Propylene glycol (C3H8O2) is a versatile chemical compound used as a solvent, humectant, and emulsifier in various industries, including food, pharmaceutical, and cosmetics. It’s also used in antifreeze and de-icing solutions.
| IUPAC Name | Propane-1,2-diol |
| Molecular Formula | C3H8O2 |
| CAS Number | 57-55-6 |
| Synonyms | 1,2-Dihydroxypropane, 1,2-Propanediol, Methyl ethyl glycol, Methylethylene glycol, PG |
| InChI | InChI=1S/C3H8O2/c1-3(5)2-4/h3-5H,2H2,1H3 |
Propylene Glycol Properties
Propylene glycol molar mass
Propylene glycol has a molar mass of 76.09 g/mol. It is a colorless and odorless liquid with a slightly sweet taste. The molar mass of propylene glycol is important in determining its physical and chemical properties. It is commonly used as a solvent, humectant, and emulsifier in various industries such as food, pharmaceuticals, cosmetics, and more.
Propylene glycol boiling point
The boiling point of 1,2-propanediol is 188.2 °C (370.8 °F) at atmospheric pressure. This temperature is significantly higher than the boiling point of water, which makes it a useful component in antifreeze and de-icing solutions. The high boiling point of 1,2-propanediol also makes it useful in heat transfer fluids, such as those used in solar water heaters.
Propylene glycol melting point
1,2-propanediol has a melting point of -60 °C (-76 °F). This low melting point makes it useful in the manufacturing of certain types of polymers, such as polyester resins. The low melting point also makes it useful as a freezing point depressant, which is why it is commonly used in antifreeze and de-icing solutions.
Propylene glycol density g/ml
The density of 1,2-propanediol is 1.036 g/mL at 25 °C (77 °F). This density is slightly higher than that of water, which has a density of 1 g/mL. The density of 1,2-propanediol is important in determining its concentration in solutions, such as antifreeze, de-icing solutions, and heat transfer fluids.
Propylene glycol molecular weight
The molecular weight of 1,2-propanediol is 76.09 g/mol. This is calculated by adding the atomic weights of its constituent atoms, which are carbon, hydrogen, and oxygen. The molecular weight is important in determining the amount of 1,2-propanediol needed in a specific application and in understanding its physical and chemical properties.
Propylene glycol structure
The structure of propylene glycol consists of two hydroxyl groups (-OH) attached to a propane chain. This gives it the chemical formula C3H8O2. The structure of propylene glycol is important in understanding its properties, such as its solubility in water and its ability to form hydrogen bonds.
Propylene glycol formula
The chemical formula for 1,2-propanediol is C3H8O2. This formula represents the number and types of atoms present in one molecule of 1,2-propanediol. The formula is important in understanding the chemical properties of 1,2-propanediol, such as its reactivity with other chemicals and its ability to form various types of bonds.
| Appearance | Colorless, odorless liquid |
| Specific Gravity | 1.036 at 25 °C |
| Color | Colorless |
| Odor | Odorless |
| Molar Mass | 76.09 g/mol |
| Density | 1.036 g/mL at 25 °C |
| Melting Point | -60 °C (-76 °F) |
| Boiling Point | 188.2 °C (370.8 °F) at atmospheric pressure |
| Flash Point | 110 °C (230 °F) closed cup |
| Water Solubility | Completely soluble in water |
| Solubility | Soluble in ethanol, acetone, and chloroform |
| Vapour Pressure | 0.0007 mmHg at 25 °C |
| Vapour Density | 2.62 (air = 1) |
| pKa | pKa1= 13.5, pKa2= 13.2 |
| pH | Neutral (pH 7) |
Propylene Glycol Safety and Hazards
Chemists generally consider 1,2-propanediol safe for use in food, pharmaceuticals, cosmetics, and more. However, exposure to high concentrations of 1,2-propanediol vapor or mist can cause respiratory irritation, coughing, and shortness of breath. Ingesting large amounts of 1,2-propanediol can cause gastrointestinal discomfort and nausea. 1,2-propanediol is flammable and may form explosive mixtures with air. It can also react with oxidizing agents, such as hydrogen peroxide, and produce a hazardous reaction. Proper handling and storage are necessary to minimize the risk of fire and exposure.
| Hazard Symbols | None assigned, but it is flammable and a respiratory irritant |
| Safety Description | P261, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P405 |
| UN IDs | UN 3082 |
| HS Code | 2905.32.00 |
| Hazard Class | 9 (Miscellaneous dangerous goods) |
| Packing Group | III |
| Toxicity | Low to moderate |
Propylene Glycol Synthesis Methods
Chemists can synthesize 1,2-propanediol using various methods.
