CYCLOMETHICONE 4

Cyclomethicone 4 is a low-viscosity, highly volatile, four-ring cyclic siloxane that delivers exceptional spreading, slip, and fast-evaporation performance in both cosmetic and industrial formulations.
Cyclomethicone 4's symmetrical Si–O cyclic backbone with methyl substitutions gives it extremely low surface tension, rapid volatility, chemical inertness, and outstanding sensory properties, making it one of the most efficient carrier fluids in silicone technology.
Cyclomethicone 4 evaporates quickly after application, depositing active ingredients or silicone resins while leaving a dry, weightless, non-greasy finish that is essential for modern skin care, hair care, and color cosmetic products.

CAS Number: 556-67-2
EC Number: 209-136-7
Molecular Formula: C8H24O4Si4
Molecular Weight: 296.62 g/mol

Synonyms: Cyclomethicone, Cyclopolydimethylsiloxane, DERMFREE SCAR SHEETS, DOW CORNING ST CYCLOMETHICONE 56, DTXSID8041820, Dimethylcyclopolysiloxane, EHP Cleansing, NMQ347994Z, Polydimethyl siloxy cyclics, Polydimethylcyclosiloxane, RefChem:54913, Silicone gel 1% SCAR SHEETS, 69430-24-6, Cyclomethicone-4, Cyclomethicone (D4), Octamethylcyclotetrasiloxane, OMCTS, D4 Cyclic Siloxane, Cyclic Siloxane D4, Tetrameric Dimethylsiloxane, Silicone Cyclic Tetramer, VMS D4 (Volatile Methyl Siloxane D4), Volatile Cyclic Siloxane 4-ring, Octamethylcyclotetrasiloxane Fluid, Tetramethylsiloxane Cyclic Tetramer, Silicone Tetramer Fluid, D4 Silicone Monomer, Cyclic Dimethylsiloxane Tetramer, OMCTS Silicone Fluid, Low-Viscosity Cyclic Siloxane, High-Volatility Siloxane D4, Siloxane Tetramer 556-67-2, Organosiloxane D4, Cyclotetradimethylsiloxane, Cyclic Siloxy Tetramer, Volatile Silicone Carrier D4, Cosmetic Cyclomethicone 4, Personal Care Grade D4, Industrial Grade D4 Siloxane, Silicone Solvent D4, Silicone Evaporating Fluid D4, Fast-Evaporating Siloxane Tetramer, Skin-Feel Enhancer D4, Spreadability Agent D4, Slip Modifier Siloxane D4, Volatile Silicone Oil D4, Octamethyl-Tetrasiloxane, Dimethylsiloxane Cyclic Tetramer

Cyclomethicone 4 is a low-viscosity, highly volatile, four-ring cyclic siloxane widely used for its exceptional spreading, slip, and fast-evaporation properties.
Cyclomethicone 4's molecular structure consists of a cyclic arrangement of four Si–O units, each substituted with methyl groups, giving the material extremely low surface tension, rapid volatility, and excellent sensory performance in cosmetic and industrial formulations.

Commercially, Cyclomethicone 4 appears as a clear, colorless, water-insoluble liquid with a very light, non-greasy skin feel and a characteristic silky glide.
Cyclomethicone 4 evaporates quickly after application, leaving minimal residue, making it valuable in products requiring a dry, weightless finish.
Due to Cyclomethicone 4's chemical inertness and thermal stability, it blends easily with silicones, oils, waxes, and emollients without causing instability or viscosity drift.

In personal care applications, Cyclomethicone 4 is used in skin creams, lotions, serums, color cosmetics, antiperspirants, deodorants, and makeup primers to enhance spreadability, improve slip, and reduce tackiness.
Cyclomethicone 4's rapid evaporation creates a smooth, elegant application without altering product texture or long-term feel.
In hair care, Cyclomethicone 4 improves combability, shine, and lightweight conditioning without buildup.

