Polyethylene glycol (PEG) is a versatile compound used in various industries. It’s soluble in water and commonly employed as a lubricant, solvent, or ingredient in pharmaceuticals, cosmetics, and personal care products.
| IUPAC Name | Poly(oxyethylene) |
| Molecular Formula | (C2H4O)n |
| CAS Number | 25322-68-3 |
| Synonyms | Polyethylene oxide, PEG, Macrogol, Carbowax, Polyethylene glycol monomethyl ether, Polyethylene glycol dimethyl ether, Polyethylene glycol monobutyl ether, Polyethylene glycol dibutyl ether, Polyethylene glycol monoethyl ether |
| InChI | InChI=1S/C2H4O/c1-2-3/h2-3H,1H2 |
Polyethylene Glycol Properties
Polyethylene Glycol Formula
The formula of polyethylene glycol is (C2H4O)n, where “n” represents the number of repeating ethylene oxide units in the polymer chain. It is a linear polymer composed of ethylene oxide monomer units.
Polyethylene Glycol Molar Mass
The molar mass of PEG varies depending on the length of the polymer chain. It is calculated by multiplying the molar mass of each repeating unit by the number of units in the chain. The average molar mass ranges from a few hundred to several thousand grams per mole.
Polyethylene Glycol Boiling Point
PEG has a relatively high boiling point compared to other common organic compounds. The boiling point increases with the increase in the molar mass of the polymer. For example, PEG with a molar mass of around 200 has a boiling point of approximately 325 degrees Celsius.
Polyethylene Glycol Melting Point
The melting point of PEG is relatively low, typically ranging from around 20 to 70 degrees Celsius. The melting point also depends on the molar mass of the polymer. Lower molar mass PEGs tend to have lower melting points.
Polyethylene Glycol Density g/mL
The density of PEG varies with the molar mass and concentration. Generally, PEGs have a density ranging from approximately 1.12 to 1.23 grams per milliliter. Higher molar mass PEGs tend to have higher densities.
Polyethylene Glycol Molecular Weight
The molecular weight of PEG refers to the average weight of the polymer chains. It is calculated by summing the molar masses of all the repeating units in the chain. The molecular weight is an important parameter for determining the physical and chemical properties of PEG.
Polyethylene Glycol Structure
The structure of PEG consists of a chain of repeating ethylene oxide units. Each ethylene oxide unit is composed of two carbon atoms, four hydrogen atoms, and one oxygen atom. The oxygen atom of one unit is bonded to the carbon atom of the adjacent unit, forming a linear polymer chain.
Polyethylene Glycol Solubility
PEG is highly soluble in water due to the presence of hydrophilic (-OH) groups in the polymer chain. The solubility of PEG in organic solvents varies depending on the molar mass and the nature of the solvent. Generally, lower molar mass PEGs exhibit better solubility in organic solvents.
| Appearance | Clear, colorless to pale yellow liquid |
| Specific Gravity | 1.12 – 1.23 g/mL (at 20°C) |
| Color | Colorless |
| Odor | Odorless |
| Molar Mass | Varies (typically several hundred to several thousand g/mol) |
| Density | Varies with molar mass and concentration |
| Melting Point | 20°C – 70°C (varies with molar mass) |
| Boiling Point | Approximately 325°C (varies with molar mass) |
| Flash Point | Non-flammable |
| Water Solubility | Highly soluble |
| Solubility | Soluble in organic solvents (varies with molar mass and nature of the solvent) |
| Vapor Pressure | Low |
| Vapor Density | Greater than air (approximately 3.5 g/L) |
| pKa | Varies with different functional groups present on PEG |
| pH | Neutral (pH 7) |
Polyethylene Glycol Safety and Hazards
PEG is considered safe for use in various applications. It is non-toxic and generally does not pose significant health hazards when handled properly. However, like any chemical, it should be handled with care. Avoid eye and skin contact, ingestion, or inhalation of dust or vapors. In high concentrations, it may cause mild skin irritation or allergic reactions in sensitive individuals. Adequate ventilation and personal protective equipment should be used when working with PEG. It is important to follow proper storage and disposal procedures to prevent environmental contamination. Always refer to safety data sheets and handle them according to local regulations and guidelines.
| Hazard Symbols | None |
| Safety Description | Non-toxic; handle with care |
| UN IDs | Not applicable |
| HS Code | 39072000 |
| Hazard Class | Not classified |
| Packing Group | Not applicable |
| Toxicity | Low toxicity; may cause mild skin irritation or allergic reactions in sensitive individuals |
Polyethylene Glycol Synthesis Methods
PEG synthesis involves multiple methods. One common approach is to polymerize ethylene oxide monomers under controlled conditions, typically using catalysts like potassium hydroxide or sulfuric acid. The reaction occurs at elevated temperatures and pressures, resulting in the formation of a PEG chain.
