Glycerols

Glycerol, also known as glycerin, is a simple polyol with the chemical formula C3H8O3. The term glycerols can be used to refer to glycerol molecules in general and to related glyceride derivatives such as mono-, di-, and triacylglycerols.

Glycerol is a colorless, odorless, viscous liquid that is highly hygroscopic and miscible with water and many organic solvents. It has a high boiling point (about 290°C) and a melting point near 18°C, so it is liquid at room temperature but can solidify under cooler conditions.

It occurs naturally in lipids in plants and animals and is produced commercially as a byproduct of biodiesel production from fats and oils through transesterification, as well as by hydrolysis of fats. Refined glycerol is obtained by purification of crude glycerol.

Uses include use as a humectant, solvent, sweetener, and plasticizer in foods, cosmetics, and pharmaceuticals. In industry it serves as a versatile chemical intermediate for the production of esters, glycols, glycerol derivatives, and polymers. It is also used as a solvent for tinctures and as an antifreeze and moisture-retaining agent.

Biologically, glycerol is an intermediate in energy metabolism. Glycerol released from triglycerides is phosphorylated to glycerol-3-phosphate by glycerol kinase and oxidized to dihydroxyacetone phosphate, which enters glycolysis or gluconeogenesis.

Regulatory agencies commonly classify glycerol as generally recognized as safe (GRAS) for many applications. It is considered low-toxicity, but ingesting large amounts can act as a laxative and excessive exposure can have osmotic effects.