Beyond cosmetics, Cyclomethicone 4 is used in polishes, release agents, silicone processing, mold lubricants, cleaning formulations, and industrial surface treatments where fast evaporation and low surface tension are required.
Cyclomethicone 4's volatility also makes it a functional carrier fluid for delivering actives, fragrances, or silicone resins that remain on the surface after the D4 evaporates.

Cyclomethicone 4 is a 100% active cyclic silicone polymer blend consisting of siloxane D4 (cyclotetrasiloxane) and siloxane D5 (cyclopentasiloxane).
Cyclic silicones are low-molecular weight silicones and are not viscous but very fluid and often used as solvents.

Cyclomethicone 4 belongs to the family of liquid methyl siloxanes known as Cyclomethicone 4s.
Cyclomethicone 4 is the octamethyl derivative of cyclotetrasiloxane.

Cyclomethicone 4 is a super light silicone that is the small sister of the more commonly used 5-unit long cyclic structured Cyclopentasiloxane.
Cyclomethicone 4 is used as an emollient and solvent in cosmetics.

Cyclomethicone 4 is a volatile polydimethylcyclosiloxane composed mainly of cyclotetrasiloxane.
Cyclomethicone 4 is clear, tasteless, essentially odorless, non-greasy and non-stinging. 

Cyclomethicone 4 is a highly volatile, low-viscosity cyclic siloxane widely used across personal care, cosmetic, household, and industrial sectors due to its exceptional spreading characteristics, sensory performance, and rapid evaporation profile.
Structurally, Cyclomethicone 4 consists of a four-ring Si–O cyclic backbone, with each silicon atom substituted by two methyl groups.

This symmetrical configuration gives the molecule extremely low surface tension, excellent mobility, high volatility, and remarkable resistance to oxidation and chemical degradation.
These combined properties make Cyclomethicone 4 one of the most efficient carrier fluids and slip enhancers in silicone technology.
Commercially, Cyclomethicone 4 appears as a clear, water-insoluble, odorless or very low-odor liquid with ultra-low viscosity, allowing it to spread instantly and evenly across skin, hair, and hard surfaces.

Cyclomethicone 4's most defining feature is rapid evaporation:
Cyclomethicone 4 deposits a smooth film, delivers active ingredients or silicone resins, and then evaporates without leaving an oily trace.
The high vapor pressure ensures a dry, weightless sensory finish, making Cyclomethicone 4 indispensable in modern cosmetic formulations where elegance, fast absorption, and non-greasiness are critical performance attributes.

In skin care applications, Cyclomethicone 4 enhances product aesthetics by reducing greasiness, improving spreadability, and providing a silky, elegant glide during application.
Cyclomethicone 4 is widely used in moisturizers, serums, lotions, sunscreens, primers, BB/CC creams, and foundations to achieve uniform application and a refined after-feel.

Because Cyclomethicone 4 evaporates quickly, it improves formula aesthetics without contributing to long-term occlusiveness.
Cyclomethicone 4 also serves as an efficient carrier for volatile or heat-sensitive actives and enhances the distribution of pigments, UV filters, and silicone elastomer networks within formulations.

In hair care products, Cyclomethicone 4 provides lightweight conditioning, improved combability, and enhanced shine without buildup.
Cyclomethicone 4's rapid evaporation leaves behind other conditioning agents or silicone polymers such as dimethicone or amodimethicone, allowing better deposition on hair fibers while avoiding heaviness or oiliness.
This makes Cyclomethicone 4 valuable in leave-in treatments, anti-frizz sprays, shine serums, and heat-protection formulations.

In color cosmetics, Cyclomethicone 4 plays a key role in achieving smooth application, improved blendability, and uniform pigment dispersion.
Cyclomethicone 4 is especially useful in longwear foundations, cream-to-powder formulas, stick products, eyeshadows, and complexion enhancers where slip and sensory refinement are crucial.
Cyclomethicone 4's fast flash-off supports rapid setting of films, primers, and hybrid silicone matrices.

