2295-17-2Relevant academic research and scientific papers
Host-guest chemistry in a urea matrix: Catalytic and selective oxidation of triorganosilanes to the corresponding silanols by methyltrioxorhenium and the urea/hydrogen peroxide adduct
Adam, Waldemar,Mitchell, Catherine M.,Sana-Moeller, Chantu R.,Weichold, Oliver
, p. 2097 - 2103 (1999)
The oxidation of silanes to silanols, catalyzed by methyltrioxorhenium (MTO), proceeds in high conversions and excellent selectivities in favor of the silanol (no disiloxane product) when the urea/hydrogen peroxide adduct (UHP) is used as oxygen source instead of 85% aqueous H2O2. It is proposed that this novel Si-H oxidation takes place in the helical urea channels, in which the urea matrix serves as host for the silane substrate, the H2O2 oxygen source, and the MTO metal catalyst as guests. In this confined environment, the metal catalyst is stabilized against decomposition, and this enhances higher conversions while condensation of the silanol to its disiloxane is avoided for steric reasons. The oxidation of the optically active silane (S)-(α-Np)PhMeSiH proceeds with retention of configuration in excellent yield. To date, no catalytic Si-H oxygen insertion has been reported for the preparation of optically active silanols. In analogy with the stereoselectivity in the dioxirane oxidation of (+)-(α-Np)PhMeSiH to (+)-(α-Np)PhMeSiOH, a concerted spiro-type transitionstate structure is proposed for this novel Si-H oxidation. Herewith, a valuable synthetic method for the preparation of silanols has been made available through catalytic and selective oxidation of silanes to silanols by the MTO/UHP system.
The Stabilization of Three-Coordinate Formal Mn(0) Complex with NHC and Alkene Ligation
Cheng, Jun,Chen, Qi,Leng, Xuebing,Ouyang, Zhongwen,Wang, Zhenxing,Ye, Shengfa,Deng, Liang
, p. 2844 - 2860 (2018)
Low-coordinate zero-valent metal species are implicated as key intermediates in various transition-metal-catalyzed and -mediated reactions. However, knowledge on this type of metal species has been mainly restricted to the metals in groups 8–10, and that
FTIR study of thermally induced transformations of trimethylsilylmethyl acetate in the temperature range 623-813 K
Ball, Ian K.,Harrison, Philip G.,Torr, Ashley
, p. 185 - 194 (2000)
The chemistry of trimethylsilylmethyl acetate in the gas phase in the temperature range 623-813 K has been investigated under static conditions using Fourier transform IR spectroscopy. Little change occurs at temperatures lower than 623 K, at which temperature a thermally induced isomerization to form ethyldimethylsilyl acetate occurs. Some ethanoic acid is also produced at this temperature. The ethyldimethylsilyl acetate produced undergoes thermolysis at temperatures > 723 K giving methane, ethene, carbon monoxide, carbon dioxide, ethanoic acid, 1,3-diethyl-1,1,3,3-tetramethyldisiloxane, cyclohexamethyltrisiloxane, and cyclooctamethyltetrasiloxane as products. Loss of ethyldimethylsilyl acetate is first order over the whole temperature range, and first-order rate constants vary from 4.87 × 10-5 s-1 at 723 K to 33.5 × 10-5 s-1 at 813 K, respectively, leading to an activation energy, Ea,, of 110(4) kJ mol-1. An intramolecular five-centre process is proposed for the isomerization reaction. The thermolysis is interpreted in terms of principally radical reactions involving initial homolytic dissociation of the EtMe2SiO-C(O)CH3 bond.
Preparation method of 1,3-diphenyl-1,1,3,3-tetramethyl disiloxane
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Paragraph 0018; 0020, (2017/05/25)
The invention discloses a preparation method of 1,3-diphenyl-1,1,3,3-tetramethyl disiloxane. The preparation method is characterized in that the Wurtz method or Grignard method is adopted, and 1,3-diphenyl-1,1,3,3-tetramethyl disiloxane is synthesized through disiloxane rectified from an organosilicon high-boiling component and a halogenated compound. According to the preparation method, market application and high-value utilization of the organosilicon high-boiling component are expanded, and a raw material basis can be further provided for preparation of organosilicon materials with special functions.
An efficient iridium catalyst for reduction of carbon dioxide to methane with trialkylsilanes
Park, Sehoon,Bezier, David,Brookhart, Maurice
supporting information; experimental part, p. 11404 - 11407 (2012/09/05)
Cationic silane complexes of general structure (POCOP)Ir(H)(HSiR 3) {POCOP = 2,6-[OP(tBu)2]2C6H 3} catalyze hydrosilylations of CO2. Using bulky silanes results in formation of bis(silyl)acetals and methyl silyl ethers as well as siloxanes and CH4. Using less bulky silanes such as Me 2EtSiH or Me2PhSiH results in rapid formation of CH 4 and siloxane with no detection of bis(silyl)acetal and methyl silyl ether intermediates. The catalyst system is long-lived, and 8300 turnovers can be achieved using Me2PhSiH with a 0.0077 mol % loading of iridium. The proposed mechanism for the conversion of CO2 to CH4 involves initial formation of the unobserved HCOOSiR3. This formate ester is then reduced sequentially to R3SiOCH2OSiR 3, then R3SiOCH3, and finally to R 3SiOSiR3 and CH4.
