Glycols

GLYCOLS

Glycols are alcohols that have two OH groups on them. The most important of these is ethylene glycol, which is 1,2-ethanediol, which goes by the simple formula of HOCH2CH2OH. Another common one is propylene glycol, which is 1,2-propanediol. In nature, the most common related compound is glycerol or glycerin, which is actually a trihydroxy alcohol with the IUPAC name of 1,2,3-propanetriol, having a hydroxyl group on all three carbon atoms. This is the molecule that fatty acids attach in order to make triglycerides.

Ethylene glycol is sweet but it is very toxic. Similar to methanol and ethanol, there are liver enzymes that contribute to its toxicity. It forms an oxalate ion with no hydrogen atoms whatsoever, which binds with calcium to form a calcium oxalate precipitate. This results in kidney failure and death. Propylene glycol is nontoxic—used in certain drugs and as a “food moisturizer”. It gets oxidized by liver enzymes to form “pyruvate”, which is an intermediary in cellular metabolism.