Beyond personal care, Cyclomethicone 4 is widely utilized in polishes, surface treatments, mold release agents, lubricants, and household cleaning formulations.
Cyclomethicone 4's low surface tension enables rapid wetting of surfaces, efficient spread, and uniform deposition of protective or functional coatings.

In industrial silicone curing and processing, Cyclomethicone 4 acts as a temporary plasticizer or carrier for silicone gums and resins, aiding processability before evaporating cleanly.
Cyclomethicone 4's chemical inertness and compatibility with silicone elastomers, fluorosilicones, hydrocarbons, and various organic solvents make it a robust processing aid in silicone rubber fabrication, coatings, and release technologies.

Cyclomethicone 4's volatility and spreading behavior also make it an excellent fragrance carrier, allowing rapid lift-off of volatile aromatic compounds and helping top notes bloom more strongly in perfumes, body sprays, and personal care products.
As a delivery solvent, Cyclomethicone 4 enhances the dispersion of lipophilic actives such as vitamins, plant extracts, and sunscreen filters.

From a physico-chemical standpoint, Cyclomethicone 4 is valued for its thermal stability, oxidative resistance, and low reactivity.
Cyclomethicone 4 does not easily undergo hydrolysis under neutral conditions and remains stable across a wide range of pH values typical of cosmetic products.
Cyclomethicone 4's inert nature makes it compatible with polymers, oils, esters, waxes, surfactants, emulsifiers, and silicone elastomers, enabling formulators to design complex systems without destabilization.

Due to its ultra-low viscosity, Cyclomethicone 4 can significantly reduce the viscosity of high-molecular-weight silicone gels, helping to produce soft, smooth, and cushiony textures.
Upon evaporation, these systems regain their structure, contributing to powdery or semi-matte finishes.

In packaging and application systems, Cyclomethicone 4 performs reliably in pump sprays, aerosols, droppers, roll-on applicators, and fine atomizers due to its low viscosity and excellent flow properties.
Cyclomethicone 4's purity and stability support long shelf life and consistent performance even under variable temperature conditions.

Market Overview of Cyclomethicone 4:
Cyclomethicone 4, occupies a significant position in the global silicone fluids market due to its unique combination of volatility, spreading efficiency, sensory performance, and compatibility with a broad range of personal care and industrial formulations.
The market is shaped by a balance between strong functional demand—especially in cosmetics, skin care, hair care, and silicone manufacturing—and evolving regulatory frameworks in Europe, the Americas, and Asia that influence production, usage limits, and long-term formulation strategies.

Globally, the demand for Cyclomethicone 4 is driven predominantly by the personal care and cosmetics sector, which accounts for a substantial share of D4’s consumption.
Cyclomethicone 4's ability to improve spreadability, reduce greasiness, enhance glide, and evaporate quickly without residue has made it an essential ingredient in moisturizers, foundations, serums, deodorants, antiperspirants, and hair products.
The shift toward lightweight, elegant textures in skin care and color cosmetics continues to sustain demand across North America, Asia-Pacific, and parts of Latin America, where regulatory pressure is lower and sensory-driven formulations remain in high demand.

At the same time, Cyclomethicone 4 is widely used in industrial applications, including silicone rubber processing, mold release agents, surface treatments, automotive polishes, lubricants, and cleaning formulations.
These sectors value Cyclomethicone 4's low surface tension, chemical inertness, and ability to act as a temporary plasticizer or carrier solvent in high-performance silicone systems.
Cyclomethicone 4’s use in silicone polymer production (as both a building block and processing aid) also contributes to a stable baseline of industrial consumption.

However, the market structure is strongly influenced by regulatory developments, particularly in the EU and UK, where Cyclomethicone 4 has been classified under restrictions related to environmental persistence and bioaccumulation.
These regulatory actions have placed thresholds on allowable concentrations in rinse-off cosmetic formulations and have incentivized manufacturers to reduce reliance on pure Cyclomethicone 4 or shift toward alternative materials such as D5, D6, or low-VOC volatile silicone blends.
Despite these guidelines, Cyclomethicone 4 remains legally used in many regions, and in non-EU markets demand continues to remain robust for both cosmetic and industrial applications.

