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DESCRIPTION
Propylene Glycol Isostearate is a clear, odor-free liquid.
Propylene Glycol Isostearate is a non-ionic emollient derived from isostearic acid that improves skin elasticity in facial and body care formulations, particularly anti-aging formulas and shaving preparations.
CAS Number
68171-38-0
Propylene glycol isostearate (PGIS) is an ester formed by the reaction of propylene glycol and isostearic acid.
Propylene Glycol Isostearate is widely used in cosmetics, pharmaceuticals, and industrial applications due to its excellent emollient, solubilizing, and moisturizing properties.
Key Details:
Chemical Name:
Propane-1,2-diol mono(isooctadecanoate)
Molecular Formula:
C₂₁H₄₂O₃
Molecular Weight:
~342 g/mol
CAS Number: 27194-74-7
Natural Occurrence:
PGIS is a synthetic compound and does not naturally occur.
However, its components—propylene glycol and isostearic acid—are commonly derived from petrochemical or renewable sources.
PHYSICAL AND CHEMICAL PROPERTIES
Physical Properties:
Appearance:
Clear, pale yellow liquid.
Odor:
Faint, characteristic odor.
Density: ~0.9 g/cm³ at 25°C.
Melting Point: Typically liquid at room temperature.
Solubility:
Insoluble in water.
Soluble in organic solvents (e.g., ethanol, isopropanol).
Chemical Properties:
Functional Groups:
Ester group (-COO-) and hydroxyl group (-OH).
Stability:
Stable under normal storage conditions but may hydrolyze under extreme pH or heat.
3. Synthesis of Propylene Glycol Isostearate
PGIS is synthesized via esterification or transesterification processes.
Esterification:
Reactants:
Propylene glycol and isostearic acid.
Catalyst:
Acidic catalysts like sulfuric acid or p-toluenesulfonic acid.
Conditions:
Heated to 180–220°C under vacuum or inert atmosphere.
Reaction:
C₃H₈O₂ (Propylene Glycol)+C₁₈H₃₆O₂ (Isostearic Acid)→C₂₁H₄₂O₃ (PGIS)+H₂OC₃H₈O₂ (Propylene Glycol)+C₁₈H₃₆O₂ (Isostearic Acid)→C₂₁H₄₂O₃ (PGIS)+H₂O
Transesterification:
Reactants:
Isostearic acid methyl ester and propylene glycol.
Catalyst:
Alkali metal hydroxides (e.g., NaOH).
APPLICATIONS
In Cosmetics:
Moisturizer:
PGIS forms a barrier on the skin, reducing transepidermal water loss (TEWL).
Emollient:
Provides a smooth and silky texture to formulations.
Solvent:
Enhances the solubility of hydrophobic active ingredients.
Common Products:
Lotions
Creams
Lip balms
Hair conditioners
In Pharmaceuticals:
Used as a base in topical formulations for drug delivery.
Acts as a skin penetration enhancer, increasing the efficacy of active drugs.
Industrial Applications:
Lubricant Additive:
Improves lubricity and stability of oils.
Plasticizer:
In polymer processing.
Mechanism of Action in Cosmetics
PGIS improves the skin's hydration by forming an occlusive film that traps moisture.
Its hydroxyl group allows mild solubilization of water-soluble actives, while the fatty acid moiety provides lipid replenishment to the skin barrier.
Safety in Cosmetics:
Approved by regulatory agencies (e.g., FDA, EU Cosmetics Regulation).
Concentration limits depend on application but are typically ≤10%.
Irritation and Sensitization:
Skin:
Non-irritating at normal usage levels.
Eyes:
Mildly irritating at high concentrations.
Environmental Impact
Biodegradability:
PGIS is moderately biodegradable under aerobic conditions, breaking down into its components: propylene glycol and fatty acids.
Ecotoxicity:
Minimal toxicity to aquatic organisms when used in small amounts.
Avoid large-scale release to prevent localized environmental harm.
Analytical Methods
Chromatography:
Gas Chromatography (GC):
Quantitative analysis of PGIS in mixtures.
HPLC:
Identification and purity assessment.
Spectroscopy:
IR Spectroscopy: Peaks at 1735 cm⁻¹ (ester) and 3300 cm⁻¹ (hydroxyl).
NMR:
¹H NMR: Distinguishes protons of ester and hydroxyl groups.
¹³C NMR: Ester carbonyl and aliphatic carbon chains.
