip
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experimental part
p. 4459 - 4463
(2011/01/10)
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- An original synthesis of highly ordered organosilica with a high content of thiol groups
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Well ordered bridged organosilica highly functionalised with disulfide groups were obtained by self-assembly of α,ω-bis(trimethoxysilyl) alkyldisulfide under hydrophilic conditions; the reduction of disulfide cores to SH groups gave rise to material having a high mercury ion adsorption capacity. The Royal Society of Chemistry 2006.
- Alauzun, Johan,Mehdi, Ahmad,Reye, Catherine,Corriu, Robert J. P.
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p. 347 - 349
(2008/02/08)
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- Process for the production of sulfur containing organosilicon compounds
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Compounds are prepared having the formula wherein Z is STR1 where R1 is an alkyl group of 1 to 4 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms or phenyl, R2 is an alkoxy group of 1 to 8 carbon atoms, a cycloalkoxy group of 5 to 8 carbon atoms or phenoxy, Alk is a divalent hydrocarbon chain of 1 to 10 carbon atoms which can be interrupted with one or two --O--, --S-- or --NH group, and X is a number of 2 to 6 by reacting a compound having the formula Ii. z--alk--SH with sulfur. Some of the compounds are novel and some are old, e.g., in Meyer-Simon U.S. Pat. No. 3,842,111. The compounds are useful as bonding agents in sulfur vulcanizable rubbers.
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