In Asia-Pacific—particularly China, South Korea, India, and Southeast Asia—Cyclomethicone 4 experiences steady demand due to large-scale silicone manufacturing, expanding personal care production, and more flexible regulatory environments.
China is a major producer and consumer of Cyclomethicone 4, supported by strong domestic silicone fluid capacity and integration with upstream siloxane monomer plants.
This regional production dominance influences global pricing, supply stability, and raw-material availability.

In North America, demand is stable, with personal care, household products, and industrial lubricants forming the core application base.
Market growth in this region is supported by consumer preference for high-performance sensory silicones and the presence of major multinational silicone manufacturers.
While regulatory discussion exists, Cyclomethicone 4 usage remains permitted in most applications, preserving market continuity.

The overall supply chain for Cyclomethicone 4 is closely tied to siloxane monomer production capacity, as D4 is both an intermediate and a finished fluid depending on the application.
Price fluctuations are usually linked to upstream silicon metal markets, energy costs, and environmental regulations affecting silicone monomer manufacturing plants.

From a competitive perspective, the market includes both large multinational silicone companies and regional producers offering high-purity Cyclomethicone 4 for cosmetic and industrial grades.
Differentiation is typically based on purity, odor profile, volatility control, and compliance documentation (such as IFRA, ISO, cosmetic regulations, and environmental certifications).

Despite regulatory pressures, Cyclomethicone 4 continues to maintain strong demand in markets where performance, volatility, sensory enhancement, and formulation flexibility are key value drivers.
The transition toward cleaner, more controlled silicone chemistries—including blends of Cyclomethicone 4 with other volatile silicones, or D4-free alternatives—will shape the market’s long-term evolution, but in the near to mid term, D4 remains a widely used and high-value ingredient in both consumer and industrial sectors.

Uses of Cyclomethicone 4:
Cyclomethicone 4 is widely used across the global personal care, cosmetic, household, and industrial sectors due to its exceptional volatility, high spreading efficiency, and lightweight sensory profile.
Cyclomethicone 4's ability to evaporate quickly while delivering actives, dispersing pigments, and improving glide makes it a key functional ingredient in modern formulations.

In skin care, Cyclomethicone 4 is used in moisturizers, lotions, gels, serums, and sunscreens to enhance spreadability and reduce greasiness.
Cyclomethicone 4 provides a smooth, silky glide during application and quickly evaporates from the skin, leaving a dry, elegant, non-tacky after-feel.
Cyclomethicone 4 serves as an effective carrier fluid for silicone elastomers, vitamin oils, botanical extracts, and UV filters, allowing formulators to achieve lighter, more stable textures.

In hair care, Cyclomethicone 4 improves combability, reduces friction, enhances shine, and improves slip without leaving buildup on the hair shaft.
Cyclomethicone 4 is commonly used in leave-in conditioners, anti-frizz treatments, shine sprays, styling serums, and heat-protection products.
Because Cyclomethicone 4 evaporates rapidly, it helps deliver conditioning polymers or silicone resins to the hair surface without weighing the hair down.

In color cosmetics, Cyclomethicone 4 plays a major role in foundations, primers, lipsticks, concealers, cream-to-powder products, eyeshadows, and stick formulations.
Cyclomethicone 4 improves pigment dispersion, enhances blendability, increases slip, and supports even application.
Cyclomethicone 4's rapid evaporation contributes to long-wear effects by allowing film-formers to set more efficiently.

In antiperspirants and deodorants, Cyclomethicone 4 is a primary volatile carrier that helps deliver active ingredients, improves spreadability, reduces tack, and accelerates drying.
Cyclomethicone 4 also contributes to a light, silky sensory feel that is desirable in both roll-on and aerosol formulations.

In fragrance formulations, Cyclomethicone 4 is used as a highly effective volatile carrier that enhances the release of top notes and improves fragrance diffusion.
Cyclomethicone 4 leaves no oily residue and evaporates cleanly, making it suitable for body mists, perfume gels, and room sprays.

