Glycerol Formula: Introduction, Structure, and Properties

Have you ever wondered what chemical compounds are present in soap and other personal care products or what makes soap slippery? Why is shaving cream so soft, smooth, and has a slippery texture? You must have noticed glycerine as one of the ingredients on the product labels. Glycerine is not only used for personal care but is also used for pharmaceutical purposes as well as in the food industry. In this article, we will learn more about the structure, properties, and applications of glycerol, also known as glycerine.

What is Glycerol?

Glycerol, also known as glycerin or glycerine, is a chemical compound that is a sweet-tasting viscous liquid that is generally nontoxic. When we say a substance is viscous, we mean that it is a liquid with a thick and sticky consistency. Glycerol has the formula \({{\rm{C}}_3}{{\rm{H}}_8}{{\rm{O}}_3}\). It consists of three carbon \(\left( {\rm{C}} \right)\) atoms, eight hydrogen \(\left( {\rm{H}} \right)\) atoms, and three oxygen \(\left( {\rm{O}} \right)\) atoms. Furthermore, glycerol’s \({\rm{IUPAC}}\) name is \(1,\,2,\,3\)- Trihydroxypropane or \(1,\,2,\,3\)- Propanetriol. Because every carbon atom in it has an \({\rm{s}}{{\rm{p}}^3}\) conformation, the molecule has rotation about all bonds.

Glycerol’s chemical structure illustrates that each carbon atom is bonded to a \({ – {\rm{OH}}}\) group. These \({ – {\rm{OH}}}\) groups are referred to as hydroxyl groups. As a result, glycerol is classified as a polyol, which is alcohol with multiple hydroxyl groups. Because of the hydroxyl \(\left( { – {\rm{OH}}} \right)\) groups attached to the carbon atoms, glycerol is water-soluble. These hydroxyl groups are also responsible for glycerol’s hygroscopic nature, which means that it readily retains or absorbs water.

Occurrence of Glycerol

Glycerol is typically obtained from plant and animal sources, where it can be found in triglycerides, which are glycerol esters with long-chain carboxylic acids. These triglycerides are hydrolyzed, saponified, or transesterified to produce glycerol as well as the fatty acid derivative.

Preparation of Glycerol

All fats contain glycerine as the backbone. It was originally produced during the saponification of animal fats. Glycerine is also a byproduct of biodiesel production. It is also derived petrochemically from propene. Furthermore, it can be produced through fermentation. If sulphite is added, the yeasts switch to glycerin production.

Properties of Glycerol

Glycerol is a clear, colourless, and very viscous liquid (similar to that of syrup). It has a density of \(1.261{\rm{ g}}/{\rm{ml}}\). It has a melting point of \({17.8^{\rm{o}}}{\rm{C}}\) and a boiling point of \({290^{\rm{o}}}{\rm{C}}\). These values show that glycerol is denser than water (because water has a density of \(1\,{\text{g}}/{\text{mL}}\)), has a higher boiling point than water (which has a boiling point of \({100^{\rm{o}}}{\rm{C}}\)), and has a higher melting point than water (water has a melting point of \({0^{\rm{o}}}{\rm{C}}\)). Glycerol dissolves easily in alcohol and water. It turns into white vapour when heated. If the reaction occurs during deoxygenation, it degrades to aldehyde acrolein, a toxic substance known as acrylaldehyde.

Uses of of Glycerol

There are many applications of glycerine. Some of them are discussed below:

• i. Food industry: Glycerol is used as a humectant, solvent, and sweetener in food and beverages, and it may help preserve foods. It is also used as a filler in low-fat commercially prepared foods (such as cookies) and a thickening agent in liqueurs. Certain types of plant leaves are preserved using glycerol and water.
• ii. Medical, pharmaceuticals, and personal care applications: Glycerol is commonly used in medical, pharmaceutical, and personal care preparations to improve smoothness, provide lubrication, and as a humectant. It is present in allergy immunotherapies, cough syrups, elixirs and expectorants, toothpaste, mouthwashes, skincare products, shaving cream, hair care products, soaps, and water-based personal lubricants. Glycerol is used as a tablet-holding agent in solid dosage forms such as tablets
• iii. Antifreeze: Due to the depression of thezing temperature, glycerol is a common component of solvents for enzymatic reagents stored at temperatures below \({0^{\rm{o}}}{\rm{C}}\) in the laboratory. It is also used as a cryoprotectant, in which glycerol is dissolved in water to protect laboratory organisms stored in frozen solutions, such as fungi, bacteria, nematodes, and mammalian embryos, from ice crystal damage.
• iv. Chemical intermediate: Because of the reliance on soap production to supply co-product glycerol, it was difficult to increase production to meet wartime demand. Glycerol was used to make nitroglycerin, which is a key component of explosives such as dynamite and gelignite and propellants such as cordite. 

Summary

The formula for glycerol, also known as glycerine, is \({{\rm{C}}_3}{{\rm{H}}_8}{{\rm{O}}_3}\). Glycerol is commonly found in the food industry and personal care products. It belongs to the alcohol group and contains three hydroxyl groups. It is also used in the manufacture of explosives, as antifreeze, and as one of the ingredients in the food industry. We also studied some of the physical and chemical properties of glycerol, and now we know that glycerol is a colourless and viscous liquid that is denser than water and has a high melting point than that of water.

FAQs on Glycerol

Q.1. Can we apply glycerol to our skin?
Ans: Yes, glycerol can be applied to the skin. Glycerin is a moisturising agent, which draws water from deeper layers of your skin and air into the outer layer of your skin. Glycerol is commonly used in skincare products with occlusives, another type of moisturising agent, to capture the moisture that is drawn into the skin.

Q.2. What foods have glycerol in them?
Ans: Glycerin can be found in pre-cooked pasta, rolled oats, breakfast cereals, rice or tapioca pudding, breading or batters, pre-cooked rice products, and baked goods. Glycerol is also present in processed fruits and vegetables (dried or canned vegetables or fruits, pre-cooked vegetables).

Q.3. Is it possible to make glycerol at home? Explain.
Ans: We can make glycerol at home. In a saucepan, combine one cup of coconut oil and one cup of olive oil. Maintain a low temperature and gradually add \(1\) teaspoon of lye and \(1\) cup of water. Heat the mixture for \(15\) minutes, constantly stirring, until it thickens. Allow the mixture to cool after adding \(1/2\) cup salt as the tracing reflects in the pan.

Q.4. Is glycerol a type of alcohol?
Ans: Glycerol is a simple trihydric alcohol that appears as a clear, odourless, viscous liquid with a sweet taste. It is also naturally hygroscopic.

Q.5. What is the difference between glycerol and glycerine?
Ans: The difference between glycerol and glycerin is that glycerol is a pure form, whereas glycerin contains \(95\) percent glycerol. Although they have the same chemical formula, they cannot be used interchangeably, especially when purity is desired.

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