Bis(triethoxysilylpropyl)tetrasulfide

Bis(triethoxysilylpropyl)tetrasulfide is an organosulfur compound with the formula S4[C3H6Si(OEt)3]2 (Et = C2H5). The molecule consists of two trialkoxysilyl propyl groups linked with a polysulfide. It is often sold as a mixture with the trisulfide. The compound is a colorless viscous liquid that is soluble in ordinary organic solvents such as toluene. Commercial samples often are yellowish. The compound is added to rubber compositions that contain silica filler.[1][2][3]

Bis(triethoxysilylpropyl)tetrasulfide
Names
IUPAC name
TESPT
Other names
bis[3-(triethoxysilyl)propyl]tetrasulfide, bis(3-triethoxysilylpropyl)tetrasulfane, Si-69
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.049.888
EC Number
  • 254-896-5
UNII
Properties
C18H42O6S4Si2
Molar mass 538.95
Appearance yellow syrup
Density 1.08 g/cm3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Synthesis and reactivity

The compound was first prepared by the reaction of 3-(triethoxysilyl)propyl chloride with sodium tetrasulfide:[4]

Na2S4 + 2 ClC3H6Si(OEt)3 → S4[C3H6Si(OEt)3]2 + 2 NaCl

Bis(triethoxysilylpropyl)tetrasulfide is a bifunctional molecule in that it contains two kinds of reactive functional groups. The tetrasulfide group is a polysulfide, which means that it consists of a chain of sulfur atoms. S-S bonds are susceptible to reduction (to thiols), attachment to metals (e.g., for protection against corrosion), and vulcanization. The triethoxysilyl groups are susceptible to hydrolysis, resulting in cross-linking via sol-gel condensation. In the usual application of this chemical, the hydrolyzed siloxy groups attach to silica particles and the polysulfide groups link to the organic polymer.[5]

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References
  1. Kohjiya, Shinzo; Ikeda, Yuko (2000). "Reinforcement of general-purpose grade rubbers by silica generated in situ". Rubber Chemistry and Technology. 73: 534–550. doi:10.5254/1.3547604.
  2. Wolff, Siegfried (1996). "Chemical aspects of rubber reinforcement by fillers". Rubber Chemistry and Technology. 69: 325–346. doi:10.5254/1.3538376.
  3. Vilmin, F.; Bottero, I.; Travert, A.; Malicki, N.; Gaboriaud, F.; Trivella, A.; Thibault-Starzyk, F. (2014). "Reactivity of Bis[3-(triethoxysilyl)propyl] Tetrasulfide (TESPT) Silane Coupling Agent over Hydrated Silica: Operando IR Spectroscopy and Chemometrics Study". The Journal of Physical Chemistry C. 118: 4056-4071. doi:10.1021/jp408600h.CS1 maint: multiple names: authors list (link)
  4. Thurn, Friedrich; Meyer-Simon, Eugen; Michel, Rudolf "Verfahren zur Herstellung von Organosiliziumverbindungen (Continuous manufacture of bis[3-(triethoxysilyl)propyl] tetrasulfide)" Ger. Offen. (1973), DE 2212239 A1 19731004.
  5. Choi, S.-S.; Kim, I.-S.; Woo, C.-S. (2007). "Influence of TESPT Content on Crosslink Types and Rheological Behaviors of Natural rubber compounds reinforced with Silica". Journal of Applied Polymer Science. 106: 2753-2758. doi:10.1002/app.25744.CS1 maint: multiple names: authors list (link)
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