Hexamethylcyclotrisiloxane

Hexamethylcyclotrisiloxane, also known as D3 and D3, 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]

Not to be confused with Cholecalciferol.
Hexamethylcyclotrisiloxane
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
ECHA InfoCard 100.007.970
EC Number
  • 208-765-4
UNII
  • InChI=1S/C6H18O3Si3/c1-10(2)7-11(3,4)9-12(5,6)8-10/h1-6H3
    Key: HTDJPCNNEPUOOQ-UHFFFAOYSA-N
  • C[Si]1(O[Si](O[Si](O1)(C)C)(C)C)C
Properties
[(CH3)2SiO]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 labelling:
GHS02: FlammableGHS07: Exclamation mark
Warning
H228, H315, H319, H335
P210, P240, P241, P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P370+P378, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Structure and reactions

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

[(CH3)2SiO]3 + 3 RLi → 3 RSi(CH3)2OLi
RSi(CH3)2OLi + H2O → RSi(CH3)2OH + LiOH

Safety and environmental considerations

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

See also

References
  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. Retrieved 2018-07-20.
  3. Scott E. Denmark; Christopher R. Butler (2007). "Hexamethylcyclotrisiloxane". 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.
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