What Is Isopropyl Propionate?
Isopropyl propionate is a colorless liquid ester with a mild, fruity odor. It is made by reacting isopropyl alcohol with propionic acid. This reaction forms a stable compound that is commonly used as a solvent, flavoring agent, and fragrance ingredient.
From a chemical point of view, isopropyl propionate belongs to the ester group of organic compounds. Esters are known for their pleasant smells and good solvent properties, which is why they are widely used in food, cosmetic, and industrial applications.
Isopropyl propionate has a low boiling point and fast evaporation rate, making it useful where quick drying is needed. It dissolves well in many organic materials but has limited solubility in water. These characteristics make it suitable for use in coatings, inks, perfumes, and flavor formulations.
In simple terms, isopropyl propionate is a functional ester valued for its mild odor, good solvency, and wide range of practical uses.
Chemical Identity of Isopropyl Propionate
Isopropyl propionate is the common name used in industrial, food, and fragrance sectors. Its official chemical name is propan-2-yl propanoate, which follows standard chemical naming rules. This name clearly shows that the compound is formed from propionic acid and isopropyl alcohol. Both names refer to the same substance and are used depending on technical or commercial context.
Molecular Formula and Structure
The molecular formula of isopropyl propionate is C₆H₁₂O₂. This means the compound contains six carbon atoms, twelve hydrogen atoms, and two oxygen atoms. These elements combine to form an ester structure, which is responsible for its mild odor and good solvent properties. The structure is stable under normal storage and usage conditions.
Molecular Weight Information
Isopropyl propionate has a molecular weight of 116.16 g/mol. This value is important in chemical formulation, quality control, and laboratory calculations. It helps manufacturers measure accurate quantities during production and application.
CAS Number and Chemical Identification
The CAS number of isopropyl propionate is 637-78-5. This unique number is used worldwide to identify the compound in safety data sheets, regulatory documents, and chemical databases.
Common Synonyms Used in Industry
Isopropyl propionate is also known as propionic acid isopropyl ester and isopropyl propanoate. These names are commonly seen in technical documents and product specifications.
Chemical Structure of Isopropyl Propionate
Isopropyl propionate is an ester, meaning it is formed by joining an alcohol part with an acid part through a chemical link called an ester bond. Understanding its structure helps explain why it behaves the way it does in different uses.
What Is an Isopropyl Group?
The isopropyl group is a part of the molecule derived from isopropyl alcohol. It contains three carbon atoms arranged so that one central carbon is attached to two others and a hydrogen atom. This branched shape makes the group slightly bulkier than a straight-chain group. The isopropyl part contributes to the compound’s mild odor and influences how it interacts with other chemicals, especially in solvent applications.
What Is a Propionate Group?
The propionate group comes from propionic acid, which contains three carbon atoms with a characteristic acid group (-COOH). When propionic acid reacts with alcohol, its acid group becomes part of the ester. The propionate portion helps give the compound its overall structure and affects its physical properties, such as boiling point and solubility.
Role of the Ester Linkage
The ester linkage (-COO-) connects the isopropyl group and the propionate group. This bond forms when the hydrogen from the acid’s carboxyl group and the hydroxyl group from the alcohol are removed and water is released. The ester bond is responsible for many of the compound’s key traits, including its fruity odor, solvent ability, and relative stability under normal conditions. Because of this linkage, isopropyl propionate can evaporate at moderate temperatures, making it useful in coatings, fragrances, and flavoring.
Physical and Chemical Properties of Isopropyl Propionate
Isopropyl propionate has several physical and chemical properties that explain how it behaves during storage, handling, and use in different applications.
Appearance and Odor Characteristics
Isopropyl propionate is a clear and colorless liquid at room temperature. It has a light, fruity, and slightly sweet odor. The smell is not sharp or irritating, which makes the compound suitable for use in flavor and fragrance products.
Boiling Point and Thermal Behavior
The boiling point of isopropyl propionate is around 108–111°C. This moderate boiling range allows the liquid to evaporate easily when heated. Because of this property, it is often used where fast drying or quick solvent release is required.
