Diphenyldimethoxysilane (DDS)—also known as dimethoxydiphenylsilane, DMDPS, or DPDMS (CAS No. 6843-66-9)—is an important functional organosilicon compound. It has the molecular formula C14H16O2Si and a molecular weight of approximately 244.36 g/mol. The product typically appears as a liquid with a density of about 1.08 g/mL (at 20°C) and a refractive index of approximately 1.541.

Structurally, the silicon atom in DDS is bonded to two phenyl groups and two methoxy groups, thereby possessing both an organosilicon backbone and reactive methoxy functional groups. This unique structure enables it to function as a silane-based electron donor within polyolefin catalyst systems.

In the field of polypropylene production, one of the most significant applications of CAS 6843-66-9 is its use as an external electron donor for Ziegler-Natta catalysts. Research indicates that diphenyldimethoxysilane can influence the active sites of the catalyst and significantly affect the stereoregularity of the resulting polypropylene. Researchers also employ DDS—often in combination with other external electron donors—to modulate the structure and properties of polypropylene and polypropylene/ethylene-propylene rubber materials.

Currently, DDS is of particular interest to manufacturers of polypropylene catalysts, polyolefin materials, and organosilicon products. Beyond its role in polypropylene polymerization, product literature indicates that DDS can serve as a raw material for the synthesis of various organosilicon materials, including phenyl silicone resins, phenyl silicone rubbers, and phenyl silicone oils.