ZUR SYNTHESE VON SILOXANEN. II, STERISCHE SUBSTITUENTENKONSTANTEN FUER SILOXYRESTE

Article abstract of DOI:10.1016/0022-328X(85)80242-4

The acetolysis reactions of compounds of the type XSiMe2Cl (I) with acetic acid in the presence of acetic anhydride were studied kinetically by means of 1H NMR spectroscopy.We found these reactions exclusively influenced by steric effects (ρ=0).The steric susceptibility constant (δ) of the acetolysis reaction, using alkylchlorodimethylsilanes was found to be 1.3.In this investigation the Taft E_s nvalues showed a better correlation than the E_s(Si) values of Cartledge.From the rate constants of the acetolysis reactions with I (X=Cl, acetoxy or siloxy) we could then obtain for the first time E_s values for Cl, acetoxy and a series of siloxy groups at silicon.