Density and Physical State
Isopropyl propionate has a density of about 0.87 g/cm³ at 20°C, which is lower than water. Due to this lower density, it floats on water. Its liquid state and light density make it easy to blend with other organic materials.
Solubility in Water and Organic Solvents
Isopropyl propionate is slightly soluble in water but dissolves well in alcohols and many organic solvents. This limited water solubility is typical for ester compounds and supports its use as an effective solvent.
Volatility and Chemical Stability
The compound is volatile, meaning it can evaporate at normal temperatures. It remains chemically stable under normal storage conditions and does not break down easily unless exposed to strong acids, bases, or high heat.
Manufacturing Process of Isopropyl Propionate
Isopropyl propionate is produced through a controlled chemical reaction that combines specific raw materials to form an ester. The process focuses on efficiency and product purity.
Raw Materials Required
The main raw materials in manufacturing are isopropyl alcohol and propionic acid. Isopropyl alcohol acts as the alcohol component, while propionic acid provides the acid component. Both are commonly available industrial chemicals and are chosen for their reactivity and ability to form the desired ester.
Esterification Process Explained
The esterification process is the core chemical reaction used to make isopropyl propionate. In this reaction, the hydroxyl group (-OH) from isopropyl alcohol reacts with the carboxyl group (-COOH) of propionic acid. When these two groups combine, a molecule of water is released, and an ester bond (-COO-) is formed. This reaction results in the formation of isopropyl propionate.
Catalysts and Reaction Conditions
To speed up the reaction, a catalyst such as sulfuric acid or another strong acid is added. The catalyst helps the reaction occur faster and improves yield. The reaction is usually carried out under moderate heat to ensure that enough energy is available for the molecules to react. The conditions are controlled to prevent unwanted side reactions.
Overview of Industrial Production
In industrial settings, the reactants are mixed with the catalyst in a reactor. Heat is applied, and the mixture is maintained at the right temperature until the reaction is complete. The water formed during the reaction is removed to push the reaction forward. After the reaction finishes, the crude product is purified through distillation to remove unreacted materials and by-products. The result is a high-purity isopropyl propionate suitable for use in coatings, flavors, fragrances, and other applications.
Key Functional Characteristics of Isopropyl Propionate
Isopropyl propionate has specific features that make it useful in many applications. These features relate to how it evaporates, dissolves other substances, smells, and mixes with different materials.
Evaporation Rate and Drying Behavior
Isopropyl propionate has a moderate to fast evaporation rate compared to heavier solvents. This means it turns into vapor relatively quickly at room temperature and under mild heat. Because of this property, it is widely used in coatings, inks, and cleaning solutions where quick drying is needed without leaving residues behind.
Solvent Strength and Dissolving Ability
The compound shows good solvent strength for many organic materials. It can dissolve resins, oils, and certain polymers effectively. This makes it valuable in industries that require a solvent that breaks down or carries organic substances without reacting with them. It is not as strong as some aggressive solvents, but it has a balanced performance that suits many formulations.
Odor Profile in Practical Use
Isopropyl propionate has a light, mild, fruity odor. The smell is not sharp or overpowering, which makes it suitable in products used around people, such as fragrances, cosmetics, and flavor blends. Its odor is one reason it is chosen over harsher smelling solvents.
Compatibility With Other Substances
The compound is compatible with a wide range of organic solvents and materials. It mixes well with alcohols, ethers, ketones, and many resins. It does not mix well with water, but this limited water solubility does not affect most industrial or commercial uses. This compatibility helps formulators create stable and effective products across coatings, personal care, and chemical applications.
Industrial Uses of Isopropyl Propionate
Isopropyl propionate is valued in many industrial settings because of its solvent properties and mild odor. Its physical and chemical traits make it useful in manufacturing processes where good solubility and controlled evaporation are needed.