In industrial and household applications, Cyclomethicone 4 is used in polishes, cleaners, lubricants, and surface treatment products due to its low surface tension and rapid evaporation.
Cyclomethicone 4 improves wetting on metal, plastic, glass, and ceramic surfaces and helps deposit protective silicone films without streaking.

In silicone rubber processing, Cyclomethicone 4 serves as a temporary processing aid and solvent for silicone gums and resins.
Cyclomethicone 4 lowers viscosity during mixing and compounding, enhances flow, and evaporates during curing without leaving contamination.
This makes Cyclomethicone 4 valuable in mold release formulations, sealant production, and silicone elastomer manufacturing.

In mold release and surface finishing, Cyclomethicone 4 provides excellent spreadability and slip, allowing uniform deposition of release agents on molds and tooling.
Cyclomethicone 4 evaporates cleanly, leaving behind the active silicone layer that ensures smooth demolding in plastics, rubber, and composite fabrication.

In coatings and surface treatments, Cyclomethicone 4 is used as a wetting agent and slip enhancer, improving flow-out and reducing surface defects.
Cyclomethicone 4's volatility helps coating surfaces level more uniformly without leaving residue.

In cleaning formulations, particularly in automotive and electronics care, Cyclomethicone 4 acts as a fast-evaporating solvent that removes fingerprints, oils, and residues while leaving surfaces streak-free.
Cyclomethicone 4 is valued in screen cleaners, lens treatments, and specialty wipes.

Across all applications, the primary value of Cyclomethicone 4 lies in its unique blend of high volatility, excellent sensory behavior, broad compatibility, strong spreading power, and clean evaporation profile.
This makes Cyclomethicone 4 a versatile and high-performance ingredient in both consumer and industrial formulations where lightweight feel, fast drying, and smooth application are required.

Applications of Cyclomethicone 4:
A base fluid in a number of personal care products, with excellent spreading and lubrication properties and unique volatility characteristics.
Cyclomethicone 4 can be used in anitperspirants, deodorants, skin creams, lotions, bath oils, suntan and shaving products, make-up, nail polishes.

In hair spray; faster drying time in low VOC formula.
In cleansing products; Cyclomethicone 4 lifts and removes dirt without leaving any greasy residue or stinging sensation.
Cyclomethicone 4 is a volatile fluid with appreciable vapor pressure at ambient temperature.

Benefits of Cyclomethicone 4:
Cyclomethicone 4 offers a broad range of performance advantages that make it one of the most valuable volatile silicones in both cosmetic and industrial applications.
Cyclomethicone 4's exceptionally high spreadability allows formulas to glide smoothly over skin, hair, or solid surfaces with minimal drag, significantly improving user experience and application efficiency.
This ultra-fast spreading capability results from Cyclomethicone 4’s extremely low surface tension and low viscosity, enabling rapid dissemination across large surface areas even at low usage levels.

One of the most important benefits of Cyclomethicone 4 is its high volatility and clean evaporation profile.
Cyclomethicone 4 evaporates rapidly after application, leaving behind non-volatile actives, conditioners, pigments, or silicone polymers without contributing to long-term greasiness or buildup.

This makes Cyclomethicone 4 ideal for lightweight skincare, fast-drying deodorants, long-wear makeup, and quick-setting hair treatments.
Cyclomethicone 4's volatility also enhances fragrance lift by promoting the diffusion of top notes and improving overall scent perception.

Cyclomethicone 4 provides an elegant sensory profile, imparting a silky, dry, powdery feel that improves the aesthetics of creams, serums, foundations, primers, and hair serums.
By reducing tack, heaviness, and greasiness, Cyclomethicone 4 improves consumer acceptance and transforms the tactile performance of formulas.
In high-pigment systems, Cyclomethicone 4 helps reduce drag and improves blendability, enabling smooth, uniform application even in long-lasting color cosmetics.

