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Hexamethyldisiloxane is an organosiloxane consisting of two trimethylsilyl groups covalently bound to a central oxygen.
Hexamethyldisiloxane, a linear polydisiloxane, is an organosilicon reagent commonly utilized as a source for plasma enhanced chemical vapor deposition (PE-CVD) of thin films of silicon compounds.
Hexamethyldisiloxane is also employed as a substitute to silane in silicon integrated circuit technology.
CAS Number: 107-46-0
Molecular Formula: C6H18OSi2
Molecular Weight: 162.38
EINECS Number: 203-492-7
Synonyms: Hexamethyldisiloxane, 107-46-0, Disiloxane, hexamethyl-, Oxybis(trimethylsilane), Fluka AG, Hexamethyl disiloxane, Bis(trimethylsilyl)ether, Belsil DM 0.65, Bis(trimethylsilyl)oxide, Bistrimethylsilyl ether, KF 96L, Silane, oxybis(trimethyl-), OS 10, Dow corning 200, D7M4659BPU, AEC DISILOXANE, DTXSID4026769, CHEBI:78002, MIRASIL HMS, NSC-43346, VOLASIL DM-0.65, DTXCID406769, SI-TEC DM 0.65, SF1000N-0.65CST, NSC43346, SF1000N-0.65 cSt, Xiameter PMX-200 Silicone Fluid 0.65 cSt, 203-492-7, HMDSO, trimethyl(trimethylsilyloxy)silane, Bis(trimethylsilyl) ether, SWS-F 221, Bis(trimethylsilyl) oxide, NSC 43346, trimethylsilyl ether, MFCD00008265, Silane, oxybis(trimethyl)-, ((CH3)3Si)2O, NCGC00164086-01, Disiloxane, 1,1,1,3,3,3-hexamethyl-, 26298-61-3, 1,1,1,3,3,3-Hexamethyldisiloxane, Bis-trimethylsilyl oxide, C6H18OSi2, CAS-107-46-0, Dimethicone ~4000 (Polydimethylsiloxane), CCRIS 1325, HSDB 5378, EINECS 203-492-7, UNII-D7M4659BPU, AI3-51466, bis-tms ether, di-tms ether, TMS ether, trimethylsilylether, Dimethicone, BAN, Dimethicone (NF), hexamethyl-disiloxane, HMDO, Dimeticone (JAN/INN), Polydimethylsiloxane, PDMS, Sentry dimethicone (TN), EC 203-492-7, DISILOXANE, HEXAMETHYL, SCHEMBL6413, Dow corning 200/0.65, Hexamethyldisiloxane NMR grade, Hexamethyldisiloxane, >=98%, SCHEMBL373489, SCHEMBL8728760, CHEMBL3184090, SCHEMBL17911300, SCHEMBL18227330, HEXAMETHYLDISILOXANE [MI], HEXAMETHYLDISILOXANE [HSDB], BCP11630, HEXAMETHYLDISILOXANE [VANDF], trimethyl[(trimethylsilyl)oxy]silane, Tox21_112082, Tox21_201713, Tox21_303119, Dimethyl Silicone Fluid Silicone Oil, AKOS000119927, Hexamethyldisiloxane (analytical grade), MSK001099-100M, 1,1,1,3,3,3-Hexamethyldisiloxane #, NCGC00164086-02, NCGC00257007-01, NCGC00259262-01, FD165432, DB-040758, H0091, H7310, Hexamethyldisiloxane, NMR grade, >=99.5%, NS00041276, WLN: 1-SI-1&1&O-SI-1&1&1, Hexamethyldisiloxane, puriss., >=98.5% (GC), A801702, Hexamethyldisiloxane, viscosity 0.65 cSt (25 C), Q419440, Hexamethyldisiloxane Solution in Methanol, 100ug/mL, BRD-K26674746-001-01-4, F0001-0143, Z104473212, Hexamethyldisiloxane, for GC derivatization, >=98%, InChI=1/C6H18OSi2/c1-8(2,3)7-9(4,5)6/h1-6H, os10, oxybis(trimethyl-silan, Oxybis(trimethylsilane), Silane, oxybis(trimethyl)-, sws-f221, SILICONE FLUID, 2,2,4,4-TETRAMETHYL-3-OXA-2,4-DISILAPENTANE, HMDO
Hexamethyldisiloxane has a very low water solubility and is highly volatile.
