Reaxis®  C248 - Dibutyltin Oxide

REAXIS® C248 (Dibutyltin Oxide) is a dialkyl organotin typically used as an esterification catalyst. Commonly referred as DBTO or Dibutyloxotin, REAXIS® C248 is characterized by a high tin content (~ 48%) and oxide ligand which imparts both high reactivity and high- temperature stability.  REAXIS® C248 is supplied as a solid and can be supplied as a stable liquid with suitable diluents such as plasticizers and silanes. Related liquid-grade versions include REAXIS® C248D, which includes a plasticizer and a relatively high tin content, REAXIS® C248DP, which contains a plasticizer and lower tin content, REAXIS® C248DN, which also contains a plasticizer but has a lower overall tin volume, REAXIS® C248T, which contains a silane complex, and REAXIS® C248VM, which is another variant of our DBTO and silane compound. These liquid versions are used as catalysts for silicone condensation reactions. REAXIS® C248LC is a solid-grade version with improved particle size distribution and lower chloride content. 


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Technical Information

  • Product Category Organotin

  • Chemical Name Dibutyltin Oxide

  • CAS Number 818-08-6

Typical Specifications

Parameter Range
Tin Content (%) 47.0 Min
Chloride (%) 0.2 Max
Loss On Drying (%) 0.5 Max

International Regulatory Listings

  • TSCA (US) Yes

  • TSCA (US) Yes

  • AICS (Australia) Yes

  • KECI (South Korea) Yes

  • IECSC (China) Yes

  • ENCS (Japan) Yes

  • TCSI (Taiwan) Yes

  • NZloC (New Zealand) Yes

  • PICCS (The Philippines) Yes

  • NDSL (Canada) No

  • REACH (EU) No


REAXIS® C248 is primarily used as a homogenous catalyst for fatty acid -based saturated and unsaturated monomeric and polymeric esters. REAXIS® C248 can be used as a transesterification catalyst and is this used in the synthesis of alkyd resins. REAXIS® C248 and REAXIS® C248LC are used in electro-coat (E-coat) applications, where the latter is preferred given the more controlled particle size and lower chlorides. In its plasticizer and silane liquid forms, Dibutyltin Oxide DBTO is a good silicone condensation catalyst for adhesive, sealant, and coatings formulations, especially those formulations using silane terminated polymers (STPs).Alternative catalysts for esterification reactions include REAXIS® C220 (Monobutyltin Tris-(Ethylhexanaote)), REAXIS® C160 (Stannous Oxalate) and REAXIS® C129 (Stannous Octoate).



REAXIS® C248 has a few characteristics that make it a suitable catalyst for a wide range of high-temperature esterification reactions. These include a high active tin content, dialkyl content, and the presence of an oxide ligand. These characteristics result in a tin catalyst with good compatibility in a wide range of ester formulations, high reactivity leading to lower reaction times and the synthesis of low color end products, stability at typical reactions temperatures (180-230C), and hydrolytic stability in the presence of water generated during esterification. 


Package & Storage

  • 55 lb (25 kg) pails

REAXIS® C248 should be stored in the original packaging at moderate temperatures. The container should be closed tightly after each use to maximize shelf life. 


Safety and Handling

Before use of Reaxis products please refer to the relevant Safety Data Sheet (SDS) for safety and toxicological data as well as for the information on proper transportation, storage, and use. SDSs are available by request via our web site, contacting your local representative, or emailing direct to




This information is provided to the best of our knowledge but without obligation. Reaxis is not liable for any incorrect or missing information. This data sheet becomes invalid upon publication of a new version. Please contact us for the latest version.

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