Industrial Production and Economics
The production of PGIS is driven by the demand in the cosmetics industry, which constitutes over 80% of its use. Emerging applications in pharmaceuticals and bioplastics are expanding its market.
Cost Factors:
Availability of raw materials (propylene glycol, isostearic acid).
Efficiency of production processes.
Future Trends
Bio-based PGIS:
Development of formulations using renewable feedstocks.
Enhanced Functionality:
Incorporating PGIS in advanced drug delivery systems.
Sustainability:
Optimization of production to minimize environmental impact.
Regulatory Status
Approved for use in the US, EU, Japan, and other regions.
Listed in the Cosmetic Ingredient Review (CIR) database as safe when used appropriately.
Physical Properties of PGIS
Property Value
Molecular Weight ~342 g/mol
Melting Point Liquid at RT
Boiling Point ~250°C
Solubility Soluble in oils, alcohols
Diagram: Synthesis Pathway
(A reaction scheme showing esterification of propylene glycol with isostearic acid.)
Propylene glycol isostearate is a versatile and widely used compound in the cosmetics and pharmaceutical industries.
Its excellent emollient properties, low toxicity, and environmental compatibility make it a valuable ingredient for diverse applications.
SYNTHESIS OF PROPYLENE GLYCOL ISOSTEARATE
Catalysis and Process Optimization:
Catalyst Choice: Acidic (e.g., sulfuric acid) versus enzymatic catalysts (lipase-based for eco-friendly processes).
Reaction Conditions: Optimization parameters include:
Molar ratio of reactants: Typically 1:1.1 (excess isostearic acid to drive reaction).
Reaction time: 4–8 hours under reduced pressure.
Temperature: 180–200°C.
Eco-Friendly Methods:
Enzymatic esterification using lipase enzymes avoids the need for harsh chemical catalysts, producing purer products with fewer by-products.
Analytical Methods
Spectroscopic Data (Detailed Examples):
IR Spectrum of PGIS:
Characteristic Peaks:
Ester carbonyl stretch at 1735 cm⁻¹.
Hydroxyl group (O–H stretch) at ~3300 cm⁻¹.
Aliphatic C–H stretches at ~2800–2900 cm⁻¹.
¹H NMR Peaks:
Multiplet at δ 4.0–4.3 ppm: Methine proton adjacent to ester oxygen.
Broad peak at δ 1.0–1.5 ppm: Long aliphatic chain protons.
Chromatographic Quantification:
HPLC Method:
Mobile phase: Methanol/water gradient.
Detection: UV at 220 nm.
GC-MS:
Derivatization required to enhance volatility.
Retention time calibration with standards.
Applications
Comparison Table: PGIS vs. Other Emollients
Property PGIS Isopropyl Myristate Cetearyl Alcohol
Emollient Efficacy High Moderate High
Solubility in Oils Excellent Excellent Poor
Moisturization Retention High Moderate High
Skin Irritation Potential Low Moderate Low
Advanced Applications:
Controlled-Release Drug Delivery:
PGIS can encapsulate active ingredients and release them gradually when applied topically.
Hair Care:
Enhances shine and prevents split ends by forming a smooth protective layer.
Visual Content
Diagram:
Molecular Structure of Propylene Glycol Isostearate
(A labeled diagram showing the ester linkage and hydroxyl group functionality.)
Reaction Pathway:
(A visual schematic of the esterification process highlighting reactants, catalysts, and products.)
Flowchart: Applications of PGIS
A flowchart linking PGIS properties (e.g., emolliency, solubilization) to its industrial uses.
Human Patch Testing:
Conducted at 5% and 10% concentrations; no irritation in 98% of participants.
Regulatory Limits:
Cosmetic Use: EU mandates ≤5% in rinse-off products and ≤3% in leave-on products.
Industrial Safety: Classified as non-hazardous for routine handling.
Advanced Chemical Characterization
Structural Features:
PGIS combines the hydrophilic propylene glycol backbone and the lipophilic isostearic acid tail, creating an amphiphilic molecule.
Amphiphilic Nature:
Hydrophilic Propylene Glycol Unit:
Facilitates water compatibility and mild moisturization.
Lipophilic Isostearate Chain:
Enhances solubility in oils and creates occlusive properties for skin protection.
Thermodynamic and Rheological Properties
Thermal Properties:
Glass Transition Temperature (Tg):
Below room temperature, indicating flexibility in emulsions.
Thermal Stability:
Stable up to 250°C under inert conditions.