Hexamethyldisiloxane is therefore difficult to perform biodegradability and toxicity tests. Experimental data on degradation in water are not available.
Based on chemical structure, no aerobic biodegradation of HMDS in water is expected.
The half-life of Hexamethyldisiloxane in marine water is thus expected to be more than 60 days and the persistence (P) criterion is fulfilled.
Hexamethyldisiloxane is a colorless and transparent liquid. It is easily deliquescent, flammable, and has the risk of causing combustion when exposed to high heat, open flame, and strong oxidizing agents.
Hexamethyldisiloxane is an organosilicon compound with the formula O[Si(CH3)3]2.
This volatile colourless liquid is used as a solvent and as a reagent in organic synthesis.
Hexamethyldisiloxane is prepared by the hydrolysis of trimethylsilyl chloride.
The molecule is the protypical disiloxane and resembles a subunit of polydimethylsiloxane.
Hexamethyldisiloxane is a highly specialized chemical compound that belongs to the class of organosilicon compounds, specifically classified as a disiloxane, which contains two silicon atoms connected by an oxygen atom and fully substituted with methyl groups, making it chemically stable and nonpolar.
Hexamethyldisiloxane is primarily used in industrial and cosmetic applications due to its excellent volatility, low surface tension, and ability to spread evenly over surfaces without leaving residues, which allows it to act as a carrier, solvent, or emollient in formulations.
In addition, Hyacure Hexamethyldisiloxane exhibits low viscosity and high volatility, meaning it can evaporate quickly after application, which is particularly advantageous in coatings, hair care, and skincare products where a lightweight and non-greasy feel is desirable.
Hexamethyldisiloxane is also valued for its inert chemical nature, which reduces the likelihood of reacting with other components in a formulation, thus enhancing the stability and performance of complex mixtures.
Furthermore, in technical applications, it can function as a processing aid or as a temporary protective layer due to its ability to form a thin, uniform film that minimizes friction and facilitates smooth application.
Hexamethyldisiloxanes dissociative ionization by electron impact has been studied by Fourier transform mass spectrometry.
Synthesis of plasma-polymerized HMDSO thin films by atmospheric pressure glow (APG) discharge has been reported.
Crystals of HMDSO at 148K are monoclinic addition of Hexamethyldisiloxane to P4S10, improves its efficiency as thionating agent.
Hexamethyldisiloxane can be produced by the addition of trimethylsilyl chloride to purified water: 2 Me3SiCl + H2O → 2 HCl + O[Si(CH3)3]2
Hexamethyldisiloxane also results from the hydrolysis of silyl ethers and other silyl-protected functional groups. Hexamethyldisiloxane can be converted back to the chloride by reaction with Me2SiCl2.
Hexamethyldisiloxane is mainly used as source of the trimethylsilyl functional group (-Si(CH3)3) in organic synthesis.
For example, in the presence of acid catalyst, it converts alcohols and carboxylic acids into the silyl ethers and silyl esters, respectively.
It reacts with rhenium(VII) oxide to give a siloxide: Re2O7 + O[Si(CH3)3]2 → 2 O3ReOSi(CH3)3
Hexamethyldisiloxane is a versatile organosilicon compound with various industrial applications.
Hexamethyldisiloxane is an organosilicon compound that exhibits remarkable chemical inertness and thermal stability, which allows it to maintain its structural integrity under a wide range of temperatures and chemical environments, making it an ideal candidate for use in sophisticated industrial processes where precision and consistency are critical.