A strong acid, such as sulfuric acid, catalyzes the hydration of propylene oxide, which results from the chlorohydrination of propylene with hypochlorous acid. To produce 1,2-propanediol, water must be added to the propylene oxide.
Another chemical method involves the hydrogenolysis of glycerol, a byproduct of biodiesel production. To create 1,2-propanediol, first, convert glycerol to 1,2-propanediol, and then hydrogenate the 1,2-propanediol.
Biological methods for producing 1,2-propanediol include the fermentation of sugars or carbohydrates by certain microorganisms, such as bacteria or yeasts. These microorganisms can produce 1,2-propanediol from various carbon sources, including glucose, fructose, and sucrose.
Another biological method involves the use of enzymes to convert renewable resources, such as cornstarch or cellulose, into 1,2-propanediol. This process is more environmentally friendly than chemical methods and has the potential to be a more sustainable way to produce 1,2-propanediol.
Propylene Glycol Uses
Propylene glycol is a versatile compound with a wide range of uses in various industries. Here are some of its common applications:
- Food and Beverage Industry: Used as a humectant, solvent, and preservative in food and beverages.
- Pharmaceutical Industry: Used as a solvent and excipient in pharmaceuticals and as a carrier for delivering active ingredients in topical preparations.
- Cosmetics Industry: Used as a humectant, solvent, and viscosity regulator in cosmetics, skincare products, and haircare products.
- Personal Care Industry: Used in deodorants, toothpaste, and mouthwash for its antibacterial properties.
- Industrial Applications: Used as a coolant and heat transfer fluid in industrial processes, as a solvent in paint and coatings, and as a component of hydraulic fluids.
- E-Cigarettes: Used as a main component in the e-liquids of e-cigarettes.
- Animal Feed: Used as a feed supplement for livestock and poultry to help maintain moisture content in feed and prevent spoilage.
- Anti-Freeze: Used as a component of anti-freeze and de-icing solutions for automobiles, aircraft, and runways.
Questions:
Q: What is propylene glycol?
A: 1,2-propanediol is a synthetic organic compound with the chemical formula C3H8O2. It is a clear, colorless, odorless liquid that is commonly used as a solvent, humectant, and preservative in a variety of industries, including food and beverage, pharmaceutical, cosmetics, and industrial applications.
Q: Is propylene glycol bad for you?
A: 1,2-propanediol is considered safe for use in consumer products by regulatory agencies, such as the FDA and the European Food Safety Authority, when used within acceptable levels. However, some people may experience irritation or allergic reactions to 1,2-propanediol, and it should be used with caution by individuals with certain health conditions, such as kidney or liver disease.
Q: Where to buy propylene glycol locally?
A: 1,2-propanediol can be purchased at local stores that carry DIY supplies for e-cigarettes or vaping, as well as at some craft stores that carry soap-making or lotion-making supplies. It may also be available at specialty chemical stores or industrial suppliers.
Q: What is propylene glycol and is it safe?
A: 1,2-propanediol is a synthetic organic compound commonly used as a solvent, humectant, and preservative in various industries. When used within acceptable levels, it is considered safe for use by regulatory agencies, such as the FDA and the European Food Safety Authority. However, it should be used with caution by individuals with certain health conditions, and some people may experience irritation or allergic reactions to it.
Q: Where to buy propylene glycol antifreeze?
A: 1,2-propanediol antifreeze can be purchased at most auto parts stores, as well as at some home improvement stores and online retailers that specialize in automotive products.
Q: What is propylene glycol vape?
A: 1,2-propanediol is commonly used as a base liquid in e-liquids for electronic cigarettes or vaping. It helps to deliver the flavor and nicotine in the e-liquid, as well as create the vapor that is inhaled. While it is generally considered safe for use, some individuals may experience irritation or allergic reactions to 1,2-propanediol when vaping.