Basic information
- Name:
Octamethylcyclotetrasiloxane
- CAS No.:
556-67-2
- Molecular Structure:
- Formula:
- C8H24O4Si4
- Molecular Weight:
- 296.68
- Synonyms:
- Cyclotetrasiloxane,octamethyl- (8CI,9CI);Cyclic dimethylsiloxane tetramer;DWQ 110;DWQ 120;Dabco DC 5258;Dow Corning 244;KF 994;LS 8620;Mirasil CM 4;NSC 345674;NUCSilicone VS 7207;
- EINECS:
- 209-136-7
- Density:
- 0.95 g/cm3
- Melting Point:
- 17-18 °C(lit.)
- Boiling Point:
- 175 °C at 760 mmHg
- Flash Point:
- 63.2 °C
- Solubility:
- insoluble in water
- Appearance:
- Colorless clear liquid
- Hazard Symbols:
N- Risk Codes:
- 53-62
- Safety Description:
- 36/37-46-51-61 Details
- Transport Information:
- UN 1993 3/PG 3
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Chemistry
The Molecular Structure of Octamethylcyclotetrasiloxane (CAS NO.556-67-2):
Empirical Formula: C8H24O4Si4
Molecular Weight: 296.6158
Nominal Mass: 296 Da
Average Mass: 296.6158 Da
Monoisotopic Mass: 296.075163 Da
Index of Refraction: 1.423
Molar Refractivity: 79.02 cm3
Molar Volume: 310 cm3
Surface Tension: 18.4 dyne/cm
Density: 0.95 g/cm3
Flash Point: 63.2 °C
Enthalpy of Vaporization: 39.44 kJ/mol
Boiling Point: 175 °C at 760 mmHg
Vapour Pressure: 1.57 mmHg at 25°C
Appearance: Colorless to brown liquid
IUPAC Name: 2,2,4,4,6,6,8,8-octamethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane
Product Categories: Chloro;Silicon Compounds;Organics;Dichlorosilanes;Dichlorosilanes (for Polysilanes);Functional Materials;Reagent for High-Performance Polymer Research;Si (Classes of Silicon Compounds);Si-Cl Compounds;Silicon Compounds (for Synthesis);Synthetic Organic Chemistry;Chloro Silanes
Storage temp: Store at 0-5°C
Water Solubility: reacts
Sensitive: Moisture Sensitive
Stability: Stable. Reacts violently with water and alcohols. Highly flammable. Incompatible with strong oxidizing agents, water, alcohols, caustics, ammonia
Uses
Octamethylcyclotetrasiloxane (CAS NO.556-67-2) is commonly used as raw materials of organic silicon, also used in the electronics industry.
Toxicity Data With Reference
| 1. | skn-rbt 500 mg/24H MLD | 85JCAE Prehled Prumyslove Toxikologie; Organicke Latky Marhold, J.,Prague, Czechoslovakia.: Avicenum,1986,1230. | ||
| 2. | eye-rbt 500 mg/24H MLD | 85JCAE Prehled Prumyslove Toxikologie; Organicke Latky Marhold, J.,Prague, Czechoslovakia.: Avicenum,1986,1230. |
Consensus Reports
Reported in EPA TSCA Inventory.
Safety Profile
A skin irritant. When heated to decomposition it emits acrid smoke and irritating vapors.
Hazard Codes: 
XiXn
F
N
Risk Statements: 20-59-36/37/38-11-67-65-63-48/20-38-20/21-50/53
R20: Harmful by inhalation
R59: Dangerous to the ozone layer
R36/37/38: Irritating to eyes, respiratory system and skin
R11: Highly flammable
R67: Vapours may cause drowsiness and dizziness
R65: Harmful: may cause lung damage if swallowed
R63: Possible risk of harm to the unborn child
R38: Irritating to skin
R20/21: Harmful by inhalation and in contact with skin
R50/53: Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment
Safety Statements: 60-61-62-36/37-59
S60: This material and its container must be disposed of as hazardous waste
S61: Avoid release to the environment. Refer to special instructions / safety data sheets
S62: If swallowed, do not induce vomitting; seek medical advice immediately and show this container or label
S36/37: Wear suitable protective clothing and gloves
S59: Refer to manufacturer / supplier for information on recovery / recycling
RIDADR: UN 2924 3/PG 2
WGK Germany: 3
F: 3-10-19-21
TSCA: Yes
HazardClass: 3
PackingGroup: II
HS Code: 29310095