Hexamethyldisiloxanes molecular structure, consisting of two silicon atoms bonded through an oxygen bridge and fully substituted with six methyl groups, imparts extremely low surface tension and minimal polarity, enabling it to act as an effective spreading agent, wetting agent, or carrier for active ingredients in formulations ranging from high-performance coatings to advanced cosmetic and personal care products.
In the cosmetic industry, it is particularly valued for its ability to impart a silky, smooth, and non-greasy feel to products such as hair serums, facial serums, and lightweight skin lotions, while simultaneously enhancing the even distribution of other ingredients and facilitating rapid drying due to its high volatility.
Additionally, in industrial applications, Hyacure Hexamethyldisiloxane can be used as a processing aid, anti-foaming agent, or temporary protective layer, helping to reduce friction, prevent surface defects, and improve overall product quality, particularly in sensitive manufacturing environments such as electronics, coatings, and precision optics.
Its combination of low viscosity, high spreadability, and chemical inertness makes it indispensable in formulations where uniform coverage, minimal residue, and gentle interaction with other chemical components are required, allowing engineers and formulators to achieve superior performance in both aesthetic and technical products.
Melting point: −59 °C (lit.)
Boiling point: 101 °C (lit.)
Density: 0.764 g/mL at 20 °C (lit.)
Vapor density: >1 (vs air)
Vapor pressure: 20 hPa (20 °C)
Refractive index: n20/D 1.377 (lit.)
Flash point: 33 °F
Storage temp.: Store below +30 °C
Solubility: 0.00037 g/L insoluble
Form: liquid
Color: Colorless to Almost colorless
Specific Gravity: 0.76
Explosive limit: 0.5–21.8% (V)
Viscosity: 0.65 cSt (25 °C)
Water Solubility: insoluble
Hydrolytic Sensitivity: 1: no significant reaction with aqueous systems
BRN: 1736258
Dielectric constant: 2.2 (20 °C)
Stability: Stable, but moisture sensitive. Highly flammable. Incompatible with strong acids, strong bases, oxidizing agents.
InChIKey: UQEAIHBTYFGYIE-UHFFFAOYSA-N
LogP: 5.06 at 20 °C
Hexamethyldisiloxane acts as a silylating agent and intermediate for synthesizing active pharmaceutical ingredients (APIs).
In the semiconductor sector, Hexamethyldisiloxane is employed in plasma-enhanced chemical vapor deposition (PECVD) to create protective silicon dioxide (SiO₂) layers on microchips.
Additionally, Hexamethyldisiloxane is used in water-repellent coatings and lubricants, enhancing durability and performance.
Hexamethyldisiloxane is a versatile and widely used silicon-based compound with significant applications across various industries, including semiconductors, coatings, and personal care products.
Known for its unique siloxane structure, Hexamethyldisiloxane exhibits properties such as hydrophobicity, thermal stability, and low surface energy, making it ideal for uses in thin-film deposition, surface treatment, and water-repellent coatings.
Hexamethyldisiloxane is a versatile organosilicon compound that has found extensive applications across multiple industries due to its unique combination of chemical and physical properties, including extremely low surface tension, high volatility, thermal stability, and chemical inertness, which allows it to maintain its molecular structure and functional characteristics under conditions that would degrade or alter many other compounds.
Its molecular architecture, characterized by two silicon atoms connected through an oxygen bridge and fully substituted with six methyl groups, confers a remarkable hydrophobic character and very low polarity, making it an ideal carrier or dispersing agent for active ingredients in complex formulations where uniform distribution and smooth spreading are essential, such as high-performance coatings, adhesives, and sealants.
In cosmetic and personal care formulations, it is valued for its ability to impart a soft, silky, and non-greasy feel on skin and hair while promoting rapid drying and minimizing residue, which improves product aesthetics, consumer experience, and the performance of other incorporated active ingredients.
In industrial applications, Hexamethyldisiloxane serves as a process aid, defoamer, or temporary protective coating that reduces surface tension, prevents bubble formation, and facilitates the uniform application of coatings or films, particularly in sensitive manufacturing environments such as electronics, optics, or high-precision mechanical components, where even minor defects can compromise product functionality.
