Glycidol

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.

References

References

1. ''Merck Index'', 11th Edition, '''4385'''
2. {{GESTIS
3. [[Food and Cosmetics Toxicology]]. Vol. 19, Pg. 347, 1981
4. {{PGCH. 0303
5. {{IDLH. 556525. Glycidol
6. (2001). "Encyclopedia of Reagents for Organic Synthesis".
7. Guenter Sienel, Robert Rieth, Kenneth T. Rowbottom "Epoxides" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. {{doi. 10.1002/14356007.a09_531
8. [http://www.chemicalland21.com/specialtychem/finechem/GLYCIDOL.htm Glycidol at chemicalland21.com]
9. Bruce H. Lipshutz, Robert Moretti, and Robert Crow. (1990). "Mixed Higher-Order Cyanocuprate-Induced Epoxide Openings: 1-Benzyloxy-4-Penten-2-Ol". Organic Syntheses.
10. (2015). "Glycerol Ether Synthesis: A Bench Test for Green Chemistry Concepts and Technologies". Chemical Reviews.
11. (2017). "Glycidyl Fatty Acid Esters in Refined Edible Oils: A Review on Formation, Occurrence, Analysis, and Elimination Methods". Comprehensive Reviews in Food Science and Food Safety.
12. "OSHA guidelines for glycidol".
13. . (July 7, 2019). ["List of Classifications, Agents classified by the IARC Monographs, Volumes 1–124"](https://monographs.iarc.fr/list-of-classifications). *IARC*.
14. [https://www.cdc.gov/niosh/npg/npgd0303.html CDC - NIOSH Pocket Guide to Chemical Hazards]