Base cleavage of the benzyl–silicon bonds in m-ClC6H4CH2SiMe(OH)2 and m-ClC6H4CH2Si(OH)3. Proposed formation of metasilicate intermediates
Abstract
A kinetic study of the base-catalysed cleavage of the diol RSiMe(OH)2(R =m-ClC6H4CH2) in Me2SO–H2O or MeOH–H2O has indicated that at high base concentrations the main process is the unimolecular dissociation of the dianion RSiMe(O–)2 into R– and Me(O–)SiO (an analogue of acetate ion), both of which then react rapidly with the solvent. Likewise for the triol RSi(OH)3 in Me2SO–H2O the main process appears to be the formation of R– and the metasilicate ion HO(O–)SiO from the dianion R(OH)Si(O–)2. Base cleavage of the silanols RSiMe2OH (R = PhCH2 or m-ClC6H4CH2) in Me2SO–H2O probably involves a contribution from the unimolecular dissociation of the anion RSiMe2O– to give R– and Me2SiO.