Octamethylsilsesquioxane
Also known as: 1,3,5,7,9,11,13,15-Octamethylpentacyclo[9.5.1.1(3,9).1(5,15).1(7,13)]octasiloxane, Permethyloctasilsesquioxane, PSS-Octamethyl substituted, Octamethyl-POSS
Octamethylsilsesquioxane (CAS 17865-85-9) is a compound in the Organic Compounds category listed in the Jingsj chemical database. It has the molecular formula C8H24O12Si8 and a molecular weight of 536.95300 g/mol. Key properties include a melting point of >350ºC, a boiling point of 235ºC at 760 mmHg and a density of 1.26g/cm3. No supplier offers are currently listed; request a quote. Record last updated Nov 3, 2026.
- CAS No.
- 17865-85-9
- Jingsj CID
- J-1394834-0
- Molecular Formula
- C8H24O12Si8
- Molecular Weight
- 536.95300 g/mol
- Category
- Organic Compounds
- Last updated
- 11/3/2026
No offers for this compound yet.
Request a quotePhysicochemical Properties
| Melting Point | >350ºC |
|---|---|
| Boiling Point | 235ºC at 760 mmHg |
| Density | 1.26g/cm3 |
| Exact Mass | 535.94200 |
| PSA | 110.76000 |
| LogP | 0.80320 |
Frequently Asked Questions
What is the CAS number of Octamethylsilsesquioxane?
The CAS number of Octamethylsilsesquioxane is 17865-85-9.
What are the molecular formula and molecular weight of Octamethylsilsesquioxane?
Octamethylsilsesquioxane has molecular formula C8H24O12Si8 and molecular weight 536.95300 g/mol.
What are the upstream and downstream products of Octamethylsilsesquioxane?
For Octamethylsilsesquioxane, Upstream Products: 2,4,6,8-Tetramethylcyclotetrasiloxane, Methyltrimethoxysilane, Methyltriethoxysilane.
Data compiled from public chemical databases such as PubChem and supplier catalogs; supplier offers are provided by suppliers.
Last updated:
How to cite: Jingsj. "Octamethylsilsesquioxane (CAS 17865-85-9)". Jingsj Chemical Database. https://www.jingsj.com/compound/J-1394834-0 (accessed 2026-11-09).
Data for reference only; verify product details with suppliers before purchase.