Reaxis®  C320 - Dioctyltin Dilauryl Mercaptide

REAXIS® C320 (Dioctyltin Dilauryl Mercaptide), also commonly known as Bis(dodecylthio)dioctyltin or Dioctyltin didodecylmercaptide, is an octyl-based dialkyl organotin with added functionality.  REAXIS® C320 has the characteristic reactivity of a Sn (IV) organotin catalyst with improved upfront delay and improved hydrolytic stability due to the presence of a ligand with thiol functionality. Used primarily in polyurethanes, REAXIS® C320 imparts more controlled reactivity versus standard metal carboxylates such as REAXIS® C218 (Dibutyltin Dilaurate), REAXIS® C216 (Dioctyltin Dilaurate), and REAXIS® C325 (Dimethyltin Dineodecanoate). Catalysts similar to REAXIS® C320 include, REAXIS® C319 (Dibutyltin Dilauryl Mercaptide), REAXIS® C214 (Dioctyltin bis-(isooctyl Mercaptoacetate) and its isomer, REAXIS® C416 (Dioctyltin bis-(2-Ethylhexyl Mercaptocetate)).

For more information, we invite you to read our technical bulletins on Iron Catalysts for Urethane Chemistries and Strategies for Improving Back-End Reactivity of Bismuth Carboxylate Catalysts.

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Technical Information

  • Product Category Organotin

  • Chemical Name Dioctyltin Dilauryl Mercaptide

  • CAS Number 22205-30-7

Typical Specifications

Parameter Range
Tin Content (%) 15.7 - 16.8
Color (Gardner Number) 5 Max
Viscosity (cP @ 20°C) 20 - 60
Density (g/ml) 0.95 - 1.05

International Regulatory Listings

  • TSCA (US) Yes

  • DSL (Canada) Yes

  • AICS (Australia) Yes

  • KECI (South Korea) Yes

  • IECSC (China) Yes

  • ENCS (Japan) Yes

  • DSL (Canada) No

  • REACH (EU) No

  • TCSI (Taiwan) No

  • NZloC (New Zealand) No

  • PICCS (The Philippines) No


Unlike standard organotin carboxylates, sulfur-bearing organotins like Dioctyltin Dilauryl Mercaptide are primarily used as a catalyst for polyurethanes. Reactivity of catalysts such REAXIS® C320, tend to be inactive in silicone and esterification-related applications.   As the sulfur ligand acts as a blocking agent, thermal deblocking is required to initiate the back-end cure. Thus, catalysts such as REAXIS® C3320 tend to perform best in adhesive, elastomer, and foam applications with adequate exotherms. For coatings applications, REAXIS® C320 can be used in baked cured systems in contrast to ambient cured systems.


As is typical of most organotin and inorganic tin catalysts, the specific ligand in addition to the tin metal concentration contributes a major influence on overall reactivity. This is specifically highlighted in regard to sulfur- bearing ligands. In general, these sulfur ligands impart improved front-end delay and hydrolytic stability versus standard tin carboxylates. Standard ligands include thiols, mercaptides and mercaptoacetates. Reactivity as defined by delay, thermal availability, hydrolytic stability, and final cure will depend on the specific ligand, tin content, alkyl group and, most importantly, other raw materials used in the specific polyurethane formulation. As REAXIS® C320 is a mercaptan based catalyst, its delay should be less pronounced compared mercaptoacetates such REAXIS® C416, REAXIS® C214, and REAXIS® C322. In regard to the reactivity of the various urethane reactions, catalysts such as REAXIS® C320 will selectively catalyze the isocyanate-polyol reaction, with less of an effect on the water reaction. REAXIS® C320 tends to give longer delay and slower reactivity versus its butyl analogue, REAXIS® C319. 


Package & Storage

  • 44 lb (20 kg) plastic pail
  • 440 lb (200 kg) plastic drum

REAXIS® C320 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. Although more stable compared to organotin carboxylates, long-term contact with moisture could result in hydrolysis with the formation of tin oxide insolubles leading to deactivation of REAXIS® C320. 

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

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Technical Bulletins

Hazard Classification (US SDS)

Section Hazard Class Category Hazard Statement
A.10 acute toxicity (oral) 4 H302
A.9 specific target organ toxicity - repeated exposure 1 H372

Hazard Pictograms (US SDS)


Transportation Information (US SDS)

DOT IMDG ICAO Environment Hazard
UN Number not assigned not assigned not assigned non-environmentally hazardous acc. to the dangerous goods regulations
UN Proper Shipping Name not relevant not relevant not relevant
Transport Class none none none
Packing Group not assigned not assigned not assigned

Primary Composition Substance(s)

  • Bis(dodecylthio)dioctylstannane

Alternative Product(s) to Consider

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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