glycerin

Glycerin, also known as glycerol, is a simple polyol with the chemical formula C3H8O3 and the IUPAC name propane-1,2,3-triol. It is a colorless, odorless, and sweet-tasting liquid that is highly viscous and hygroscopic. It is miscible with water, ethanol, and acetone, and it has a boiling point around 290°C and a melting point near 17.8°C. Glycerin is chemically stable under normal conditions.

Natural occurrence and production

Glycerol occurs naturally as the backbone of triglycerides in fats and oils. Industrially, it is produced mainly as a byproduct of soap manufacture from fats and oils, or via catalytic processing of propylene oxide. It can also be obtained from other fat-derivative routes and, in some cases, from fermentation processes. In biochemistry, glycerol is central to metabolism as a three-carbon alcohol that can be phosphorylated to glycerol-3-phosphate.

Uses and applications

Glycerin serves as a versatile humectant, solvent, plasticizer, and sweetener. In the food industry it is used as a stabilizer and additive (often labeled as E422). In cosmetics and personal care, it functions as a moisturizer and solvent. In pharmaceuticals, it acts as a solvent and lubricant. It is also used as an osmotic laxative for medical purposes. Glycerol is a key precursor in the production of nitroglycerin, a compound historically important as an explosive and used in medicine as a vasodilator.

Safety and regulation

Glycerin is generally regarded as safe for use in regulated amounts in foods and consumer products. High oral doses can have a laxative effect and may cause dehydration. Skin contact may cause irritation in sensitive individuals. It is relatively non-toxic but should be handled with normal industrial hygiene and safety practices.