PAC Database - Detailed Chemical Data
Chemical Identity
| Chemical | CAS# | UN# | Health Code Numbers | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dimethylpolysilane; (Poly(dimethylsilane)) | 28883-63-8 |
4.00
3.00
|
||||||||||
| Formula | Synonyms | |||||||||||
| (C2.H6.Si)x | ||||||||||||
Physical Properties
| Mol Wt | State | MP (°C) | BP (°C) | VP (Hg) | VP (°C) | SG | LEL (ppm) |
|---|---|---|---|---|---|---|---|
| 290.77 | S |
PAC Values
| PAC-1 | PAC-2 | PAC-3 |
|---|---|---|
| 0.50 | 0.83 | 2.5 |
| PAC-1 | PAC-2 | PAC-3 |
|---|---|---|
| 5.9 | 9.9 | 30 |
Technical Basis
A review of available sources did not identify exposure limits or acute toxicity data for dimethylpolysilane. The molecular weight for the monomer is reported as 58.15 Da; however, the PAC/TEEL database reports a weight of 290.77 Da. Given that this is a polymer, it is reasonable to assume greater than n=1; considering this, analysts assumed n=5 for consistency with the PAC/TEEL database record of molecular weight for this chemical. Analysts evaluated exposure limits (AEGLs, ERPGs, TWAs) for similar chemicals silane (CASRN: 7803-62-5), trimethoxysilane (CASRN: 2487-90-3), and triethoxysilane (CASRN: 998-30-1) for TEEL development (Section 3.4.6). Data sources were selected according to the hierarchy listed in Table 3.1. Since there were no sources available for alkyl silanes to evaluate, alkoxysilanes were selected for TEEL calculations over silane sources because they are more structurally similar and a more conservative evaluation of alkyl silane toxicity. Exposure limits (AEGL-3, AEGL-2, ERPG-1) for trimethoxysilane (CASRN: 2487-90-3) were selected due to their priority among Protective Action Criteria (Section 1 and Section 3.4.6). The molecular weight use for conversion is what is reported in the PAC/TEEL database (n=5).
• PAC-1 = TEEL-1 = ERPG-1 (trimethoxysilane, CASRN: 2487-90-3)
• PAC-2 = TEEL-2 = AEGL-2 (trimethoxysilane, CASRN: 2487-90-3)
• PAC-3 = TEEL-3 = AEGL-3 (trimethoxysilane, CASRN: 2487-90-3)
This review generated PAC values consistent with Rev. 29A.
• PAC-1 = TEEL-1 = ERPG-1 (trimethoxysilane, CASRN: 2487-90-3)
• PAC-2 = TEEL-2 = AEGL-2 (trimethoxysilane, CASRN: 2487-90-3)
• PAC-3 = TEEL-3 = AEGL-3 (trimethoxysilane, CASRN: 2487-90-3)
This review generated PAC values consistent with Rev. 29A.
References
Chemical information: https://haz-map.com/Agents/13216
AEGLs for trimethoxysilane (CASRN: 2487-90-3, Table 7-1) retrieved from: https://www.epa.gov/aegl/trimethoxysilane-results-aegl-program
ERPG: https://cameochemicals.noaa.gov/chemical/12878