Octamethyltrisiloxane

Structural formula
General
Surname	Octamethyltrisiloxane
other names	Dimethyl bis (trimethylsilyloxy) silane MDM L 3
Molecular formula	C 8 H 24 O 2 Si 3
Brief description	colorless liquid
External identifiers / databases
CAS number 107-51-7 EC number 203-497-4 ECHA InfoCard 100.003.181 PubChem 24705 Wikidata Q2013799
properties
Molar mass	236.53 g mol −1
Physical state	liquid
density	0.82 g cm −3
Melting point	−82  ° C
boiling point	153 ° C
solubility	almost insoluble in water (34.5 ± 1.0  μg l −1 at 23 ° C)
Refractive index	1.384 (20 ° C)
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 226 P: 210-243-403 + 235
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Octamethyltrisiloxane is a chemical compound from the group of siloxanes .

Extraction and presentation

Octamethyltrisiloxane is formed when chlorotrimethylsilane and dichlorodimethylsilane (2: 1) come into contact with water, which initially hydrolyze to trimethylsilanol and dimethylsilanediol with the development of heat and formation of hydrogen chloride . These are unstable and condense to octamethyltrisiloxane with elimination of water.

properties

Octamethyltrisiloxane is a clear, transparent, viscous liquid. It consists of two M units and one D unit (MDM).

The vapors of octamethyltrisiloxane can form an explosive mixture with air ( flash point 29 ° C).

use

Octamethyltrisiloxane is used in the cosmetics industry. It is also used as a working fluid in ORC turbines.

Risk assessment

Octamethyltrisiloxane was included by the EU in 2015 in accordance with Regulation (EC) No. 1907/2006 (REACH) in the context of substance evaluation in the Community's rolling action plan ( CoRAP ). The effects of the substance on human health and the environment are re-evaluated and, if necessary, follow-up measures are initiated. The reasons for the uptake of octamethyltrisiloxane were concerns regarding consumer use and widespread use as well as the dangers arising from a possible assignment to the group of PBT / vPvB substances. The re-evaluation has been running since 2015 and is carried out by Norway . In order to be able to reach a final assessment, further information was requested.

Web links

• Entry on Octamethyltrisiloxane in the Spectral Database for Organic Compounds (SDBS) of the National Institute of Advanced Industrial Science and Technology (AIST)
• Entry on Octamethyltrisiloxane in the ChemIDplus database of the United States National Library of Medicine (NLM)

Individual evidence

1. ↑ ^{a b c d e} data sheet Octamethyltrisiloxane from Sigma-Aldrich , accessed on November 4, 2016 ( PDF ).
2. ↑ Sudarsanan Varaprath, Cecil L. Frye, Jerry Hamelink: Aqueous solubility of permethylsiloxanes (silicones). In: Environmental Toxicology and Chemistry . 15, 1996, pp. 1263-1265, doi : 10.1002 / etc.5620150803 .
3. ↑ ^{a b} Entry on octamethyltrisiloxane in the GESTIS substance database of the IFA , accessed on July 23, 2016(JavaScript required) .
4. ↑ Community rolling action plan ( CoRAP ) of the European Chemicals Agency (ECHA): Octamethyltrisiloxane , accessed on March 26, 2019.