Another major benefit is Cyclomethicone 4's excellent compatibility with silicones, oils, esters, emulsifiers, waxes, and film-forming polymers.
This allows formulators to incorporate Cyclomethicone 4 into a wide range of systems without destabilizing emulsions or causing viscosity changes.
Cyclomethicone 4 is highly compatible with silicone elastomers, helping to produce soft, cushiony, gel-like textures in primers, blur creams, and silicone gel formulations.

Cyclomethicone 4 also offers significant improvements in viscosity control.
When added to high-viscosity silicone networks or heavy oil phases, Cyclomethicone 4 temporarily reduces viscosity, improving spreadability and flow during application.
After evaporation, the formula returns to Cyclomethicone 4's intended final structure, allowing for innovative sensory transformations such as cream-to-powder finishes.

In hair care, Cyclomethicone 4 provides lightweight conditioning and shine without buildup.
Cyclomethicone 4's rapid flash-off leaves behind beneficial conditioning agents while preserving hair volume and preventing heaviness.
This makes Cyclomethicone 4 ideal for anti-frizz serums, shine sprays, and leave-in treatments where softness and smoothness must be achieved without oiliness.

From an industrial perspective, Cyclomethicone 4 provides excellent surface wetting, lubricity, and clean evaporation that enhance the performance of polishes, mold release agents, cleaning formulations, and surface treatments.
Cyclomethicone 4 spreads quickly over metals, plastics, and glass, depositing protective silicone films while evaporating cleanly to avoid streaking or residue.
Cyclomethicone 4's thermal and oxidative stability ensure consistent performance even under challenging processing conditions.

In silicone elastomer and rubber manufacturing, Cyclomethicone 4 acts as a temporary plasticizer and processing aid, lowering viscosity during mixing and compounding, improving flow, and evaporating during curing without contamination.
This contributes to improved process efficiency, cleaner molds, and higher-quality elastomeric components.

Cyclomethicone 4 is also valued as an effective carrier fluid for fragrances, actives, and volatile ingredients, enabling efficient delivery and enhanced sensorial performance.
Cyclomethicone 4's high volatility accelerates drying and improves product feel in sprays, aerosols, and lightweight skincare products.

Synthesis of Cyclomethicone 4:
Cyclomethicone 4 is produced through a multi-step siloxane synthesis process that begins with silicon metal, transitions through chlorosilane intermediates, and culminates in hydrolysis–condensation reactions that form cyclic siloxanes.
The synthesis route is strongly integrated with the overall silicone monomer manufacturing chain, and Cyclomethicone 4 emerges as one of the primary cyclic by-products of these reactions.

The process begins with the reduction of high-purity quartz (SiO₂) using silicon metal in an arc furnace.
Silicon metal is then reacted with methyl chloride (CH₃Cl) in the presence of a copper-based catalyst, producing a mixture of methylchlorosilanes such as dimethyldichlorosilane (Me₂SiCl₂), methyltrichlorosilane (MeSiCl₃), and trimethylchlorosilane (Me₃SiCl).
This reaction is known as the direct process or Rochow process, the foundational industrial method for silicone production.

Dimethyldichlorosilane, the main precursor, is then subjected to controlled hydrolysis.
Water reacts with the chlorosilanes to generate silanols, with hydrochloric acid released as a by-product.

These silanols undergo polycondensation, forming linear siloxane chains (polydimethylsiloxane oligomers) and a distribution of cyclic siloxanes, including D3, D4, D5, and D6.
Cyclomethicone 4 is one of the major cyclic species formed due to the favorable energetics of the four-membered siloxane ring.

Following condensation, the reaction mixture is heated under reduced pressure, promoting ring-closure reactions that increase the yield of cyclic siloxanes.
The mixture of linear oligomers and cyclic siloxanes is then separated using fractional distillation, the core purification step.

Because Cyclomethicone 4 has a well-defined boiling point (typically around 175–180°C), it can be isolated efficiently by vacuum distillation.
Precise temperature and pressure control ensures separation from neighboring cyclics such as D3 (lower boiling) and D5 (higher boiling).