Use in Coatings and Paints
In coatings and paints, isopropyl propionate acts as an effective solvent and thinning agent. It helps dissolve resins and binders so that paint and coating formulations are smooth and easy to apply. Its moderate evaporation rate allows coatings to level properly and dry evenly without defects. This makes it suitable for industrial coatings, automotive finishes, and specialty paint applications where controlled drying and good finish quality are important.
Use in Inks and Adhesives
Isopropyl propionate is also used in ink formulations and adhesive systems. In printing inks, it aids in dissolving colorants and resin components, which helps deliver consistent ink flow and good print quality. In adhesives, its ability to dissolve polymer components ensures uniform application and bonding performance. The mild odor of isopropyl propionate is a benefit in applications where strong solvent smells are undesirable.
Role as an Industrial Solvent
As an industrial solvent, isopropyl propionate dissolves a variety of organic materials, including oils, resins, and some polymers. It is used in chemical processing, cleaning formulations, and as a carrier in various product blends. Its compatibility with many organic substances makes it versatile in manufacturing settings. The solvent’s volatility and mild scent contribute to its selection over harsher or slower‑evaporating alternatives in many industrial applications.
Use of Isopropyl Propionate in Flavors and Fragrances
Isopropyl propionate is used in the flavor and fragrance industry for its pleasant sensory properties and good blending ability. It is recognized by flavor and fragrance authorities and assigned a FEMA number 2959 and JECFA number 306, which identify it as a flavouring ingredient in official databases.
Flavor Profile and Sensory Description
In flavor applications, isopropyl propionate contributes a fruity and sweet profile that can enhance fruit‑like notes in food and beverage formulations. At low concentration, it provides a subtle fruity aroma that blends well with other flavor components in fruit complexes and similar profiles.
Use in Food Flavoring
Isopropyl propionate is permitted for use in food flavorings under established guidelines. It is included in the list of synthetic flavoring substances recognized for food use, and its use must follow basic safety practices such as using it in minimum quantities required for the intended effect and in line with good manufacturing practices.
Use in Perfumes and Air Fresheners
In fragrance formulations, isopropyl propionate’s light fruity odor makes it a useful blending ingredient for mild, fresh scents. It is selected for products where a soft, non‑intrusive aroma is desired. Its volatility and compatibility with other fragrance ingredients help deliver consistent scent performance in products like air fresheners and personal care fragrances.
Regulatory Limits and Safety Use
As a flavor ingredient, isopropyl propionate is subject to regulatory use levels that ensure it is included only at safe concentrations in food. In fragrance use, there are generally no specific restrictions under IFRA standards for this compound, meaning it can be used in typical fragrance categories without set percentage limits, provided it meets safety and product requirements.
Use of Isopropyl Propionate in Cosmetics and Personal Care
Isopropyl propionate finds practical use in cosmetic and personal care products because of its mild odor, good compatibility with other ingredients, and ability to blend well with oils and fragrances. It helps improve the sensory experience of products and supports formulation performance in many daily consumer items.
Function in Cosmetic Formulations
In cosmetic formulations, isopropyl propionate serves mainly as a fragrance carrier and solvent. Because it mixes easily with aromachemicals and has a light, refreshing scent, it helps deliver pleasant fragrance notes in creams, lotions, shampoos, and deodorants. Its ability to mix with oils and other organic ingredients supports uniform distribution of scent throughout a product.
Benefits in Personal Care Products
Isopropyl propionate contributes to the overall feel and performance of personal care products. It helps enhance the texture and scent without making formulas heavy or greasy. In products like body lotions and hair care items, it supports a smooth, fresh‑feeling finish and complements other functional ingredients. Its low odor also makes it a preferred choice when a subtle fragrance is needed rather than a strong or overpowering smell.
Typical Cosmetic Products That Use It
This ingredient is found in a range of everyday products where mild scent and good formulation compatibility matter. It is used in hand and body lotions, shower gels, shampoos, conditioners, deodorants, and other fragranced personal care items. In these products, it helps carry the desired scent, blend other oil‑soluble ingredients, and improve the overall user experience by supporting pleasant texture and aroma.
