Silicon Functions

The aim of this research was the preparation of unique silicon-functional macroreagents, particularly linear polyolefins carrying one or two Si-Cl or Si-H termini and thus to combine the excellent physical properties offered by these polyhydrocarbons with the versatility and chemical reactivity of the Si-Cl and Si-H bonds. 

Since a thorough review of the scientific and patent literature failed to produce any information relative to die preparation of silicon-functional polyolefins by cationic methods, this untapped field appeared particularly attractive for systematic research. Added justification for this objective was provided by the possible exploitation of the vast synthetic possibilities offered by a combination of the chemistries of cationic polymerization and that of organosilanes24. ... 

Table 1. Novel silicon-functional initiators synthesized...

Table 1 shows the structures of the novel silicon-functional initiators synthesized. All the initiators are mixtures of 80-85% main product (left column) plus 15-20% isomer (right column). The subsequent sections give synthesis details. 

Silaheterocycles from Intramolecular Reactions of Silicon-functionalized Diazoacetic Esters... 

A variety of silicon-functionalized diazoacetic esters are available by reacting (trifloxysilyl)- or (chlorosilyl)diazoacetic esters with appropriate nucleophiles [1]. Thermally, photochemically, or transition metal induced intramolecular carbene reactions of these novel diazoesters lead to four-, five-, and six-membered silaheterocycles. 

Silicone fluids can be discussed in two categories inert fluids and functional fluids, the latter including silicon-functional and organo-functional210 (modified) polymers. The methods of synthesis of functional siloxanes have recently been reviewed.378... 

Silicone functionalized PIB is particularly suitable as a pressure sensitive adhesive composition in medical applications including transdermal drug delivery applications (83). 

Silicon-Functionalized Ligands as Supercritical Fluid-Soluble Complexants... 

During the past decade, however, significant advances have been made in the preparation and chemistry of aliphatic organopolysilanes. A large number of silicon-silicon compounds of various types (peralkylated, silicon-functional, and carbon-functional) have been prepared, and mechanisms of some of their reactions elucidated. It is hoped that this review will demonstrate how the chemistry of aliphatic organopolysilanes is unique as well as similar to that of organomonosilanes. 

The discovery by Iwao that gramme bearing the large N-silicon functionality TIPS, 49, undergoes 4-deprotonation to give, after electrophile quench, products 50 (Scheme 17) [31] is of great synthetic consequence for the preparation of difficult to access 4-substituted indoles, e.g. 51. 

Cleavage of the silicon carbon bond to give silicon-functionalized silanes. 

Diethylamino-substituted silyllithium is prepared successfully and used for the preparation of silicon-functional compounds (equation 18). ... 

Synthesis of Silicon-functionalized Silanes by Cleavage of the Silicon-Carbon Bond... 

Synthesis of Silicon-functional Silanes by the Substitution Reactions on Silicon... 

Silicon-fimctional silyllithium should be interesting intermediates to a variety of silicon-functional compounds. Chlorine substituted silyllithium is unstable to undergo a-elimination to give silylenes. Alkoxy-substituted sUyllithium may be generated in situ reaction conditions and undergoes useful substitution reaction (equation 66). ... 

Y = organofunctional group OX = silicon-functional group n = typically 0 or 3... 

The organofunctional group Y links with the polymer. This group must be chosen carefully to ensure maximum compatibility with the resin. The silicon-functional groups OX, usually alkoxy groups, must be hydrolyzed to the silanol (Si-OH) first before they can bond to the substrate or crosslink. 

Catalytic Carbon-Carbon Hydrogenation of Silicon-Functionalized Olefins... 

Summary From catalytic hydrogenation of olefinic silicon-functionalized compounds (chloro-Si, alkoxy-Si, alkyl-Si, and aryl-Si) the saturated products are available in good yield. In general, the chloro- and alkoxy substituents are unaffected and for silaheterocyclic compounds the cyclic or the bicyclic moieties, respectively, remain intact. Thus, the silanorbomenes 1, 2, and 3, compounds containing cyclopentenyl groups 13 and 15, and various carbon vinyl substituted silacyclobutanes 7, 8, and 11 were hydrogenated in a simple apparatus. The reactions were performed in ether and THF as solvents the hydrogenation catalyst Pd/C can be used several times. 

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