The Cyclomethicone 4 fraction undergoes additional refining to remove trace moisture, acidity, volatile impurities, and unreacted chlorosilanes.
Neutralization steps, adsorption treatments, and fine distillation polishing may be applied depending on the required purity grade (cosmetic, industrial, or polymer-grade).
High-purity cosmetic-grade Cyclomethicone 4 must meet strict limits on acidity, volatile impurities, odor, metal content, and residual chlorosilanes.

The purified Cyclomethicone 4 product is then stabilized, filtered, and packaged as a clear, colorless, ultra-low-viscosity volatile silicone fluid ready for use in personal care, home care, and industrial applications.

Stability and Reactivity of Cyclomethicone 4:

Chemical Stability:
Stable under normal handling, storage, and processing conditions.
Highly resistant to oxidation and hydrolysis in neutral environments.

Reactivity:
Low reactivity; chemically inert toward most cosmetic and industrial ingredients.
May react slowly with strong oxidizers.

Conditions to Avoid:
Excessive heat, open flames, ignition sources, strong acids or strong bases at elevated temperatures.

Incompatible Materials:
Strong oxidizing agents, strong acids, strong alkalis.

Hazardous Decomposition Products:
Thermal decomposition may produce formaldehyde, silicon oxides, carbon monoxide, and carbon dioxide.

Handling and Storage of Cyclomethicone 4:

Safe Handling:
Avoid inhalation of vapors in poorly ventilated areas. Prevent contact with eyes.
Keep away from sparks, heat, and flames due to volatility.

Storage Conditions:
Store in tightly closed containers in a cool, dry, well-ventilated area.
Keep away from heat and direct sunlight.
Protect from moisture.

Shelf Stability:
Excellent long-term stability when stored under recommended conditions.

First Aid Measures of Cyclomethicone 4:

Inhalation:
Move the person to fresh air.
Seek medical attention if dizziness, headache, or respiratory irritation occurs.

Skin Contact:
Wash with soap and water.
Seek medical attention if irritation develops.

Eye Contact:
Rinse carefully with water for several minutes.
Remove contact lenses if present.
Continue rinsing and seek medical attention if irritation persists.

Ingestion:
Rinse mouth.
Do not induce vomiting.
Seek medical advice if large amounts are ingested or if symptoms appear.

Firefighting Measures of Cyclomethicone 4:

Suitable Extinguishing Media:
Dry chemical, foam, CO₂, or water spray.

Specific Hazards:
Vapors may form flammable mixtures with air.
Burning produces irritating or toxic fumes including silicon oxides and formaldehyde.

Firefighter Protection:
Wear self-contained breathing apparatus and full protective clothing.

Accidental Release Measures of Cyclomethicone 4:

Personal Precautions:
Eliminate ignition sources.
Provide adequate ventilation.
Avoid breathing vapor; avoid skin and eye contact.

Environmental Precautions:
Prevent entry into drains, soil, or surface water in large quantities.

Cleanup Methods:
Absorb with inert material (sand, clay, absorbent pads).
Collect in suitable containers for disposal.
Wash residue with detergent and water.

Exposure Controls / Personal Protective Equipment of Cyclomethicone 4:

Engineering Controls:
Ensure good ventilation, especially in areas where vapors may accumulate.
Use explosion-proof ventilation when necessary.

Respiratory Protection:
Not required under normal conditions; use a vapor respirator if ventilation is inadequate.

Skin Protection:
Protective gloves recommended for prolonged or repeated contact.

Eye Protection:
Safety glasses or chemical splash goggles recommended.

Body Protection:
Standard industrial protective clothing.

Hygiene Measures:
Wash hands after handling.
Do not eat, drink, or smoke while working with the material.

