Silanol synthesis from

Synthesis from Dehydrolinalool. Dehydrolinalool is produced on a large scale from 6-methyl-5-hepten-2-one and acetylene and can be isomerized to citral in high yield by a number of catalysts. Preferred catalysts include organic orthovanadates [55], organic trisilyl oxyvanadates [56], and vanadium catalysts with silanols added to the reaction system [57]. 

The above studies [8-10] strongly indicate the participation of silanol groups as acid sites in the amine-catalyzed reactions. The synergistic catalysis of immobilized organic bases and silanol groups has been highlighted by the cyclic carbonate synthesis from carbon dioxide and epoxide. Acid-base dual activation mechanism of the cyclic carbonate synthesis is widely accepted. Sakakura and coworkers [11] reported silica-supported phosphonium salts as highly active catalysts for the cyclic carbonate synthesis. The results for propylene carbonate synthesis are summarized... 

The hydrogel is allowed to stand for a few days during which time a process called sinerisis takes place. During sinerisis the condensation of the primary particles, one with another, continues and the gel shrinks further, accompanied by the elimination of more saline solution that exudes from the gel. After three or four days, sinerisis is complete and the gel becomes firm and can now be washed free of residual electrolytes with water. The washed product is finally heated to 120°C to complete the condensation of the surface silanol groups between the particles, and a hard xerogel is formed. It is this xerogel that is used as the LC stationary phase and for bonded phase synthesis. It is not intended to discuss the production of silica gel in detail and those interested are referred to "Silica Gel and Bonded Phases", published by Wiley (1). 

A novel potentially useful route for the synthesis of metallo-silanols is based on the reaction of metallohydridosilanes with 1,1-dimethyldioxirane [7,8] resulting in the insertion of oxygen into the Si-H bond. This procedure is supplementary to the hydrolysis route, since, in addition to the transformation of the "normal" ferrio-hydridosilanes 9a,b to the silanols 10a,b, it guarantees the formation of chiral 10c, not available by hydrolysis, from "electron rich" phosphine iron fragment substituted 9c (Eq. (2)). 

APSQ Is soluble in a dilute aqueous solution of tetramethylam-monium hydroxide (TMAH). When APSQ was treated with trimethylsilyl chloride (TMSC1), the solubility of APSQ In the TMAH solution decreased, because silanol groups were terminated with TMS groups. This Indicates that APSQ Is alkali-soluble due to the presence of silanol groups. The solubility depended on the silanol content, which can be controlled by synthesis conditions or appropriate termination of silanol groups. APSQ obtained from Owens-Illinois PSQ was more soluble In TMAH solutions than that from Petrarch Systems, probably due to lower molecular weight (Mw). We used the former (Mw = 1,500) In this study. 

From such silanol-functional cyclics, the polycyclic (ladder) siloxanes are made in a controlled manner. Thus, the reaction of (7-PrSi(0H)0)4 with ((-PrPhClSiO)2 in pyridine was described, leading to the formation of tetraphenyl tricyclic ladder siloxane. Dephenylchlorination with A1C13/HC1, and the hydrolysis allowed isolation of tetrahydroxyl tricyclic ladder siloxane in good yield. Using a similar reaction starting from tetrahydroxyl ladder siloxane, the first pentacyclic ladder siloxane was obtained.38 Abe et al. describe the synthesis of... 

The tris-neopentyl Mo(VI) nitride, Mo(-CH2- Bu)3(=N) [134], reacts with surface silanols of silica to yield the tris-neopentyl derivative intermediate [(=SiO)Mo (-CH2- Bu)3(=NH)] followed by reductive elimination of neopentane, as indicated by labeling studies from labeled starting organometallic complex, to yield the final imido neopentylideneneopentyl monosiloxy complex [(=SiO)Mo(=CH- Bu)(-CH2 - Bu)(=NH)] [135]. The surface-bound neopentylidene Mo(VI) complex is an active olefin metathesis catalyst [135]. Improved synthesis of the same surface complex with higher catalytic activity by benzene impregnation rather than dichlorometh-ane on silica dehydroxylated at 700 °C has been reported [136],... 

SYNTHESIS OF NOVEL SILANOL POLYMERS AND COPOLYMERS BY A SELECTIVE OXIDATION OF SI—H BOND FROM CORRESPONDING PRECURSOR POLYMERS... 

A new convenient polymer modification for the conversion of the Si—H to Si—OH by the selective oxidation of the Si—H bond by dimethyldioxirane has been described. The oxyfunctionalization of the silane precursor polymers proceeded rapidly and quantitatively and can be applied to the synthesis of a wide variety of novel silanol polymers with specific properties from the corresponding precursor polymers containing Si—H functional groups. Control over the properties of these silanol polymers, such as reactivity and self-association of silanols, was realized through the placement of different substitute groups bonded directly to the silicon atom and by the variation of silanol composition in a copolymer. These novel silanol polymers with a... 

The synthesis of MCM-41 structure in fluoride medium has been reported by Silva and Pastore [10], who used sodium silicate as silica source and carried out crystallization at 150 °C. They suggested the behaviour of Si02-CTMA+-F system was significantly different from that reported previously on the mesophase system. It is known that fluoride ions do influence the nature, activity and polymerizing capacity of silica precursors, and a fluorinated silica surface is much more hydrophobic and more resistant to the attack of water molecules than a silanol silica surface [11]. 

The synthesis of cyclic polydimethylsiloxane was first achieved through ring-chain equilibration of siloxane oligomers in the presence of potassium silanolate, as shown in Fig. 51 [163-165]. Cyclics recovered from ring-chain equilibration reactions have been fractionated by preparative GPC, yielding... 

The trimethylsilylated ylides (1), easily generated from trimethyl chlorosilane and ylides, react with aldehydes 2 to form vi-nylsilanes 3 (2,3). The vinylphosphonium silanolates 4 are also formed. Compounds 3 are versatile reagents for further reactions (4). The ylide J (with R1 =H) reacts with aldehydes 2 to give the dienes j). The oxidation of with the adduct 6, from triphenyl-phosphite and ozone, gives access to a generaT synthesis of acyl-silanes (trimethylsilylketones) (2). The silylated ylides react to form phosphonium salts 7 with halogen compounds. The salts 7.can be desilylated by fluorine ions. The disubstituted ylides JO Tormed can be converted in statu nascendi with aldehydes V[ into the tris-substituted olefin J2 (2,3). In the case of R3-I, vinyl... 

---