REAXIS® C325 (Dimethyltin Dineodecanoate) is a methyl-based Sn (IV) organotin that finds use mainly as a homogenous tin catalyst for polyurethanes and silicones. Similar products within the methyl-organotin family include REAXIS® C316 (Dimethyltin Dioleate). Catalysts that have a similar neodecanoate ligand include the butyl analogue, REAXIS® C221 (Dibutyltin Dineodecanoate), the octyl analogue, REAXIS® C318 (Dioctyltin Dineodecanoate) and the inorganic tin analogue, REAXIS® C125 (Stannous Neodecanoate). As catalysts for polyurethanes and silicones, the methyl organotin family is known for its relatively high reactivity, owing mainly to the presence of the reduced steric methyl group and the related high tin content. Dimethyltin Dineodecanoate is characterized by a relatively low viscosity resulting in efficient use and dosing. REAXIS® C325 has been a commonly used product for many years and is present on most global regulatory lists, making it an ideal choice for international formulation development. REAXIS® C325 is present on most international regulatory lists for commercial use.
|Tin Content (%)
|22.5 - 24. 5
|Color (Gardner Number)
|1.11 - 1.14
|Viscosity (cP @ 20°C)
|1000 - 5000
|Refractive Index (nD @20°C)
|1.456 - 1.470
REAXIS® C325 is used primarily as a catalyst for polyurethanes and silicones. In polyurethanes, REAXIS® C325 can be used in formulations using aromatic isocyanates andis primarily used in adhesive, elastomer, and rigid foams applications. Polyurethane catalysts used in similar applications include REAXIS® C125 (Stannous Neodecanoate), REAXIS® C3208 (Bismuth Neodecanoate), and REAXIS® C233 (Dibutyltin Diacetate). Silicone-based applications include: acetoxy-, ethoxy- and oxime-based Room Temperature Vulcanizing (RTV) adhesives and sealants, polyethylene crosslinked silanes (PEX), and select silane modified polymers (SMPs).
Typical of most metal-based catalysts, tin catalysts will preferentially catalyze the urethane reaction (NCO/OH or gelation reaction), with minimal catalysis of the water reaction. Methyl organotins are used for the relatively high reactivity compared to butyl- and octyl- organotins. Steric effects and compatibility with the raw materials on reactivity can be enhanced by inclusion of the ideal ligand. REAXIS® C325 includes a ligand based on neodecanoic acid which will have the effect of enhancing reactivity across a broad range of formulations. In regard to silicone reactions, REAXIS® C325, like all tin-based catalysts, will catalyze the silanol/silane condensation reaction thus acting as both a polymerization and crosslinking catalyst. REAXIS® C325 and its neodecanoate-based analogues are preferentially used in formulations with oxime functionality.
REAXIS® C325 should be stored in the original packaging at moderate temperatures and kept from freezing. The container should be closed tightly after each use to maximize shelf life. Characteristic of most Sn (IV) organotins, the primary cause of instability would be hydrolysis. Hydrolysis results in the formation of tin hydroxide insolubles leading to deactivation of REAXIS® C325.