Base cleavage of R–Si bonds of silanols RSiMe2OH. A proposed new mechanism of substitution at silicon
- 1 January 1984
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 12,p. 2099-2103
- https://doi.org/10.1039/p29840002099
Abstract
Cleavage of R–Si bonds has been found to occur unexpectedly rapidly in solutions of RSiMe2OMe (R =m-ClC6H4CH2 or PhC⋮C) in 5 vol-% H2O–MeOH containing relatively small concentrations of NaOMe, but with a levelling off of the rate at high concentrations of the base. The behaviour is attributed to the formation of RSiMe2OH and hence RSiMe2O–, and it is suggested that unimolecular dissociation of the silanolate anion RSiMe2O– to give R– and the silianone Me2SiO (both of which react rapidly with the solvent) plays a significant role. The silanols RSiMe2OH are roughly estimated to have pKa values of 11 (R =m-ClC6H4CH2) and 9.8 (R = PhC⋮C) in water.Keywords
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