An-Najah Staff

Tris (acetylacetonato) cobalt (III), (Co(acac)3), has been used to catalyse o-silylation reactions of R 3 Siff (R.z.Et,Et0) with R OH (Rt-Et, i-Pr, t-.Bu and C6Hj-). No reaction has been observed at room temperature, but the reaction is apparently enhanced when carried out at a higher temperature. The rate of the reaction varies with varying the concentration of the saline or the alcohol. Using different types of alcohols and silanes greatly affects the rate of the reaction. The rate of the reaction is affected by varying the concentration of the complex (Co(acaci6).

Octacarbonyldicobalt(O) has been used to catalyze the reaction of R3SiH (R = Et and EtO) with R′OH (R′ = Me, Et, n-Pr, i-Pr, and t-Bu). The reaction of MeOH with (EtO)3SiH, in toluene at 27 °C, was first-order with respect to the catalyst, to the silane, and to the alcohol. The order of reactivity of the alcohols was MeOH > EtOH > n-PrOH > i-PrOH > t-BuOH, reflecting the steric effect associated with the size of the organic group. Addition of triphenyl phosphine (Ph3P) to the reaction mixture slowed down the reaction. The reaction proceeds faster if nonpolar solvents are used, and the rate of the reaction is very sensitive to temperature.