31835-97-9Relevant academic research and scientific papers
Kinetic Control in the Cleavage of Unsymmetrical Disilanes
Hevesi, Laszlo,Dehon, Michael,Crutzen, Raphael,Lazarescu-Grigore, Adriana
, p. 2011 - 2017 (2007/10/03)
A series of 12 phenyl-substituted arylpentamethyldisilanes 1a-1 have been synthesized in order to examine the regioselectivity of their nucleophilic Si,Si bond cleavage reactions under Still's conditions (MeLi/HMPA/0°C). It has been found that the sensitivity of these reactions to the electronic effects of the substituents in the phenyl ring could be described by the Hammett-type equation log(kA/kB) = 0.4334 + 2.421(Σσ); (correlation coefficient R = 0.983). The kA/kB ratio represents the relative rate of attack at silicon atom A (linked to the aryl ring) or at silicon atom B (away from the aryl ring) of the unsymmetrical disilanes. Thus, the present investigation shows that the earlier belief according to which the nucleophilic cleavage of unsymmetrical disilanes always produces the more stable silyl anionic species (thermodynamic control) should be abandoned, or at least seriously amended: kinetic factors appear to exert a primary influence on the regioselectivity of such reactions. Since the two major kinetic factors (i.e., electrophilic character of and steric hindrance at a given silicon atom) have opposite effects on the orientation of the reaction, it may happen that kinetic and thermodynamic control lead to the same result. For some of the unsymmetrical disilanes studied, the major reaction path was not the Si,Si bond cleavage; instead, Si-aryl bond breaking occurred, producing the corresponding aryl anions.
Silicon-carbon unsaturated compounds XXXII. Photolysis of tolyl- and xylylpentamethyldisilanes
Ishikawa, Mitsuo,Sakamoto, Hiromu
, p. 1 - 10 (2007/10/02)
The photolysis of ortho- and meta-tolypentamethyldisilane (1 and 2) and 2,5- and 2,6-xylylpentamethyldisilane (3 and 4) in the presence of isobutene and acetone as trapping agents has been studied.All reactions investigated, with the single exception of compound 4, afforded the 1:1 adducts derived from the silene as a result of a 1,3-silyl shift to the aryl ring with the trapping agents.The photolysis of 1 and 3 in the presence of isobutene or acetone afforded a single adduct, but 2 gave 5,6-bis(silyl)-substituted toluene and 3,4-bis(silyl)-substituted toluene, respectively.Irradiation of 4 in the presence of isobutene afforded no volatile products, while in the presence of methanol it gave methoxypentamethyldisilane and m-xylene.
