Six-and eight-membered cyclic silicates with reactive Si H or Si-vinyl functional groups have been prepared: hexakis (dimethylsiloxy) cyclotrisiloxane (I), hexakis (vinyldimethylsiloxy) cyclotrisiloxane (II), octakis (dimethylsiloxy) cyclotetrasiloxane (III) and octakis (vinyldimethylsiloxy) cyclotetrasiloxane (IV). Reaction of pseudo wollastonite (Ca3Si3O9) with dimethylchlorosilane or vinyldimethylchlorosilane gives I and II, ...