Using “Anhydrous” Hydrolysis To Favor Formation of Hexamethylcyclotrisiloxane from Dimethyldichlorosilane

The reaction between dimethyl sulfoxide and Me2SiCl2 leads to the formation of cyclic siloxanes, principally the more highly strained six-membered ring hexamethylcyclotrisiloxane (D3), via linear α,ω-dichlorosiloxanes. At short reaction times (∼15 min), the reaction was shown not to be undergoing equilibration reactions (ligand metathesis) to a significant degree. A mechanism for the formation of D3 and D4 (octamethylcyclotetrasiloxane) is …