REAXIS® C220 (Monobutyltin Tris-(2-Ethylhexanoate)) is a liquid organotin homogenous catalyst that is used primarily as an esterification catalyst. Alternatively, but less common, REAXIS® C220 can be used as a polyurethane catalyst. REAXIS® C220 is a monobutyltin -based organotin that is lower in toxicity compared to dibutyl-based organotins. Of the commonly used esterification tin catalysts, REAXIS® C220 is the only liquid catalyst available. Other commonly used esterification catalysts include REAXIS® C248 (Dibutyltin Oxide) and inorganic tin products including REAXIS® C129 (Stannous Octoate), REAXIS® C160 (Stannous Oxalate), REAXIS® C162 (Stannous Chloride), and REAXIS® C188 (Stannous Oxide).
|Tin Content (%)
|Viscosity (cP @ 20°C)
|Color (Gardner Number)
|Acid Number (mgKOH/g)
|255 - 285
REAXIS® C220 is primarily used as an esterification catalyst, specifically for both monomeric and polymeric saturated and unsaturated esters. End-use applications include personal care, lubricants, coatings and plastics. REAXIS® C220 is ideal for applications where end-product toxicity is of critical concern given its monoalkyl makeup. REAXIS® C220 can also be used as a polyurethane catalyst in select formulations.
Like most organotins used in esterifications, the key attributes of REAXIS® C220 are its high-temperature stability, low color as supplied, good reactivity as evidenced by low acid number endpoints, and minimal reactivity-derived color effects on the final product. Compared to titanium catalysts, REAXIS® C220 also has improved hydrolytic stability, which is especially important during the initial stages of the esterification reaction. As tin concentration is more correlated with reactivity in esterifications, the use of REAXIS® C220 must be increased when compared to higher tin products such as REAXIS® C248 and REAXIS® C160. But as these effects are formulation/raw material dependent, the negative effects of lower tin content on reactivity can be overcome, either when a liquid catalyst will compatibilize more efficiently with alcohol/acid raw materials used, or there is related ligand compatibility.
REAXIS® C220 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 oxide insolubles leading to deactivation of REAXIS® C220.