| Identification | More | [Name]
Octamethylcyclotetrasiloxane | [CAS]
556-67-2 | [Synonyms]
D4
DIMETHYLSILOXANE CYCLIC TETRAMER
OCTAMETHYLCYCLOTETRASILOXANE
OCTAMETHYLTETRASILOXANE
VOLASIL(TM) 244
2,2,4,4,6,6,8,8-Octamethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane
CO9810
cyclicdimethylsiloxanetetramer
Cyclotetrasiloxane,octamethyl-
kf994
NUC Silicone VS 7207
nucsiliconevs7207
O9810
Octamethylcyclotetraoxysilane
octamethyl-cyclotetrasiloxan
octamethylcyclotetrasiloxane(volasil244)
Oktamethylcyklotetrasiloxan
sf1173
siliconesf1173
tetracyclosiloxane,octamethyl- | [EINECS(EC#)]
209-136-7 | [Molecular Formula]
C8H24O4Si4 | [MDL Number]
MFCD00003269 | [Molecular Weight]
296.62 | [MOL File]
556-67-2.mol |
| Chemical Properties | Back Directory | [Appearance]
Colorless clear liquid | [Melting point ]
17-18 °C (lit.) | [Boiling point ]
175-176 °C (lit.) | [density ]
0.956 g/mL at 25 °C(lit.)
| [vapor density ]
1 (vs air)
| [vapor pressure ]
1.32hPa at 25℃ | [refractive index ]
n20/D 1.396(lit.)
| [Fp ]
140 °F
| [storage temp. ]
2-8°C | [solubility ]
<0.001g/l Hydrolysis | [form ]
liquid | [color ]
colorless | [Specific Gravity]
0.956 | [explosive limit]
0.4-11.7%(V) | [Water Solubility ]
INSOLUBLE | [Sensitive ]
Moisture Sensitive | [Usage]
Fungicide | [Merck ]
14,6747 | [BRN ]
1787074 | [Dielectric constant]
2.4（20℃） | [InChIKey]
HMMGMWAXVFQUOA-UHFFFAOYSA-N | [LogP]
6.98 at 21.7℃ | [Uses]
Polydimethylsiloxane by the Polymerization of Octamethylcyclotetrasiloxane: To a resin flask equipped with a thermometer, stirrer, and reflux eondenser is added 1000 gm of octamethylcyclotetrasiloxane. The siloxane is heated to 165°C, and then 0.14gm of a potassium hydroxide-isopropanol complex (neutral equivalent = 193.5) is added to give a Si : Κ ratio of 4470:1. In 25 min the stirrer begins to stall, and the polymer is now heated for 3(1/2) hr at 150°C to complete polymerization. The resulting polymer has an intrinsic viscosity of 1.5 dl/gm corresponding to a molecular weight of 804,600. | [CAS DataBase Reference]
556-67-2(CAS DataBase Reference) | [NIST Chemistry Reference]
Cyclotetrasiloxane, octamethyl-(556-67-2) | [EPA Substance Registry System]
556-67-2(EPA Substance) |
| Safety Data | Back Directory | [Hazard Codes ]
Xn | [Risk Statements ]
R53:May cause long-term adverse effects in the aquatic environment.
R62:Possible risk of impaired fertility. | [Safety Statements ]
S36/37:Wear suitable protective clothing and gloves .
S46:If swallowed, seek medical advice immediately and show this container or label .
S51:Use only in well-ventilated areas .
S61:Avoid release to the environment. Refer to special instructions safety data sheet . | [RIDADR ]
UN 1993 3/PG 3
| [WGK Germany ]
1
| [RTECS ]
GZ4397000
| [TSCA ]
Yes | [HazardClass ]
3 | [PackingGroup ]
III | [HS Code ]
29319090 | [Hazardous Substances Data]
556-67-2(Hazardous Substances Data) | [Toxicity]
LD50 oral in rat: 1540mg/kg |
| Hazard Information | Back Directory | [Chemical Properties]
Colorless clear liquid | [Definition]
ChEBI: A cyclosiloxane that is the octamethyl derivative of cyclotetrasiloxane. | [Preparation]
Commercially Octamethylcyclotetrasiloxane is produced from dimethyldichlorosilane. Dimethyldichlorosilane is added dropwise to water, the temperature is maintained at 30-40°C, stratified, the acid water is released, the oily material is hydrolyzed with sodium hydroxide solution, the hydrolysate and 0.5%-2% potassium hydroxide are added to the cracking kettle and cracked at 120-140°C and 99.8 kPa vacuum. The cracked material is fractionated and the fraction is collected at 173-176°C to obtain octamethylcyclotetraoxysilane. | [General Description]
Octamethylcyclotetrasiloxane (D4) is a volatile methylsiloxane (VMS) with a relatively low molecular weight. This silicone fluid has a silicon-oxygen bond in a cyclic arrangement and methyl groups are attached to the silicon atom. D4 can be used in the manufacture of silicone based polymers for use in medical devices and personal care products. | [Health Hazard]
Octamethylcyclotetrasiloxane (D4) can interfere with the body’s hormones. In animals, it can affect the reproductive system.
D4 is classified as a category 1 endocrine disruptor by the European Commission. A 2018 study commissioned by the Danish EPA identified D4 as an endocrine disruptor. The Global Harmonized System Label Requirements classified D4 as suspected to produce reproductive toxicity. D4 was added to the Toxic Substances Control Act work plan due to reproductive toxicity, moderate environmental persistence, and high bioaccumulation potential.
Adverse reproductive effects including estrogenic effects have been observed in rodents. The European Chemicals Agency characterized D4 as a persistent, bioaccumulative, and toxic chemical, and designated D4 as a Substance of Very High Concern. | [Flammability and Explosibility]
Flammable | [Safety Profile]
A skin irritant. When heated todecomposition it emits acrid smoke and irritating vapors. | [Purification Methods]
The solid exists in two forms, m 16.30o and 17.65o. Dry it over CaH2 and distil it. Further fractionation can be effected by repeated partial freezing and discarding the liquid phase. [Osthoff & Grubb J Am Chem Soc 76 399 1954, Hoffman J Am Chem Soc 75 6313 1953, Beilstein 4 IV 4125.] |
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