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Cyclopentasiloxane (D5) is a type of silicone compound that belongs to the family of cyclomethicones.
Cyclopentasiloxane (D5) is widely used in cosmetics, personal care products, and industrial applications due to its unique properties.
Cas Number: 541-02-6
SYNONYMS
Decamethylcyclopentasiloxane,2,2,4,4,6,6,8,8,10,10-Decamethyl-1,3,5,7,9-pentaoxapentasilecane,Cyclopentasiloxane, decamethyl-,Dimethylsiloxane pentamer,Cyclic dimethylsiloxane pentamer.
Cyclopentasiloxane (D5) is a volatile, low-viscosity siloxane commonly employed in cosmetics, personal care products, and industrial applications.
This comprehensive review explores the chemical properties, synthesis methods, environmental behavior, and toxicity of D5.
Furthermore, we evaluate its uses, regulatory considerations, and future implications in green chemistry.
The review integrates insights from recent scientific studies, regulatory frameworks, and industrial advancements to provide a thorough understanding of D5.
Cyclopentasiloxane, also known as decamethylcyclopentasiloxane (D5), is a cyclic siloxane characterized by its unique physicochemical properties.
It plays a critical role in a variety of industries, particularly in cosmetics and personal care products, where its ability to enhance sensory attributes and formulation performance is highly valued.
The increasing use of D5 has raised questions about its environmental and health impacts, spurring extensive research and regulatory scrutiny.
This review aims to provide an exhaustive overview of D5, exploring its chemistry, applications, and the challenges associated with its use.
Chemical Structure and Properties
Molecular Structure
D5 is a cyclic organosilicon compound with the molecular formula [(CH₃)₂SiO]₅.
Its structure consists of a five-membered ring of alternating silicon and oxygen atoms, with two methyl groups attached to each silicon atom.
This arrangement confers unique properties such as high flexibility and thermal stability, making D5 distinct among siloxanes.
Physical Properties
D5 is a clear, odorless, and colorless liquid under standard conditions.
Its physical properties include:
Density: Approximately 0.95 g/cm³
Viscosity: Low viscosity of about 4.1 mm²/s, facilitating its spreadability
Boiling Point: Around 210°C, indicative of its volatility
Surface Tension: Approximately 20 mN/m, contributing to its excellent wetting and spreading properties
Chemical Properties
The siloxane bond (Si-O-Si) is a defining feature of D5, imparting several chemical characteristics:
Resistance to Hydrolysis: Stable under neutral and basic conditions, although susceptible to acidic hydrolysis
Volatility: Despite its molecular size, the cyclic structure facilitates evaporation, reducing residue formation
Thermal Stability: Retains its properties across a wide temperature range, crucial for industrial applications
Synthesis and Production
Raw Materials
The primary raw material for D5 synthesis is dimethyldichlorosilane, a silicon-based compound derived from the reaction of metallic silicon with methyl chloride in the presence of a copper catalyst. Water serves as a key reactant for hydrolysis.
3.2 Synthesis Process
The production of D5 involves two main stages:
Hydrolysis: Dimethyldichlorosilane reacts with water, forming silanols and releasing hydrochloric acid.
This reaction requires careful control to minimize side reactions.
(CH₃)₂SiCl₂ + 2H₂O → (CH₃)₂Si(OH)₂ + 2HCl
Cyclization: The silanols condense to form cyclic structures, including D5.
Catalysts such as potassium hydroxide enhance the cyclization efficiency.
Scale-Up and Industrial Production
Industrial-scale production employs continuous distillation and purification to isolate D5.
Advances in process engineering focus on optimizing yields and minimizing by-products.
Applications
Personal Care and Cosmetics
D5 is a cornerstone ingredient in the cosmetics industry.
Its rapid evaporation and non-greasy feel make it ideal for:
Skincare Products: Improves spreadability and sensory experience in creams and lotions
Haircare Products: Adds shine and smoothness without weighing down hair
Deodorants: Acts as a carrier fluid for active ingredients, enhancing application uniformity
Medical and Pharmaceutical Applications
In medicine, D5’s biocompatibility and volatility are leveraged in:
Topical Formulations: Delivers active ingredients with minimal residue
Drug Delivery Systems: Serves as a solvent or carrier in transdermal and inhalation therapies
Industrial Uses
D5’s stability and low viscosity make it valuable in:
Lubricants: Reduces friction in mechanical systems
Solvents: Used in cleaning agents and dielectric fluids
Specialty Coatings: Enhances durability and water repellency
Environmental Behavior
Persistence and Bioaccumulation
D5’s resistance to biodegradation and potential to bioaccumulate in aquatic organisms have raised environmental concerns.
Studies reveal its tendency to partition into sediments and biota.
Degradation Pathways
Atmospheric degradation of D5 occurs primarily through photolysis and reactions with hydroxyl radicals, leading to the formation of silicic acids and other siliceous by-products.
In aquatic systems, hydrolytic breakdown is slower.
Environmental Monitoring
Monitoring efforts include:
Analytical Methods: Advanced techniques such as gas chromatography-mass spectrometry (GC-MS) enable precise detection
Field Studies: Assess concentrations in water, soil, and biota to inform risk assessments
Regulatory Considerations
D5 is subject to regulatory frameworks aimed at mitigating its environmental impact.
Key measures include:
EU REACH Regulations: Restrictions on use in certain products and reporting requirements
US Environmental Protection Agency (EPA): Monitoring under the Toxic Substances Control Act (TSCA)
International Initiatives: Collaborative efforts to develop safer alternatives
Future Perspectives
Innovations in green chemistry aim to address the challenges posed by D5. Strategies include:
Developing Biodegradable Alternatives: Research focuses on creating compounds with similar properties but improved environmental profiles
Molecular Modifications: Adjusting the structure of D5 to enhance degradation rates
Circular Economy Models: Encouraging recycling and reuse within industrial applications
Cyclopentasiloxane (D5) is a versatile compound with applications spanning cosmetics, medicine, and industry.
Balancing its benefits with environmental and safety concerns is critical for its sustainable use.
Ongoing research and regulatory measures will shape the future of D5, ensuring its contributions to science and industry align with ecological and public health priorities.
SAFETY INFORMATION ABOUT CYCLOPENTASILOXANE (D5)
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
