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Octamethylcyclotetrasiloxane

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Name

Octamethylcyclotetrasiloxane

EINECS 209-136-7
CAS No. 556-67-2 Density 0.95 g/cm3
PSA 36.92000 LogP 2.87360
Solubility insoluble in water Melting Point 17-18 °C(lit.)
Formula C8H24O4Si4 Boiling Point 175 °C at 760 mmHg
Molecular Weight 296.618 Flash Point 63.2 °C
Transport Information UN 1993 3/PG 3 Appearance Colorless clear liquid
Safety 36/37-46-51-61 Risk Codes 53-62
Molecular Structure Molecular Structure of 556-67-2 (Octamethylcyclotetrasiloxane) Hazard Symbols DangerousN
Synonyms

Dimethylcyclosiloxane;Cyclic dimethylsiloxane tetramer;Dow Corning 244;KF 994;LS 8620;Mirasil CM 4;NSC 345674;NUCSilicone VS 7207;Octamethylcyclotetrasiloxane;DMC;

Article Data 107

Octamethylcyclotetrasiloxane Synthetic route

433725-45-2

2,2,4,4,6,6-hexamethyl-8,8-divinylcyclotetrasiloxane

A

556-67-2

octamethylcyclotetrasiloxane

B

541-02-6

decamethylcyclopentasiloxane

C

tetravinyltetramethylcyclotetrasiloxane

D

copoly(dimethylsiloxane/divinylsiloxane), prepared by anionic polymerization of 2,2,4,4,6,6-hexamethyl-8,8-divinylcyclotetrasiloxane; monomer(s): 2,2,4,4,6,6-hexamethyl-8,8-divinylcyclotetrasiloxane

copoly(dimethylsiloxane/divinylsiloxane), prepared by anionic polymerization of 2,2,4,4,6,6-hexamethyl-8,8-divinylcyclotetrasiloxane; monomer(s): 2,2,4,4,6,6-hexamethyl-8,8-divinylcyclotetrasiloxane

Conditions
ConditionsYield
With P4-t-Bu at 80℃; for 0.333333h; Further byproducts given;A n/a
B n/a
C n/a
D 80%
67-68-5

dimethyl sulfoxide

75-78-5

dimethylsilicon dichloride

A

2373-51-5

chloro-methylsulfanyl-methane

B

541-05-9

Hexamethylcyclotrisiloxane

C

556-67-2

octamethylcyclotetrasiloxane

D

541-02-6

decamethylcyclopentasiloxane

E

540-97-6

dodecamethyl-cyclohexasiloxane

Conditions
ConditionsYield
at 0℃; Mechanism; other diorganyldichlorosilanes; reactions in the presence of hexamethyldisiloxane, trimethylchlorosilane, tetramethoxysilane, tetraethoxysilane;A 79%
B 48%
C 35%
D 12%
E 5%
67-68-5

dimethyl sulfoxide

A

2373-51-5

chloro-methylsulfanyl-methane

B

541-05-9

Hexamethylcyclotrisiloxane

C

556-67-2

octamethylcyclotetrasiloxane

D

541-02-6

decamethylcyclopentasiloxane

Conditions
ConditionsYield
With dimethylsilicon dichloride at 0℃; Further byproducts given;A 79%
B 48%
C 35%
D 5%
1529-17-5

phenyltrimethylsilyl ether

A

556-67-2

octamethylcyclotetrasiloxane

B

3440-02-6

dimethyl-diphenoxy-silane

C

18406-79-6

C13H26O3Si3

D

C11H20O2Si2

Conditions
ConditionsYield
With gallium(III) iodide at 175 - 180℃; for 3h; Yield given; Further byproducts given. Title compound not separated from byproducts;A n/a
B 79%
C n/a
D n/a
19061-00-8

bis(trimethylsilyl)ketene

A

541-05-9

Hexamethylcyclotrisiloxane

B

556-67-2

octamethylcyclotetrasiloxane

C

1066-54-2

trimethylsilylacetylene

Conditions
ConditionsYield
at 700℃; flash vacuum pyrolysis;A 22%
B 16%
C 76%
98991-82-3

(trimethylsilyl)(dimethylsilyl)ketene

A

541-05-9

Hexamethylcyclotrisiloxane

B

556-67-2

octamethylcyclotetrasiloxane

C

1066-54-2

trimethylsilylacetylene

Conditions
ConditionsYield
at 700℃;A 22%
B 16%
C 76%
87594-05-6

1-(1-Adamantyl)-2-diazo-2-(pentamethyldisilanyl)ethanone

A

541-05-9

Hexamethylcyclotrisiloxane

B

556-67-2

octamethylcyclotetrasiloxane

C

82094-48-2

1-(trimethylsilylethynyl)adamantane

Conditions
ConditionsYield
at 400℃;A 21%
B 20%
C 73%
52826-45-6

(benzylimino)triphenylphosphorane

65181-02-4

3,3-dimethyl-6-oxa-3-silabicyclo<3.1.0>hexane

A

541-05-9

Hexamethylcyclotrisiloxane

B

556-67-2

octamethylcyclotetrasiloxane

C

113017-78-0

2,2,4,4-tetramethyl-6-vinyl-1,3-dioxa-2,4-disilacyclohexane

D

106-99-0

buta-1,3-diene

Conditions
ConditionsYield
at 130℃; for 1h;A n/a
B n/a
C 70%
D n/a
at 130℃; for 1h;
75-78-5

dimethylsilicon dichloride

A

541-05-9

Hexamethylcyclotrisiloxane

B

556-67-2

octamethylcyclotetrasiloxane

Conditions
ConditionsYield
With water Autoclave;A 63.7%
B 27.2%
With water In toluene at 20℃; for 27h;A 17 % Chromat.
B 38%
With water Autoclave;A 15.9%
B 17.4%
With water In toluene at 20℃; for 27h;A 4%
B 44 % Chromat.
With tetrabutylammonium tetrafluoroborate; oxygen In tetrahydrofuran Product distribution; Further Variations:; Reagents; amount of electricity; type of electrolysis cell; Electrochemical reaction;
541-05-9

Hexamethylcyclotrisiloxane

88703-87-1

1,2-silaoxetene 2,2-dimethyl-3-(trimethylsilyl)-4-adamantyl-1-oxa-2-silacyclobutene

A

556-67-2

octamethylcyclotetrasiloxane

B

82094-48-2

1-(trimethylsilylethynyl)adamantane

Conditions
ConditionsYield
In benzene at 120℃;A 48%
B 62%

Octamethylcyclotetrasiloxane Chemical Properties

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 

Octamethylcyclotetrasiloxane Uses

 Octamethylcyclotetrasiloxane (CAS NO.556-67-2) is commonly used as raw materials of organic silicon, also used in the electronics industry.

Octamethylcyclotetrasiloxane 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.

 

Octamethylcyclotetrasiloxane Consensus Reports

Reported in EPA TSCA Inventory.

Octamethylcyclotetrasiloxane Safety Profile

A skin irritant. When heated to decomposition it emits acrid smoke and irritating vapors.
Hazard Codes: IrritantXiIrritantXnFlammableFDangerousN
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

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