Abstract: A method for preparing a highly heat-resistant and burning-resistant poly(silyleneethynylene phenyleneethynylene) having a repeated unit represented by the following structural formula (1A): ##STR1## wherein the phenylene group may be in the o-, m- or p-form, R represents a halogen atom or an alkyl group, alkoxy group, phenoxy group, alkenyl group, alkynyl group, aromatic group, disubstituted amino group or silanyl group; n is an integer ranging from 0 to 4; and R' represents a hydrogen atom, an alkyl group, alkenyl group, alkynyl group or aromatic group, a product obtained by the method and a hardened product obtained by heat-treating, at a temperature ranging from 50.degree.to 700.degree. C., the poly(silyleneethynylene phenyleneethynylene).

Abstract: A process for preparing an organic silicon compound is here disclosed which comprises the step of reacting a halogenated hydrocarbon selected from the group consisting ##STR1## wherein each of X.sup.1 to X.sup.16 is selected from the group consisting of hydrogen, an alkyl group, alkenyl group, phenyl group, naphthyl group, alkoxy group, acyl group, alkylamino group and dialkylamino group having 1 to 20 carbon atoms which are unsubstituted or substituted and a halogen atom; and each of at least one of X.sup.1 to X.sup.4, at least one of X.sup.8 to X.sup.10 and at least one of X.sup.11 to X.sup.16 is a halogen atom,with a silane selected from the group consisting of SiH.sub.4, Si.sub.2 H.sub.6 and Si.sub.3 H.sub.8.