Safety, Handling, and Storage Guidelines for Isopropyl Propionate
Isopropyl propionate is a flammable liquid and vapor that needs careful handling and proper storage to reduce risks. It can catch fire easily if exposed to heat, sparks, or open flame. Vapors are heavier than air and can travel to distant ignition sources before igniting, so ignition control is essential.
Flammability and Fire Risk
This compound is classified as highly flammable. Its liquids and vapors can ignite at room temperature if they contact a flame, hot surface, or spark. Keeping it away from any source of heat or flame is critical. The flash point is low, indicating a high risk of rapid vapor ignition under normal conditions.
Safe Handling Practices
Handling should always be done in a well‑ventilated area to limit vapor build‑up. Avoid breathing vapors and avoid contact with skin or eyes. Keep containers tightly closed when not in use. Use non‑spark‑producing tools and make sure equipment is grounded to prevent static discharge.
Proper Storage Conditions
Store isopropyl propionate in a cool, dry, and well‑ventilated area. Containers should be kept tightly sealed and placed away from heat, sparks, and open flame. It should be segregated from strong oxidizing agents, acids, and bases because reactions with these materials can be vigorous.
Personal Protective Equipment (PPE)
When handling this chemical, wear chemical‑resistant gloves and safety goggles to protect skin and eyes. A protective lab coat or flame‑resistant clothing is recommended. If ventilation is not adequate, use a NIOSH‑approved respirator with organic vapor cartridges to prevent inhalation of vapors.
Health and Environmental Impact of Isopropyl Propionate
Isopropyl propionate can affect health and the environment if not handled properly. Knowing how it behaves helps ensure safe use and responsible disposal.
Exposure Effects on Health
Direct contact with isopropyl propionate can irritate the skin, eyes, and respiratory tract. Breathing high concentrations of vapors may cause dizziness or breathing difficulty, especially in enclosed spaces with poor ventilation. Prolonged or repeated exposure should be avoided to reduce risk of irritation. These effects are typical for many volatile organic esters and should be taken seriously during handling.
Environmental Behavior
Isopropyl propionate is a volatile organic compound (VOC) that can enter the air easily because of its fast evaporation rate. Once released into the environment, it does not persist for long in the air compared to heavier pollutants. It can float on water surfaces if spilled due to its lower density than water. Runoff into drains or sewers may cause environmental contamination and should be prevented.
Biodegradability in Natural Conditions
Data on biodegradability for isopropyl propionate specifically is limited. Like many simple ester compounds, it is expected to break down over time through natural chemical reactions and microbial action in soil and water. However, the rate of breakdown depends on environmental conditions such as sunlight, temperature, and microbial activity.
Disposal Guidelines for Safety
Waste containing isopropyl propionate should be handled as hazardous chemical waste. It should not be poured down drains or released into natural water systems. Disposal is best done through licensed waste management services that can incinerate or chemically treat the waste. Containers with residues must be triple‑rinsed, sealed, and directed to proper hazardous waste collection.
Regulatory Status and Compliance of Isopropyl Propionate
Understanding the rules and approvals for isopropyl propionate is important for its safe use in food, cosmetics, and industrial products. Regulations help ensure the compound is used within safe limits.
Food Safety Approvals and Flavor Regulation
Isopropyl propionate is recognized for use as a food flavoring substance in several regulatory frameworks. It has a Joint FAO/WHO Expert Committee on Food Additives (JECFA) number 306 and a FEMA (Flavor and Extract Manufacturers Association) number 2959, indicating it has been evaluated and included in official flavoring databases. Under U.S. food regulations (21 CFR 172.515), substances used as synthetic flavoring agents are permitted when used according to good manufacturing practices and at safe levels for intended food and beverage products.
Compliance in Cosmetics and Personal Care Products
For cosmetic and fragrance use, isopropyl propionate does not appear in major restricted lists of banned ingredients and is generally allowed in formulations where its fruity odor and solvent properties are desired. It also shows no specific restrictions under the International Fragrance Association’s (IFRA) standards, meaning formulations containing it are not limited to a set maximum concentration in finished products. However, individual manufacturers must still follow applicable cosmetic safety rules in their markets.