Identifiers of Cyclomethicone 4:
CAS Number: 556-67-2
EC/EINECS Number: 209-136-7
Molecular Formula: C8H24O4Si4
Molecular Weight: 296.62 g/mol
Chemical Family: Cyclic volatile siloxane (VMS)
Chemical Structure: Four-membered cyclic siloxane ring (Si–O–Si backbone with methyl substituents)
UN Number: Not classified as hazardous
HS Code: Typically 2931.90 or 3910.00 (silicone fluids / organosiloxanes)
Appearance: Clear, colorless, low-viscosity liquid
Odor: Very low to mild characteristic silicone odor
Purity Grade: Cosmetic, industrial, or polymer-grade depending on specification
Stability Class: Highly volatile, chemically inert silicone fluid

Stereochemistry: ACHIRAL
Molecular Formula: C8H24O4Si4
Molecular Weight: 296.62
Optical Activity: NONE
Defined Stereocenters: 0 / 0
E/Z Centers: 0

CAS Number: 556-67-2 / 293-51-6
Chem/IUPAC Name: 2,2,4,4,6,6,8,8-octamethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane
EINECS/ELINCS No: 209-136-7
COSING REF No: 33104

Linear Formula: [-Si(CH3)2O-]4
CAS Number: 556-67-2
Molecular Weight: 296.62
Beilstein: 1787074
MDL number: MFCD00003269
UNSPSC Code: 41116107
PubChem Substance ID: 329749481
NACRES: NA.24

Properties of Cyclomethicone 4:
Physical State: Liquid
Appearance: Clear, colorless, water-insoluble fluid
Odor: Very low to mild characteristic silicone odor
Molecular Formula: C8H24O4Si4
Molecular Weight: 296.62 g/mol
Viscosity (25°C): Very low; typically ~2.2–2.5 cSt
Density (25°C): 0.95 – 0.96 g/cm³
Refractive Index (25°C): ~1.396 – 1.398
Boiling Point: 175–180°C (at atmospheric pressure)
Flash Point (Closed Cup): approx. 77–85°C (grade-dependent)
Vapor Pressure (25°C): ~0.7–1.0 mmHg (high volatility)
Evaporation Rate: Very fast; significantly higher than most cosmetic solvents
Surface Tension: Very low (~18–20 dyn/cm) enabling excellent spreadability
Solubility: Insoluble in water; soluble in silicones, hydrocarbons, and many organic solvents
pH: Not applicable (non-aqueous)
Hygroscopicity: Non-hygroscopic
Thermal Stability: High stability under normal formulation temperatures
Oxidative Stability: Excellent; resists oxidation and degradation
Dielectric Constant: Very low (~2.7)
Volatility Class: High-volatile cyclic siloxane
Partition Coefficient (Log P): Very high (hydrophobic, lipophilic)
Compatibility: Excellent compatibility with silicone fluids, oils, esters, waxes, elastomers, and polymers
Color: Typically <10 APHA (very low color)

Cyclotetrasiloxane (D4) content: > 96 %
Appearance: Colorless liquid
Specific gravity: (25°C/77°F) 0.95
Viscosity: (25°C/77°F) 2.4 mm2/s
Refractive index: (25°C/77°F) 1.394
Surface tension: (25°C/77°F) 17.8 mN/m
Flash point: (Closed Cup) 55°C (131°F)
Freezing point: 18°C (64°F)
Boiling point: (760 mmHg) 172°C (342°F)
Water content: 250 ppm 

grade: pharmaceutical primary standard
vapor density: 1 (vs air)
API family: Cyclomethicone 4
form: liquid
manufacturer/tradename: USP
refractive index: n20/D 1.396 (lit.)
bp: 175-176 °C (lit.)
mp: 17-18 °C (lit.)
density: 0.956 g/mL at 25 °C (lit.)
application(s): pharmaceutical (small molecule)
format: neat
storage temp.: 2-8°C
SMILES string: C[Si]1(C)O[Si](C)(C)O[Si](C)(C)O[Si](C)(C)O1
InChI: 1S/C8H24O4Si4/c1-13(2)9-14(3,4)11-16(7,8)12-15(5,6)10-13/h1-8H3
InChI key: HMMGMWAXVFQUOA-UHFFFAOYSA-N