so as to provide 0 9 to 1 1 moles of si u2014 h bonds on the compound of formula 2 per mole of the compound of formula 1 a reaction solvent is not always necessary especially when both the reaction substrates 1 and 2 are liquid the reaction can proceed in a solventless system of course a solvent may be used for the reaction to take place suitable solvents include hydrocarbon solvents such as hexane isooctane benzene toluene and xylene and halogenated hydrocarbon solvents such as dichloromethane and dichloroethane a polymerization inhibitor is optionally added during the reaction suitable polymerization inhibitors if used are hindered phenols such as 2 6 di tert butyl 4 methylphenol bht and 1 3 5 tris 3 5 di tert butyl 4 hydroxybenzyl 2 4 6 trimethylbenzene by the process in the first embodiment of the invention described above the silyl ketene acetals of the following general formula 3 are obtainable in formula 3 r 1 r 2 r 3 r 4 r a r b and r c are as defined above in the second embodiment of the invention disilyl ketene acetals are prepared using u03b1 u03b2 unsaturated carboxylic acid esters of the general formula 4 as the starting material in formula 4 each of r 5 r 6 and r 7 is independently hydrogen or a substituted or unsubstituted monovalent hydrocarbon group of 1 to 60 carbon atoms preferably 1 to 20 carbon atoms preferred unsubstituted monovalent hydrocarbon groups are those of 1 to 20 carbon atoms the substituted monovalent hydrocarbon groups correspond to the unsubstituted monovalent hydrocarbon groups in which some or all of the hydrogen atoms bonded to carbon atoms are substituted with substituent groups suitable substituent groups include halogen atoms alkoxy groups of 1 to 20 carbon atoms.