Glycidol is an organic compound with the formula HOCH2CHOCH2. The molecule contains both epoxide and alcohol functional groups. Being simple to make and bifunctional, it has a variety of industrial uses. The compound is a colorless, slightly viscous liquid that is slightly unstable and is not often encountered in pure form.

Synthesis and applications

Glycidol is prepared by the epoxidation of allyl alcohol. A typical catalyst is tungstic acid, and a typical O-atom source is aqueous peroxyacetic acid. Some useful products derived from glycidol are 2,3-epoxypropyloxy chloroformate (from phosgene) and glycidyl urethanes (by addition of isocyanates: Glycidol is used as a chemical intermediate in the synthesis of other glycidyl ethers, esters, and amines. Glycidol can be O-benzylated in the presence of strong base. More typically, such glycidol ethers are produced by reaction of epichlorohydrin with alkoxides. Glycidol is a precursor to diproqualone (by alkylation of 2-methylquinazolin-4(3H)-one) and dyphylline (by alkylation of theophylline).

Occurrence

Glycidyl fatty acid esters that are thought to contaminate some edible oils could be a source of traces of glycidol in the diet. These esters are formed during the deodorization step of edible oil refining, which uses vapor and high temperatures to remove impurities. The reaction conditions in that step can allow monoglyceride and diglycerides (MAG, DAG) naturally present in the oil to rearrange into glycidyl fatty acid esters.

Safety

Glycidol is an irritant of the skin, eyes, mucous membranes, and upper respiratory tract. Exposure to glycidol may also cause central nervous system depression, followed by central nervous system stimulation. It is listed as an IARC Group 2A Agent, meaning that it is "probably carcinogenic to humans". In regards to occupational exposures, the Occupational Safety and Health Administration has set a permissible exposure limit at 50 ppm over an eight-hour work shift, while the National Institute for Occupational Safety and Health recommends a limit at 25 ppm over an eight-hour work shift.