Bis[3-(triethoxysilyl)propyl] tetrasulfide | CAS No. 40372-72-3

Bis[3-(triethoxysilyl)propyl] tetrasulfide, also known as TESPTS or 3,3′-Tetrathiobis(propyl-triethoxysilane), is a bifunctional organosilane with the molecular formula C18H42O6S4Si2 and the CAS number 40372-72-3. It has a technical grade purity of ≥90% (NMR) and a molecular weight of 538.95. It is a liquid at room temperature with a density of 1.08 g/mL and a refractive index of 1.49.

TESPTS is widely used as a crosslinking agent and reinforcing filler in the manufacturing of rubber. It can form covalent bonds with both organic and inorganic substrates, such as rubber polymers and silica fillers, through its triethoxysilyl and tetrasulfide groups. This results in improved mechanical properties, such as tensile strength, elongation, abrasion resistance, and heat resistance, of the rubber products. TESPTS also enhances the dispersion and adhesion of silica fillers in rubber matrices, reducing the rolling resistance and improving the fuel efficiency of tires.

TESPTS can also provide corrosion protection to metallic substrates by forming a thin film on their surface. The film acts as a barrier against moisture, oxygen, and chloride ions, which are the main causes of corrosion. The film also has self-healing properties, as it can re-form covalent bonds with the metal after being damaged by mechanical or chemical stress.

TESPTS is also used as a precursor in the synthesis of mesoporous organosilicas, which are hybrid materials with tunable pore size, shape, and functionality. TESPTS can be co-condensed with other organosilanes or tetraethyl orthosilicate (TEOS) under acidic or basic conditions to form mesoporous organosilicas with various structures, such as hexagonal, cubic, lamellar, or wormlike. The tetrasulfide groups in TESPTS can act as functional sites for further modification or catalysis.

TESPTS is a versatile organosilane that can be used for various applications in rubber, metal, and mesoporous materials.

Technical parameters:

This product is a light yellow transparent liquid with a slight ethanol odor, soluble in ethanol, ketones, benzene, acetonitrile, dimethylformamide, dimethyl sulfoxide, chlorinated hydrocarbons, insoluble in water.

Light yellow to yellow transparent liquid in appearance.



  1. It is often used to treat carbon black, SiO2 and other inorganic fillers, not only has the role of activator and coupling agent,
  2. It also has the role of cross-linking agent, softener and reinforcing agent
  3. It is used as a reinforcing agent and vulcanizing agent in the rubberindustry.
  4. It can be used for natural rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, butyl ester rubber, neoprene rubber, butyl rubber, halogenated butyl rubber, EPDM rubber and oil-filled rubber of these rubbers, which can also be used in the combined rubber of these rubbers.
  5. Applied to sulfurized rubber, it can improve crosslinking stability, tear resistance, shear resistance, water resistance, etc., and reduce compression deformation.
  6. Applicable inorganic fillers: carbon black, silica, glass fiber, talc, mica, fly ash, clay, etc.
  7. Suitable for rubber products, tires (tread, carcass, tire outer wall), solid rubber tire rubber roller surface. Conveyor belt surfaces, steel brush wire adhesives, cables (absolute and cladding), shoes (pullback shoes, marathon shoes, tennis shoes).

The functions are:

  1. Unvulcanized rubber material

(1) Reduce Mooney viscosity; (2) Reduce scorching; (3) Increase the degree of vulcanization; (4) The mixing, calendering and extrusion characteristics are greatly improved.

  1. Vulcanized rubber

(1) Increased tensile strength; (2) Increase the fixed extension strength; (3) Permanent deformation reduction; (4) Heat generation and dynamic characteristics are improved; (5) Silicon wear performance is improved: (6) tear strength is improved; (7) The swelling property in water and other substances is improved.

Packing: The finished product is packed in 5KG, 10KG, 25KG, 200KG plastic drum, other specifications need to be booked.

Product Code Si69
English Name: Bis[3-(triethoxysilyl)propyl]tetrasulfide
Alias: 3,3′-Bis(triethoxysilylpropyl)tetrasulfide;
A 1289;
B 2494;
Bis[3-(triethoxysilyl)propyl] tetrasulfide;
Bis[g-(triethoxysilyl)propyl] tetrasulfide;
Cabrus 4;
Degussa Si 69;
EF 60;
EF 60 (coupling agent);
KBE 846;
KBE 849;
KH 845-4;
MB 69;
SCA 98;
SIB 1825.0;
Si 29;
Si 69;
Silane 69;
Silquest A 1289;
TM 69;
Unisilan 41;
WD 40;
WD 40 (coupling agent);
Z 6940
Molecular formula: C18H42O6S4Si2
Molecular weight: 538.94
CAS Number: 40372-72-3
EINECS Registration Number: 254-896-5
Physicochemical properties
Refractive index: 1.49
Density: 1.08
Content(%) ≥22.5


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