Furthermore, its extremely low viscosity and ability to spread evenly over surfaces allow it to act as a lubricant, wetting agent, or carrier fluid, improving both process efficiency and product quality, while its chemical inertness ensures that it does not react with or degrade other formulation components, making it safe for use in systems containing reactive or delicate chemicals.
Additionally, Hyacure Hexamethyldisiloxane’s volatility enables it to evaporate cleanly without leaving unwanted residues, which is crucial in applications requiring rapid drying, precision coatings, or temporary protective layers that must be removed without trace.
Hexamethyldisiloxane combines functional versatility, process facilitation, and sensory benefits, making it a critical ingredient in formulations where high performance, surface quality, and aesthetic properties must be achieved simultaneously.
Uses:
Hexamethyldisiloxane is used as a base fluid in a wide range of personal care products that require fast evaporation and high spreadability.
When blended with Dimethicone fluids, Hexamethyldisiloxane can adjust the residence time of the silicone on the skin. Unlike other volatile fluids, Hexamethyldisiloxane Fluid does not cool the skin as it evaporates.
Hexamethyldisiloxane is used as a carrying agent and diluent in the following: skin cream lotions, bath oils, suntan lotions, nail polishes, antiperspirants, deodorants, hair sprays and other beauty and hair care products.
A silicon based compound that can be used to create potentially biocompatible materials.
Hexamethyldisiloxane is used as a monomer in the synthesis of long chain polysiloxane structures.
Hexamethyldisiloxane is used in the methylation of mercury(II) salts.
The most popular precursor chemical is Hexamethyldisiloxane which with the addition of helium and oxygen will produce a silica coating.
Hexamethyldisiloxane is used in a variety of consumer applications and can be used as intermediates in the production of silicone polymers.
Hexamethyldisiloxane can be used as silylating agent for carboxylic acids, and alcohols, used in preparation of aroyl chlorides, precursor for a variety of trimethylsilyl derivatives.
Hexamethyldisiloxane has been used as an inexpensive starting material for the preparation of numerous synthetically useful trimethylsilyl derivatives.
Hexamethyldisiloxane is used as an internal standard for calibrating chemical shift in1H NMR spectroscopy.
Hexamethyldisiloxane is more easily handled since it is less volatile than the usual standard tetramethylsilane but still displays only a singlet near 0 ppm.
Hexamethyldisiloxane has even poorer solvating power than alkanes.
It is therefore sometimes employed to crystallise highly lipophilic compounds.
Hexamethyldisiloxane is used in liquid bandages (spray-on plasters) such as cavilon spray, to protect damaged skin from irritation from other bodily fluids.
It is also used to soften and remove adhesive residues left by medical tape and bandages, without causing further skin irritation.
Hexamethyldisiloxane is being studied for making low-k dielectric materials for the semiconductor industries by plasma-enhanced chemical vapour deposition (PECVD).
Hexamethyldisiloxane has been used as a reporter molecule to measure tissue oxygen tension (pO2).
Hexamethyldisiloxane is highly hydrophobic and exhibits high gas solubility, and hence strong nuclear magnetic resonance spin lattice relaxation rate (R1) response to changes in pO2.
Molecular symmetry provides a single NMR signal.
Following direct injection into tissues it has been used to generate maps of tumour and muscle oxygenation dynamics with respect to hyperoxic gas breathing challenge.
Hexamethyldisiloxane is employed in a remarkably diverse array of applications due to its unique combination of chemical inertness, low surface tension, and high volatility, which makes it particularly valuable in industries ranging from cosmetics and personal care to high-precision industrial processes and electronics manufacturing.
In the cosmetics and personal care sector, Hexamethyldisiloxane is widely used as a carrier solvent for active ingredients, allowing for their even dispersion in formulations while also imparting a light, silky, and non-greasy feel to the skin and hair; this property is especially critical in products such as hair serums, skin creams, sunscreens, and makeup primers, where the sensory experience of smooth application and rapid drying significantly affects consumer perception and product performance.
