What is the Difference Between Polyethylene Glycol and Propylene Glycol

The key difference between polyethylene glycol and propylene glycol is that polyethylene glycol is a polymer, whereas propylene glycol is a single molecular compound that can be named a diol.

Polyethylene glycol and propylene glycol are important organic compounds. Polyethylene glycol is a polymer compound derived from petroleum, and its structure can be expressed as H-(O-CH₂-CH₂)_n-OH. Propylene glycol is a viscous, colorless liquid, having the chemical formula CH3CH(OH)CH2OH.

CONTENTS

1. Overview and Key Difference
2. What is Polyethylene Glycol
3. What is Propylene Glycol
4. Polyethylene Glycol vs Propylene Glycol in Tabular Form
5. Summary – Polyethylene Glycol vs Propylene Glycol

What is Polyethylene Glycol?

Polyethylene glycol is a polymer compound that derives from petroleum, and its structure can be expressed as H-(O-CH₂-CH₂)_n-OH. There are many applications of this substance ranging from industrial applications to medicine.

The applications of polyethylene glycol include use of it as a basis of a number of laxatives, as an excipient, in medicine to treat disimpaction, to fuse axons, as a lubricating coating for different surfaces in aqueous and non-aqueous environments, to create high osmotic pressures, as a polar stationary phase for gas chromatography, as surfactants, as a crowing agent in biology, to concentrate viruses in virology, etc.

Polyethylene glycol is biologically inert and considered safe by FDA. Moreover, there are some research studies ongoing about the allergy reactions related to this component added in processed foods, cosmetics, drugs, etc.

The first production of polyethylene glycol was in 1859 by A.V. Lourenco and Charles Adolphe Wurtz. At present, we can produce this substance by the interaction of ethylene glycol or ethylene glycol oligomers.

What is Propylene Glycol?

Propylene glycol is a viscous, colorless liquid, having the chemical formula CH3CH(OH)CH2OH. It is odorless but faintly sweet tasting. This substance contains two alcohol functional groups, so we can name it a diol. Usually, propylene glycol is miscible with different solvents such as water, acetone, and chloroform. Generally, these liquids are non-irritating but have very low volatility.

Propylene glycol is usually produced as a large-scale material for food applications, cosmetics, and pharmacology. Sometimes, we call this substance an alpha-propylene glycol to easily distinguish it from propane-1,3-diol.

We can prepare this compound in two ways: industrial production and laboratory production. Industrially, we can produce propylene glycol from propylene oxide. However, in the laboratory, the most common method for this production include fermentation methods.

There are many applications of propylene glycol: use of it as a feedstock for the production of polymers, as a component in some food items, as an anti-icing fluid, manufacture of electronic cigarettes, etc.

What is the Difference Between Polyethylene Glycol and Propylene Glycol?

Polyethylene glycol and propylene glycol are important organic compounds. Polyethylene glycol is a polymer compound derived from petroleum, and the structure can be expressed as H-(O-CH₂-CH₂)_n-OH, while propylene glycol is a viscous, colorless liquid having the chemical formula CH3CH(OH)CH2OH. The key difference between polyethylene glycol and propylene glycol is that polyethylene glycol is a polymer material, whereas propylene glycol is a single molecular compound that can be named a diol.

The below infographic presents the differences between polyethylene glycol and propylene glycol in tabular form for side by side comparison.

Summary – Polyethylene Glycol vs Propylene Glycol

Polyethylene glycol is a polymer compound derived from petroleum, and the structure can be expressed as H-(O-CH₂-CH₂)_n-OH. Propylene glycol is a viscous, colorless liquid, having the chemical formula CH3CH(OH)CH2OH. The key difference between polyethylene glycol and propylene glycol is that polyethylene glycol is a polymer material, whereas propylene glycol is a single molecular compound that can be named a diol.

Reference:

1. “Polyethylene Glycol 3350: MEDLINEPLUS Drug Information.” MedlinePlus, U.S. National Library of Medicine.

Image Courtesy:

1. “PEG Structural Formula V1” By Jü – Own work (Public Domain) via Commons Wikimedia
2. “Propylene glycol chemical structure” (CC BY-SA 3.0) via Commons Wikimedia