Rheology:
Exhibits Newtonian behavior in pure form but alters the viscosity profile of emulsions, acting as a viscosity modifier.
Expanded Applications
Skin-Care Innovations:
PGIS's unique combination of properties makes it pivotal in:
Anti-aging Formulations:
Supports active delivery of retinoids and peptides.
Reduces transepidermal water loss (TEWL), enhancing skin elasticity.
Sensitive Skin Products:
Non-comedogenic and suitable for acne-prone or sensitive skin types.
Reduces irritation from actives like salicylic acid or benzoyl peroxide.
Pharmaceutical Delivery Systems:
PGIS has found application in:
Transdermal Drug Delivery:
Increases the bioavailability of drugs like lidocaine or hydrocortisone.
Antimicrobial Systems:
Enhances the solubility and efficacy of lipophilic antimicrobial agents.
Industrial Applications:
Coatings and Polymers:
Used as a plasticizer in PVC and other flexible materials.
Reduces brittleness in cold temperatures.
Eco-Friendly Lubricants:
Improves lubrication while maintaining biodegradability.
Detailed Synthesis Methods
Enzymatic Pathways:
Benefits of Lipase-Catalyzed Esterification:
Operates under milder conditions.
Eliminates by-product contamination.
Example enzymes: Candida antarctica lipase B (CALB).
Process Design for Scale-Up:
Reactor Configuration:
Batch Reactors:
Common for small-scale production.
Continuous Stirred-Tank Reactors (CSTRs):
Used for high-throughput manufacturing.
Process Optimization Parameters:
Reactant Molar Ratios: Propylene glycol:isostearic acid, typically 1:1.1 to minimize side reactions.
Catalyst Loading: 0.1–0.5% by weight for acid catalysts.
Advanced Analytical Techniques
Fourier Transform Infrared (FTIR) Spectroscopy:
Ester C=O stretching frequency: ~1735 cm⁻¹.
Hydroxyl group broad peak: 3200–3600 cm⁻¹.
Thermal Analysis:
Differential Scanning Calorimetry (DSC):
Detects thermal transitions (e.g., Tg, melting points).
Thermogravimetric Analysis (TGA):
Assesses thermal decomposition, showing weight loss onset at ~250°C.
PGIS in Emerging Technologies
Bio-based PGIS:
Growing emphasis on sustainable chemistry has led to the exploration of bio-based feedstocks:
Renewable Propylene Glycol: Produced via glycerol hydrogenolysis.
Bio-Isostearic Acid: Derived from oleic acid through dimerization and hydrogenation.
Nanotechnology Applications:
Nanocarrier Systems:
PGIS can be incorporated into liposomes and nanogels for targeted drug delivery.
3D-Printed Cosmetics:
Used as an ingredient in formulations tailored for 3D-printed beauty products.
In-Depth Toxicological Profile
Cellular Studies:
Cytotoxicity:
PGIS demonstrates minimal toxicity at concentrations ≤10%.
Skin Penetration Studies:
Enhances active ingredient absorption without disrupting the stratum corneum integrity.
Regulatory Updates:
Cosmetics:
Listed as safe by CIR with no restrictions for rinse-off products.
Food Additive Potential:
Being explored as an emulsifier in functional beverages, though not yet widely approved.
Industrial Feasibility
Production Costs:
Raw Material Availability:
Isostearic acid: Available globally from vegetable oils.
Propylene glycol: Produced at scale in the petrochemical industry.
Sustainability Costs:
Enzymatic methods costlier but environmentally advantageous.
Market Trends:
PGIS demand is growing at ~5% CAGR due to rising interest in multi-functional emulsifiers.
Environmental Impact
Lifecycle Assessment:
Carbon Footprint:
Moderate impact, reduced significantly when bio-based feedstocks are used.
Degradation Pathway:
Hydrolyzed in the environment to produce benign by-products: propylene glycol and isostearic acid.
Future Directions
Innovations:
Hybrid Emulsifiers:
Combining PGIS with other esters for tailored emulsification profiles.
Smart Cosmetics:
PGIS as a responsive emulsifier in pH-sensitive formulations.
Challenges:
Regulatory Hurdles:
Approval processes for new applications.
Cost Optimization:
Reducing the cost of enzymatic production at scale.
Detailed Figures
Molecular Structure of PGIS:
A 3D representation showing the ester linkage.
Reaction Pathways:
Visual breakdown of esterification and enzymatic synthesis.
SAFETY INFORMATION ABOUT PROPYLENE GLYCOL ISOSTEARATE
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
