Bis(triethoxysilylpropyl)tetrasulfide

Bis(triethoxysilylpropyl)tetrasulfide

Names
Other names bis[3-(triethoxysilyl)propyl]tetrasulfide, bis(3-triethoxysilylpropyl)tetrasulfane, Si-69
Identifiers
CAS Number	40372-72-3
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL3188179
ChemSpider	142291
ECHA InfoCard	100.049.888
EC Number	254-896-5
PubChem CID	162012
UNII	J98V193ZRY
InChI InChI=1S/C18H42O6S4Si2/c1-7-19-29(20-8-2,21-9-3)17-13-15-25-27-28-26-16-14-18-30(22-10-4,23-11-5)24-12-6/h7-18H2,1-6H3 Key: VTHOKNTVYKTUPI-UHFFFAOYSA-N
SMILES CCO[Si](CCCSSSSCCC[Si](OCC)(OCC)OCC)(OCC)OCC
Properties
Chemical formula	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

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.

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

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.