Bis(triethoxysilylpropyl)tetrasulfide
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| Names | |
|---|---|
| Other names
bis[3-(triethoxysilyl)propyl]tetrasulfide, bis(3-triethoxysilylpropyl)tetrasulfane, Si-69
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| Identifiers | |
| ECHA InfoCard | 100.049.888 |
CompTox Dashboard (EPA)
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| 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).
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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]
Synthesis and reactivity
The compound was first prepared by the reaction of 3-(triethoxysilyl)propyl chloride with sodium tetrasulfide:[3]
- 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 polysufide groups link to the organic polymer.
References
- ^ 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.
- ^ Wolff, Siegfried (1996). "Chemical aspects of rubber reinforcement by fillers". Rubber Chemistry and Technology. 69: 325–346. doi:10.5254/1.3538376.
- ^ 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.