Another method includes reacting ethylene glycol with an alkaline catalyst such as sodium hydroxide or potassium hydroxide. This base-catalyzed condensation process leads to the creation of PEG.
To prepare PEG, one can react ethylene oxide with water in the presence of an acid or base catalyst. This ring-opening polymerization process produces PEG chains with hydroxyl groups at both ends.
The aid of a catalyst facilitates the reaction between ethylene oxides and various alcohols, such as methanol or ethanol, to obtain PEG.
It is important to note that the choice of catalyst, reaction conditions, and starting materials can impact the properties and molecular weight of the resulting PEG. These synthesis methods offer flexibility in producing PEG with different molecular weights and tailored properties to meet specific applications in industries such as pharmaceuticals, cosmetics, and industrial processes.
Polyethylene Glycol Uses
Polyethylene glycol (PEG) finds numerous applications across various industries due to its versatile properties. Here are some common uses of PEG:
- The pharmaceutical industry utilizes PEG as a key ingredient in various pharmaceutical formulations, including oral suspensions, ointments, creams, and suppositories. It solubilizes, binds, and modifies viscosity in drug formulations.
- Cosmetics and personal care products employ PEG as a thickener, emulsifier, and humectant in moisturizers, lotions, shampoos, and toothpaste. It enhances product stability and moisturizing properties.
- PEG serves as a lubricant in numerous industrial processes, such as metalworking, textile manufacturing, and plastic production. It reduces friction and acts as a mold-release agent.
- In the food and beverage industry, PEG functions as a food additive, enhancing the texture, stability, and consistency of products like ice cream, chocolate, and baked goods.
- Medical devices and procedures incorporate PEG as a crucial component. Catheters, wound dressings, and medical examinations utilize PEG as a bowel cleanser.
- Veterinary medicine utilizes PEG for various purposes, including the formulation of medicines, topical preparations, and as a laxative for animals.
- PEG acts as a reaction medium and solvent in chemical reactions and polymerizations, aiding in the synthesis of polymers, resins, and other specialty chemicals.
- Researchers in the field of biological research employ PEG as a precipitant for protein purification. PEG serves as a cryoprotectant in cell preservation within the realms of biochemistry and molecular biology.
The diverse range of applications showcases the importance of PEG in numerous industries, thanks to its ability to modify viscosity, solubility, and stability in various formulations and processes.
Questions:
Q: What is polyethylene glycol?
A: Polyethylene glycol (PEG) is a versatile compound used in various industries for its lubricating, solubilizing, and moisturizing properties.
Q: How to remove polyethylene glycol?
A: PEG can be removed by washing with soap and water or using cleansing agents that are effective in removing oil-based substances.
Q: Is polyethylene glycol safe?
A: PEG is generally considered safe when used properly, but it may cause mild skin irritation or allergic reactions in sensitive individuals.
Q: Is polyethylene glycol 3350 the same as polyethylene glycol with electrolytes?
A: PEG 3350 is a type of PEG used as a laxative, while PEG with electrolytes is a formulation used for bowel preparation before medical procedures.
Q: How can polyethylene glycol harm me?
A: PEG can cause skin irritation, allergic reactions, or, in rare cases, adverse effects such as renal toxicity or electrolyte imbalances if used improperly or in excessive amounts.
Q: How do I know if I am allergic to polyethylene glycol?
A: Allergic reactions to PEG may manifest as skin redness, itching, rash, swelling, or difficulty breathing. Consult a healthcare professional for proper diagnosis and advice.
Q: What is polyethylene glycol found in?
A: PEG can be found in various products such as pharmaceuticals, cosmetics, personal care items, industrial lubricants, food additives, and medical devices.