556-67-2

Name Octamethylcyclotetrasiloxane
CAS 556-67-2
EINECS(EC#) 209-136-7
Molecular Formula C8H24O4Si4
MDL Number MFCD00003269
Molecular Weight 296.62
MOL File 556-67-2.mol
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Chemical Properties

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
biological source rabbit
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℃）
Cosmetics Ingredients Functions SOLVENT
SKIN CONDITIONING - EMOLLIENT
HAIR CONDITIONING
InChI 1S/C8H24O4Si4/c1-13(2)9-14(3,4)11-16(7,8)12-15(5,6)10-13/h1-8H3
InChIKey HMMGMWAXVFQUOA-UHFFFAOYSA-N
SMILES C[Si]1(C)O[Si](C)(C)O[Si](C)(C)O[Si](C)(C)O1
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)
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Safety Data

Symbol(GHS)  Flame (GHS02)Health Hazard (GHS08)Environment (GHS09)
GHS02,GHS08,GHS09
Signal word  Warning
Hazard statements  H226-H361f-H410
Precautionary statements  P202-P210-P233-P240-P273-P308+P313
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
Autoignition Temperature 400°C
TSCA  Yes
HazardClass  3
PackingGroup  III
HS Code  29319090
Storage Class 3 - Flammable liquids
Hazard Classifications Aquatic Acute 1
Aquatic Chronic 1
Flam. Liq. 3
Repr. 2
Hazardous Substances Data 556-67-2(Hazardous Substances Data)
Toxicity
LD50 oral in rat: 1540mg/kg

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