Chemistry:Hexamethylcyclotrisiloxane

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Hexamethylcyclotrisiloxane
Hexamethylcyclotrisiloxan.svg
Names
IUPAC name
2,2,4,4,6,6-hexamethyl-1,3,5,2,4,6-trioxatrisilinane
Other names
  • Hexamethyltrisiloxane
  • Dimethylsiloxane trimer
  • D3
  • D3
Identifiers
3D model (JSmol)
ChemSpider
EC Number
  • 208-765-4
UNII
Properties
[(CH
3
)
2
SiO]
3
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 GHS02: FlammableGHS07: Harmful
GHS Signal word Warning
H228, H315, H319, H335
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, also known as D3 and D3, is the organosilicon compound with the formula [(CH
3
)
2
SiO]
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:

[(CH
3
)
2
SiO]
3
+ 3 RLi → 3 RSi(CH
3
)
2
OLi
RSi(CH
3
)
2
OLi + H
2
O → RSi(CH
3
)
2
OH + LiOH

Safety and environmental considerations

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

See also

References

  1. 1.0 1.1 Moretto, Hans-Heinrich; Schulze, Manfred; Wagner, Gebhard (2005). "Silicones". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a24_057. ISBN 3-527-30673-0. 
  2. "InfoCard – Hexamethylcyclotrisiloxane". ECHA. https://echa.europa.eu/substance-information/-/substanceinfo/100.007.970. 
  3. Scott E. Denmark; Christopher R. Butler (2007). eEROS. doi:10.1002/047084289X.rn00784. ISBN 978-0-471-93623-7. 
  4. Brook, Michael A. (2000). Silicon in Organic, Organometallic and Polymer Chemistry. New York: Wiley. p. 262. ISBN 0-471-19658-4.