Copper(I) chloride catalyzed cross-dehydrocoupling reactions between silanes and ethynyl compounds. A new method for the copolymerization of silanes and alkynes

In the presence of an amine, copper(I) chloride is an effective catalyst for the cross-dehycrocoupling of silanes with alkynes. The reactions proceed at useful rates above 100 °C, but rates drop dramatically on going from 1° to 2° to 3° organosilanes. Primary silanes, RSiH 3 (R = Ph,n-hexyl), react in a stepwise fashion with phenylacetylene to give the products RSiH 3−x (CCPh) x (x = 1-3), each of which has been isolated and characterized. The secondary silanes RR′SiH 2 (R = R′ = Ph; R = Ph, R′ = Me; R = n-Bu, R′ = Me) also give mono- and diphenylethynyl products. The dehydrocoupling reaction has been applied to the synthesis of new polymers containing both acetylene units and silicon atoms in the backbone. 1,3-Diethynylbenzene gives polymers of relatively high molecular weight with phenylsilane and phenylmethylsilane, but reactions of phenylmethyldiethynylsilane are too slow to give anything beyond low molecular weight oligomers. Keywords: organosilanes, alkynes, dehydrocoupling, copper(I) chloride, polymers, catalysis.