E. Frainnet

Etude de l'obtention d'enoxysilanes par action du triethylsilane sur des cetones enolisables, aliphatiques ou cyclaniques, en presence de catalyseurs au nickel

Abstract The preparion of alkoxysilanes and alkenoxysilanes has been achieved by the reaction of enolizable aliphatic or cyclic ketones with triethylsilane in the presence of nickel catalysts. For some catalysts, the reaction can be directed to give exclusively one or the other of these derivatives. The use of certain nickel catalysts gives very high yields of alkenoxysilanes, and this has been closely investigated.

Action de trialkylsilanes sur les aldehydes aliphatiques : II. Etude de l'obtention d'enoxysilanes en presence de certains catalyseurs au nickel☆

Abstract The possibility of obtaining enoxysilanes by action of trialkylsilanes HSiR′ 3 on aliphatic aldehydes RCHO in the presence of various nickel catalysts has been closely studied. Mechanisms are proposed to interpret the results.

Etude structurale d'enoxysilanes : I. Attribution des spectres de vibration du trimethylsiloxyethylene, de ses homologues deuteries et des methoxytrimethylsilanes diversement deuteries. Discussion des conformations moleculaires de l'enoxysilane

Abstract The infrared and Raman spectra of six compounds (trimethylsiloxyethylene, (CH 3 ) 3 SiOCHCH 2 , methoxytrimethylsilane, (CH 3 ) 3 SiOCH 3 , and their deuterated derivatives: (CD 3 ) 3 SiOCHCH 2 , (CH 3 ) 3 SiOCDCD 2 , (CD 3 ) 3 SiOCH 3 , (CH 3 ) 3 SiOCD 3 have been analysed. The majority of the bands observed have been assigned, in particular those due to ν(SiO). The study of the vinyl compounds shows that the enoxysilane exists in two conformers, the major being the gauche and the minor the s-cis one.

Action de trialkylsilanes sur des aldehydes aromatiques en presence de catalyseurs au nickel

Abstract The reactions of HSiEt 3 have been studied with aromatic aldehydes using two types of nickel catalysts and under different experimental conditions. The three main reactions are: ether oxide formation, hydrosilylation of the aldehyde to form alkoxysilane and formation of disilyloxy hydrobenzoinic derivative. The selectivity of the reaction is monitored by the catalyst and the experimental conditions; in particular we can obtain almost exclusively either the alkoxysilane or the disilyloxy derivative. The mechanisms of these reactions are proposed and discussed.

Étude structurale d'hexaalkyldisiloxanes et de trialkylalcoxyou aryloxysilanes : I. Détermination par dipolemétrie d′angles SiOC ET SiOSi

Abstract The authors have determined the dipole moments of hexaalkyldisiloxanes, trialkylalkoxysilanes and trialkylaryloxysilanes, having the formula R3SiOΣ with R=Me, Et, Pr and Σ=SiR3′ (R′= Me, Et, Pr), or Σ=Me, t-Bu, Ph, p-ClC6H4−, in benzene, dioxane and cyclohexane solutions. The atomic and electronic polarizations of these compounds have been estimated; the moments of the R3Si-O groups and oxygen valence angles of these compounds have been calculated. This study shows that the moments of the R3Si-O groups are constants, (1.10±0.05 D in benzene and 1.03 ±0.05 D in dioxane) whatever R may be, and that the oxygen valence angles in compounds of the ΣOΣ′ type vary on a wide scale according to the nature of Σ and of Σ′.

Étude structurale d'hexaalkyldisiloxanes, et de trialkylalcoxy - ou aryloxysilanes : II. Influence des facteurs électroniques et stériques sur les angles de valence de l'oxygène dans ces composés☆

Abstract Electronic and steric factors which influence oxygen valence angles in R3SiOΣ compounds (Σ=R, Ar, SiR′3) have been analysed.

Action du triethylsilane sur des aldehydes α-ethyl-eniques en presence de catalyseurs au nickel ou au palladium

Abstract The action of triethylsilane on α-ethylenic aldehydes has been studied in the presence of two types of nickel catalysts as well as palladium on charcoal. Two phenomena can result: either 1,2 or 1,4 additions only, the trans-1,4 adduct being predominant, or a competition between these two additions and coupling reactions. A comparative regioselective and stereoselective study was carried out making use of, in addition to the preceding catalysis, the Speier platinum catalyst. An interpretation of the results is given.

N-trimethylsilyldiphenylcetenimine: Reaction avec les chlorures d'acides

Abstract N-trimethylsilyldiphenylketenimine reacts with acid chlorides leading to β keto nitriles of the general formula RCOC(Ph)2CN (R = CH3, CH3CHCl, Ph, C6H11).

Étude structurale d'hexaalkyldisiloxanes et de trialkylalcoxysilanes : III. Determination par diffusion rayleigh depolarisée des anisotropies optiques des groupes t-BuO et R3SiO (R = Me, Et, Pr).

Abstract Molecular optical anisotropies of some ethers, alcoxysilanes and disiloxanes have been measured both in cyclohexane solution and in pure liquid state, using depolarized light scattering. Optical anisotropies of the t-BuO and R3SiO groups (R = Me, Et, Pr) were deduced assuming an ∞-fold symmetry axis for the groups. The difference of optical anisotropy between the SiC and SiO bonds has been evaluated. The optical anisotropy invariability of the Me3SiO group has been taken to be indicative of the lack of conjugation between the two (p→d)π bonds of the SiOSi system. It has also been shown for the Et3SiO and Pr3SiO groups that the absolute value of the optical anisotropy decreases when the steric hindrance of the antagonist group increases.

Action des trialkylsilanes sur les aldehydes aliphatiques : I. Etude des evolutions en presence d'un catalyseur au nickel en l'absence de solvant

Abstract Two competing reactions ensue when trialkylsilanes HSiR′ 3 are treated with aliphatic aldehydes RCHO in the absence of a solvent and using a nickel catalyst (obtained by the treatment of anhydrous NiCl 2 with a trialkylsilane); one gives an alcoxysilane RCH 2 OSiR′ 3 , the other an ether oxide (RCH 2 ) 2 O and a siloxane (R′ 3 Si) 2 O. By variation of the reaction conditions, either reaction can be made exclusive. Reaction mechanisms are proposed.