56998-71-1Relevant articles and documents
Cleavage of siloxanes with organyltrifluoro- and diorganyldifluorosilanes
Voronkov, M.G.,Basenko, S.V.,Gebel, I.A.,Vitkovskii, V.Yu.,Mirskov, R.G.
, p. 1 - 9 (2007/10/02)
Hexamethyldisiloxane is cleaved with organyltrifluoro- or diorganyldifluorosilanes as low as 20 deg C in the absence of catalysts to from earlier unknown 1,1,1-trimethyl, 3-organyl-3,3-difluoro- or 1,1,1-trimethyl-, 3,3-diorganyl-3-difluorodisiloxanes with the general formula R4-nSiFn-1OSi(CH3)3 (n = 2-3) in 57-97percent yield.The Si-O bond in 1,1,3,3-tetramethyldisiloxane is broken with organyltrifluoro- or diorganyldifluorosilanes in a similar manner but more slowly to give 1,1-dimethyl-, 3-organyl-, 3,3-difluoro- or 1,1-dimethyl, 3,3-diorganyl-, 3-fluorodisiloxanes with the general formula R4-nSiFn-1OSiH(CH3)2 (n = 2-3) in 50-70percent yield.The reaction of phenyltrifluorosilane with 1,1,1,3,3,5,5,5-octamethyltrifluorosiloxane leads to 1,1,1,3,3-pentamethyl-, 5,5-difluoro-, 5-phenyltrisiloxane, whereas the reaction with tetrakis (trimethylsiloxy)siloxane gives tri(trimethylsiloxy)difluoro(phenyl)silane.Even under normal conditions of storage, the cleavage products disproportionate readily in different directions.The ability of these compounds to disproportionation depends on the nature of the substituents attached to the silicon atom and the number of fluorine atoms in the molecule.
Zur Synthese von Siloxanen XI. Spaltung von Siloxanen durch Bortrifluorid
Scheim, U.,Porzel, A.,Ruehlmann, K.
, p. 31 - 38 (2007/10/02)
The cleavage of siloxane bonds by BF3 was investigated kinetically by 1H NMR spectroscopy.The reactions could be evaluated by use ofa pseudo-first order rate law, when a sufficiently large excess of BF3 was used.The order with respect to BF3 was found to be 4.7.The rate constants obtained could be correlated to ?*- values with a ρ*-value of -1.0.The ?*-value found previously by 29Si NMR spectroscopy for the Me3SiO group of 0.35 was confirmed.
