PAC Database - Detailed Chemical Data
Chemical Identity
| Chemical | CAS# | UN# | Health Code Numbers | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hexamethyldisilazane | 999-97-3 | 1993 |
14.01
11.00
14.02
7.01
8.00
4.08
4.07
3.05
3.10
7.11
|
|||||||||
| Formula | Synonyms | |||||||||||
| C6H19NSi2 | HEXAMETHYL DISILAZANE, 1,1,1,3,3,3-HEXAMETHYLDISILAZANE, BIS(TRIMETHYLSILYL)AMINE, DI(TRIMETHYLSILYL)AMINE, DISILAZANE, 1,1,1,3,3,3-HEXAMETHYL-, HEXAMETHYLDISILAZANE, HEXAMETHYLDISILYLAMINE, HMDS, HMDS (SILAZANE), HMDS 3, LS 7150, OAP, SZ 6079, TSL 8802 | |||||||||||
Physical Properties
| Mol Wt | State | MP (°C) | BP (°C) | VP (Hg) | VP (°C) | SG | LEL (ppm) |
|---|---|---|---|---|---|---|---|
| 161.44 | L | 125 | 13.8 | 25 | 0.76 |
PAC Values
| PAC-1 | PAC-2 | PAC-3 |
|---|---|---|
| 5.8 | 64 | 380 |
| PAC-1 | PAC-2 | PAC-3 |
|---|---|---|
| 0.88 | 9.7 | 58 |
Technical Basis
A review of available sources identified the following: LD50 toxicity data for rat and mouse for intraperitoneal, oral, and intravenous routes, and rat and mouse LC50 toxicity data. Data sources were selected according to the hierarchy listed in Table 3.1. Toxicity data were selected according to type of exposure, species, and route according to the hierarchies stated in Sections 3.3.1, 3.3.2, and evaluated using factors in Tables 3.2, 3.3, and 3.4. Inhalation exposures were scaled to 60-minute equivalents using the ten Berge equation (Section 3.3.4). The preferred starting point to estimate the TEEL-3 value was inhalation exposure data, a rat 4-hr LC50. TEEL-1 and TEEL-2 values were derived according to Table 3.5.
• TEEL-1 = TEEL-2/11
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat LC50 (8700 mg/m3/4H)
This review generated TEEL values that were less conservative and inconsistent with those found in Rev. 29A. In Rev. 29A the TEEL-3 basis was a rat oral LD50, however this review found and used LC50 toxicity data, which is more preferred.
• TEEL-1 = TEEL-2/11
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat LC50 (8700 mg/m3/4H)
This review generated TEEL values that were less conservative and inconsistent with those found in Rev. 29A. In Rev. 29A the TEEL-3 basis was a rat oral LD50, however this review found and used LC50 toxicity data, which is more preferred.
References
Rat LC50: Gigiena Truda i Professional'nye Zabolevaniya. Labor Hygiene and Occupational Diseases., 30(5)(52), 1986 via PubChem; National Center for Biotechnology Information (2023). PubChem Compound Summary for CID 13838, Hexamethyldisilazane. Retrieved from https://pubchem.ncbi.nlm.nih.gov/compound/Hexamethyldisilazane.