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Bis[3-(triethoxysilyl)propyl] Disulfide (TESPD)

Si-75
CAS 56706-10-6 · Formula C18H42O6S2Si2 · MW 474.8 g/mol

A disulfide-functional organosilane that couples silica filler into rubber networks during mixing. It is used as an adhesion/cohesion promoter, intermediate, processing aid, and chemical reaction regulator.

Part of Specialty Silanes · Sulfide & Mercapto Silanes · Silane Coupling Agents
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HS Code
2931.90
At a Glance
Material Family
Silicone Fluids & Oils
Record Type
Pure compound
Primary Role
Coupling / Adhesion Promotion · Crosslinking / Curing
Functional Roles
Coupling / Adhesion Promotion Crosslinking / Curing
Industries Served
Plastics & Polymers Industrial Manufacturing
Applications & Use Cases
  • ▸ Coupling agent: Links silica filler to rubber and polymer matrices.
  • ▸ Adhesion promoter: Promotes filler-to-polymer adhesion in compounds.
  • ▸ Processing aid: Acts as a processing aid and reaction regulator in compounding.
  • ▸ Intermediate: Used as a chemical intermediate.
Physical Properties
Physical Description
Dry powder or liquid
Safety & Handling
Full SDS available on request

A grade-specific Safety Data Sheet (SDS) — with the complete hazard classification, handling precautions, and transport information — is supplied with every shipment and available on request. Confirm all safety and regulatory details against the SDS for your specific grade.

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HS / Tariff Classification
Harmonized System (HS) Code — 6-digit international heading
2931 . 90
Chapter 29
Organic chemicals
Heading 29.31
Internationally harmonized (WCO HS)
Subheading 2931.90
6-digit international code — national tariff line adds further digits
Chemical Identity
CAS Number
56706-10-6
Molecular Formula
C18H42O6S2Si2
Molecular Weight
474.8 g/mol
IUPAC Name
triethoxy-[3-(3-triethoxysilylpropyldisulfanyl)propyl]silane
PubChem CID
92506
InChI Key
FBBATURSCRIBHN-UHFFFAOYSA-N
Synonyms & Trade Names
4,4,13,13-Tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane 3,14-Dioxa-8,9-dithia-4,13-disilahexadecane, 4,4,13,13-tetraethoxy- Bis(triethoxysilylpropyl) disulfide Bis(triethoxysilylpropyl)disulfide triethoxy-[3-(3-triethoxysilylpropyldisulfanyl)propyl]silane C18H42O6S2Si2 Bis[3-(triethoxysilyl)propyl]disulfide bis(3-triethoxysilylpropyl)disulfide Bis (triethoxysilyl propyl) disulfide Bis[3-(triethoxysilyl)propyl]-disulfide Bis(Triethoxysilylpropyl)
Full Description

Bis[3-(triethoxysilyl)propyl] disulfide (CAS 56706-10-6) is a sulfur-functional organosilicon compound. It is used as an adhesion/cohesion promoter, intermediate, processing aid, and chemical reaction regulator. Its triethoxysilyl groups react with silica surfaces while the disulfide bridge links to the polymer.

Frequently Asked Questions

What does "bis" mean in the name of this silane?

In chemical nomenclature "bis" means two of the named group. Here it indicates two 3-(triethoxysilyl)propyl groups joined by a disulfide bridge, giving the structure of CAS 56706-10-6 (C18H42O6S2Si2).

What is bis-[3-(triethoxysilyl)propyl] disulfide (Si-75, TESPD) used for?

It is a sulfur-functional organosilicon coupling agent. The triethoxysilyl groups react with silica surfaces while the disulfide bridge links to the polymer, making it an adhesion/cohesion promoter, processing aid, and reaction regulator that bonds silica filler to rubber and polymer matrices.

How does TESPD (Si-75) differ from the tetrasulfide (Si-69, TESPT)?

Both are triethoxysilylpropyl silica coupling agents; the difference is the sulfur bridge. Si-75 is the disulfide (two sulfur atoms, CAS 56706-10-6) while Si-69 is the tetrasulfide (four sulfur atoms, CAS 40372-72-3). The lower sulfur rank affects scorch behavior and crosslink contribution in rubber compounding.

What is the CAS number and HS code for this coupling agent?

Bis[3-(triethoxysilyl)propyl] disulfide is CAS 56706-10-6, molecular formula C18H42O6S2Si2. It classifies under HS 2931.90 (organo-inorganic compounds, other); we confirm the destination-specific code on the quote.

How is this silane supplied in bulk and can you provide a CoA and SDS?

We supply TESPD/Si-75 in bulk industrial packaging for rubber and polymer compounders, with packaging and MOQ confirmed per order. A Certificate of Analysis and Safety Data Sheet are available with each shipment; request a bulk quote with your target volume.

Disclaimer. Information on this page — including properties, identifiers, hazard, transport (DOT/UN) and tariff (HS) classifications, and applications — is provided for general reference and is compiled from authoritative public sources (e.g. PubChem/ECHA, 49 CFR 172.101, the Harmonized Tariff Schedule). Values are typical and are not a guaranteed specification; the Certificate of Analysis (CoA) for the lot purchased governs. Products are sold for industrial and professional use only. Nothing here is a medical, health, or efficacy claim or advice. Always consult the current Safety Data Sheet (SDS) before handling, storage, transport or disposal, and confirm regulatory status, classification and suitability for your application and jurisdiction. Hazard, transport and tariff classifications must be verified for your specific shipment. RawSource makes no warranty, express or implied, and assumes no liability for use of this information. Trademarks. Third-party trademarks and brand names are the property of their respective owners; any reference is nominative — used only to identify a comparable product — and does not imply affiliation with, sponsorship by, or endorsement by the trademark owner.
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