OCTAMETHYLCYCLOTETRASILOXANE

556-67-2

Cyclotetrasiloxane, octamethyl-

2,2,4,4,6,6,8,8-Octamethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane

Oktamethylcyklotetrasiloxan

Cyclic dimethylsiloxane tetramer

NUC silicone VS 7207

Oktamethylzyklotetrasiloxan

DTXSID7027205

CHEBI:25640

CZ227117JE

2,2,4,4,6,6,8,8-octamethyl-1,3,5,7,2,4,6,8-tetroxatetrasilocane

NSC-345674

OMCTS

DTXCID107205

Union carbide 7207

Silicone SF 1173

MFCD00003269

Cyclomethicone 4

CAS-556-67-2

CCRIS 1327

HSDB 6131

Oktamethylcyklotetrasiloxan [Czech]

EINECS 209-136-7

KF 994

NSC 345674

octamethyl cyclotetrasiloxane

SF 1173

UC 7207

VS 7207

BRN 1787074

UNII-CZ227117JE

bmse000765

EC 209-136-7

octamethyl-cyclotetrasiloxane

SCHEMBL18354

BIDD:ER0157

Dimethylsiloxane Cyclic Tetramer

CHEMBL1869229

CYCLOTETRASILOXANE [INCI]

HMMGMWAXVFQUOA-UHFFFAOYSA-

OCTAMETHYCYCLOTETRASILOXANE

Octamethylcyclotetrasiloxane, 98%

CYCLOMETHICONE 4 [USP-RS]

Tox21_201398

Tox21_300547

CO9810

CYCLOTETRASILOXANE, OCTAMETHYL

NSC345674

AKOS008901191

MCULE-2162943570

OCTAMETHYLCYCLOTETRASILOXANE [MI]

NCGC00164099-01

NCGC00164099-02

NCGC00164099-03

NCGC00254406-01

NCGC00258949-01

OCTAMETHYLCYCLOTETRASILOXANE [HSDB]

CS-0213747

NS00043628

O0142

O9810

F83065

Octamethylcyclotetrasiloxane, analytical standard

Cyclotetrasiloxane, 2,2,4,4,6,6,8,8-octamethyl-

Q2013804

2,2,4,4,6,6,8,8-Octamethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane #

Cyclomethicone 4, United States Pharmacopeia (USP) Reference Standard

D4 Cyclomethicone, Pharmaceutical Secondary Standard; Certified Reference Material

d-4

InChI=1/C8H24O4Si4/c1-13(2)9-14(3,4)11-16(7,8)12-15(5,6)10-13/h1-8H3

The Henry's Law constant for octamethylcyclotetrasiloxane is 13.4 atm-cu m/mole(1). This Henry's Law constant indicates that octamethylcyclotetrasiloxane is expected to volatilize rapidly from water surfaces(2). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(2) is estimated as 5 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as 6.8 days(SRC). However, volatilization from water surfaces is expected to be attenuated by adsorption to suspended solids and sediment in the water column. The estimated volatilization half-life from a model pond is 140 days if adsorption is considered(3). Octamethylcyclotetrasiloxane's Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). Octamethylcyclotetrasiloxane is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 1.05 mm Hg(4). Evaporation of octamethylcyclotetrasiloxane was measured in soil studies and found to occur with rates varying with moisture content, soil type and relative humidity(5). 14C-Labeled octamethylcyclotetrasiloxane was removed from municipal waste by both adsorption to sludge and volatilization(6); the majority of the material was removed via volatilization(6); after 3 days, 49% of the material in the aeration/secondary clarifier was removed by volatilization while only 10% was removed by adsorption to sludge(6).

Adsorption studies using three soils from the United Kingdom (silt loam, sandy loam and sandy clay loam) determined octamethylcyclotetrasiloxane log Koc values of 4.17-4.27 with an average log Koc of 4.22 (Koc of 16600)(1). According to a classification scheme(2), these Koc values suggest that octamethylcyclotetrasiloxane is expected to be immobile in soil.