556-67-2 Usage
Description
Octamethylcyclotetrasiloxane is a colorless, odorless, and viscous liquid with the chemical formula C8H24O4Si4. It is a cyclic siloxane compound consisting of a ring structure made up of silicon and oxygen atoms, with methyl groups attached to each silicon atom. Octamethylcyclotetrasiloxane is known for its thermal stability, low toxicity, and high volatility, making it a versatile building block in various industries.
Uses
Used in Chemical Industry:
Octamethylcyclotetrasiloxane is used as a monomer in the production of silicone polymers, which are high-performance materials with unique properties such as heat resistance, flexibility, and biocompatibility. These polymers are widely used in various applications, including sealants, adhesives, and coatings.
Used in Electronics Industry:
In the electronics industry, Octamethylcyclotetrasiloxane serves as an intermediate in the production of other organosilicon substances, which are used as electrical insulators, encapsulants, and thermal interface materials. These materials help protect electronic components from heat, moisture, and other environmental factors, ensuring their reliable performance.
Used in Textile Industry:
Octamethylcyclotetrasiloxane is used in the textile industry as a softening agent, providing a smooth and silky feel to fabrics. It also acts as a water repellent, making textiles more resistant to stains and water damage.
Used in Personal Care Products:
In personal care products, Octamethylcyclotetrasiloxane is used as a conditioning agent, providing a smooth and silky texture to hair and skin. It is also used as a defoamer in various cosmetic formulations, helping to prevent the formation of foam and ensuring a smooth application.
Used in Household Care Products:
Octamethylcyclotetrasiloxane is used in household care products as a surfactant, helping to lower the surface tension of water and improve the cleaning efficiency of detergents and cleaners. It also acts as a defoamer, preventing the formation of foam that can leave residues on surfaces.
Polymerization Process:
Preparation
Commercially Octamethylcyclotetrasiloxane is produced from dimethyldichlorosilane. Dimethyldichlorosilane is added dropwise to water, the temperature is maintained at 30-40°C, stratified, the acid water is released, the oily material is hydrolyzed with sodium hydroxide solution, the hydrolysate and 0.5%-2% potassium hydroxide are added to the cracking kettle and cracked at 120-140°C and 99.8 kPa vacuum. The cracked material is fractionated and the fraction is collected at 173-176°C to obtain octamethylcyclotetraoxysilane.
Health Hazard
Octamethylcyclotetrasiloxane (D4) can interfere with the body’s hormones. In animals, it can affect the reproductive system.D4 is classified as a category 1 endocrine disruptor by the European Commission. A 2018 study commissioned by the Danish EPA identified D4 as an endocrine disruptor. The Global Harmonized System Label Requirements classified D4 as suspected to produce reproductive toxicity. D4 was added to the Toxic Substances Control Act work plan due to reproductive toxicity, moderate environmental persistence, and high bioaccumulation potential.Adverse reproductive effects including estrogenic effects have been observed in rodents. The European Chemicals Agency characterized D4 as a persistent, bioaccumulative, and toxic chemical, and designated D4 as a Substance of Very High Concern.
Flammability and Explosibility
Flammable
Purification Methods
The solid exists in two forms, m 16.30o and 17.65o. Dry it over CaH2 and distil it. Further fractionation can be effected by repeated partial freezing and discarding the liquid phase. [Osthoff & Grubb J Am Chem Soc 76 399 1954, Hoffman J Am Chem Soc 75 6313 1953, Beilstein 4 IV 4125.]
Check Digit Verification of cas no
The CAS Registry Mumber 556-67-2 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 5,5 and 6 respectively; the second part has 2 digits, 6 and 7 respectively.
Calculate Digit Verification of CAS Registry Number 556-67:
(5*5)+(4*5)+(3*6)+(2*6)+(1*7)=82
82 % 10 = 2
So 556-67-2 is a valid CAS Registry Number.
InChI:InChI=1/C8H24O4Si4/c1-13(2)9-14(3,4)11-16(7,8)12-15(5,6)10-13/h1-8H3
556-67-2Relevant articles and documents
Andrianov et al.
, p. 1992,1996 (1968)
Hydrogenolysis of Polysilanes Catalyzed by Low-Valent Nickel Complexes
Comas-Vives, Aleix,Eiler, Frederik,Grützmacher, Hansj?rg,Pribanic, Bruno,Trincado, Monica,Vogt, Matthias
supporting information, p. 15603 - 15609 (2020/04/29)
The dehydrogenation of organosilanes (RxSiH4?x) under the formation of Si?Si bonds is an intensively investigated process leading to oligo- or polysilanes. The reverse reaction is little studied. To date, the hydrogenolysis of Si?Si bonds requires very harsh conditions and is very unselective, leading to multiple side products. Herein, we describe a new catalytic hydrogenation of oligo- and polysilanes that is highly selective and proceeds under mild conditions. New low-valent nickel hydride complexes are used as catalysts and secondary silanes, RR′SiH2, are obtained as products in high purity.
Tris(pentafluorophenyl)borane-Catalyzed Reactions of Siloxanes: A Combined Experimental and Computational Study
Mathew, Jomon,Eguchi, Katsuya,Nakajima, Yumiko,Sato, Kazuhiko,Shimada, Shigeru,Choe, Yoong-Kee
, p. 4922 - 4927 (2017/09/13)
The reaction of 1,1,3,3-tetramethyldisiloxane with 1-octene as a model reaction of silicone curing catalyzed by B(C6F5)3 resulted in the redistribution of the disiloxane into dimethylsilane and cyclic oligosiloxanes, and the subsequent hydrosilylation reaction of dimethylsilane afforded dimethyldioctylsilane. To obtain insights into the reaction mechanism and possibility alter the reaction pathway to favor the hydrosilylation over the redistribution, mechanistic analysis of the reaction between a hydrosiloxane (1,1,3,3-tetramethyldisiloxane, silox-H) and a vinylsiloxane (1,1,3,3-tetramethyl-1,3-divinyldisiloxane, silox-vin) in the presence of B(C6F5)3 was performed through density functional theory calculations. The results of the calculations indicate that the activation of a Si–H bond in silox-H by B(C6F5)3 initiates the reaction to form the B(C6F5)3–silox-H complex with a Lewis acidic silicon atom and a hydridic hydrogen atom. The B(C6F5)3–silox-H complex can undergo two different reaction pathways, that is, trisiloxane formation and the hydrosilylation of silox-vin by silox-H. The trisiloxane formation involves trisilyloxonium ions as intermediates and can lead to either the homotrisiloxane of silox-H or a mixed trisiloxane of silox-H and silox-vin. The energetics of the reaction pathways predict the preference of trisiloxane formation over hydrosilylation, and the fine tuning of the steric and electronic natures of the substrates could alter the thermodynamic and kinetic favorability.