Synthesis of Aromatic Sulfones from SO2 and Organosilanes Under Metal‐free Conditions

The conversion of SO₂ into arylsulfones under metal‐free conditions was achieved for the first time by reacting SO₂ with (hetero)arylsilanes and alkylhalides in the presence of a fluoride source. The mechanism of this transformation was elucidated based on DFT calculations, which highlight the influence of SO₂ in promoting C−Si bond cleavage.     

Adsorption and Thermogravimetric Methods for Monitoring Surface and Structural Changes in Ordered Mesoporous Silicas Induced by their Chemical Modification

The current work demonstrates that the standard adsorption analysis has a limited applicability for characterization of chemically modified porous silicas. Since low-pressure nitrogen adsorption isotherms are sensitive to the surface changes caused by chemical modification of silicas, these isotherms were successfully used to evaluate their surface heterogeneity during different stages of modification. The surface analysis was accomplished by using adsorption energy distributions and high-resolution comparative plots.     

通过硅烷偶联剂在硅和铟锡氧化物(ITO)表面嫁接寡聚芴分子

通过硅烷偶联剂γ-氨丙基三乙氧基硅烷(3-aminopropyl-triethoxysilane,APTES)的“分子桥梁”作用,采用两种不同的方法,把修饰后的寡聚芴分子键联到硅表面和铟锡氧化物(ITO)表面上。X射线光电子能谱(XPS)、原子力显微镜(AFM)和循环伏安(CV)方法等的表征证实了通过硅烷偶联剂在硅表面和ITO表面嫁接寡聚芴分子可行性。     

Nebulization ionization and desorption ionization analysis of reactive organofunctionalized silanes in nanofilm products

Three different and recently developed desorption ionization techniques, transmission-mode desorption electrospray ionization (TM-DESI), low temperature plasma (LTP) ionization and nano-assisted laser desorption ionization (NALDI), are compared with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) for the analysis of two nanofilm products (NFPs) for surface coating, which contain hydrolysates and condensates of organo-functionalized silanes. The NFPs were characterized in different states from the liquid phase to the fully formed surface film. The LTP spectra were dominated by the silanes, while the corresponding di-, tri- and tetrasiloxanes were common in ESI, APCI and TM-DESI. This indicates readily condensation of the silanes during the ESI and APCI ionization processes leading to the observed siloxanes. NALDI showed larger siloxane structures than the other techniques, indicating film formation on the NALDI target. Real-time monitoring of the film formation on a glass surface by LTP showed a decreasing abundance of the silanes, while the abundances of the di-, tri and tetrasiloxanes increased significantly within the first 100 s. LTP was superior in showing the non-reacted content of the NFPs, while ESI, APCI and TM-DESI were characterized by artefact formation of siloxanes. NALDI was ideal for showing the siloxane structures of the formed film. The applicabilities of each of the ionization techniques were examined, showing the advantage of utilizing more than one ionization technique for the analysis of reactive species.     

聚有机硅结构和规整性对链柔性和极性的影响

基于旋转异构态模型的构象构型统计方法,考虑侧基的结构,导出有机硅聚合物基础量统一计算公式,得到Poly(silastyrene)(PSS)、Polysilapropylene(PSP)、Poly(methylphenylsiloxane)(PMPS)、Poly(dimethylsilmethylene)(PDMSM)和Poly(dimethylsilylene)(PDMS)无规链的均方回转半径特征比分别为1.45、0.63、0.97、0.69和1.99,均方二极矩特征比为2.49、0.99、0.61、0.48和0.27.发现PSS和PMPS的特征比随链长、链规整程度、构象能和温度等均呈现较大的变化,而侧基、构象能和温度对PSP、PDMSM基础量影响则不大,分析极性大侧基对有机硅聚合物链柔性和极性的影响十分重要.     

Transition metal-catalyzed tandem isomerization and cationic polymerization of allyl ethers. II. Structural and mechanistic studies

In the presence of organosilanes, dicobalt octacarbonyl catalyzes the polymerization of alkyl allyl ethers to give high molecular weight polymers. This article reports the results of a detailed mechanistic study of this new polymerization reaction. The evidence obtained in this study supports a stepwise process involving first, the reaction of dicobalt octacarbonyl with an organosilane to form HCo(CO)₄ and R₃SiCo(CO)₄. In subsequent steps, HCo(CO)₄ isomerizes the allyl ether to a 1-propenyl ether and then this compound is polymerized by the formal transfer of a silyl cation from R₃SiCo(CO)₄. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1985–1997, 1997     

Transition metal-catalyzed isomerization and polymerization of allylic and enolic ethers

Alkyl allyl ethers undergo facile thermally induced isomerization to alkyl 1-propenyl ethers in the presence of Group VIII transition metal carbonyl compounds as catalysts. The addition of a silane containing a Si H bond to these systems results in a catalyst system that is capable of not only isomerizing the allyl ether to the 1-propenyl ether, but further results in the polymerization of these later compounds. High molecular weight polymers can be obtained directly from the alkyl allyl ether in a single step. The scope and limitations of these polymerizations are described. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2521–2532, 1997     

Mechanism of the grafting of organosilanes on mineral surfaces

The grafting of organosilyl groups in the interlamellar space of certain crystalline silicic acids, such as H-magadiite, occurs when the interlayer spaces have been expanded previously by intercalation of some polar organic substances. The interlamellar Si-OH groups are then accessible to silylating reagents and Si-O-Si bridges form between the silicic acid surface and the organic groups.The grafting reaction is controlled by a diffusion mechanism: desorption of the polar organic guest molecules has to occur simultaneously with the diffusion of the reacting molecules into the interlayer space.The resulting materials are organosilicic compounds which retain the lamellar structure of the starting crystalline silicic acids. Their surface properties are determined by the grafted groups.Part I: This Journal 256:135 (1978); Part II: This Journal 257:178 (1979).     

Synthesis and Stereoselective Functionalization of Sulfur-Containing Silyl Heterocycles

Abstract

2-Silylated five-membered heterocycles can be easily accessed through reaction of bromo(methoxy)methylsilane and dithiols, mercapto amines, and mercapto alcohols. Further reaction of the obtained silylated heterocycles with electrophiles under fluoride ion conditions afford an easy functionalization of such molecules.