Silane substituents

The use of aryltrimethylsilanes as intermediates has been found to be a useful complement to direct thallation in the preparation of arylthallium intermediates. The advantages are (a) position specificity, because the thallium always replaces the silane substituent, and (b) improved ability to effect thallation of certain deactivated rings, such as those having trifluoromethyl substituents. What role does the silyl substituent play in these reactions ... 

The effects of the cr—JT interaction on the ground-state properties of allyltrimethylmetal compounds are paralleled by the effect on reactivity towards electrophilic reagents. Mayr demonstrated that allyltrialkylsilanes, allyltrialkyl-germanes, and trialkylstannanes react with diphenylcarbenium ions at rates 105,5.6 x 105, and 109, respectively, relative to propene.158 The reaction rates were also found to be sensitive to the inductive effects of the other substituents attached to the metal. A theoretical evaluation of the factors determining the regiochemistry and stereochemistry of electrophilic addition to allylsilanes and other allyl systems is reported by Hehre et al.159 They predict a preference for electrophilic attack anti with respect to the silane substituent, a prediction that is supported by many experimental studies.82,160... 

Silicon oxide containing structures can be formed from the pyrolysis of functionalized phosphazenes. First linear phosphazenes (53) were formed with silane substituents. Pyrolysis of these polymer resulted in porous substrates that were characterized by ED AX, SEM, TEM, and XRD. Most significantly, XRD revealed the presence of both monoclinic and cubic SiP207, for which the authors suggest that this is the first report of this particular oxide of Si. 

Azo reagents carrying an alkoxy silane substituent have three distinct areas of application. Added to NR latex they react and are also... 

In general the rate of silane dehydrocoupling catalyzed by late transition metal homogeneous complexes decreases in the order primary > secondary > tertiary. Other clear-cut relationships between the rate of dehydrocoupling to factors such as the metal catalyst precursor, its ligands, or the silane substituents are difficult to make from the limited data. This is shown in several examples. Brown-Wensley showed that the complex (Ph2P) RhCl is the best catalyst precursor for the conversion of the secondary silane Et2SiH2 to the... 

To be classified as an organosilane, one of the silane substituents must be an organic group that is directly attached to silicon via a Si—C bond. Organic substituents attached to silicon are either nonreac-tive, such as methyl, ethyl, butyl, octyl, phenyl, and others, or organofunctlonal that is, they contain an organic reactive group, such as amino, epoxy. 

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