1591-02-2Relevant articles and documents
The Disproportionation of Dimethyldialkoxysilanes Catalyzed by Iodine Monobromide
Ibaraki, Takeshi,Ito, Katsuko
, p. 3235 - 3236 (1981)
Iodine monobromide is an extremely effective catalyst for the redistribution of alkoxyl groups on silicon atoms in dimethyldialkoxysilanes.The equilibrium constants of these reactions were determined at 40 deg C by means of gas chromatography.Assuming that the reaction intermediate is the dative form of a dimethyldialkoxysilaneiodine monobromide complex, a mechanism of the reaction was proposed.
Synthesis of Preceramic Organometallic Polymers by Reaction of Titanium and Zirconium Alkoxides with Silazanes
Kotrelev, G. V.,Mitrofanov, M. Yu.,Gruzinova, E. A.,Svistunov, V. S.,Zakharov, A. I.,Abysheva, N. V.
, p. 510 - 515 (2007/10/03)
The main features of model reactions of titanium and zirconium alkoxides with silazanes were studied. A method was developed for incorporating titanium and zirconium atoms into the structure of silazane polymers prepared by coammonolysis of dichlorodimethylsilane and trichloromethylsilane or by catalytic polycondensation of dimethylcyclosilazanes. These polymers were studied as ceramics precursors.
Synthesis of dialkoxydimethylsilanes and 2,2-dimethyl-1,3-dioxa-1- silacyclo compounds
Lin, Ji-Mao,Zhou, Ai-Min,Zhang, Hui,Hao, Ai-You
, p. 2527 - 2532 (2007/10/03)
In the presence of iodine, magnesium reacts with alcohols to give magnesium alkoxides, which are treated with octamethylcyclotetrasiloxane to produce dialkoxydimethylsilanes. Similarly, magnesium reacts with 1,3, 1,4 and 1,5 diols and then with octamethylcyclotetrasiloxane, producing 2, 2- dimethyl-1 3-dioxa-2-silacyclo compounds.
Catalytic Activity of Titanium Alkoxy Derivatives in Alcoholysis of Ethoxysilanes
Khonina,Kochneva,Suvorov
, p. 79 - 82 (2007/10/03)
Titanium tetraalkooxides, regardless of their structure, are effective catalysts for alcoholysis of ethoxysilanes. Titanium alkoxychlorides demonstrate the highest catalytic activity, whereas the catalytic activity of coordination-saturated titanium compounds is the lowest. The influence of the catalyst nature on its activity is analyzed.
Transesterification of Ethoxysilanes with Butyl Acetate in the Presence of Alkoxy Derivatives of Titanium
Khonina,Suvorov,Soldatova,Kozlov
, p. 729 - 732 (2007/10/03)
It was found for the first time that alkoxy derivatives of titanium of various structure act as effective catalysts in alkoxysilane transesterification with esters. Kinetic studies showed that both the catalytic activity of alkoxytitaniums and the reactivity of alkoxysilanes are structure-dependent. The preparative usefulness of titanium tetraalkoxides was demonstrated.
Reaction of Tetraalkoxysilanes with Alkyl(aryl)chlorosilanes
Chernyshev, E. A.,Komalenkova, N. G.,Tagachenkov, A. A.,Bykovchenko, V. G.
, p. 241 - 243 (2007/10/03)
Alkyl(aryl)trichloro- or dialkyl(diaryl)dichlorosilanes react with tetraalkoxysilanes Si(OMe)4, Si(OEt)4, and Si(OBu)4 to give partially etherfied alkyl(aryl)chlorosilanes RSiCl2(OAlk), RSiCl(OAlk)2, and R2SiCl(OAlk).
Iodine- or Iodine Monobromide-Catalyzed Alkoxy-Alkoxy Exchange Reactions of Alkylalkoxysilanes: Formation of the Catalyst-Alkoxysilane Complexes and the Reaction Mechanism
Ito, Katsuko,Ibaraki, Takeshi
, p. 2853 - 2858 (2007/10/02)
The formation of charge-transfer complexes of iodine and of iodine monobromide with alcohols and alkoxysilanes has been established spectroscopically, and the formation constants of iodine-ethoxytriethylsilane and iodine-diethoxydimethylsilane complexes has been determined as 0.55+/-0.01 and 0.61+/-0.02, respectively.On the basis of these observations and the kinetic information recently reported, the previously proposed mechanism for the iodine or iodine monobromide catalyzed alkoxy-alkoxy exchange reactions of alkoxysilanes is dicussed afresh.It has been confirmed that a mechanism involving a four-centered transition state containing a CT-complex is most favorable.
Alcoholysis Equilibria of Dialkoxydimethylsilanes Catalyzed by Iodine or Iodine Monobromide
Ito, Katsuko,Ibaraki, Takeshi
, p. 295 - 297 (2007/10/02)
Iodine or iodine monobromide was found to be an especially favorable catalyst for the study of the alcoholysis equilibria of dialkoxydimethylsilanes by gas chromatography.Iodine monobromide was employed to promote the reactions associated with tertiary alcohols, and iodine was used for the other reactions.Eight alcohols were allowed to react with diethoxydimethylsilane, and successive equilibrium constants, K1 and K2, were determined at 20 deg C.K1=2.36-2.75 and K2=0.66-0.69 (by the use of primary alcohols), K1=1.34-1.38 and K2=0.28-0.30 (secondary alcohols), and K1=0.15-0.16 (tertiary alcohols) were observed.These values express precisely the difference of reactivities of the three groups of alcohols with diethoxydimethylsilane.Out of the dialkoxydimethylsilanes used in this study, eight unreported compounds were isolated and characterized.