Industrial Safety Standards and Hazard Compliance
From a workplace safety and industrial perspective, isopropyl propionate must be classified and handled under standard hazardous materials regulations. It is labeled as a flammable liquid, and safety data sheets must reflect that hazard. Industrial safety rules require proper hazard communication, appropriate labeling, and protective measures during transport and storage under systems like the Globally Harmonized System (GHS) and regional transport directives.
These regulatory frameworks ensure that isopropyl propionate is used safely and legally across different applications, keeping health and environmental risks under control.
Common Mistakes and Misunderstandings About Isopropyl Propionate
Even experienced users sometimes make errors when working with isopropyl propionate. Knowing these common mistakes can help avoid safety issues and poor performance in products.
Confusion With Other Propionate Esters
One frequent misunderstanding is confusing isopropyl propionate with other propionate esters. Propionate esters have different alcohol parts, such as ethyl propionate or butyl propionate. These compounds have different smells, evaporation rates, and solvent behavior. Assuming they are interchangeable can lead to wrong formulations or poor product performance. Always check the chemical name and CAS number before use.
Incorrect Storage Practices
Another common mistake is improper storage. Isopropyl propionate is flammable and volatile, so storing it in warm areas or near heat sources increases fire risk. Some users store it in open containers or near strong oxidizers, which can cause dangerous reactions. The correct practice is to store it sealed in cool, dry, well‑ventilated areas away from ignition sources and incompatible materials.
Misuse in Product Formulations
Misuse in formulations happens when people add too much of this compound expecting it to improve product performance. In food, fragrance, or cosmetic products, using isopropyl propionate above recommended levels can harm flavor balance, scent profile, or skin feel. It should be used in appropriate concentrations based on formulation guidelines and safety limits. Incorrect assumptions about its strength can also lead to poor solubility or separation in mixtures, especially when mixed with materials that are not compatible with esters.
Understanding these points helps ensure safe handling and effective use of isopropyl propionate in various applications.
Frequently Asked Questions (FAQs) About Isopropyl Propionate
Is isopropyl propionate safe for food use?
Yes. It is approved as a flavoring agent by regulatory authorities like JECFA and FEMA when used in recommended amounts. It should be used according to good manufacturing practices to ensure safety.
Is it suitable for cosmetic formulations?
Yes. It is commonly used in cosmetics and personal care products as a solvent and fragrance carrier. It is compatible with most oils and resins and has a mild odor, making it suitable for creams, lotions, and hair care products.
Does it have a strong odor?
No. Isopropyl propionate has a light, fruity, and slightly sweet smell. It is not overpowering, which is why it is widely used in flavors and fragrances.
Is it environmentally friendly?
It is volatile and breaks down over time in air and soil, so it does not persist like some heavier chemicals. However, spills should be avoided, and it should not be released into drains or water systems. Proper handling and disposal are important.
How long is its shelf life?
When stored in cool, dry, and well-sealed containers away from heat and flame, isopropyl propionate generally has a shelf life of 2–3 years. Exposure to light, heat, or air may reduce its quality over time.
Conclusion
Isopropyl propionate is a versatile and widely used ester with applications across industrial, cosmetic, flavor, and fragrance industries. Its pleasant fruity odor, good solvent properties, and moderate evaporation rate make it suitable for coatings, inks, adhesives, perfumes, and food flavorings. The compound is generally safe when used according to recommended guidelines, and its chemical structure, composition, and properties contribute to its effectiveness in various formulations.
Proper handling, storage, and adherence to regulatory standards are essential to ensure safety in both industrial and consumer applications. Misunderstandings, such as confusing it with other esters or incorrect usage, can affect performance and safety. By following good manufacturing practices and safety measures, users can maximize its benefits while minimizing risks to health and the environment.
Overall, isopropyl propionate remains a reliable and effective chemical ingredient in multiple sectors, valued for its functionality, compatibility, and ease of use. It is an important compound for professionals in chemistry, manufacturing, and product formulation to understand and use responsibly.
