Hexamethylcyclotrisiloxane

Hexamethylcyclotrisiloxane
Names
	IUPAC name 2,2,4,4,6,6-hexamethyl-1,3,5,2,4,6-trioxatrisilinane
	Other names hexamethyltrisiloxane, dimethylsiloxane trimer, D3
Identifiers
CAS Number	541-05-9;
3D model (JSmol)	Interactive image;
ChemSpider	10452;
ECHA InfoCard	100.007.970
EC Number	208-765-4;
PubChem CID	10914;
UNII	EPV75L8O0R;
CompTox Dashboard (EPA)	DTXSID6027185 ;
	InChI InChI=1S/C6H18O3Si3/c1-10(2)7-11(3,4)9-12(5,6)8-10/h1-6H3 Key: HTDJPCNNEPUOOQ-UHFFFAOYSA-N;
	SMILES C[Si]1(O[Si](O[Si](O1)(C)C)(C)C)C;
Properties
Chemical formula	C6H18O3Si3
Molar mass	222.462 g·mol−1
Appearance	Colorless or white solid
Density	1.02 g/cm3
Melting point	64 °C (147 °F; 337 K)
Boiling point	134 °C (273 °F; 407 K)
Hazards
GHS pictograms
GHS Signal word	Warning
GHS hazard statements	H228, H315, H319, H335
GHS precautionary statements	P210, P240, P241, P261, P264, P271, P280, P302+352, P304+340, P305+351+338, P312, P321, P332+313, P337+313, P362, P370+378, P403+233, P405, P501
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	Infobox references

Hexamethylcyclotrisiloxane is the organosilicon compound with the formula [(CH₃)₂SiO]₃. It is a colorless or white volatile solid. It finds limited use in organic chemistry. The larger tetrameric and pentameric siloxanes, respectively octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane, are of significant industrial interest,[1] whereas 1,000–10,000 tonnes per year of the trimer is manufactured and/or imported in the European Economic Area.[2]

Structure and reactions

Hexamethylcyclotrisiloxane adopts a planar structure and is considered strained.[3][4] It reacts with organolithium reagents to give, after hydrolysis, dimethylsilanols:

1/3 [(CH₃)₂SiO]₃ + RLi → RSiMe₂OLi

RSiMe₂OLi + H₂O → RSiMe₂OH + LiOH

Safety and environmental considerations

The LD₅₀ for the related pentamer (D₅) is >50 g/kg in rats.[1]

References

Moretto, Hans-Heinrich; Schulze, Manfred; Wagner, Gebhard (2005). "Silicones". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a24_057.
"InfoCard – Hexamethylcyclotrisiloxane". ECHA. Retrieved 2018-07-20.
Scott E. Denmark Christopher R. Butler. "Hexamethylcyclotrisiloxane". eEROS. doi:10.1002/047084289X.rn00784.CS1 maint: uses authors parameter (link)
Brook, Michael A. (2000). Silicon in Organic, Organometallic and Polymer Chemistry. New York: Wiley. p. 262. ISBN 0-471-19658-4.

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[Ullmann-1] Moretto, Hans-Heinrich; Schulze, Manfred; Wagner, Gebhard (2005). "Silicones". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a24_057.

[2] "InfoCard – Hexamethylcyclotrisiloxane". ECHA. Retrieved 2018-07-20.

[3] Scott E. Denmark Christopher R. Butler. "Hexamethylcyclotrisiloxane". eEROS. doi:10.1002/047084289X.rn00784.CS1 maint: uses authors parameter (link)

[Brook-4] Brook, Michael A. (2000). Silicon in Organic, Organometallic and Polymer Chemistry. New York: Wiley. p. 262. ISBN 0-471-19658-4.