- Synthesis of (trichloromethyl)organosilanes by catalytic decarboxylation of (trichloroacetoxy)organosilanes
-
A method for preparing (trichloromethyl)organosilanes by the catalytic decarboxylation of the corresponding trichloroacetoxysilanes RMe2SiOC(O)CCl3 (R=Me, ClCH2, Ph, Me3Si, and H) has been developed.The method involves heating the starting compounds without a solvent in the presence of a catalyst (quaternary ammonium salts or potassium salts with the addition of crown ethers).Tertiary amines (Et3N, Bu3N) catalyze this reaction only when heating is carried out in donor aprotic solvents (THF, acetonitrile) in the presence of oxygen.Thermal decomposition of (trichloroacetoxy)organosilanes, in contrast to catalytic decarboxylation, begins at a higher temperature and yields a mixture of products.Key words: organosilanes, trichloroacetoxy and trichloromethyl derivatives; catalytic decarboxylation.
- Kornev, A. N.,Donnikova, O. S.,Semenov, V. V.,Kurskii, Yu. A.
-
p. 145 - 148
(2007/10/02)
-
- N-(DIMETHYLCHLOROSILYLMETHYL)LACTAMS AND RELATED COMPOUNDS IN THE SYNTHESIS OF DISILOXANES. MOLECULAR AND CRYSTAL STRUCTURE OF 2,2,5-TRIMETHYL-3-(DIMETHYLCHLOROSILYLMETHYL)OXAZOLIDIN-4-ONE, 2,2-DIMETHYL-3-(DIMETHYLCHLOROSILYLMETHYL)-2H-1,3-BENZOXAZIN-4-ONE, AND 1-(DIMETHYLCHLOROSILYLME..
-
By hydrolysis of N-(dimethylchlorosilylmethyl)lactams and some related oxygen-containing heteroanalogs in the presence of sodium hydrocarbonate or triethylamine and also by exchange reaction of 1-(dimethylchlorosilylmethyl)-2-pyrrolidone with hexamethyl- or bis(dimethylchloromethyl)disiloxane the corresponding disiloxanes were obtained.These compounds, according to IR data, lack intramolecular silicon-oxygen interaction.The x-ray structural data show that with decreasing size of the ring the length of the covalent O-Si bond increases from 1.988(2) Angstroem in 2,2-dimethyl-3-(dimethylchlorosilylmethyl)-2H-1,3-benzoxazin-4-one to 2.050(2) Angstroem in 1-(dimethylchlorosilylmethyl)-4-phenyl-2-pyrrolidone and still more sharply on introduction of an ether oxygen atom into the γ-lactam ring in 2,2,5-trimethyl-3-(dimethyl-chlorosilylmethyl)oxazolidin-4-one.
- Artamkina, O. B.,Kramarova, E. P.,Shipov, A. G.,Baukov, Yu. I.,Macharashvili, A. A.,et al.
-
p. 237 - 245
(2007/10/02)
-
- Synthesis of siloxanes. XII. Cleavage of siloxanes by hydrogen chloride
-
1H NMR spectroscopy has been used in a kinetic study of the cleavage of siloxane bonds by hydrogen chloride in dioxane.The cleavages show an induction period which is associated with the autocatalytic effect of the water formed during the reaction.The kinetic behavior can be expressed in terms of a rate law that includes rate constants for cleavage by both dioxane*HCl (k1) and H2O*HCl (k2).The k'1 (k'1 = k1*-4) and k'2 (k'2 = k2*-3) values correlate with ?* values; thus ρ* values of -1.4 and -0.7 were obtained for k'1 and k'2, respectively.The ?* value of 0.35 that we previously derived for the Me3SiO group applies in this reaction.The reaction of 1,3-bis(p-methoxyphenyl)tetramethyldisiloxane with hydrogen chloride involves cleavage of silicon-aryl rather than Si-O bonds.
- Scheim, U.,Lehnert, R.,Porzel, A.,Ruehlmann, K.
-
p. 141 - 150
(2007/10/02)
-
- Selectivite de la scission Si-C dans des composes du type Me3SiCH2Σ; une synthese originale et sure de l'iodoacetate d'ethyle
-
The regiochemistry of the electrophilic cleavage of the SiCsp3 bond in compounds Me3SiCH2Σ (Σ = Me, Pr, Cl, COOEt) and Me3SiCHΣ2 (Σ = Cl) has been investigated using ICl, Me3SiOSO2Cl and HO3SCl as the electrophiles.When Σ = Pr or Cl a regioselective cleavage of the Si-CH3 bond was observed, producing silylated chlorosulfonates or sulfates which often were new compounds.With Σ = COOEt a regiospecific splitting of the Si-CH2COOEt bond was observed.This confirms the synthetic potential of ethyl trimethylsilylacetate.
- Bordeau, M.,Djamei, S. M.,Dunogues, J.
-
p. 413 - 417
(2007/10/02)
-
- Synthetic Pathways to Simple Di- and Trisilylmethanes: Potential Starting Materials for the CVD Deposition of Amorphous Silicon a-SiC:H
-
Methods for the preparation of simple silaalkanes with a high content of silicon and hydrogen have been explored.Target molecules, like H3SiCH2SiH3 and HC(SiH3)3, may serve as precursor molecules for the production of photovoltaic elements through thermal or discharge (plasma) CVD processes.Among a variety of synthetic pathways, the reactions between HSiCl3 and HCCl3 in the presence of an amine (Benkeser reaction) and the direct synthesis from silicon and polychloromethanes proved most promising for large scale preparations.The CH2X2/KSiH3 metathesis is most useful on the laboratory scale. - The Grignard synthesis was employed for partly methylated homologues, like H3SiCH2SiH2CH3, H3SiCH2SiH(CH3)2, H3SiCH2Si(CH3)3, and related molecules.The magnesium reduction of CHBr3/SiCl4 and CHBr3/CH3SiCl3 mixtures serves best for the preparation of HC(SiCl3)3, which can be converted into HC(SiH3)3 using LiAlH4.Attempts to synthesize tetrasilylmethane via the same route, C(SiH3)4, led only to the formation of HC(SiH3)3. - Key words: Amorphous Silicon a-SiC:H, Disilylmethane, Trisilylmethane, Direct Synthesis, Polysilylmethanes
- Schmidbaur, Hubert,Ebenhoech, Jan
-
p. 1527 - 1534
(2007/10/02)
-
- SILAETHENE II. DARSTELLUNG UND CHARAKTERISIERUNG VON 1,3-DISILACYCLOBUTANEN
-
1,3-Disilacyclobutanes of the types R1R2SiSiR1R2 are prepared (a) by ring synthesis from chloromethylchlorosilanes R1R2Si(CH2Cl)Cl, (b) by thermolysis of monosilacyclobutanes , and (c) by substitution of chlorine with alkyl groups in SiCl-containing 1,3-disilacyclobutanes, obtained by procedures (a) or (b).The compounds have been characterized by analytical and spectroscopic investigations.The synthetic methods are critically compared.
- Auner, N.,Grobe, J.
-
p. 151 - 178
(2007/10/02)
-
- Cleavage of silicon-to-carbon bonds by means of hydrogen halide
-
In a process for preparing a halogen alkyl silane by contacting an alkyl silane of the formula wherein R represents a substituted or unsubstituted alkyl or alkenyl group, R' represents an alkyl group, and N represents 0, 1, or 2 With a hydrogen halide in the presence of a catalyst, the improvement which comprises employing as the catalyst an aluminum oxide-containing composition.
- -
-
-