Cleavage of siloxanes with organyltrifluoro- and diorganyldifluorosilanes

Article abstract of DOI:10.1016/0022-328X(92)80125-H

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.