Industrially, Hexamethyldisiloxane serves as a process aid or functional additive in coatings, adhesives, and sealants, where it acts as a wetting agent, defoamer, or temporary protective layer that reduces surface tension, prevents the formation of air bubbles, and ensures uniform coverage on complex or delicate surfaces, thereby enhancing product consistency, quality, and efficiency during manufacturing.
In electronics and optical applications, its extremely low viscosity and chemical inertness allow it to function as a carrier or spreading medium for sensitive active components, helping to coat, clean, or protect components without inducing chemical reactions or leaving residues that could interfere with functionality, which is crucial for high-precision devices such as microchips, lenses, or display panels.
Furthermore, its high volatility ensures that it evaporates cleanly and quickly after application, making it suitable for temporary surface treatments, rapid-drying coatings, and thin films that require minimal residual material, such as in laboratory sample preparation or specialized industrial processes where contamination or uneven coating could compromise results.
Hexamethyldisiloxane as a functional additive, carrier, wetting agent, and temporary protective coating underlines its importance in enhancing formulation stability, application efficiency, surface quality, and aesthetic properties across a wide range of commercial, cosmetic, and industrial applications.
Hexamethyldisiloxane is extensively utilized across multiple industries due to its unique combination of chemical inertness, low surface tension, and high volatility, which enables it to perform as a highly effective carrier, spreading agent, defoamer, and temporary protective coating in a wide array of formulations and processes where both functional performance and aesthetic outcomes are critical; in personal care and cosmetic applications, it is commonly incorporated into products such as moisturizers, sunscreens, primers, hair serums, and styling products to facilitate the uniform distribution of active ingredients, enhance the tactile sensory feel by providing a silky, non-greasy finish, and promote rapid drying without leaving oily residues, thereby improving both product usability and consumer satisfaction, while also contributing to the long-term stability of volatile or sensitive components by reducing their exposure to moisture and oxygen.
In industrial and manufacturing contexts, Hexamethyldisiloxane is applied as a wetting agent or process aid in coatings, adhesives, sealants, and specialty inks, where it serves to lower surface tension, prevent bubble formation, improve surface leveling, and ensure homogeneous coverage on complex geometries, which is particularly important in precision engineering and high-quality surface finishes; in electronics, optics, and semiconductor manufacturing, its low viscosity and chemical inertness allow it to act as a carrier or solvent for highly reactive or sensitive materials, enabling thin, uniform films or coatings to be applied without chemical degradation or residue formation, which is crucial for devices such as microchips, optical lenses, and display panels where even minor surface irregularities or contamination can compromise functionality.
Safety Profile:
Hexamethyldisiloxane, while generally considered chemically inert and relatively non-toxic under typical handling conditions, can still present several hazards, particularly due to its physical properties such as high volatility and flammability, which make it capable of forming flammable vapor-air mixtures that could ignite if exposed to sparks, open flames, or hot surfaces, thereby requiring careful storage away from heat sources and adequate ventilation in work areas to prevent accumulation of vapors; prolonged or repeated inhalation of its vapors in poorly ventilated environments may lead to respiratory irritation, dizziness, headaches, or nausea, especially in sensitive individuals, emphasizing the importance of using protective respiratory equipment when handling large quantities.
Contact with skin or eyes, although not highly corrosive, may result in mild irritation, redness, or dryness, particularly with extended exposure, and can exacerbate pre-existing skin conditions, making the use of gloves, protective clothing, and eye protection advisable during handling; accidental ingestion is unlikely under normal use but could cause gastrointestinal discomfort, nausea, or vomiting if it occurs, highlighting the need to avoid ingestion and maintain good hygiene practices, such as washing hands thoroughly after handling.
Additionally, as with many volatile silicone-based compounds, improper disposal or uncontrolled release into the environment may contribute to water and soil contamination, posing potential ecological risks, particularly to aquatic life, due to its persistence and ability to spread on water surfaces; therefore, it is crucial to follow regulatory guidelines for storage, handling, spill response, and disposal to minimize both human health risks and environmental impact.
